Apparent magnitude

<h2 id="history">History</h2>

<table><tbody><tr><th>Visible totypicalhumaneye<a class="footnote-ref" id="fnref:5" href="#fn:5">5</a></th><th>Apparentmagnitude</th><th>Bright-nessrelativeto <a href="/facts/Vega/G3wJwhhl">Vega</a></th><th>Number of stars (other than the <a href="/facts/Sun/CadPCVHh">Sun</a>) brighter thanapparent magnitude<a class="footnote-ref" id="fnref:6" href="#fn:6">6</a>in the night sky</th></tr><tr><td rowspan="9">Yes</td><td>−1.0</td><td>251%</td><td>1 (<a href="/facts/Sirius/sHCkClse">Sirius</a>)</td></tr><tr><td>00.0</td><td>100%</td><td>5(<a href="/facts/Vega/G3wJwhhl">Vega</a>, <a href="/facts/Canopus/zD5WcDy5">Canopus</a>, <a href="/facts/Alpha_Centauri/6BlySfIj">Alpha Centauri</a>,<a href="/facts/Arcturus/8W0qslPJ">Arcturus</a>)</td></tr><tr><td>01.0</td><td>40%</td><td>15</td></tr><tr><td>02.0</td><td>16%</td><td>48</td></tr><tr><td>03.0</td><td>6.3%</td><td>171</td></tr><tr><td>04.0</td><td>2.5%</td><td>513</td></tr><tr><td>05.0</td><td>1.0%</td><td>1602</td></tr><tr><td>06.0</td><td>0.4%</td><td>4800</td></tr><tr><td>06.5</td><td>0.25%</td><td>9100<a class="footnote-ref" id="fnref:7" href="#fn:7">7</a></td></tr><tr><td rowspan="4">No</td><td>07.0</td><td>0.16%</td><td>14000</td></tr><tr><td>08.0</td><td>0.063%</td><td>42000</td></tr><tr><td>09.0</td><td>0.025%</td><td>121000</td></tr><tr><td>10.0</td><td>0.010%</td><td>340000</td></tr></tbody></table>
The scale used to indicate magnitude originates in the <a href="/facts/Hellenistic_Greece/45ye3dGC">Hellenistic</a> practice of dividing stars visible to the naked eye into six magnitudes. The <a href="/facts/List_of_brightest_stars/0vDnLEYM">brightest stars</a> in the night sky were said to be of <a href="/facts/First_magnitude_star/how71YFQ">first magnitude</a> (m = 1), whereas the faintest were of sixth magnitude (m = 6), which is the limit of <a href="/facts/Human/rlcTENsr">human</a> <a href="/facts/Visual_perception/g7Tfaq2l">visual perception</a> (without the aid of a <a href="/facts/Telescope/BDwYahhR">telescope</a>). Each grade of magnitude was considered twice the brightness of the following grade (a <a href="/facts/Logarithmic_scale/CvIGK5TQ">logarithmic scale</a>), although that ratio was subjective as no <a href="/facts/Photodetector/7cSkXS6s">photodetectors</a> existed. This rather crude scale for the brightness of stars was popularized by <a href="/facts/Ptolemy/htudGQTQ">Ptolemy</a> in his <a href="/facts/Almagest/30qaBRAq">Almagest</a> and is generally believed to have originated with <a href="/facts/Hipparchus/pHld5PfE">Hipparchus</a>. This cannot be proved or disproved because Hipparchus's original star catalogue is lost. The only preserved text by Hipparchus himself (a commentary to Aratus) clearly documents that he did not have a system to describe brightness with numbers: He always uses terms like "big" or "small", "bright" or "faint" or even descriptions such as "visible at full moon".<a class="footnote-ref" id="fnref:8" href="#fn:8">8</a>
In 1856, <a href="/facts/Norman_Robert_Pogson/R7B0yo3C">Norman Robert Pogson</a> formalized the system by defining a first magnitude star as a star that is 100 times as bright as a sixth-magnitude star, thereby establishing the logarithmic scale still in use today. This implies that a star of magnitude m is about 2.512 times as bright as a star of magnitude m + 1. This figure, the <a href="/facts/Generalized_continued_fraction/kbj3glnP">fifth root of 100</a>, became known as Pogson's Ratio.<a class="footnote-ref" id="fnref:9" href="#fn:9">9</a> The 1884 Harvard Photometry and 1886 Potsdamer Durchmusterung star catalogs popularized Pogson's ratio, and eventually it became a de facto standard in modern astronomy to describe differences in brightness.<a class="footnote-ref" id="fnref:10" href="#fn:10">10</a>
Defining and calibrating what magnitude 0.0 means is difficult, and different types of measurements which detect different kinds of light (possibly by using filters) have different zero points. Pogson's original 1856 paper defined magnitude 6.0 to be the faintest star the unaided eye can see,<a class="footnote-ref" id="fnref:11" href="#fn:11">11</a> but the true limit for faintest possible visible star varies depending on the atmosphere and how high a star is in the sky. The Harvard Photometry used an average of 100 stars close to Polaris to define magnitude 5.0.<a class="footnote-ref" id="fnref:12" href="#fn:12">12</a> Later, the Johnson UVB photometric system defined multiple types of photometric measurements with different filters, where magnitude 0.0 for each filter is defined to be the average of six stars with the same spectral type as Vega. This was done so the <a href="/facts/Color_index/0SVRKKk0">color index</a> of these stars would be 0.<a class="footnote-ref" id="fnref:13" href="#fn:13">13</a> Although this system is often called "Vega normalized", Vega is slightly dimmer than the six-star average used to define magnitude 0.0, meaning Vega's magnitude is normalized to 0.03 by definition.

Limiting Magnitudes for Visual Observation at High Magnification<a class="footnote-ref" id="fnref:14" href="#fn:14">14</a><table><tbody><tr><th>Telescopeaperture(mm)</th><th>LimitingMagnitude</th></tr><tr><td>35</td><td>11.3</td></tr><tr><td>60</td><td>12.3</td></tr><tr><td>102</td><td>13.3</td></tr><tr><td>152</td><td>14.1</td></tr><tr><td>203</td><td>14.7</td></tr><tr><td>305</td><td>15.4</td></tr><tr><td>406</td><td>15.7</td></tr><tr><td>508</td><td>16.4</td></tr></tbody></table>
With the modern magnitude systems, brightness is described using Pogson's ratio. In practice, magnitude numbers rarely go above 30 before stars become too faint to detect. While Vega is close to magnitude 0, there are four brighter stars in the night sky at visible wavelengths (and more at infrared wavelengths) as well as the bright planets Venus, Mars, and Jupiter, and since brighter means smaller magnitude, these must be described by negative magnitudes. For example, <a href="/facts/Sirius/sHCkClse">Sirius</a>, the brightest star of the <a href="/facts/Celestial_sphere/TYAtXgor">celestial sphere</a>, has a magnitude of −1.4 in the visible. Negative magnitudes for other very bright astronomical objects can be found in the table below.
Astronomers have developed other photometric zero point systems as alternatives to Vega normalized systems. The most widely used is the <a href="/facts/AB_magnitude/9BSyI5cK">AB magnitude</a> system,<a class="footnote-ref" id="fnref:15" href="#fn:15">15</a> in which photometric zero points are based on a hypothetical reference spectrum having constant <a href="/facts/Spectral_flux_density/anI2uoGS">flux per unit frequency interval</a>, rather than using a stellar spectrum or blackbody curve as the reference. The AB magnitude zero point is defined such that an object's AB and Vega-based magnitudes will be approximately equal in the V filter band. However, the AB magnitude system is defined assuming an idealized detector measuring only one wavelength of light, while real detectors accept energy from a range of wavelengths.

<h2 id="measurement">Measurement</h2>
Main article: <a href="/facts/Photometry_(astronomy)/fnV9JdSa">Photometry (astronomy)</a>
Precision measurement of magnitude (photometry) requires calibration of the photographic or (usually) electronic detection apparatus. This generally involves contemporaneous observation, under identical conditions, of standard stars whose magnitude using that spectral filter is accurately known. Moreover, as the amount of light actually received by a telescope is reduced due to transmission through the <a href="/facts/Earth%2527s_atmosphere/FV97Am25">Earth's atmosphere</a>, the <a href="/facts/Airmass/EFw2A0sa">airmasses</a> of the target and <a href="/facts/Calibration_stars/b1goFfwJ">calibration stars</a> must be taken into account. Typically one would observe a few different stars of known magnitude which are sufficiently similar. Calibrator stars close in the sky to the target are favoured (to avoid large differences in the atmospheric paths). If those stars have somewhat different <a href="/facts/Zenith_angle/tcm21e6t">zenith angles</a> (<a href="/facts/Horizontal_coordinate_system/msJQPYg0">altitudes</a>) then a correction factor as a function of airmass can be derived and <a href="/facts/Photometry_(astronomy)/fnV9JdSa">applied</a> to the airmass at the target's position. Such calibration obtains the brightness as would be observed from above the atmosphere, where apparent magnitude is defined.
The apparent magnitude scale in astronomy reflects the received power of stars and not their amplitude. Newcomers should consider using the relative brightness measure in astrophotography to adjust exposure times between stars. Apparent magnitude also integrates over the entire object, regardless of its focus, and this needs to be taken into account when scaling exposure times for objects with significant apparent size, like the Sun, Moon and planets. For example, directly scaling the exposure time from the Moon to the Sun works because they are approximately the same size in the sky. However, scaling the exposure from the Moon to Saturn would result in an overexposure if the image of Saturn takes up a smaller area on your sensor than the Moon did (at the same magnification, or more generally, f/#).

<h2 id="calculations">Calculations</h2>

The dimmer an object appears, the higher the numerical value given to its magnitude, with a difference of 5 magnitudes corresponding to a brightness factor of exactly 100. Therefore, the magnitude m, in the <a href="/facts/Photometric_system/7tUmLBGR">spectral band</a> x, would be given by

m
          
            x
          
        
        =
        −
        5
        
          log
          
            100
          
        
        ⁡
        
          (
          
            
              
                F
                
                  x
                
              
              
                F
                
                  x
                  ,
                  0
                
              
            
          
          )
        
        ,
      
    
    {\displaystyle m_{x}=-5\log _{100}\left({\frac {F_{x}}{F_{x,0}}}\right),}

which is more commonly expressed in terms of <a href="/facts/Common_logarithm/q6EhDnWk">common (base-10) logarithms</a> as

m
          
            x
          
        
        =
        −
        2.5
        
          log
          
            10
          
        
        ⁡
        
          (
          
            
              
                F
                
                  x
                
              
              
                F
                
                  x
                  ,
                  0
                
              
            
          
          )
        
        ,
      
    
    {\displaystyle m_{x}=-2.5\log _{10}\left({\frac {F_{x}}{F_{x,0}}}\right),}

where Fx is the observed <a href="/facts/Irradiance/fgHwu7uh">irradiance</a> using spectral filter x, and Fx,0 is the reference flux (zero-point) for that <a href="/facts/Photometric_system/7tUmLBGR">photometric filter</a>. Since an increase of 5 magnitudes corresponds to a decrease in brightness by a factor of exactly 100, each magnitude increase implies a decrease in brightness by the factor 
 
 
 
 
 
 100
 
 5
 
 
 
 ≈
 2.512
 
 
 {\displaystyle {\sqrt[{5}]{100}}\approx 2.512}
 
 (Pogson's ratio). Inverting the above formula, a magnitude difference m1 − m2 = Δm implies a brightness factor of

F
              
                2
              
            
            
              F
              
                1
              
            
          
        
        =
        
          100
          
            
              
                Δ
                m
              
              5
            
          
        
        =
        
          10
          
            0.4
            Δ
            m
          
        
        ≈
        
          2.512
          
            Δ
            m
          
        
        .
      
    
    {\displaystyle {\frac {F_{2}}{F_{1}}}=100^{\frac {\Delta m}{5}}=10^{0.4\Delta m}\approx 2.512^{\Delta m}.}

<h3>Example: Sun and Moon</h3>
What is the ratio in brightness between the <a href="/facts/Sun/CadPCVHh">Sun</a> and the full <a href="/facts/Moon/zKHqEMPb">Moon</a>?
The apparent magnitude of the Sun is −26.832<a class="footnote-ref" id="fnref:16" href="#fn:16">16</a> (brighter), and the mean magnitude of the <a href="/facts/Full_moon/NRMWFPh2">full moon</a> is −12.74<a class="footnote-ref" id="fnref:17" href="#fn:17">17</a> (dimmer).
Difference in magnitude:

x
        =
        
          m
          
            1
          
        
        −
        
          m
          
            2
          
        
        =
        (
        −
        12.74
        )
        −
        (
        −
        26.832
        )
        =
        14.09.
      
    
    {\displaystyle x=m_{1}-m_{2}=(-12.74)-(-26.832)=14.09.}

Brightness factor:

v
          
            b
          
        
        =
        
          10
          
            0.4
            x
          
        
        =
        
          10
          
            0.4
            ×
            14.09
          
        
        ≈
        432
        
        513.
      
    
    {\displaystyle v_{b}=10^{0.4x}=10^{0.4\times 14.09}\approx 432\,513.}

The Sun appears to be approximately 400000 times as bright as the full Moon.

<h3>Magnitude addition</h3>
Sometimes one might wish to add brightness. For example, <a href="/facts/Photometry_(astronomy)/fnV9JdSa">photometry</a> on closely separated <a href="/facts/Double_star/FLXY1tD1">double stars</a> may only be able to produce a measurement of their combined light output. To find the combined magnitude of that double star knowing only the magnitudes of the individual components, this can be done by adding the brightness (in linear units) corresponding to each magnitude.<a class="footnote-ref" id="fnref:18" href="#fn:18">18</a>

10
          
            −
            
              m
              
                f
              
            
            ×
            0.4
          
        
        =
        
          10
          
            −
            
              m
              
                1
              
            
            ×
            0.4
          
        
        +
        
          10
          
            −
            
              m
              
                2
              
            
            ×
            0.4
          
        
        .
      
    
    {\displaystyle 10^{-m_{f}\times 0.4}=10^{-m_{1}\times 0.4}+10^{-m_{2}\times 0.4}.}

Solving for 
 
 
 
 
 m
 
 f
 
 
 
 
 {\displaystyle m_{f}}
 
 yields

m
          
            f
          
        
        =
        −
        2.5
        
          log
          
            10
          
        
        ⁡
        
          (
          
            
              10
              
                −
                
                  m
                  
                    1
                  
                
                ×
                0.4
              
            
            +
            
              10
              
                −
                
                  m
                  
                    2
                  
                
                ×
                0.4
              
            
          
          )
        
        ,
      
    
    {\displaystyle m_{f}=-2.5\log _{10}\left(10^{-m_{1}\times 0.4}+10^{-m_{2}\times 0.4}\right),}

where mf is the resulting magnitude after adding the brightnesses referred to by m1 and m2.

<h3>Apparent bolometric magnitude</h3>
While magnitude generally refers to a measurement in a particular filter band corresponding to some range of wavelengths, the apparent or absolute bolometric magnitude (mbol) is a measure of an object's apparent or absolute brightness integrated over all wavelengths of the electromagnetic spectrum (also known as the object's <a href="/facts/Irradiance/fgHwu7uh">irradiance</a> or power, respectively). The zero point of the apparent bolometric magnitude scale is based on the definition that an apparent bolometric magnitude of 0 mag is equivalent to a received irradiance of 2.518×10−8 <a href="/facts/Watt/VK8oqRrm">watts</a> per square metre (W·m−2).<a class="footnote-ref" id="fnref:19" href="#fn:19">19</a>

<h3>Absolute magnitude</h3>
Main article: <a href="/facts/Absolute_magnitude/R8RVxkLx">Absolute magnitude</a>
While apparent magnitude is a measure of the brightness of an object as seen by a particular observer, absolute magnitude is a measure of the intrinsic brightness of an object. Flux decreases with distance according to an <a href="/facts/Inverse-square_law/DxG4T15l">inverse-square law</a>, so the apparent magnitude of a star depends on both its absolute brightness and its distance (and any extinction). For example, a star at one distance will have the same apparent magnitude as a star four times as bright at twice that distance. In contrast, the intrinsic brightness of an astronomical object, does not depend on the distance of the observer or any <a href="/facts/Extinction_(astronomy)/rLNLDfe1">extinction</a>.<a class="footnote-ref" id="fnref:20" href="#fn:20">20</a>
The absolute magnitude M, of a star or astronomical object is defined as the apparent magnitude it would have as seen from a distance of 10 parsecs (33 <a href="/facts/Light-year/IGc5NdQb">ly</a>). The absolute magnitude of the Sun is 4.83 in the V band (visual), 4.68 in the <a href="/facts/Gaia_(spacecraft)/dlvcdkoN">Gaia satellite's</a> G band (green) and 5.48 in the B band (blue).<a class="footnote-ref" id="fnref:21" href="#fn:21">21</a><a class="footnote-ref" id="fnref:22" href="#fn:22">22</a><a class="footnote-ref" id="fnref:23" href="#fn:23">23</a>
In the case of a planet or asteroid, the absolute magnitude H rather means the apparent magnitude it would have if it were 1 <a href="/facts/Astronomical_unit/gjsbu5xU">astronomical unit</a> (150,000,000 km) from both the observer and the Sun, and fully illuminated at maximum opposition (a configuration that is only theoretically achievable, with the observer situated on the surface of the Sun).<a class="footnote-ref" id="fnref:24" href="#fn:24">24</a>

<h2 id="standard-reference-values">Standard reference values</h2>
Standard apparent magnitudes and fluxes for typical bands<a class="footnote-ref" id="fnref:25" href="#fn:25">25</a><table><tbody><tr><th rowspan="2">Band</th><th rowspan="2">λ(μm)</th><th rowspan="2">⁠Δλ/λ⁠(<a href="/facts/Full_width_at_half_maximum/oXSLXf7S">FWHM</a>)</th><th colspan="2">Flux at m = 0, Fx,0</th></tr><tr><th><a href="/facts/Jansky/8m8DQU5F">Jy</a></th><th>10−20 erg/(s·cm2·Hz)</th></tr><tr><td>U</td><td>0.36</td><td>0.15</td><td>1810</td><td>1.81</td></tr><tr><td>B</td><td>0.44</td><td>0.22</td><td>4260</td><td>4.26</td></tr><tr><td>V</td><td>0.55</td><td>0.16</td><td>3640</td><td>3.64</td></tr><tr><td>R</td><td>0.64</td><td>0.23</td><td>3080</td><td>3.08</td></tr><tr><td>I</td><td>0.79</td><td>0.19</td><td>2550</td><td>2.55</td></tr><tr><td>J</td><td>1.26</td><td>0.16</td><td>1600</td><td>1.60</td></tr><tr><td>H</td><td>1.60</td><td>0.23</td><td>1080</td><td>1.08</td></tr><tr><td>K</td><td>2.22</td><td>0.23</td><td>0670</td><td>0.67</td></tr><tr><td>L</td><td>3.50</td><td></td><td></td><td></td></tr><tr><td>g</td><td>0.52</td><td>0.14</td><td>3730</td><td>3.73</td></tr><tr><td>r</td><td>0.67</td><td>0.14</td><td>4490</td><td>4.49</td></tr><tr><td>i</td><td>0.79</td><td>0.16</td><td>4760</td><td>4.76</td></tr><tr><td>z</td><td>0.91</td><td>0.13</td><td>4810</td><td>4.81</td></tr></tbody></table>
The magnitude scale is a reverse logarithmic scale. A common misconception is that the logarithmic nature of the scale is because the <a href="/facts/Human_eye/a24ua4fy">human eye</a> itself has a logarithmic response. In Pogson's time this was thought to be true (see <a href="/facts/Weber%25E2%2580%2593Fechner_law/K2dNPlbW">Weber–Fechner law</a>), but it is now believed that the response is a <a href="/facts/Power_law/DhAjYwwz">power law</a> (see <a href="/facts/Stevens%2527_power_law/Ut9MBQzr">Stevens' power law</a>).<a class="footnote-ref" id="fnref:26" href="#fn:26">26</a>
Magnitude is complicated by the fact that light is not <a href="/facts/Monochromatic/CMCsjH2N">monochromatic</a>. The sensitivity of a light detector varies according to the wavelength of the light, and the way it varies depends on the type of light detector. For this reason, it is necessary to specify how the magnitude is measured for the value to be meaningful. For this purpose the <a href="/facts/UBV_system/eoJL34eN">UBV system</a> is widely used, in which the magnitude is measured in three different wavelength bands: U (centred at about 350 nm, in the near <a href="/facts/Ultraviolet/kncBUqn5">ultraviolet</a>), B (about 435 nm, in the blue region) and V (about 555 nm, in the middle of the human visual range in daylight). The V band was chosen for spectral purposes and gives magnitudes closely corresponding to those seen by the human eye. When an apparent magnitude is discussed without further qualification, the V magnitude is generally understood.<a class="footnote-ref" id="fnref:27" href="#fn:27">27</a>
Because cooler stars, such as <a href="/facts/Red_giant/lla6Bsvy">red giants</a> and <a href="/facts/Red_dwarf/56CMQcF0">red dwarfs</a>, emit little energy in the blue and UV regions of the spectrum, their power is often under-represented by the UBV scale. Indeed, some <a href="/facts/Stellar_classification/dYrIuK9H">L and T class</a> stars have an estimated magnitude of well over 100, because they emit extremely little visible light, but are strongest in <a href="/facts/Infrared/44XdJNcc">infrared</a>.<a class="footnote-ref" id="fnref:28" href="#fn:28">28</a>
Measures of magnitude need cautious treatment and it is extremely important to measure like with like. On early 20th century and older orthochromatic (blue-sensitive) <a href="/facts/Photographic_film/37aFq6ls">photographic film</a>, the relative brightnesses of the blue <a href="/facts/Supergiant/y7w8WEcm">supergiant</a> <a href="/facts/Rigel/WeeIXAAv">Rigel</a> and the red supergiant <a href="/facts/Betelgeuse/BsD9Ap7C">Betelgeuse</a> irregular variable star (at maximum) are reversed compared to what human eyes perceive, because this archaic film is more sensitive to blue light than it is to red light. Magnitudes obtained from this method are known as <a href="/facts/Photographic_magnitude/oJCVD4gd">photographic magnitudes</a>, and are now considered obsolete.<a class="footnote-ref" id="fnref:29" href="#fn:29">29</a>
For objects within the <a href="/facts/Milky_Way/ulF6lccN">Milky Way</a> with a given absolute magnitude, 5 is added to the apparent magnitude for every tenfold increase in the distance to the object. For objects at very great distances (far beyond the Milky Way), this relationship must be <a href="/facts/K_correction/PW9GgT05">adjusted for redshifts</a> and for <a href="/facts/Non-Euclidean_geometry/efKa7De2">non-Euclidean</a> distance measures due to <a href="/facts/General_relativity/jVsoIg8X">general relativity</a>.<a class="footnote-ref" id="fnref:30" href="#fn:30">30</a><a class="footnote-ref" id="fnref:31" href="#fn:31">31</a>
For planets and other Solar System bodies, the apparent magnitude is derived from its <a href="/facts/Phase_curve_(astronomy)/uGAEx4tY">phase curve</a> and the distances to the Sun and observer.<a class="footnote-ref" id="fnref:32" href="#fn:32">32</a>

<h2 id="list-of-apparent-magnitudes">List of apparent magnitudes</h2>

See also: <a href="/facts/List_of_brightest_stars/0vDnLEYM">List of brightest stars</a>
Some of the listed magnitudes are approximate. Telescope sensitivity depends on observing time, optical bandpass, and interfering light from <a href="/facts/Rayleigh_scattering/o0MQtPMM">scattering</a> and <a href="/facts/Airglow/9yMhcjB4">airglow</a>.

Apparent visual magnitudes of celestial objects<table><tbody><tr><th>Apparentmagnitude(V)</th><th>Object</th><th>Seen from...</th><th>Notes</th></tr><tr><td>−67.57</td><td><a href="/facts/Gamma-ray_burst/oRRU6Fhn">gamma-ray burst</a> <a href="/facts/GRB_080319B/7XcLcly2">GRB 080319B</a></td><td>seen from 1 <a href="/facts/Astronomical_unit/gjsbu5xU">AU</a> away</td><td>would be over 2×1016 (20 quadrillion) times as bright as the Sun when seen from the Earth</td></tr><tr><td>−43.27</td><td>star NGC 2403 V14</td><td>seen from 1 AU away</td><td></td></tr><tr><td>−41.82</td><td>star <a href="/facts/NGC_2363-V1/JRoTfNCr">NGC 2363-V1</a></td><td>seen from 1 AU away</td><td></td></tr><tr><td>−41.39</td><td>star <a href="/facts/Cygnus_OB2-12/uj3bCPWS">Cygnus OB2-12</a></td><td>seen from 1 AU away</td><td></td></tr><tr><td>−40.67</td><td>star <a href="/facts/M33-013406.63/eQdE0YRS">M33-013406.63</a></td><td>seen from 1 AU away</td><td></td></tr><tr><td>−40.17</td><td>star <a href="/facts/Eta_Carinae/zsrmE2Lo">η Carinae</a> A</td><td>seen from 1 AU away</td><td></td></tr><tr><td>−40.07</td><td>star <a href="/facts/Zeta1_Scorpii/EyqzR0pH">Zeta1 Scorpii</a></td><td>seen from 1 AU away</td><td></td></tr><tr><td>−39.66</td><td>star <a href="/facts/R136a1/4kMEN0aX">R136a1</a></td><td>seen from 1 AU away</td><td></td></tr><tr><td>−39.47</td><td>star <a href="/facts/P_Cygni/2DX0AFCD">P Cygni</a></td><td>seen from 1 AU away</td><td></td></tr><tr><td>−38.00</td><td>star <a href="/facts/Rigel/WeeIXAAv">Rigel</a></td><td>seen from 1 AU away</td><td>would be seen as a large, very bright bluish disk of 35° apparent diameter</td></tr><tr><td>−37.42</td><td>star <a href="/facts/Betelgeuse/BsD9Ap7C">Betelgeuse</a></td><td>seen from 1 AU away</td><td></td></tr><tr><td>−30.30</td><td>star <a href="/facts/Sirius/sHCkClse">Sirius</a> A</td><td>seen from 1 AU away</td><td></td></tr><tr><td>−29.30</td><td>star <a href="/facts/Sun/CadPCVHh">Sun</a></td><td>seen from <a href="/facts/Mercury_(planet)/lVa1GIyX">Mercury</a> at <a href="/facts/Perihelion/VaL6ow9w">perihelion</a></td><td></td></tr><tr><td>−27.40</td><td>star Sun</td><td>seen from <a href="/facts/Venus/pADnueP6">Venus</a> at perihelion</td><td></td></tr><tr><td>−26.83</td><td>star Sun</td><td>seen from <a href="/facts/Earth/HLLmDfj0">Earth</a><a class="footnote-ref" id="fnref:33" href="#fn:33">33</a></td><td>about 400,000 times as bright as mean full Moon</td></tr><tr><td>−25.60</td><td>star Sun</td><td>seen from <a href="/facts/Mars/AQGtVvz0">Mars</a> at <a href="/facts/Aphelion/VaL6ow9w">aphelion</a></td><td></td></tr><tr><td>−25</td><td colspan="3">Minimum brightness that causes the typical eye slight pain to look at</td></tr><tr><td>−23.00</td><td>star Sun</td><td>seen from <a href="/facts/Jupiter/95m7XjMT">Jupiter</a> at aphelion</td><td></td></tr><tr><td>−21.70</td><td>star Sun</td><td>seen from <a href="/facts/Saturn/D54LcGJ9">Saturn</a> at aphelion</td><td></td></tr><tr><td>−21.00</td><td>star Sun</td><td>seen from Earth on an overcast midday</td><td>measuring about 1000 lux</td></tr><tr><td>−20.20</td><td>star Sun</td><td>seen from <a href="/facts/Uranus/x7YwT1ar">Uranus</a> at aphelion</td><td></td></tr><tr><td>−19.30</td><td>star Sun</td><td>seen from <a href="/facts/Neptune/1eucwHIC">Neptune</a></td><td></td></tr><tr><td>−19.00</td><td>star Sun</td><td>seen from Earth on a very strongly overcast midday</td><td>measuring about 100 lux</td></tr><tr><td>−18.20</td><td>star Sun</td><td>seen from <a href="/facts/Pluto/egq7MBeR">Pluto</a> at aphelion</td><td></td></tr><tr><td>−17.70</td><td>planet Earth</td><td>seen fully illuminated as <a href="/facts/Earthlight_(astronomy)/VJCNGllv">earthlight</a> from the <a href="/facts/Moon/zKHqEMPb">Moon</a><a class="footnote-ref" id="fnref:34" href="#fn:34">34</a></td><td></td></tr><tr><td>−16.70</td><td>star Sun</td><td>seen from <a href="/facts/Eris_(dwarf_planet)/vuaR65F7">Eris</a> at aphelion</td><td></td></tr><tr><td>−16.00</td><td>star Sun</td><td>as <a href="/facts/Twilight/hNUKeCT8">twilight</a> on Earth</td><td>measuring about 10 lux<a class="footnote-ref" id="fnref:35" href="#fn:35">35</a></td></tr><tr><td>−14.2</td><td colspan="3">An illumination level of 1 <a href="/facts/Lux/xa3AAqWd">lux</a><a class="footnote-ref" id="fnref:36" href="#fn:36">36</a><a class="footnote-ref" id="fnref:37" href="#fn:37">37</a></td></tr><tr><td>−12.60</td><td><a href="/facts/Full_moon/NRMWFPh2">full moon</a></td><td>seen from Earth at perihelion</td><td>maximum brightness of perigee + perihelion + full Moon (~0.267 lux; mean distance value is −12.74,<a class="footnote-ref" id="fnref:38" href="#fn:38">38</a> though values are about 0.18 magnitude brighter when including the <a href="/facts/Opposition_surge/AGmGzU4C">opposition effect</a>)</td></tr><tr><td>−12.40</td><td><a href="/facts/Betelgeuse/BsD9Ap7C">Betelgeuse</a> (when supernova)</td><td>seen from Earth when it goes supernova<a class="footnote-ref" id="fnref:39" href="#fn:39">39</a></td><td></td></tr><tr><td>−11.20</td><td>star Sun</td><td>seen from <a href="/facts/90377_Sedna/6aXuaYoM">Sedna</a> at aphelion</td><td></td></tr><tr><td>−10.00</td><td>Comet <a href="/facts/Comet_Ikeya%25E2%2580%2593Seki/VEAQohoq">Ikeya–Seki</a> (1965)</td><td>seen from Earth</td><td>which was the brightest <a href="/facts/Kreutz_Sungrazer/DS5MAJ9l">Kreutz Sungrazer</a> of modern times<a class="footnote-ref" id="fnref:40" href="#fn:40">40</a></td></tr><tr><td>−9.50</td><td><a href="/facts/Iridium_flare/w5ug87En">Iridium (satellite) flare</a></td><td>seen from Earth</td><td>maximum brightness</td></tr><tr><td>−9 to −10</td><td><a href="/facts/Phobos_(moon)/qqS9JvuG">Phobos (moon)</a></td><td>seen from Mars</td><td>maximum brightness</td></tr><tr><td>−7.50</td><td><a href="/facts/SN_1006/jus9wu5p">supernova of 1006</a></td><td>seen from Earth</td><td>the brightest stellar event in recorded history (7200 light-years away)<a class="footnote-ref" id="fnref:41" href="#fn:41">41</a></td></tr><tr><td>−6.80</td><td><a href="/facts/Alpha_Centauri_A/6BlySfIj">Alpha Centauri A</a></td><td>seen from <a href="/facts/Proxima_Centauri_b/k6nG5yrG">Proxima Centauri b</a></td><td><a class="footnote-ref" id="fnref:42" href="#fn:42">42</a></td></tr><tr><td>−6.00</td><td>The total <a href="/facts/Integrated_magnitude/xN0jmKkw">integrated magnitude</a> of the <a href="/facts/Night_sky/IM1PakDh">night sky</a> (incl. <a href="/facts/Airglow/9yMhcjB4">airglow</a>)</td><td>seen from Earth</td><td>measuring about 0.002 lux</td></tr><tr><td>−6.00</td><td><a href="/facts/SN_1054/bJhHbu4S">Crab Supernova of 1054</a></td><td>seen from Earth</td><td>(6500 light-years away)<a class="footnote-ref" id="fnref:43" href="#fn:43">43</a></td></tr><tr><td>−5.90</td><td><a href="/facts/International_Space_Station/VNPUBz9m">International Space Station</a></td><td>seen from Earth</td><td>when the ISS is at its <a href="/facts/Perigee/VaL6ow9w">perigee</a> and fully lit by the Sun<a class="footnote-ref" id="fnref:44" href="#fn:44">44</a></td></tr><tr><td>−4.92</td><td>planet Venus</td><td>seen from Earth</td><td>maximum brightness<a class="footnote-ref" id="fnref:45" href="#fn:45">45</a> when illuminated as a crescent</td></tr><tr><td>−4.14</td><td>planet Venus</td><td>seen from Earth</td><td>mean brightness<a class="footnote-ref" id="fnref:46" href="#fn:46">46</a></td></tr><tr><td>−4</td><td colspan="3">Faintest objects observable during the day with naked eye when Sun is high. An astronomical object casts human-visible shadows when its apparent magnitude is equal to or lower than −4 <a class="footnote-ref" id="fnref:47" href="#fn:47">47</a></td></tr><tr><td>−3.99</td><td>star <a href="/facts/Epsilon_Canis_Majoris/gE97FrYP">Epsilon Canis Majoris</a></td><td>seen from Earth</td><td>maximum brightness of 4.7 million years ago, the historical <a href="/facts/List_of_brightest_stars/0vDnLEYM">brightest star</a> of the <a href="/facts/Historical_brightest_stars/59KsexKU">last and next five million years</a>.<a class="footnote-ref" id="fnref:48" href="#fn:48">48</a></td></tr><tr><td>−3.69</td><td>Moon</td><td>lit by earthlight, reflecting <a href="/facts/Earthshine/VJCNGllv">earthshine</a> seen from Earth (maximum)<a class="footnote-ref" id="fnref:49" href="#fn:49">49</a></td><td></td></tr><tr><td>−2.98</td><td>planet Venus</td><td>seen from Earth</td><td>minimum brightness during <a href="/facts/Transit_of_Venus/Ygk5w0WC">transits</a>.</td></tr><tr><td>−2.94</td><td>planet Jupiter</td><td>seen from Earth</td><td>maximum brightness<a class="footnote-ref" id="fnref:50" href="#fn:50">50</a></td></tr><tr><td>−2.94</td><td>planet Mars</td><td>seen from Earth</td><td>maximum brightness<a class="footnote-ref" id="fnref:51" href="#fn:51">51</a></td></tr><tr><td>−2.5</td><td colspan="3">Faintest objects visible during the day with naked eye when Sun is less than 10° above the horizon</td></tr><tr><td>−2.50</td><td><a href="/facts/New_moon/uab6r7yY">new moon</a></td><td>seen from Earth</td><td>minimum brightness</td></tr><tr><td>−2.50</td><td>planet Earth</td><td>seen from Mars</td><td>maximum brightness</td></tr><tr><td>−2.48</td><td>planet Mercury</td><td>seen from Earth</td><td>maximum brightness at <a href="/facts/Superior_conjunction/TgujumHI">superior conjunction</a> (unlike Venus, Mercury is at its brightest when on the far side of the Sun, the reason being their different phase curves)<a class="footnote-ref" id="fnref:52" href="#fn:52">52</a></td></tr><tr><td>−2.20</td><td>planet Jupiter</td><td>seen from Earth</td><td>mean brightness<a class="footnote-ref" id="fnref:53" href="#fn:53">53</a></td></tr><tr><td>−1.66</td><td>planet Jupiter</td><td>seen from Earth</td><td>minimum brightness<a class="footnote-ref" id="fnref:54" href="#fn:54">54</a></td></tr><tr><td>−1.47</td><td>star system Sirius</td><td>seen from Earth</td><td>Brightest star except for the Sun at visible wavelengths<a class="footnote-ref" id="fnref:55" href="#fn:55">55</a></td></tr><tr><td>−0.83</td><td>star <a href="/facts/Eta_Carinae/zsrmE2Lo">Eta Carinae</a></td><td>seen from Earth</td><td>apparent brightness as a <a href="/facts/Supernova_impostor/zgXxf6rp">supernova impostor</a> in April 1843</td></tr><tr><td>−0.72</td><td>star <a href="/facts/Canopus_(star)/zD5WcDy5">Canopus</a></td><td>seen from Earth</td><td>2nd brightest star in night sky<a class="footnote-ref" id="fnref:56" href="#fn:56">56</a></td></tr><tr><td>−0.55</td><td>planet Saturn</td><td>seen from Earth</td><td>maximum brightness near opposition and perihelion when the rings are angled toward Earth<a class="footnote-ref" id="fnref:57" href="#fn:57">57</a></td></tr><tr><td>−0.30</td><td><a href="/facts/Halley%2527s_Comet/DQongwTQ">Halley's comet</a></td><td>seen from Earth</td><td>Expected apparent magnitude at 2061 passage</td></tr><tr><td>−0.27</td><td>star system <a href="/facts/Alpha_Centauri/6BlySfIj">Alpha Centauri</a> AB</td><td>seen from Earth</td><td>Combined magnitude (3rd brightest star in night sky)</td></tr><tr><td>−0.04</td><td>star <a href="/facts/Arcturus_(star)/8W0qslPJ">Arcturus</a></td><td>seen from Earth</td><td>4th brightest star to the naked eye<a class="footnote-ref" id="fnref:58" href="#fn:58">58</a></td></tr><tr><td>−0.01</td><td>star Alpha Centauri A</td><td>seen from Earth</td><td>4th brightest individual star visible telescopically in the night sky</td></tr><tr><td>+0.03</td><td>star <a href="/facts/Vega/G3wJwhhl">Vega</a></td><td>seen from Earth</td><td>originally chosen as a definition of the zero point<a class="footnote-ref" id="fnref:59" href="#fn:59">59</a></td></tr><tr><td>+0.23</td><td>planet Mercury</td><td>seen from Earth</td><td>mean brightness<a class="footnote-ref" id="fnref:60" href="#fn:60">60</a></td></tr><tr><td>+0.46</td><td>star Sun</td><td>seen from Alpha Centauri</td><td></td></tr><tr><td>+0.46</td><td>planet Saturn</td><td>seen from Earth</td><td>mean brightness<a class="footnote-ref" id="fnref:61" href="#fn:61">61</a></td></tr><tr><td>+0.71</td><td>planet Mars</td><td>seen from Earth</td><td>mean brightness<a class="footnote-ref" id="fnref:62" href="#fn:62">62</a></td></tr><tr><td>+0.90</td><td>Moon</td><td>seen from Mars</td><td>maximum brightness</td></tr><tr><td>+1.17</td><td>planet Saturn</td><td>seen from Earth</td><td>minimum brightness<a class="footnote-ref" id="fnref:63" href="#fn:63">63</a></td></tr><tr><td>+1.33</td><td>star Alpha Centauri B</td><td>seen from Earth</td><td></td></tr><tr><td>+1.86</td><td>planet Mars</td><td>seen from Earth</td><td>minimum brightness<a class="footnote-ref" id="fnref:64" href="#fn:64">64</a></td></tr><tr><td>+1.98</td><td>star <a href="/facts/Polaris/s9k0Irh3">Polaris</a></td><td>seen from Earth</td><td>mean brightness<a class="footnote-ref" id="fnref:65" href="#fn:65">65</a></td></tr><tr><td>+2.00</td><td>star system <a href="/facts/T_Coronae_Borealis/XeRSPPHw">T CrB</a> (when nova)</td><td>seen from Earth</td><td>Star system that goes nova every 80 years</td></tr><tr><td>+2.40</td><td><a href="/facts/Halley%2527s_Comet/DQongwTQ">Halley's Comet</a></td><td>seen from Earth</td><td>About <a href="/facts/Magnitude_(astronomy)/f4FbscJu">Magnitude</a> during 1986 <a href="/facts/Apsis/VaL6ow9w">perihelion</a></td></tr><tr><td>+3</td><td colspan="3">Faintest objects visible in an urban neighborhood with naked eye</td></tr><tr><td>+3.03</td><td>supernova <a href="/facts/SN_1987A/zHyoUpBC">SN 1987A</a></td><td>seen from Earth</td><td>in the <a href="/facts/Large_Magellanic_Cloud/7VYAehNa">Large Magellanic Cloud</a> (160,000 light-years away)</td></tr><tr><td>+3.44</td><td><a href="/facts/Andromeda_Galaxy/MjmSLV6m">Andromeda Galaxy</a></td><td>seen from Earth</td><td>M31<a class="footnote-ref" id="fnref:66" href="#fn:66">66</a></td></tr><tr><td>+4</td><td colspan="3">Faintest objects visible in a suburban neighborhood with naked eye</td></tr><tr><td>+4.00</td><td><a href="/facts/Orion_Nebula/6VWbcqzL">Orion Nebula</a></td><td>seen from Earth</td><td>M42</td></tr><tr><td>+4.38</td><td>moon <a href="/facts/Ganymede_(moon)/AmKsF10c">Ganymede</a></td><td>seen from Earth</td><td>maximum brightness<a class="footnote-ref" id="fnref:67" href="#fn:67">67</a> (moon of Jupiter and the largest moon in the Solar System)</td></tr><tr><td>+4.50</td><td>open cluster <a href="/facts/Messier_41/U7zoR4pr">M41</a></td><td>seen from Earth</td><td>an open cluster that may have been seen by <a href="/facts/Aristotle/U2bDlBFW">Aristotle</a><a class="footnote-ref" id="fnref:68" href="#fn:68">68</a></td></tr><tr><td>+4.50</td><td><a href="/facts/Sagittarius_Dwarf_Spheroidal_Galaxy/9IfJCbtl">Sagittarius Dwarf Spheroidal Galaxy</a></td><td>seen from Earth</td></tr><tr><td>+5.20</td><td>asteroid <a href="/facts/4_Vesta/xnQ8acw1">Vesta</a></td><td>seen from Earth</td><td>maximum brightness</td></tr><tr><td>+5.38<a class="footnote-ref" id="fnref:69" href="#fn:69">69</a></td><td>planet <a href="/facts/Uranus/x7YwT1ar">Uranus</a></td><td>seen from Earth</td><td>maximum brightness<a class="footnote-ref" id="fnref:70" href="#fn:70">70</a> (Uranus comes to perihelion in 2050)</td></tr><tr><td>+5.68</td><td>planet Uranus</td><td>seen from Earth</td><td>mean brightness<a class="footnote-ref" id="fnref:71" href="#fn:71">71</a></td></tr><tr><td>+5.72</td><td>spiral galaxy <a href="/facts/Triangulum_Galaxy/etLCCGhP">M33</a></td><td>seen from Earth</td><td>which is used as a test for <a href="/facts/Naked_eye/ePEIa0lK">naked eye</a> seeing under dark skies<a class="footnote-ref" id="fnref:72" href="#fn:72">72</a><a class="footnote-ref" id="fnref:73" href="#fn:73">73</a></td></tr><tr><td>+5.80</td><td><a href="/facts/Gamma-ray_burst/oRRU6Fhn">gamma-ray burst</a> <a href="/facts/GRB_080319B/7XcLcly2">GRB 080319B</a></td><td>seen from Earth</td><td>Peak visual magnitude (the "Clarke Event") seen on Earth on 19 March 2008 from a distance of 7.5 billion light-years.</td></tr><tr><td>+6.03</td><td>planet Uranus</td><td>seen from Earth</td><td>minimum brightness<a class="footnote-ref" id="fnref:74" href="#fn:74">74</a></td></tr><tr><td>+6.49</td><td>asteroid <a href="/facts/2_Pallas/onjUgYtA">Pallas</a></td><td>seen from Earth</td><td>maximum brightness</td></tr><tr><td>+6.5</td><td colspan="3">Approximate limit of <a href="/facts/Star/PFbd6ICx">stars</a> observed by a mean naked eye observer under very good conditions. There are about 9,500 stars visible to mag 6.5.<a class="footnote-ref" id="fnref:75" href="#fn:75">75</a></td></tr><tr><td>+6.50</td><td>global cluster <a href="/facts/Messier_2/W0GKQ0vv">M2</a></td><td>seen from Earth</td><td>mean naked-eye target</td></tr><tr><td>+6.64</td><td>dwarf planet <a href="/facts/Ceres_(dwarf_planet)/yIVEMYtG">Ceres</a></td><td>seen from Earth</td><td>maximum brightness</td></tr><tr><td>+6.75</td><td>asteroid <a href="/facts/7_Iris/32DM41fM">Iris</a></td><td>seen from Earth</td><td>maximum brightness</td></tr><tr><td>+6.90</td><td>spiral galaxy <a href="/facts/Messier_81/p91h990c">M81</a></td><td>seen from Earth</td><td>This is an extreme naked-eye target that pushes human eyesight and the Bortle scale to the limit<a class="footnote-ref" id="fnref:76" href="#fn:76">76</a></td></tr><tr><td>+7.25</td><td>planet Mercury</td><td>seen from Earth</td><td>minimum brightness<a class="footnote-ref" id="fnref:77" href="#fn:77">77</a></td></tr><tr><td>+7.67<a class="footnote-ref" id="fnref:78" href="#fn:78">78</a></td><td>planet Neptune</td><td>seen from Earth</td><td>maximum brightness<a class="footnote-ref" id="fnref:79" href="#fn:79">79</a> (Neptune comes to perihelion in 2042)</td></tr><tr><td>+7.78</td><td>planet Neptune</td><td>seen from Earth</td><td>mean brightness<a class="footnote-ref" id="fnref:80" href="#fn:80">80</a></td></tr><tr><td>+8</td><td colspan="3">Extreme naked-eye limit, Class 1 on <a href="/facts/Bortle_scale/IFXbNMQ2">Bortle scale</a>, the darkest skies available on Earth.<a class="footnote-ref" id="fnref:81" href="#fn:81">81</a></td></tr><tr><td>+8.00</td><td>planet Neptune</td><td>seen from Earth</td><td>minimum brightness<a class="footnote-ref" id="fnref:82" href="#fn:82">82</a></td></tr><tr><td>+8.10</td><td>moon <a href="/facts/Titan_(moon)/lg0l9PCH">Titan</a></td><td>seen from Earth</td><td>maximum brightness; largest moon of Saturn;<a class="footnote-ref" id="fnref:83" href="#fn:83">83</a><a class="footnote-ref" id="fnref:84" href="#fn:84">84</a> mean opposition magnitude 8.4<a class="footnote-ref" id="fnref:85" href="#fn:85">85</a></td></tr><tr><td>+8.29</td><td>star <a href="/facts/UY_Scuti/W7JxIxRQ">UY Scuti</a></td><td>seen from Earth</td><td>Maximum brightness; one of largest known stars by radius</td></tr><tr><td>+8.94</td><td>asteroid <a href="/facts/10_Hygiea/XVbUCggT">10 Hygiea</a></td><td>seen from Earth</td><td>maximum brightness<a class="footnote-ref" id="fnref:86" href="#fn:86">86</a></td></tr><tr><td>+9.30</td><td>spiral galaxy <a href="/facts/Messier_63/CFwGPW9D">M63</a></td><td>seen from Earth</td></tr><tr><td>+9.5</td><td colspan="3">Faintest objects visible using common 10×50 <a href="/facts/Binoculars/DPHVmKIL">binoculars</a> under typical conditions<a class="footnote-ref" id="fnref:87" href="#fn:87">87</a></td></tr><tr><td>+10</td><td><a href="/facts/Apollo_8/uKkRsnSL">Apollo 8</a> <a href="/facts/Apollo_command_and_service_module/rfoTgzFx">CSM</a> in orbit around the Moon</td><td>seen from Earth</td><td>calculated (Liemohn)<a class="footnote-ref" id="fnref:88" href="#fn:88">88</a></td></tr><tr><td>+10</td><td>star system <a href="/facts/T_Coronae_Borealis/XeRSPPHw">T CrB</a>(average)</td><td>seen from Earth</td><td>Star system that goes nova every 80 years</td></tr><tr><td>+10.20</td><td>moon <a href="/facts/Iapetus_(moon)/W9PCus81">Iapetus</a></td><td>seen from Earth</td><td>maximum brightness,<a class="footnote-ref" id="fnref:89" href="#fn:89">89</a> brightest when west of Saturn and takes 40 days to switch sides</td></tr><tr><td>+11.05</td><td>star <a href="/facts/Proxima_Centauri/6vSeytbA">Proxima Centauri</a></td><td>seen from Earth</td><td>closest star (other than the Sun)</td></tr><tr><td>+11.8</td><td>moon <a href="/facts/Phobos_(moon)/qqS9JvuG">Phobos</a></td><td>seen from Earth</td><td>Maximum brightness; brighter moon of Mars</td></tr><tr><td>+12.23</td><td>star <a href="/facts/R136a1/4kMEN0aX">R136a1</a></td><td>seen from Earth</td><td>Most luminous and massive star known<a class="footnote-ref" id="fnref:90" href="#fn:90">90</a></td></tr><tr><td>+12.89</td><td>moon <a href="/facts/Deimos_(moon)/Sm30nJWY">Deimos</a></td><td>seen from Earth</td><td>Maximum brightness</td></tr><tr><td>+12.91</td><td><a href="/facts/Quasar/HS96328l">quasar</a> <a href="/facts/3C_273/P11TI6Ez">3C 273</a></td><td>seen from Earth</td><td>brightest (<a href="/facts/Luminosity_distance/x3YHoHfQ">luminosity distance</a> of 2.4 billion <a href="/facts/Light-year/IGc5NdQb">light-years</a>)</td></tr><tr><td>+13.42</td><td>moon <a href="/facts/Triton_(moon)/mxxRUygc">Triton</a></td><td>seen from Earth</td><td>Maximum brightness<a class="footnote-ref" id="fnref:91" href="#fn:91">91</a></td></tr><tr><td>+13.65</td><td>dwarf planet <a href="/facts/Pluto/egq7MBeR">Pluto</a></td><td>seen from Earth</td><td>maximum brightness,<a class="footnote-ref" id="fnref:92" href="#fn:92">92</a> 725 times fainter than magnitude 6.5 naked eye skies</td></tr><tr><td>+13.9</td><td>moon <a href="/facts/Titania_(moon)/Ts4j9JLM">Titania</a></td><td>seen from Earth</td><td>Maximum brightness; brightest moon of Uranus</td></tr><tr><td>+14.1</td><td>star <a href="/facts/WR_102/kfvEEd9Y">WR 102</a></td><td>seen from Earth</td><td>Hottest known star</td></tr><tr><td>+15.4</td><td><a href="/facts/Centaur_(minor_planet)/jXpnm7dv">centaur</a> <a href="/facts/2060_Chiron/5MpXoc0z">Chiron</a></td><td>seen from Earth</td><td>maximum brightness<a class="footnote-ref" id="fnref:93" href="#fn:93">93</a></td></tr><tr><td>+15.55</td><td>moon <a href="/facts/Charon_(moon)/elazjsMp">Charon</a></td><td>seen from Earth</td><td>maximum brightness (the largest moon of Pluto)</td></tr><tr><td>+16.8</td><td>dwarf planet <a href="/facts/Makemake/661b22C4">Makemake</a></td><td>seen from Earth</td><td>Current <a href="/facts/Opposition_(astronomy_and_astrology)/wuBoAGsS">opposition</a> brightness<a class="footnote-ref" id="fnref:94" href="#fn:94">94</a></td></tr><tr><td>+17.27</td><td>dwarf planet <a href="/facts/Haumea/C1xJDm3B">Haumea</a></td><td>seen from Earth</td><td>Current opposition brightness<a class="footnote-ref" id="fnref:95" href="#fn:95">95</a></td></tr><tr><td>+18.7</td><td>dwarf planet <a href="/facts/Eris_(dwarf_planet)/vuaR65F7">Eris</a></td><td>seen from Earth</td><td>Current opposition brightness</td></tr><tr><td>+19.5</td><td colspan="3">Faintest objects observable with the <a href="/facts/Catalina_Sky_Survey/6GmVAEdE">Catalina Sky Survey</a> 0.7-meter telescope using a 30-second exposure<a class="footnote-ref" id="fnref:96" href="#fn:96">96</a> and also the approximate <a href="/facts/Limiting_magnitude/gHexYxeX">limiting magnitude</a> of <a href="/facts/Asteroid_Terrestrial-impact_Last_Alert_System/Q72tHLVc">Asteroid Terrestrial-impact Last Alert System</a> (ATLAS)</td></tr><tr><td>+20.7</td><td>moon <a href="/facts/Callirrhoe_(moon)/5tXaGnK7">Callirrhoe</a></td><td>seen from Earth</td><td>(small ≈8 km satellite of Jupiter)<a class="footnote-ref" id="fnref:97" href="#fn:97">97</a></td></tr><tr><td>+22</td><td colspan="3">Faintest objects observable in visible light with a 600 mm (24″) <a href="/facts/Ritchey-Chr%25C3%25A9tien_telescope/oWJe1NCo">Ritchey-Chrétien telescope</a> with 30 minutes of stacked images (6 subframes at 5 minutes each) using a <a href="/facts/Charge-coupled_device/l6xffIcz">CCD detector</a><a class="footnote-ref" id="fnref:98" href="#fn:98">98</a></td></tr><tr><td>+22.8</td><td><a href="/facts/Luhman_16/AELwz9n5">Luhman 16</a></td><td>seen from Earth</td><td>Closest <a href="/facts/Brown_dwarf/fa7kr9lH">brown dwarfs</a> (Luhman 16A=23.25, Luhman 16B=24.07)<a class="footnote-ref" id="fnref:99" href="#fn:99">99</a></td></tr><tr><td>+22.91</td><td>moon <a href="/facts/Hydra_(moon)/Al9hJ1on">Hydra</a></td><td>seen from Earth</td><td>maximum brightness of Pluto's moon</td></tr><tr><td>+23.38</td><td>moon <a href="/facts/Nix_(moon)/Qf3qsr7m">Nix</a></td><td>seen from Earth</td><td>maximum brightness of Pluto's moon</td></tr><tr><td>+24</td><td colspan="3">Faintest objects observable with the <a href="/facts/Pan-STARRS/w65mMlXw">Pan-STARRS</a> 1.8-meter telescope using a 60-second exposure<a class="footnote-ref" id="fnref:100" href="#fn:100">100</a> This is currently the limiting magnitude of automated allsky <a href="/facts/Astronomical_survey/6BE1V8V6">astronomical surveys</a>.</td></tr><tr><td>+25.0</td><td>moon <a href="/facts/Fenrir_(moon)/HuNM1IaW">Fenrir</a></td><td>seen from Earth</td><td>(small ≈4 km satellite of Saturn)<a class="footnote-ref" id="fnref:101" href="#fn:101">101</a> and about 25 million times fainter than what can be seen with the naked eye.</td></tr><tr><td>+25.3</td><td>Trans-Neptunian object <a href="/facts/2018_AG37/BmxgATpX">2018 AG37</a></td><td>seen from Earth</td><td>Furthest known observable object in the Solar System about 132 AU (19.7 billion km) from the Sun</td></tr><tr><td>+26.2</td><td>Trans-Neptunian object <a href="/facts/2015_TH367/jxtJSGuH">2015 TH367</a></td><td>seen from Earth</td><td>200 km sized object about 90 AU (13 billion km) from the Sun and about 75 million times fainter than what can be seen with the naked eye.</td></tr><tr><td>+27.7</td><td colspan="3">Faintest objects observable with a single 8-meter class ground-based telescope such as the <a href="/facts/Subaru_Telescope/AwJtFuKv">Subaru Telescope</a> in a 10-hour image<a class="footnote-ref" id="fnref:102" href="#fn:102">102</a></td></tr><tr><td>+28.2</td><td><a href="/facts/Halley%2527s_Comet/DQongwTQ">Halley's Comet</a></td><td>seen from Earth (2003)</td><td>in 2003 when it was 28 AU (4.2 billion km) from the Sun, imaged using 3 of 4 synchronised individual scopes in the <a href="/facts/European_Southern_Observatory/mJtjDbwx">ESO</a>'s <a href="/facts/Very_Large_Telescope/xUQCLysQ">Very Large Telescope</a> array using a total exposure time of about 9 hours<a class="footnote-ref" id="fnref:103" href="#fn:103">103</a></td></tr><tr><td>+28.4</td><td>asteroid 2003 BH91</td><td>seen from Earth orbit</td><td>observed magnitude of ≈15-kilometer <a href="/facts/Kuiper_belt/IvLzYp5P">Kuiper belt</a> object seen by the <a href="/facts/Hubble_Space_Telescope/NQeIf0vw">Hubble Space Telescope</a> (HST) in 2003, dimmest known directly observed asteroid.</td></tr><tr><td>+29.4</td><td><a href="/facts/JADES-GS-z13-0/osKVa1cw">JADES-GS-z13-0</a></td><td>seen from Earth</td><td>Discovered by the <a href="/facts/James_Webb_Space_Telescope/w4GAWnWX">James Webb Space Telescope</a>. One of the furthest objects discovered.<a class="footnote-ref" id="fnref:104" href="#fn:104">104</a> Approximately a billion times fainter than can be observed with the naked eye.</td></tr><tr><td>+31.5</td><td colspan="3">Faintest objects observable in visible light with <a href="/facts/Hubble_Space_Telescope/NQeIf0vw">Hubble Space Telescope</a> via the <a href="/facts/EXtreme_Deep_Field/wHFEJaE7">EXtreme Deep Field</a> with ≈23 days of exposure time collected over 10 years<a class="footnote-ref" id="fnref:105" href="#fn:105">105</a></td></tr><tr><td>+35</td><td>unnamed asteroid</td><td>seen from Earth orbit</td><td>expected magnitude of dimmest known asteroid, a 950-meter Kuiper belt object discovered (by the HST) <a href="/facts/Occultation/a9Q1KTPe">passing in front of a star</a> in 2009.<a class="footnote-ref" id="fnref:106" href="#fn:106">106</a></td></tr><tr><td>+35</td><td>star <a href="/facts/LBV_1806%25E2%2588%259220/jUe9LwSA">LBV 1806−20</a></td><td>seen from Earth</td><td>a luminous blue variable star, expected magnitude at visible wavelengths due to <a href="/facts/Interstellar_extinction/rLNLDfe1">interstellar extinction</a></td></tr></tbody></table>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Angular_diameter/p2xv4vcQ">Angular diameter</a></li>
<li><a href="/facts/Distance_modulus/5Wt7RR4s">Distance modulus</a></li>
<li><a href="/facts/List_of_nearest_bright_stars/CHHePdRq">List of nearest bright stars</a></li>
<li><a href="/facts/List_of_nearest_stars/LLu2LmXq">List of nearest stars</a></li>
<li><a href="/facts/Luminosity/1tdhpk9l">Luminosity</a></li>
<li><a href="/facts/Surface_brightness/xN0jmKkw">Surface brightness</a></li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="http://www.icq.eps.harvard.edu/MagScale.html">"The astronomical magnitude scale"</a>. International Comet Quarterly.</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1">Toomer, G. J. (1984). Ptolemy's Almagest. New York: Springer-Verlag. p. 16. ISBN 0-387-91220-7. <a href="0-387-91220-7" target="_blank">0-387-91220-7</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></li>
<li id="fn:2">Curtis, Heber Doust (1903) [1901-03-27]. "On the Limits of Unaided Vision". Lick Observatory Bulletin. 2 (38). University of California: 67–69. Bibcode:1903LicOB...2...67C. doi:10.5479/ADS/bib/1903LicOB.2.67C. <a href="/wiki/Lick_Observatory" target="_blank">/wiki/Lick_Observatory</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></li>
<li id="fn:3">Matthew, Templeton (21 October 2011). "Magnitudes: Measuring the Brightness of Stars". American Association of Variable Stars (AAVSO). Archived from the original on 18 May 2019. Retrieved 19 May 2019. <a href="https://www.aavso.org/magnitude" target="_blank">https://www.aavso.org/magnitude</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></li>
<li id="fn:4">Crumey, A. (October 2006). "Human Contrast Threshold and Astronomical Visibility". Monthly Notices of the Royal Astronomical Society. 442 (3): 2600–2619. arXiv:1405.4209. Bibcode:2014MNRAS.442.2600C. doi:10.1093/mnras/stu992. <a href="https://doi.org/10.1093%2Fmnras%2Fstu992" target="_blank">https://doi.org/10.1093%2Fmnras%2Fstu992</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></li>
<li id="fn:5">"Vmag<6.5". SIMBAD Astronomical Database. Archived from the original on 22 February 2015. Retrieved 25 June 2010. <a href="http://simbad.u-strasbg.fr/simbad/sim-sam?Criteria=Vmag%3C6.5" target="_blank">http://simbad.u-strasbg.fr/simbad/sim-sam?Criteria=Vmag%3C6.5</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></li>
<li id="fn:6">"Magnitude". National Solar Observatory—Sacramento Peak. Archived from the original on 6 February 2008. Retrieved 23 August 2006. <a href="https://web.archive.org/web/20080206074842/http://www.nso.edu/PR/answerbook/magnitude.html" target="_blank">https://web.archive.org/web/20080206074842/http://www.nso.edu/PR/answerbook/magnitude.html</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></li>
<li id="fn:7">Bright Star Catalogue <a href="/wiki/Bright_Star_Catalogue" target="_blank">/wiki/Bright_Star_Catalogue</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></li>
<li id="fn:8">Hoffmann, S., Hipparchs Himmelsglobus, Springer, Wiesbaden/ New York, 2017 <a href="#fnref:8" class="footnote-back-ref">↩</a></li>
<li id="fn:9">Pogson, N. (1856). "Magnitudes of Thirty-six of the Minor Planets for the first day of each month of the year 1857". MNRAS. 17: 12. Bibcode:1856MNRAS..17...12P. doi:10.1093/mnras/17.1.12. <a href="/wiki/Norman_Robert_Pogson" target="_blank">/wiki/Norman_Robert_Pogson</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></li>
<li id="fn:10">Hearnshaw, John B. (1996). The measurement of starlight: two centuries of astronomical photometry (1. publ ed.). Cambridge: Cambridge Univ. Press. ISBN 978-0-521-40393-1. <a href="978-0-521-40393-1" target="_blank">978-0-521-40393-1</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></li>
<li id="fn:11">Pogson, N. (14 November 1856). "Magnitudes of Thirty-six of the Minor Planets for the First Day of each Month of the Year 1857". Monthly Notices of the Royal Astronomical Society. 17 (1): 12–15. Bibcode:1856MNRAS..17...12P. doi:10.1093/mnras/17.1.12. ISSN 0035-8711. <a href="https://doi.org/10.1093%2Fmnras%2F17.1.12" target="_blank">https://doi.org/10.1093%2Fmnras%2F17.1.12</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></li>
<li id="fn:12">Hearnshaw, J. B. (1996). The measurement of starlight: two centuries of astronomical photometry. Cambridge [England] ; New York, NY, USA: Cambridge University Press. ISBN 978-0-521-40393-1. <a href="978-0-521-40393-1" target="_blank">978-0-521-40393-1</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></li>
<li id="fn:13">Johnson, H. L.; Morgan, W. W. (May 1953). "Fundamental stellar photometry for standards of spectral type on the revised system of the Yerkes spectral atlas". The Astrophysical Journal. 117: 313. Bibcode:1953ApJ...117..313J. doi:10.1086/145697. ISSN 0004-637X. <a href="http://adsabs.harvard.edu/doi/10.1086/145697" target="_blank">http://adsabs.harvard.edu/doi/10.1086/145697</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></li>
<li id="fn:14">North, Gerald; James, Nick (2014). Observing Variable Stars, Novae and Supernovae. Cambridge University Press. p. 24. ISBN 978-1-107-63612-5. <a href="978-1-107-63612-5" target="_blank">978-1-107-63612-5</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></li>
<li id="fn:15">Oke, J. B.; Gunn, J. E. (15 March 1983). "Secondary standard stars for absolute spectrophotometry". The Astrophysical Journal. 266: 713–717. Bibcode:1983ApJ...266..713O. doi:10.1086/160817. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></li>
<li id="fn:16">IAU Inter-Division A-G Working Group on Nominal Units for Stellar & Planetary Astronomy (13 August 2015). "IAU 2015 Resolution B2 on Recommended Zero Points for the Absolute and Apparent Bolometric Magnitude Scales" (PDF). Resolutions Adopted at the General Assemblies. arXiv:1510.06262. Bibcode:2015arXiv151006262M. Archived (PDF) from the original on 28 January 2016. Retrieved 19 May 2019. <a href="https://www.iau.org/static/resolutions/IAU2015_English.pdf" target="_blank">https://www.iau.org/static/resolutions/IAU2015_English.pdf</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></li>
<li id="fn:17">Williams, David R. (2 February 2010). "Moon Fact Sheet". NASA (National Space Science Data Center). Archived from the original on 23 March 2010. Retrieved 9 April 2010. <a href="https://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html" target="_blank">https://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></li>
<li id="fn:18">"Magnitude Arithmetic". Weekly Topic. Caglow. Archived from the original on 1 February 2012. Retrieved 30 January 2012. <a href="http://www.caglow.com/info/wtopic/mag-arith" target="_blank">http://www.caglow.com/info/wtopic/mag-arith</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></li>
<li id="fn:19">IAU Inter-Division A-G Working Group on Nominal Units for Stellar & Planetary Astronomy (13 August 2015). "IAU 2015 Resolution B2 on Recommended Zero Points for the Absolute and Apparent Bolometric Magnitude Scales" (PDF). Resolutions Adopted at the General Assemblies. arXiv:1510.06262. Bibcode:2015arXiv151006262M. Archived (PDF) from the original on 28 January 2016. Retrieved 19 May 2019. <a href="https://www.iau.org/static/resolutions/IAU2015_English.pdf" target="_blank">https://www.iau.org/static/resolutions/IAU2015_English.pdf</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></li>
<li id="fn:20">"Lecture 4: Page 3, Properties of the Stars". homepages.uc.edu. Retrieved 5 December 2024. <a href="https://homepages.uc.edu/~hansonmm/ASTRO/LECTURENOTES/W03/Lec6/Page3.html" target="_blank">https://homepages.uc.edu/~hansonmm/ASTRO/LECTURENOTES/W03/Lec6/Page3.html</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></li>
<li id="fn:21">Evans, Aaron. "Some Useful Astronomical Definitions" (PDF). Stony Brook Astronomy Program. Archived (PDF) from the original on 20 July 2011. Retrieved 12 July 2009. <a href="http://www.astro.sunysb.edu/aevans/PHY523/classnotes523/useful-definitions-pp.pdf" target="_blank">http://www.astro.sunysb.edu/aevans/PHY523/classnotes523/useful-definitions-pp.pdf</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></li>
<li id="fn:22">Čotar, Klemen; Zwitter, Tomaž; et al. (21 May 2019). "The GALAH survey: unresolved triple Sun-like stars discovered by the Gaia mission". Monthly Notices of the Royal Astronomical Society. 487 (2). Oxford University Press (OUP): 2474–2490. arXiv:1904.04841. doi:10.1093/mnras/stz1397. ISSN 0035-8711. <a href="https://doi.org/10.1093%2Fmnras%2Fstz1397" target="_blank">https://doi.org/10.1093%2Fmnras%2Fstz1397</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></li>
<li id="fn:23">Bessell, Michael S. (September 2005). "Standard Photometric Systems" (PDF). Annual Review of Astronomy and Astrophysics. 43 (1): 293–336. Bibcode:2005ARA&A..43..293B. doi:10.1146/annurev.astro.41.082801.100251. ISSN 0066-4146. Archived (PDF) from the original on 9 October 2022. <a href="http://www.mso.anu.edu.au/~bessell/araapaper.pdf" target="_blank">http://www.mso.anu.edu.au/~bessell/araapaper.pdf</a> <a href="#fnref:23" class="footnote-back-ref">↩</a></li>
<li id="fn:24">Luciuk, M. "Astronomical Magnitudes" (PDF). p. 8. Retrieved 11 January 2019. <a href="http://www.asterism.org/tutorials/tut35%20Magnitudes.pdf" target="_blank">http://www.asterism.org/tutorials/tut35%20Magnitudes.pdf</a> <a href="#fnref:24" class="footnote-back-ref">↩</a></li>
<li id="fn:25">Huchra, John. "Astronomical Magnitude Systems". Harvard-Smithsonian Center for Astrophysics. Archived from the original on 21 July 2018. Retrieved 18 July 2017. <a href="https://www.cfa.harvard.edu/~dfabricant/huchra/ay145/mags.html" target="_blank">https://www.cfa.harvard.edu/~dfabricant/huchra/ay145/mags.html</a> <a href="#fnref:25" class="footnote-back-ref">↩</a></li>
<li id="fn:26">Schulman, E.; Cox, C. V. (1997). "Misconceptions About Astronomical Magnitudes". American Journal of Physics. 65 (10): 1003. Bibcode:1997AmJPh..65.1003S. doi:10.1119/1.18714. <a href="/wiki/Eric_Schulman" target="_blank">/wiki/Eric_Schulman</a> <a href="#fnref:26" class="footnote-back-ref">↩</a></li>
<li id="fn:27">"Magnitude | Brightness, Apparent Magnitude & Absolute Magnitude | Britannica". www.britannica.com. Retrieved 19 October 2023. <a href="https://www.britannica.com/science/magnitude-astronomy" target="_blank">https://www.britannica.com/science/magnitude-astronomy</a> <a href="#fnref:27" class="footnote-back-ref">↩</a></li>
<li id="fn:28">"Introduction to active galaxies: View as single page". www.open.edu. Retrieved 19 October 2023. <a href="https://www.open.edu/openlearn/science-maths-technology/introduction-active-galaxies/content-section-5.4/?printable=1" target="_blank">https://www.open.edu/openlearn/science-maths-technology/introduction-active-galaxies/content-section-5.4/?printable=1</a> <a href="#fnref:28" class="footnote-back-ref">↩</a></li>
<li id="fn:29">Pickering, Edward C. (1910). "1910HarCi.160....1P Page 1". Harvard College Observatory Circular. 160: 1. Bibcode:1910HarCi.160....1P. Retrieved 19 October 2023. <a href="https://adsabs.harvard.edu/full/1910HarCi.160....1P" target="_blank">https://adsabs.harvard.edu/full/1910HarCi.160....1P</a> <a href="#fnref:29" class="footnote-back-ref">↩</a></li>
<li id="fn:30">Umeh, Obinna; Clarkson, Chris; Maartens, Roy (2014). "Nonlinear relativistic corrections to cosmological distances, redshift and gravitational lensing magnification: II. Derivation". Classical and Quantum Gravity. 31 (20): 205001. arXiv:1402.1933. Bibcode:2014CQGra..31t5001U. doi:10.1088/0264-9381/31/20/205001. S2CID 54527784. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:30" class="footnote-back-ref">↩</a></li>
<li id="fn:31">Hogg, David W.; Baldry, Ivan K.; Blanton, Michael R.; Eisenstein, Daniel J. (2002). "The K correction". arXiv:astro-ph/0210394. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:31" class="footnote-back-ref">↩</a></li>
<li id="fn:32">Wing, R. F. (1967). "1967lts..conf..205W Page 205". Late-Type Stars: 205. Bibcode:1967lts..conf..205W. Retrieved 19 October 2023. <a href="https://adsabs.harvard.edu/full/1967lts..conf..205W" target="_blank">https://adsabs.harvard.edu/full/1967lts..conf..205W</a> <a href="#fnref:32" class="footnote-back-ref">↩</a></li>
<li id="fn:33">IAU Inter-Division A-G Working Group on Nominal Units for Stellar & Planetary Astronomy (13 August 2015). "IAU 2015 Resolution B2 on Recommended Zero Points for the Absolute and Apparent Bolometric Magnitude Scales" (PDF). Resolutions Adopted at the General Assemblies. arXiv:1510.06262. Bibcode:2015arXiv151006262M. Archived (PDF) from the original on 28 January 2016. Retrieved 19 May 2019. <a href="https://www.iau.org/static/resolutions/IAU2015_English.pdf" target="_blank">https://www.iau.org/static/resolutions/IAU2015_English.pdf</a> <a href="#fnref:33" class="footnote-back-ref">↩</a></li>
<li id="fn:34">Agrawal, Dulli Chandra (30 March 2016). "Apparent magnitude of earthshine: a simple calculation". European Journal of Physics. 37 (3). IOP Publishing: 035601. Bibcode:2016EJPh...37c5601A. doi:10.1088/0143-0807/37/3/035601. ISSN 0143-0807. S2CID 124231299. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:34" class="footnote-back-ref">↩</a></li>
<li id="fn:35">Polakis, Tom (10 September 1997). "Radiometry and photometry in astronomy". Home page of Paul Schlyter. Retrieved 25 April 2024. <a href="https://stjarnhimlen.se/comp/radfaq.html#11" target="_blank">https://stjarnhimlen.se/comp/radfaq.html#11</a> <a href="#fnref:35" class="footnote-back-ref">↩</a></li>
<li id="fn:36">Dufay, Jean (17 October 2012). Introduction to Astrophysics: The Stars. Courier Corporation. p. 3. ISBN 978-0-486-60771-9. Archived from the original on 24 March 2017. Retrieved 28 February 2016. <a href="978-0-486-60771-9" target="_blank">978-0-486-60771-9</a> <a href="#fnref:36" class="footnote-back-ref">↩</a></li>
<li id="fn:37">McLean, Ian S. (2008). Electronic Imaging in Astronomy: Detectors and Instrumentation. Springer. p. 529. ISBN 978-3-540-76582-0. <a href="978-3-540-76582-0" target="_blank">978-3-540-76582-0</a> <a href="#fnref:37" class="footnote-back-ref">↩</a></li>
<li id="fn:38">Williams, David R. (2 February 2010). "Moon Fact Sheet". NASA (National Space Science Data Center). Archived from the original on 23 March 2010. Retrieved 9 April 2010. <a href="https://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html" target="_blank">https://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html</a> <a href="#fnref:38" class="footnote-back-ref">↩</a></li>
<li id="fn:39">Dolan, Michelle M.; Mathews, Grant J.; Lam, Doan Duc; Lan, Nguyen Quynh; Herczeg, Gregory J.; Dearborn, David S. P. (2017). "Evolutionary Tracks for Betelgeuse". The Astrophysical Journal. 819 (1): 7. arXiv:1406.3143. Bibcode:2016ApJ...819....7D. doi:10.3847/0004-637X/819/1/7. S2CID 37913442. <a href="https://doi.org/10.3847%2F0004-637X%2F819%2F1%2F7" target="_blank">https://doi.org/10.3847%2F0004-637X%2F819%2F1%2F7</a> <a href="#fnref:39" class="footnote-back-ref">↩</a></li>
<li id="fn:40">"Brightest comets seen since 1935". International Comet Quarterly. Archived from the original on 28 December 2011. Retrieved 18 December 2011. <a href="http://www.icq.eps.harvard.edu/brightest.html" target="_blank">http://www.icq.eps.harvard.edu/brightest.html</a> <a href="#fnref:40" class="footnote-back-ref">↩</a></li>
<li id="fn:41">Winkler, P. Frank; Gupta, Gaurav; Long, Knox S. (2003). "The SN 1006 Remnant: Optical Proper Motions, Deep Imaging, Distance, and Brightness at Maximum". The Astrophysical Journal. 585 (1): 324–335. arXiv:astro-ph/0208415. Bibcode:2003ApJ...585..324W. doi:10.1086/345985. S2CID 1626564. <a href="/wiki/The_Astrophysical_Journal" target="_blank">/wiki/The_Astrophysical_Journal</a> <a href="#fnref:41" class="footnote-back-ref">↩</a></li>
<li id="fn:42">Siegel, Ethan (6 September 2016). "Ten Ways 'Proxima b' Is Different From Earth". Forbes. Retrieved 19 February 2023. <a href="https://www.forbes.com/sites/startswithabang/2016/09/06/ten-ways-proxima-b-is-different-from-earth/" target="_blank">https://www.forbes.com/sites/startswithabang/2016/09/06/ten-ways-proxima-b-is-different-from-earth/</a> <a href="#fnref:42" class="footnote-back-ref">↩</a></li>
<li id="fn:43">"Supernova 1054 – Creation of the Crab Nebula". SEDS. Archived from the original on 28 May 2014. Retrieved 29 July 2014. <a href="http://messier.seds.org/more/m001_sn.html" target="_blank">http://messier.seds.org/more/m001_sn.html</a> <a href="#fnref:43" class="footnote-back-ref">↩</a></li>
<li id="fn:44">"Heavens-above.com". Heavens-above. Archived from the original on 5 July 2009. Retrieved 22 December 2007. <a href="http://www.heavens-above.com/satinfo.aspx?SatID=25544" target="_blank">http://www.heavens-above.com/satinfo.aspx?SatID=25544</a> <a href="#fnref:44" class="footnote-back-ref">↩</a></li>
<li id="fn:45">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:45" class="footnote-back-ref">↩</a></li>
<li id="fn:46">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:46" class="footnote-back-ref">↩</a></li>
<li id="fn:47">NASA Science Question of the Week. Gsfc.nasa.gov (7 April 2006). Retrieved on 26 April 2013. <a href="https://web.archive.org/web/20070627044109/http://www.gsfc.nasa.gov/scienceques2005/20060406.htm" target="_blank">https://web.archive.org/web/20070627044109/http://www.gsfc.nasa.gov/scienceques2005/20060406.htm</a> <a href="#fnref:47" class="footnote-back-ref">↩</a></li>
<li id="fn:48">Tomkin, Jocelyn (April 1998). "Once and Future Celestial Kings". Sky and Telescope. 95 (4): 59–63. Bibcode:1998S&T....95d..59T. – based on computations from HIPPARCOS data. (The calculations exclude stars whose distance or proper motion is uncertain.)
 <a href="https://www.thefreelibrary.com/Once+and+future+celestial+kings.-a020468305" target="_blank">https://www.thefreelibrary.com/Once+and+future+celestial+kings.-a020468305</a> <a href="#fnref:48" class="footnote-back-ref">↩</a></li>
<li id="fn:49">Agrawal, Dulli Chandra (30 March 2016). "Apparent magnitude of earthshine: a simple calculation". European Journal of Physics. 37 (3). IOP Publishing: 035601. Bibcode:2016EJPh...37c5601A. doi:10.1088/0143-0807/37/3/035601. ISSN 0143-0807. S2CID 124231299. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:49" class="footnote-back-ref">↩</a></li>
<li id="fn:50">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:50" class="footnote-back-ref">↩</a></li>
<li id="fn:51">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:51" class="footnote-back-ref">↩</a></li>
<li id="fn:52">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:52" class="footnote-back-ref">↩</a></li>
<li id="fn:53">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:53" class="footnote-back-ref">↩</a></li>
<li id="fn:54">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:54" class="footnote-back-ref">↩</a></li>
<li id="fn:55">"Sirius". SIMBAD Astronomical Database. Archived from the original on 11 January 2014. Retrieved 26 June 2010. <a href="http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Sirius" target="_blank">http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Sirius</a> <a href="#fnref:55" class="footnote-back-ref">↩</a></li>
<li id="fn:56">"Canopus". SIMBAD Astronomical Database. Archived from the original on 14 July 2014. Retrieved 26 June 2010. <a href="http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Canopus" target="_blank">http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Canopus</a> <a href="#fnref:56" class="footnote-back-ref">↩</a></li>
<li id="fn:57">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:57" class="footnote-back-ref">↩</a></li>
<li id="fn:58">"Arcturus". SIMBAD Astronomical Database. Archived from the original on 14 January 2014. Retrieved 26 June 2010. <a href="http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Arcturus" target="_blank">http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Arcturus</a> <a href="#fnref:58" class="footnote-back-ref">↩</a></li>
<li id="fn:59">"Vega". SIMBAD Astronomical Database. Archived from the original on 7 July 2015. Retrieved 14 April 2010. <a href="http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Vega" target="_blank">http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Vega</a> <a href="#fnref:59" class="footnote-back-ref">↩</a></li>
<li id="fn:60">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:60" class="footnote-back-ref">↩</a></li>
<li id="fn:61">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:61" class="footnote-back-ref">↩</a></li>
<li id="fn:62">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:62" class="footnote-back-ref">↩</a></li>
<li id="fn:63">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:63" class="footnote-back-ref">↩</a></li>
<li id="fn:64">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:64" class="footnote-back-ref">↩</a></li>
<li id="fn:65">Evans, N. R.; Schaefer, G. H.; Bond, H. E.; Bono, G.; Karovska, M.; Nelan, E.; Sasselov, D.; Mason, B. D. (2008). "Direct Detection of the Close Companion of Polaris with The Hubble Space Telescope". The Astronomical Journal. 136 (3): 1137. arXiv:0806.4904. Bibcode:2008AJ....136.1137E. doi:10.1088/0004-6256/136/3/1137. S2CID 16966094. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:65" class="footnote-back-ref">↩</a></li>
<li id="fn:66">"SIMBAD-M31". SIMBAD Astronomical Database. Archived from the original on 19 May 2014. Retrieved 29 November 2009. <a href="http://simbad.u-strasbg.fr/simbad/sim-id?Ident=M31" target="_blank">http://simbad.u-strasbg.fr/simbad/sim-id?Ident=M31</a> <a href="#fnref:66" class="footnote-back-ref">↩</a></li>
<li id="fn:67">Yeomans; Chamberlin. "Horizon Online Ephemeris System for Ganymede (Major Body 503)". California Institute of Technology, Jet Propulsion Laboratory. Archived from the original on 2 February 2014. Retrieved 14 April 2010. (4.38 on 1951-Oct-03) <a href="https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=mb&sstr=503" target="_blank">https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=mb&sstr=503</a> <a href="#fnref:67" class="footnote-back-ref">↩</a></li>
<li id="fn:68">"M41 possibly recorded by Aristotle". SEDS (Students for the Exploration and Development of Space). 28 July 2006. Archived from the original on 18 April 2017. Retrieved 29 November 2009. <a href="http://messier.seds.org/more/m041_ari.html" target="_blank">http://messier.seds.org/more/m041_ari.html</a> <a href="#fnref:68" class="footnote-back-ref">↩</a></li>
<li id="fn:69">"Uranus Fact Sheet". nssdc.gsfc.nasa.gov. Archived from the original on 22 January 2019. Retrieved 8 November 2018. <a href="https://nssdc.gsfc.nasa.gov/planetary/factsheet/uranusfact.html" target="_blank">https://nssdc.gsfc.nasa.gov/planetary/factsheet/uranusfact.html</a> <a href="#fnref:69" class="footnote-back-ref">↩</a></li>
<li id="fn:70">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:70" class="footnote-back-ref">↩</a></li>
<li id="fn:71">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:71" class="footnote-back-ref">↩</a></li>
<li id="fn:72">"SIMBAD-M33". SIMBAD Astronomical Database. Archived from the original on 13 September 2014. Retrieved 28 November 2009. <a href="http://simbad.u-strasbg.fr/simbad/sim-id?Ident=M33" target="_blank">http://simbad.u-strasbg.fr/simbad/sim-id?Ident=M33</a> <a href="#fnref:72" class="footnote-back-ref">↩</a></li>
<li id="fn:73">Lodriguss, Jerry (1993). "M33 (Triangulum Galaxy)". Archived from the original on 15 January 2010. Retrieved 27 November 2009. (Shows bolometric magnitude not visual magnitude.) <a href="http://www.astropix.com/HTML/A_FALL/M33.HTM" target="_blank">http://www.astropix.com/HTML/A_FALL/M33.HTM</a> <a href="#fnref:73" class="footnote-back-ref">↩</a></li>
<li id="fn:74">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:74" class="footnote-back-ref">↩</a></li>
<li id="fn:75">"Vmag<6.5". SIMBAD Astronomical Database. Archived from the original on 22 February 2015. Retrieved 25 June 2010. <a href="http://simbad.u-strasbg.fr/simbad/sim-sam?Criteria=Vmag%3C6.5" target="_blank">http://simbad.u-strasbg.fr/simbad/sim-sam?Criteria=Vmag%3C6.5</a> <a href="#fnref:75" class="footnote-back-ref">↩</a></li>
<li id="fn:76">"Messier 81". SEDS (Students for the Exploration and Development of Space). 2 September 2007. Archived from the original on 14 July 2017. Retrieved 28 November 2009. <a href="http://messier.seds.org/m/m081.html" target="_blank">http://messier.seds.org/m/m081.html</a> <a href="#fnref:76" class="footnote-back-ref">↩</a></li>
<li id="fn:77">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:77" class="footnote-back-ref">↩</a></li>
<li id="fn:78">"Neptune Fact Sheet". nssdc.gsfc.nasa.gov. Archived from the original on 10 January 2019. Retrieved 8 November 2018. <a href="https://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html" target="_blank">https://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html</a> <a href="#fnref:78" class="footnote-back-ref">↩</a></li>
<li id="fn:79">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:79" class="footnote-back-ref">↩</a></li>
<li id="fn:80">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:80" class="footnote-back-ref">↩</a></li>
<li id="fn:81">John E. Bortle (February 2001). "The Bortle Dark-Sky Scale". Sky & Telescope. Archived from the original on 23 March 2009. Retrieved 18 November 2009. <a href="https://skyandtelescope.org/astronomy-resources/light-pollution-and-astronomy-the-bortle-dark-sky-scale/" target="_blank">https://skyandtelescope.org/astronomy-resources/light-pollution-and-astronomy-the-bortle-dark-sky-scale/</a> <a href="#fnref:81" class="footnote-back-ref">↩</a></li>
<li id="fn:82">Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:82" class="footnote-back-ref">↩</a></li>
<li id="fn:83">Yeomans; Chamberlin. "Horizon Online Ephemeris System for Titan (Major Body 606)". California Institute of Technology, Jet Propulsion Laboratory. Archived from the original on 13 November 2012. Retrieved 28 June 2010. (8.10 on 2003-Dec-30) Archived 13 November 2012 at the Wayback Machine <a href="https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=mb&sstr=606" target="_blank">https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=mb&sstr=606</a> <a href="#fnref:83" class="footnote-back-ref">↩</a></li>
<li id="fn:84">"Classic Satellites of the Solar System". Observatorio ARVAL. Archived from the original on 31 July 2010. Retrieved 25 June 2010. <a href="https://web.archive.org/web/20100731193653/http://www.oarval.org/ClasSaten.htm" target="_blank">https://web.archive.org/web/20100731193653/http://www.oarval.org/ClasSaten.htm</a> <a href="#fnref:84" class="footnote-back-ref">↩</a></li>
<li id="fn:85">"Planetary Satellite Physical Parameters". JPL (Solar System Dynamics). 3 April 2009. Archived from the original on 23 July 2009. Retrieved 25 July 2009. <a href="https://ssd.jpl.nasa.gov/?sat_phys_par" target="_blank">https://ssd.jpl.nasa.gov/?sat_phys_par</a> <a href="#fnref:85" class="footnote-back-ref">↩</a></li>
<li id="fn:86">"AstDys (10) Hygiea Ephemerides". Department of Mathematics, University of Pisa, Italy. Archived from the original on 12 May 2014. Retrieved 26 June 2010. <a href="http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.3.1&n=10&oc=500&y0=2095&m0=6&d0=27&h0=00&mi0=00&y1=2095&m1=6&d1=28&h1=00&mi1=00&ti=1.0&tiu=days" target="_blank">http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.3.1&n=10&oc=500&y0=2095&m0=6&d0=27&h0=00&mi0=00&y1=2095&m1=6&d1=28&h1=00&mi1=00&ti=1.0&tiu=days</a> <a href="#fnref:86" class="footnote-back-ref">↩</a></li>
<li id="fn:87">Zarenski, Ed (2004). "Limiting Magnitude in Binoculars" (PDF). Cloudy Nights. Archived (PDF) from the original on 21 July 2011. Retrieved 6 May 2011. <a href="http://www.cloudynights.com/documents/limiting.pdf" target="_blank">http://www.cloudynights.com/documents/limiting.pdf</a> <a href="#fnref:87" class="footnote-back-ref">↩</a></li>
<li id="fn:88">"Tracking the Apollo Flights". Static Web Pages for Physics and Astronomy. 21 December 1968. Retrieved 20 March 2024. <a href="https://pages.astronomy.ua.edu/keel/space/apollo.html" target="_blank">https://pages.astronomy.ua.edu/keel/space/apollo.html</a> <a href="#fnref:88" class="footnote-back-ref">↩</a></li>
<li id="fn:89">"Classic Satellites of the Solar System". Observatorio ARVAL. Archived from the original on 31 July 2010. Retrieved 25 June 2010. <a href="https://web.archive.org/web/20100731193653/http://www.oarval.org/ClasSaten.htm" target="_blank">https://web.archive.org/web/20100731193653/http://www.oarval.org/ClasSaten.htm</a> <a href="#fnref:89" class="footnote-back-ref">↩</a></li>
<li id="fn:90">"What Is the Most Massive Star?". Space.com. Archived from the original on 11 January 2019. Retrieved 5 November 2018. <a href="https://www.space.com/41313-most-massive-star.html" target="_blank">https://www.space.com/41313-most-massive-star.html</a> <a href="#fnref:90" class="footnote-back-ref">↩</a></li>
<li id="fn:91">"Planetary Satellite Physical Parameters". JPL (Solar System Dynamics). 3 April 2009. Archived from the original on 23 July 2009. Retrieved 25 July 2009. <a href="https://ssd.jpl.nasa.gov/?sat_phys_par" target="_blank">https://ssd.jpl.nasa.gov/?sat_phys_par</a> <a href="#fnref:91" class="footnote-back-ref">↩</a></li>
<li id="fn:92">Williams, David R. (7 September 2006). "Pluto Fact Sheet". National Space Science Data Center. NASA. Archived from the original on 1 July 2010. Retrieved 26 June 2010. <a href="https://nssdc.gsfc.nasa.gov/planetary/factsheet/plutofact.html" target="_blank">https://nssdc.gsfc.nasa.gov/planetary/factsheet/plutofact.html</a> <a href="#fnref:92" class="footnote-back-ref">↩</a></li>
<li id="fn:93">"AstDys (2060) Chiron Ephemerides". Department of Mathematics, University of Pisa, Italy. Archived from the original on 29 June 2011. Retrieved 26 June 2010. <a href="https://newton.spacedys.com/astdys/index.php?pc=1.1.3.1&n=2060&oc=500&y0=2097&m0=4&d0=3&h0=00&mi0=00&y1=2097&m1=4&d1=3&h1=00&mi1=00&ti=1.0&tiu=days" target="_blank">https://newton.spacedys.com/astdys/index.php?pc=1.1.3.1&n=2060&oc=500&y0=2097&m0=4&d0=3&h0=00&mi0=00&y1=2097&m1=4&d1=3&h1=00&mi1=00&ti=1.0&tiu=days</a> <a href="#fnref:93" class="footnote-back-ref">↩</a></li>
<li id="fn:94">"AstDys (136472) Makemake Ephemerides". Department of Mathematics, University of Pisa, Italy. Archived from the original on 29 June 2011. Retrieved 26 June 2010. <a href="https://newton.spacedys.com/astdys/index.php?pc=1.1.3.1&n=136472&oc=500&y0=2010&m0=3&d0=17&h0=00&mi0=00&y1=2010&m1=3&d1=17&h1=00&mi1=00&ti=1.0&tiu=days" target="_blank">https://newton.spacedys.com/astdys/index.php?pc=1.1.3.1&n=136472&oc=500&y0=2010&m0=3&d0=17&h0=00&mi0=00&y1=2010&m1=3&d1=17&h1=00&mi1=00&ti=1.0&tiu=days</a> <a href="#fnref:94" class="footnote-back-ref">↩</a></li>
<li id="fn:95">"AstDys (136108) Haumea Ephemerides". Department of Mathematics, University of Pisa, Italy. Archived from the original on 29 June 2011. Retrieved 26 June 2010. <a href="https://newton.spacedys.com/astdys/index.php?pc=1.1.3.1&n=136108&oc=500&y0=2010&m0=4&d0=6&h0=00&mi0=00&y1=2010&m1=4&d1=6&h1=00&mi1=00&ti=1.0&tiu=days" target="_blank">https://newton.spacedys.com/astdys/index.php?pc=1.1.3.1&n=136108&oc=500&y0=2010&m0=4&d0=6&h0=00&mi0=00&y1=2010&m1=4&d1=6&h1=00&mi1=00&ti=1.0&tiu=days</a> <a href="#fnref:95" class="footnote-back-ref">↩</a></li>
<li id="fn:96">"Catalina Sky Survey (CSS) Facilities". Archived from the original on 3 November 2019. Retrieved 3 November 2019. <a href="https://catalina.lpl.arizona.edu/about/facilities" target="_blank">https://catalina.lpl.arizona.edu/about/facilities</a> <a href="#fnref:96" class="footnote-back-ref">↩</a></li>
<li id="fn:97">"Planetary Satellite Physical Parameters". JPL (Solar System Dynamics). 3 April 2009. Archived from the original on 23 July 2009. Retrieved 25 July 2009. <a href="https://ssd.jpl.nasa.gov/?sat_phys_par" target="_blank">https://ssd.jpl.nasa.gov/?sat_phys_par</a> <a href="#fnref:97" class="footnote-back-ref">↩</a></li>
<li id="fn:98">Steve Cullen (sgcullen) (5 October 2009). "17 New Asteroids Found by LightBuckets". LightBuckets. Archived from the original on 31 January 2010. Retrieved 15 November 2009. <a href="https://web.archive.org/web/20100131051349/http://www.lightbuckets.com/news/37/17-new-asteroids-found-by-lightbuckets/" target="_blank">https://web.archive.org/web/20100131051349/http://www.lightbuckets.com/news/37/17-new-asteroids-found-by-lightbuckets/</a> <a href="#fnref:98" class="footnote-back-ref">↩</a></li>
<li id="fn:99">Boffin, H.M.J.; Pourbaix, D. (2014). "Possible astrometric discovery of a substellar companion to the closest binary brown dwarf system WISE J104915.57–531906.1". Astronomy and Astrophysics. 561: 5. arXiv:1312.1303. Bibcode:2014A&A...561L...4B. doi:10.1051/0004-6361/201322975. S2CID 33043358. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:99" class="footnote-back-ref">↩</a></li>
<li id="fn:100">"Pan-STARRS limiting magnitude". Archived from the original on 24 November 2020. Retrieved 12 August 2019. <a href="https://web.archive.org/web/20201124152242/https://panstarrs.ifa.hawaii.edu/pswww/?page_id=34" target="_blank">https://web.archive.org/web/20201124152242/https://panstarrs.ifa.hawaii.edu/pswww/?page_id=34</a> <a href="#fnref:100" class="footnote-back-ref">↩</a></li>
<li id="fn:101">Sheppard, Scott S. "Saturn's Known Satellites". Carnegie Institution (Department of Terrestrial Magnetism). Archived from the original on 15 May 2011. Retrieved 28 June 2010. <a href="/wiki/Scott_S._Sheppard" target="_blank">/wiki/Scott_S._Sheppard</a> <a href="#fnref:101" class="footnote-back-ref">↩</a></li>
<li id="fn:102">What is the faintest object imaged by ground-based telescopes? Archived 2 February 2016 at the Wayback Machine, by: The Editors of Sky Telescope, 24 July 2006 <a href="http://www.skyandtelescope.com/astronomy-resources/astronomy-questions-answers/what-is-the-faintest-object-imaged-by-ground-based-telescopes/" target="_blank">http://www.skyandtelescope.com/astronomy-resources/astronomy-questions-answers/what-is-the-faintest-object-imaged-by-ground-based-telescopes/</a> <a href="#fnref:102" class="footnote-back-ref">↩</a></li>
<li id="fn:103">"New Image of Comet Halley in the Cold". ESO. 1 September 2003. Archived from the original on 13 March 2025. Retrieved 29 April 2025. <a href="https://web.archive.org/web/20250313011405/https://www.eso.org/public/news/eso0328/" target="_blank">https://web.archive.org/web/20250313011405/https://www.eso.org/public/news/eso0328/</a> <a href="#fnref:103" class="footnote-back-ref">↩</a></li>
<li id="fn:104">Robertson, B. E.; et al. (2023). "Identification and properties of intense star-forming galaxies at redshifts z > 10". Nature Astronomy. 7 (5): 611–621. arXiv:2212.04480. Bibcode:2023NatAs...7..611R. doi:10.1038/s41550-023-01921-1. S2CID 257968812. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:104" class="footnote-back-ref">↩</a></li>
<li id="fn:105">Illingworth, G. D.; Magee, D.; Oesch, P. A.; Bouwens, R. J.; Labbé, I.; Stiavelli, M.; van Dokkum, P. G.; Franx, M.; Trenti, M.; Carollo, C. M.; Gonzalez, V. (21 October 2013). "The HST eXtreme Deep Field XDF: Combining all ACS and WFC3/IR Data on the HUDF Region into the Deepest Field Ever". The Astrophysical Journal Supplement Series. 209 (1): 6. arXiv:1305.1931. Bibcode:2013ApJS..209....6I. doi:10.1088/0067-0049/209/1/6. S2CID 55052332. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:105" class="footnote-back-ref">↩</a></li>
<li id="fn:106">"Hubble Finds Smallest Kuiper Belt Object Ever Seen". NASA. Archived from the original on 9 June 2017. Retrieved 16 March 2018. <a href="https://www.nasa.gov/mission_pages/hubble/science/hst_img_kuiper-smallest.html" target="_blank">https://www.nasa.gov/mission_pages/hubble/science/hst_img_kuiper-smallest.html</a> <a href="#fnref:106" class="footnote-back-ref">↩</a></li>
</ol>

Apparent magnitude open-in-new

Apparent magnitude