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Optical Gravitational Lensing Experiment
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<h2 id="description">Description</h2> <p>The main targets of the experiment are the <a href="/facts/Magellanic_Clouds/WEspxUJl">Magellanic Clouds</a> and the <a href="/facts/Galactic_Bulge/cjJ0LFan">Galactic Bulge</a>, because of the large number of intervening stars that can be used for microlensing during a stellar <a href="/facts/Astronomical_transit/4s6Mll1a">transit</a>. Most of the observations have been made at the <a href="/facts/Las_Campanas_Observatory/6F9vgR2t">Las Campanas Observatory</a> in <a href="/facts/Chile/uEyTfEcx">Chile</a>. Cooperating institutions include <a href="/facts/Princeton_University/n3EPGHBM">Princeton University</a> and the <a href="/facts/Carnegie_Institution/zS5MqNUP">Carnegie Institution</a>. </p><p>The project is now in its fourth phase. The first phase, OGLE-I (1992–1995), used the 1.0-metre (3 ft 3 in) Swope telescope and a single-chip <a href="/facts/Charge-coupled_device/l6xffIcz">CCD</a> sensor. For OGLE-II (1996–2000), a 1.3-metre (4 ft 3 in) <a href="/facts/Telescope/BDwYahhR">telescope</a> dedicated to the project (the Warsaw telescope) was constructed at Las Campanas Observatory. It was equipped with a single 2048×2048 pixel sensor with a field of view 0.237 degrees wide.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> </p><p>OGLE-III (2001–2009) expanded the camera to a mosaic of eight 2048×4096 pixel CCDs, and was able to search for gravitational microlensing events and transiting planets in four fields: the <a href="/facts/Galactic_Bulge/cjJ0LFan">Galactic Bulge</a>, the constellation <a href="/facts/Carina_(constellation)/WmAhubMs">Carina</a>,<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> and toward both <a href="/facts/Magellanic_Clouds/WEspxUJl">Magellanic Clouds</a>. As a byproduct of the constant monitoring of hundreds of millions of stars, the largest catalogs of variable stars were constructed, and the first exoplanets discovered using the microlensing technique were detected. </p><p>In 2010, following engineering work in 2009, the fourth and current phase, OGLE-IV, was started using a 32-chip mosaic CCD camera which fills the Warsaw telescope's 1.5° field of view.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> The main goal for this phase is to increase the number of planetary detections using microlensing, enabled by the new camera. </p><p>Recently the OGLE team, in cooperation with scientists mostly from the US, New Zealand and Japan, proved that small, Earth-like planets can exist at a significant distance from stars around which they revolve despite there being other stars near them.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a><a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> </p><p>In January 2022 in collaboration with <a href="/facts/Microlensing_Observations_in_Astrophysics/dqGxw4QI">Microlensing Observations in Astrophysics</a> (MOA) they reported in a preprint the first <a href="/facts/Rogue_black_hole/9FuK3vAU">rogue black hole</a>.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a><a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a><a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a><a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> While there have been other candidates<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> this is the most solid detection so far as their technique allowed to measure not only the amplification of light but also its deflection by the BH from the microlensing data. </p> <h2 id="planets-discovered">Planets discovered</h2> <p>At least seventeen planets have so far been discovered by the OGLE project. Eight of the planets were discovered by the <a href="/facts/Methods_of_detecting_extrasolar_planets/vFIblQe9">transit method</a> and six by the <a href="/facts/Methods_of_detecting_extrasolar_planets/vFIblQe9">gravitational microlensing method</a>. </p><p>Planets are shown in the order of discovery. Planets in multiple-planet systems are highlighted in yellow. The list below may not be complete. </p> <p><i>Notes: For events detected by the gravitational microlensing method, year stands for OGLE season, BLG means that an event detected is in the Galactic BuLGe, and the following 3-digit number is an ordinal number of microlensing event in that season. For events detected by the transit method TR stands for TRansit and the following 3-digit number is an ordinal number of transit event.</i> </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Variable_stars/Ac8mp2gy">Variable stars</a></li> <li><a href="/facts/Cepheids/WQXaAFmW">Cepheids</a></li> <li><a href="/facts/All_Sky_Automated_Survey/wK8SX3BF">All Sky Automated Survey</a></li> <li><a href="/facts/Bohdan_Paczy%C5%84ski/N1ztszkU">Bohdan Paczyński</a></li> <li><a href="/facts/Andrzej_Udalski/uQQhWkkw">Andrzej Udalski</a></li> <li><a href="/facts/Grzegorz_Pojma%C5%84ski/gDhsNkKC">Grzegorz Pojmański</a></li> <li><a href="/facts/List_of_planetary_systems/5A2I6REh">List of planetary systems</a></li> <li><a href="/facts/Microlensing_Observations_in_Astrophysics/dqGxw4QI">Microlensing Observations in Astrophysics</a> (MOA)</li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="http://ogle.astrouw.edu.pl/">OGLE Homepage in Warsaw, Poland</a></li> <li>OGLE-IV <a href="http://www.astrouw.edu.pl/~jskowron/ogle4-sky/">sky coverage maps</a></li> <li>Detailed <a href="http://ogle.astrouw.edu.pl/sky/ogle4-fields.html">OGLE-IV fields</a> diagrams</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Udalski, A.; Kubiak, M.; Szymański, M. (1997). "Optical Gravitational Lensing Experiment. OGLE-2 – the Second Phase of the OGLE Project" (PDF). Acta Astronomica. 47 (3): 319–344. arXiv:astro-ph/9710091. Bibcode:1997AcA....47..319U. CiteSeerX 10.1.1.315.9784. <a href="http://acta.astrouw.edu.pl/Vol47/n3/pap_47_3_1.pdf" target="_blank">http://acta.astrouw.edu.pl/Vol47/n3/pap_47_3_1.pdf</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Udalski, Andrzej (2003). "The Optical Gravitational Lensing Experiment. Real Time Data Analysis Systems in the OGLE-III Survey" (PDF). Acta Astronomica. 53 (4): 291–306. arXiv:astro-ph/0401123. Bibcode:2003AcA....53..291U. CiteSeerX 10.1.1.316.4693. <a href="http://acta.astrouw.edu.pl/Vol53/n4/pap_53_4_1.pdf" target="_blank">http://acta.astrouw.edu.pl/Vol53/n4/pap_53_4_1.pdf</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Udalski, A.; Szymański, M. K.; Szymański, G. (2015). "OGLE-IV: Fourth Phase of the Optical Gravitational Lensing Experiment" (PDF). Acta Astronomica. 65 (1): 1–38. arXiv:1504.05966. Bibcode:2015AcA....65....1U. <a href="http://acta.astrouw.edu.pl/Vol65/n1/pdf/pap_65_1_1.pdf" target="_blank">http://acta.astrouw.edu.pl/Vol65/n1/pdf/pap_65_1_1.pdf</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"Laureaci FNP odkryli zimną Ziemię" [FNP laureates have discovered a cold Earth] (in Polish). Foundation for Polish Science (FNP). 7 July 2014. Retrieved 13 November 2020. <a href="https://www.fnp.org.pl/laureaci-fnp-odkryli-zimna-ziemie/" target="_blank">https://www.fnp.org.pl/laureaci-fnp-odkryli-zimna-ziemie/</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Gould, A.; et al. (4 July 2014). "A terrestrial planet in a ~1-AU orbit around one member of a ~15-AU binary". Science. 345 (6192): 46–49. arXiv:1407.1115. Bibcode:2014Sci...345...46G. doi:10.1126/science.1251527. PMID 24994642. S2CID 206555598. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Sahu, Kailash C.; Anderson, Jay; Casertano, Stefano; Bond, Howard E.; Udalski, Andrzej; Dominik, Martin; Calamida, Annalisa; Bellini, Andrea; Brown, Thomas M.; Rejkuba, Marina; Bajaj, Varun (2022-05-25). "An Isolated Stellar-mass Black Hole Detected through Astrometric Microlensing". The Astrophysical Journal. 933 (1): 83. arXiv:2201.13296. Bibcode:2022ApJ...933...83S. doi:10.3847/1538-4357/ac739e. S2CID 246430448. <a href="https://doi.org/10.3847%2F1538-4357%2Fac739e" target="_blank">https://doi.org/10.3847%2F1538-4357%2Fac739e</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Lam, Casey Y.; Lu, Jessica R.; Udalski, Andrzej; Bond, Ian; Bennett, David P.; Skowron, Jan; Mroz, Przemek; Poleski, Radek; Sumi, Takahiro; Szymanski, Michal K.; Kozlowski, Szymon (2022-05-31). "An Isolated Mass-gap Black Hole or Neutron Star Detected with Astrometric Microlensing". The Astrophysical Journal Letters. 933 (1): L23. arXiv:2202.01903. Bibcode:2022ApJ...933L..23L. doi:10.3847/2041-8213/ac7442. S2CID 246608178. <a href="https://doi.org/10.3847%2F2041-8213%2Fac7442" target="_blank">https://doi.org/10.3847%2F2041-8213%2Fac7442</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Gianopoulos, Andrea (2022-06-07). "Hubble Determines Mass of Isolated Black Hole Roaming Milky Way". NASA. Retrieved 2022-06-12. <a href="https://www.nasa.gov/feature/goddard/2022/hubble-determines-mass-of-isolated-black-hole-roaming-our-milky-way-galaxy" target="_blank">https://www.nasa.gov/feature/goddard/2022/hubble-determines-mass-of-isolated-black-hole-roaming-our-milky-way-galaxy</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>O'Callaghan, Jonathan. "Astronomers Find First Ever Rogue Black Hole Adrift in the Milky Way". Scientific American. Retrieved 2022-02-08. <a href="https://www.scientificamerican.com/article/astronomers-find-first-ever-rogue-black-hole-adrift-in-the-milky-way/" target="_blank">https://www.scientificamerican.com/article/astronomers-find-first-ever-rogue-black-hole-adrift-in-the-milky-way/</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Bennett, D. P.; Becker, A. C.; Quinn, J. L.; Tomaney, A. B.; Alcock, C.; Allsman, R. A.; Alves, D. R.; Axelrod, T. S.; Calitz, J. J.; Cook, K. H.; Drake, A. J. (2002-11-10). "Gravitational Microlensing Events Due to Stellar-Mass Black Holes". The Astrophysical Journal. 579 (2): 639–659. arXiv:astro-ph/0109467. Bibcode:2002ApJ...579..639B. doi:10.1086/342225. ISSN 0004-637X. S2CID 44193135. <a href="https://iopscience.iop.org/article/10.1086/342225" target="_blank">https://iopscience.iop.org/article/10.1086/342225</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> </ol>