ASASSN-V J213939.3-702817.4 (also known as ASAS-SN-V J213939.3-702817.4 and J213939.3-702817.4) is a star, previously non-variable, found to be associated with an unusual, deep dimming event that was uncovered by the All Sky Automated Survey for SuperNovae (ASAS-SN) project, and first reported on 4 June 2019 in The Astronomer's Telegram. The star, in the constellation of Indus, about away, was first observed on 13 May 2014 (UT) by ASAS-SN, and, as of 4 June 2019, has resulted in more than 1580 data points, including a quiescent mean magnitude of g~12.95. On 4 June 2019, the star was reported to have dimmed gradually from g~12.96 at HJD 2458635.78, to g~14.22 at 2458637.95, and, as of 4 June 2019, seems to be returning to its quiescent state of g~13.29 at HJD 2458638.89. According to astronomer Tharindu Jayasinghe, one of the discoverers of the deep dimming event, "[The star has] been quiescent for so long and then suddenly decreased in brightness by a huge amount ... Why that happened, we don't know yet." See also Disrupted planet List of stars that have unusual dimming periods References External links , a presentation by Tabetha S. Boyajian (2016). , a presentation by Issac Arthur (2016). , star with unusual light fluctuations (2017). , up to 80% dimming (2019). Astronomical objects discovered in 2019 Indus (constellation) 2019 in science Unsolved problems in astronomy Unexplained phenomena F-type main-sequence stars