- vsnet-alert - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-alert 26181]TYC 1799-1159-1: eclipse predicted for Aug. 28.80 UT
by Patrick Schmeer 27 Aug '21

27 Aug '21

TYC 1799-1159-1 RA and DEC: 03 39 33.881 +22 31 40.33 (Gaia EDR3, equinox J2000.0, epoch J2016.0) Magnitude: V= 10.5 (outside eclipse) The next eclipse of this newly discovered variable star is predicted for 2021 Aug 28.80 UT. Time-resolved photometry and spectroscopy are encouraged. The following text was written by Ulrich Bastian on 11 August 2021: Back in January 2021, the bright star TYC 1799-1159-1 (9th-magnitude in the red wavelength range; in the visual range it is about 10th magnitude) was serendipitously discovered by German amateur Martin Gertz to be an eclipsing binary. In the night to March 7, a second minimum was observed, and an earlier third dimming by 0.5 mag was found in the ASAS-SN database. All three are separated by multiples of 34.987 days, so the fact is confirmed. However, the character of the light curve (period, 0.5 mag depth of the eclipse, shape and width of the minima), together with the parallax and HRD location of the star from Gaia eDR3, seemingly makes it an astrophysical impossibility. No conceivable combination of two stars could produce this whole set of characteristics, while at the same time the triple occurrence of the minima completely excludes any interstellar or solar-system occultations. Thus, more observations during the forthcoming observing season 2021/2022 are urgently desired. The star is located at 3 39 33.8 +22 31 41 (J2000), about 2 degrees south-west of the Pleiades' centre (it is not a cluster member). Minima are predicted to occur at the following times: Ep. no. JD-2459000 Date MEZ/MESZ UTC comment - 4 (140.365) (ASAS-SN dimming) - 3 175.401 21.11.2020 22:37 MEZ 21:37 observed Gertz + 0 280.362 06.03.2021 21:42 MEZ 20.42 observed Gertz + 5 455.297 28.08.2021 21:08 MESZ 19:08 Europe no; Japan? + 6 490.284 02.10.2021 20:49 MESZ 18:49 Europe no; Japan? + 7 525.271 06.11.2021 19:30 MEZ 18:30 Europe yes + 8 560.258 11.12.2021 19:11 MEZ 18:11 Europe & US yes, + 9 595.245 15.01.2022 18:53 MEZ 17:53 Europe & US yes +10 630.232 19.02.2022 18:34 MEZ 17:34 Europe & US yes The formal uncertainties of the times are less than 0.5 hours at the beginning and less than 1 hour towards the end of the observing season, but given the completely unclear nature of the system, period changes cannot be excluded. Also, the duration of the minima is unpredictable: The first lasted 40 minutes in total, the second took more than 1 hour for just the recovery from minimum to normal light. It is therefore desirable to get as much data coverage as possible for intervals of plus/minus one day around the predicted minima. Given the clear inconsistency of the two recorded minima shapes - and given the fact hat no dimmings have been found in several photometric archives before Oct 2020 - it is even possible that no further minima will occur at all.

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[vsnet-alert 26180]Gaia17bcx outburst
by Taichi Kato 27 Aug '21

27 Aug '21

Gaia17bcx outburst Relatively regular outbursts in the past ZTF data. Type not conclusive. YYYYMMDD(UT) mag observer 20210813.2639 20.441zg (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210820.2879 16.736zg (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210823.1819 16.064zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210823.2180 15.588zg (Zwicky Transient Facility Lasair (Masci+ 2019))

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[vsnet-alert 26179]CRTS J064804.5+414702 superoutburst
by Taichi Kato 27 Aug '21

27 Aug '21

CRTS J064804.5+414702 superoutburst YYYYMMDD(UT) mag observer 20210812.4971 18.805zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210812.5044 18.889zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210817.4860 16.310zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210817.4886 16.314zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210817.4911 16.353zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210817.4936 16.341zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210817.4962 16.331zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210817.4976 16.347zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210817.5000 16.321zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210817.5024 16.307zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210817.5048 16.263zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210817.5072 16.215zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210818.4863 16.495zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210818.4887 16.476zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210818.4912 16.449zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210818.4936 16.450zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210818.4960 16.401zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210818.4980 16.387zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210818.5003 16.364zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210818.5027 16.342zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210818.5051 16.330zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210818.5075 16.346zr (Zwicky Transient Facility Lasair (Masci+ 2019)) Also Gaia detection: http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia21dyz/

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[vsnet-alert 26178]V2109 Oph (1969 nova) undergoing a dwarf-nova outburst
by Taichi Kato 27 Aug '21

27 Aug '21

V2109 Oph (1969 nova) undergoing a dwarf-nova outburst http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia21dza/ ZTF data: Slowly rising. The orbital period appears to be long, which would explain why dwarf-nova outbursts occur less than 50 years after the nova eruption. YYYYMMDD(UT) mag observer 20210522.6098 <161C (Masayuki Moriyama) 20210529.5639 <162C (Masayuki Moriyama) 20210708.2728 18.919zg (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210711.2099 18.779zg (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210717.2314 18.482zg (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210728.2110 17.740zg (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210804.1900 17.560zg (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210813.1726 17.119zg (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210813.1896 16.475zr (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210815.2105 16.839zg (Zwicky Transient Facility Lasair (Masci+ 2019)) 20210821.1747 17.021zg (Zwicky Transient Facility Lasair (Masci+ 2019))

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