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

[vsnet-chat 9430] Update ephemeris for ASASSN-14ix (regarding Bruch's paper)
by Taichi Kato 31 Aug '23

31 Aug '23

Update ephemeris for ASASSN-14ix (regarding Bruch's paper) In relation to: https://arxiv.org/pdf/2308.16106.pdf > The only available information consists of informal > communications (Hambsch 2014a,b) reporting deep eclipses > and an orbital period of 0.1444610954(1) d > The formal accuracy of this value must be grossly overestimated. > It would lead to an error of eclipse epochs of merely 2.2 sec over a > time base of 100 years! I updated the ephemeris using the same data (not using TESS). Min(BJD) = 2457008.54251(3) + 0.144461097(4) E The value posted to vsnet-alert was a result of quick analysis (not involving a sufficient number of iterations), but was not "grossly overestimated". The MCMC chain is well-mixed and there is no anomaly in the posterior probability. The author needs to know that the error can be much smaller than one would assume naively or smaller than the exposure time, particularly in eclipsing systems with rapid ingress and egress, and if long-baseline collective data are analyzed. It is also not apparent in this paper who was responsible for the accuracy of this value.

1 0

[vsnet-chat 9429] AO Her in 2021 and anomaly in visual observations
by Taichi Kato 20 Jul '23

20 Jul '23

AO Her in 2021 and anomaly in visual observations Prompted by BAA VSS Circular No. 196, I checked the past light curve of the R CrB star AO Her. The observations by two most prominent visual observers around the 2021 fading did not agree at all with CCD observations. They (and also Jose Ripero, as I suggested in vsnet-alert regarding other objects) didn't notice the start of the July-Aug. fading for more than two weeks. They reported unreal fading in Apr.-June. They also didn't notice the brightening in the later half of 2020. The reported values, however, agreed very well between these observers (but no correlation with CCD observations). A naive interpretation of this strange phenomenon would be that these observers were copying other persons' observations each other. They were not correlated with actual variations and researchers should pay attention when using any database (e.g. AAVSO) containing observations of these observers. Of course, I had noticed the sign from the past (already in 1996 in V705 Cas, which was interpreted as a "telephone effect" by Gary Poyner if I remember correctly), but the present case and other cases are too apparent with sufficient evidence in the presence of modern CCD data.

1 0

[vsnet-chat 9428] VSOLK bulletin no.121
by meineko 18 Jul '23

18 Jul '23

No.121 2023 Jul. SDSS J183131.63+420220.2: AM CVn star showing ER UMa-type behavior and long standstill Taichi Kato http://vsolj.cetus-net.org/bulletin.html -------- Seiichiro Kiyota VSOLJ

1 0

[vsnet-chat 9427] No 0.1-d period in V2491 Cyg
by Taichi Kato 13 Jul '23

13 Jul '23

No 0.1-d period in V2491 Cyg https://ui.adsabs.harvard.edu/abs/2011A%26A...530A..70D/abstract "On the progenitor system of Nova V2491 Cygni" No such period was detected in the ZTF data. Two time-resolved runs in the ZTF data did not show any sign of such a period. The detection by this paper was probably spurious. There was no sign of the reported possible spin period (see Zemko et al. 2015).

1 0

[vsnet-chat 9426] ASASSN-19ir in AAVSO VSX
by Taichi Kato 05 Jul '23

05 Jul '23

https://www.aavso.org/vsx/index.php?view=detail.top&oid=687324 You may have missed vsnet-chat 9423.

1 0

[vsnet-chat 9425] VSOLJ Variable star bulletin No.120
by meineko 01 Jul '23

01 Jul '23

No.120 2023 Jul. ASASSN-22ak: La Belle au bois dormant in a hydrogen-depleted dwarf nova? Taichi Kato, Franz-Josef Hambsch, Berto Monard and Rod Stubbings http://vsolj.cetus-net.org/bulletin.html --------------- Seiichiro Kiyota VSOLJ

1 0

[vsnet-chat 9424] TCP J01050918+3928154 = 87GB_01023+3912 (AGN)
by Taichi Kato 26 Jun '23

26 Jun '23

TCP J01050918+3928154 = 87GB_01023+3912 (AGN) 010509.3 +392814 (2000.0) QSO_87GB01023+3912 19.69 z=0.083 S? 010509.1 +392815 (2000.0) ZTFJ010509.19+392815.3 r=19.996 (19.262-20.382) P=0.9942 010509.3 +392814 (2000.0) (VV12)87GB_01023+3912 AGN 19.69 z=0.083 S?

1 0

[vsnet-chat 9423] ASASSN-19ir: most likely WZ Sge star with multiple rebrightenings
by Taichi Kato 20 Jun '23

20 Jun '23

ASASSN-19ir: most likely WZ Sge star with multiple rebrightenings From ZTF data. The quiescence should be fainter.

1 0

[vsnet-chat 9422] ASASSN-18ho: WZ Sge star with long rebrightening
by Taichi Kato 16 Jun '23

16 Jun '23

ASASSN-18ho: WZ Sge star with long rebrightening From ASAS-SN DB data. Similar to WZ Sge.

1 0

[vsnet-chat 9421] ASASSN-17ju: WZ Sge star with long or multiple rebrightening
by Taichi Kato 15 Jun '23

15 Jun '23

ASASSN-17ju: WZ Sge star with long or multiple rebrightening From ATLAS data. Similar to WZ Sge.

1 0

2024

2023

2022

2021