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

[vsnet-chat 9438] TCP J08080872-1948465 = ZTF26aaeneoc; a candidate period bouncer or an AM CVn star in outburst
by Yusuke Tampo 17 Feb '26

17 Feb '26

TCP J08080872-1948465 = ZTF26aaeneoc; a candidate period bouncer or an AM CVn star in outburst The ZTF light curve shows the first plateau for ~7 days with an outburst amplitude of ~7 mag, a dip of >2 mag, and recovery on 16 Feb, currently around 18 mag. Such a double-superoutburst feature is common in period bouncers and long-period AM CVn stars. https://alerce.online/object/ZTF26aaeneoc https://vsx.aavso.org/index.php?view=detail.top&oid=10868354 -- ---------------------------------------------- South African Astronomical Observatory, Postdoc fellow Yusuke TAMPO / 反保雄介 EMAIL: tampo(a)kusastro.kyoto-u.ac.jp ALT. EMAIL: yusuke(a)saao.ac.za ----------------------------------------------

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[vsnet-chat 9437] AG Carinae Decline
by Peter Williams 12 Aug '25

12 Aug '25

The SDOR / LBV star AG Car has faded in recent weeks as indicated by the following selected visual observations. CARAG 20250202.481 66 WPX CARAG 20250215.479 67 WPX CARAG 20250221.437 66 WPX CARAG 20250402.436 69 WPX CARAG 20250411.455 67 WPX CARAG 20250418.428 69 WPX CARAG 20250423.396 70 WPX CRAAG 20250502.466 70 WPX CARAG 20250530.381 71 WPX CARAG 20250620.437 71 WPX CARAG 20250624.354 71 WPX CARAG 20250712.405 72 WPX CARAG 20250719.393 72 WPX CARAG 20250806.382 72 WPX Tks & regards Peter Williams Heathcote NSW 10x50mm binoculars

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[vsnet-chat 9436] ASASSN-15ca: SU UMa-type dwarf nova
by Yusuke Tampo 28 May '25

28 May '25

ASASSN-15ca: SU UMa-type dwarf nova According to ASAS-SN and Atlas, outbursts in Jan. 2015, Feb 2022, and May 2025 (as AT 2025mbw reported by MASTER). My observations with the SAAO/Lesedi telescope on 27 May 2025 detected superhumps with a period of ~0.0589(2) d. -- ---------------------------------------------- South African Astronomical Observatory, Postdoc fellow Yusuke TAMPO / 反保雄介 EMAIL: tampo(a)kusastro.kyoto-u.ac.jp ALT. EMAIL: yusuke(a)saao.ac.za ----------------------------------------------

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[vsnet-chat 9435] maintenance power outrage
by Katsuki Muraoka 31 Oct '24

31 Oct '24

Dear, VSNET members, I'm Katsuki Muraoka, a M2 student of Kyoto University. I must inform you all that there will be a maintenance power outage for the Kyoto Univ. building on this weekend, so VSNET server must be shut down in advance. The shutdown is scheduled to occur around 16:00 JST on November 2nd (UTC: 07:00), and the system is scheduled to be restored at around 17:30 JST (UTC: 08:30) on November 3rd. Thank you for your cooperation. Katsuki Muraoka

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[vsnet-chat 9434] Gaia J154008.28-392917.6 = ASASSN-24fy: orbital period
by Kojiguchi 09 Oct '24

09 Oct '24

Gaia J154008.28-392917.6 = ASASSN-24fy: orbital period From TESS data. Porb=0.054976(1) d.

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[vsnet-chat 9431] Patrick Schmeer contact
by Gianluca Masi 24 Jun '24

24 Jun '24

Hello everyone, I would like to kindly ask if someone has a valid email contact to reach Patrick Schmeer, his old yahoo.de account seems no longer valid. Thank you very much Gianluca Masi

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[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.

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[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.

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[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

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[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).

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