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

[vsnet-alert 28120] TCP J05384230+7051377: new WZ Sge-type dwarf nova
by 保家大将 21 Nov '25

21 Nov '25

TCP J05384230+7051377: new WZ Sge-type dwarf nova We posted our spectroscopic follow-up result of TCP J05384230+7051377 to ATel. ATel #17485: Spectroscopic confirmation of TCP J05384230+7051377 as a WZ Sge-type dwarf nova <https://www.astronomerstelegram.org/?read=17485> We concluded that this object is a new WZ Sge-type dwarf nova because Hα has a narrow emission core and its spectrum shows a blue continuum with the Balmer and HeI absorption lines. Also, we estimated this object as p ~ 0.06d from Itoh-san's data. However p ~ 0.06d is a weak signal, so further observation will provide a more accurate estimate of the period. best regard, Hiromasa Hoke

2 3

[vsnet-alert 28125] TCP J09370380+1657350: possible new superoutburst
by Kojiguchi 19 Nov '25

19 Nov '25

TCP J09370380+1657350: possible new superoutburst Gavin Ramsay reported that GOTO detected TCP J09370380+1657350 in outburst on 2025 Nov 18 03:41:50 UT (20251118.1534). Reported magnitude: L = 16.18 (400–700 nm). This object was previously identified as a WZ Sge-type system. For reference, see also the past report: [vsnet-alert 25216] TCP J09370380+1657350: new WZ Sge-type dwarf nova [vsnet-alert 25218] Spectrum of TCP J09370380+1657350 http://www.astronomerstelegram.org/?read=14309 https://vsx.aavso.org/index.php?view=detail.top&oid=2215274

2 1

[vsnet-alert 28123] TCP J21314718+3825463: new SU UMa-type dwarf nova
by tonny.vanmunster＠gmail.com 15 Nov '25

15 Nov '25

Dear colleagues, TCP J21314718+3825463 was discovered by XOSS (Xingming Observatory Sky Survey) on 2025 Nov 07.6 at mag 14.70C. The quiescent counterpart is a 22.5 g mag star, implying an outburst amplitude of ~8 mag. I have just completed the analysis of my unfiltered CCD observations of TCP J21314718+3825463, obtained on 2025 Nov 11/12 and Nov 14/15 at CBA Extremadura Observatory. The data were acquired under clear skies with a 0.40-m f/5.1 telescope and a Moravian G2-4000 CCD camera. The Nov 11/12 light curve did not reveal any obvious modulation. However, the Nov 14/15 light curve clearly shows regular superhump modulations with an amplitude of 0.23 mag. A period analysis performed with ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0567 +/- 0.0016d. The object was measured at mag CV = 16.0 on Nov 15th. Image calibration and photometry were carried out using the latest release of Phoranso, which enabled simultaneous photometry of several additional variable stars in the same field of view. These results establish TCP J21314718+3825463 as a new SU UMa-type dwarf nova. Further follow-up observations are strongly encouraged to refine the superhump period and study its evolution. I will submit my observations to AAVSO, CBA and VSNET for further analysis. With kind regards, Tonny --- Tonny Vanmunster CBA Belgium Observatory CBA Extremadura Observatory http://www.cbabelgium.co <http://www.cbabelgium.com/> m PERANSO : The Light Curve and Period Analysis Software http://www.peranso.co <http://www.peranso.com/> m PHORANSO: Photometric Reduction and Analysis Software http://www.phoranso.com <http://www.phoranso.com/>

1 0

[vsnet-alert 28122] AS 221: a possible symbiotic nova
by Berto Monard 10 Nov '25

10 Nov '25

AS 221 is a symbiotic star system that has recently become significantly brighter. Observations in V and I have been done at the Kleinkaroo Observatory for over 20 resp.10 years with magnitudes evolving in the ranges 15-18V and 12.5-13.5I. The most recent observation was on 2025 Nov 09.76: 13.74V 11.57I. With the observing season nearing the end here, I would like to encourage further observation in V and I from observers at locations that can do so. AS 221: (2000)": 17 12 12.9 -32 37 47 A starchart for photometric reference is attached. Berto Monard / KKO

1 0

[vsnet-alert 28121] TCP J00534786+1617214: new SU UMa-type dwarf nova
by tonny.vanmunster＠gmail.com 10 Nov '25

10 Nov '25

Dear colleagues, TCP J00534786+1617214 (aka ASASSN-25ei) was discovered by Y. Nakamura, Japan on 2025 Nov 1.5 at mag 14.4 U. The quiescent counterpart is a 22.0 g mag star, implying an outburst amplitude of ~7.6 mag. I have just completed the analysis of my unfiltered CCD observations of TCP J00534786+1617214, obtained on 2025 Nov 08/09 at CBA Belgium Observatory. The data were acquired under clear skies with a 0.40-m f/10.0 telescope and a QHY-268M CMOS camera under clear skies. The light curve clearly exhibits regular superhump modulations with an amplitude of 0.19 mag. Period analysis with ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0624 +/- 0.0010d. The object was measured at mag CV = 15.5 on Nov 08th. Image calibration and photometry were performed with the latest release of Phoranso. These results establish TCP J00534786+1617214 as a new SU UMa-type dwarf nova. Follow-up observations are encouraged. I will submit my observations to AAVSO, CBA and VSNET for further analysis. With kind regards, Tonny --- Tonny Vanmunster CBA Belgium Observatory CBA Extremadura Observatory http://www.cbabelgium.co <http://www.cbabelgium.com/> m PERANSO : The Light Curve and Period Analysis Software http://www.peranso.co <http://www.peranso.com/> m PHORANSO: Photometric Reduction and Analysis Software http://www.phoranso.com <http://www.phoranso.com/>

1 0

[vsnet-alert 28114] 1eRASS J072044.9-402838 = PNV J07204545-4028357 = ASASSN-25ee: new SU UMa-type dwarf nova, likely WZ Sge-type
by Yusuke Tampo 05 Nov '25

05 Nov '25

1eRASS J072044.9-402838 = PNV J07204545-4028357 = ASASSN-25ee: new SU UMa-type dwarf nova, likely WZ Sge-type 1eRASS J072044.9-402838 was originally identified as a CV candidate in Rodriguez et al. (2025), G = 19.2 mag at ~267 pc, hence its absolute magnitude of ~12 mag. https://vsx.aavso.org/index.php?view=detail.top&oid=10868116 https://ui.adsabs.harvard.edu/abs/2025PASP..137a4201R/abstract ASASSN and John Seach discovered its 2025 outburst, peaking at ~11.0 mag around 20th October. https://www.astronomy.ohio-state.edu/asassn/transients.html http://www.cbat.eps.harvard.edu/unconf/followups/J07204545-4028357.html We, the SAAO team, obtained the time-resolved photometries and a snapshot spectrum of 1eRASS J072044.9-402838 on 3rd Nov. The light curve shows likely superhumps with a rough period of ~0.059 d. The spectrum shows Balmer absorption lines from the accretion disk and a superposed narrow emission component in Hα. Hence, 1eRASS J072044.9-402838 is now confirmed as (at least) a SU UMa-type dwarf nova, and probably a WZ Sge-type dwarf nova, considering its large outburst amplitude, long outburst duration, and short superhump period. Further time-resolved observations are encouraged to establish its superhump period and changes. Best regards, Yusuke -- ---------------------------------------------- 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 ----------------------------------------------

2 2

[vsnet-alert 28117] Possible bright missed supernova in ESO 157-27 galaxy
by Filipp Romanov 04 Nov '25

04 Nov '25

I found an interesting object when I blinked images from the DSS Plate Finder https://archive.stsci.edu/cgi-bin/dss_plate_finder with photos obtained on 2025-11-03 at the remote telescope T75 of iTelescope.Net in Chile. This year I discovered SN 2025umq (Type Ia supernova https://ui.adsabs.harvard.edu/abs/2025ATel17361....1R/ in the galaxy SDSS J004819.14+075856.8) this way, but this time the object was not in new photographs, but in archival ones. I found a possible bright missed supernova in the ESO 157-27 galaxy on the POSS-II F plate (1994-12-28 12:45:00, exposure time 70 minutes). I measured magnitude R = 12.3 compared to the R magnitudes of nearby stars from the ATLAS catalog (Tonry, et al., 2018). My measured J2000.0 position: 04:25:32.31 -56:51:20.09. GSC2.3 position = 04:25:32.2 -56:51:21.8; GSC2.3 magnitude R = 10.02; name GSC2.3 S12G005521. Now this is AT 1994au https://www.wis-tns.org/object/1994au (in the TNS). For comparison: 1994-12-28 DSS Red plate and image from DESI Legacy Surveys: https://www.wis-tns.org/system/files/uploaded/F.%20D.%20Romanov/tns_1994au_… No nearby minor planets found via Minor Planet Checker, there are no similar supernovae in the list http://www.cbat.eps.harvard.edu/lists/Supernovae.html and in the Transient Name Server. It does not look like a defect in the plate because the rays are similar to those of other stars. There are no objects nearby in other images from other years. I have previously found similar astronomical transients - possible missed supernovae AT 1991bm in the galaxy UGC 11180 and AT 1992bw in the galaxy UGC 43 - in the images from the DSS Plate Finder (I mentioned this in my paper: https://ui.adsabs.harvard.edu/abs/2022arXiv221212543R ), like the possible dwarf nova Romanov V1 (on two POSS plates for 1958, more details about this: https://ui.adsabs.harvard.edu/abs/2018OEJV..190....1R/ ). This is likely one of the brightest possible missed supernovae. Filipp Romanov (AAVSO).

1 0

[vsnet-alert 28115] TCP J05415572-2308340: new WZ Sge-type dwarf nova
by Yusuke Tampo 04 Nov '25

04 Nov '25

TCP J05415572-2308340: new WZ Sge-type dwarf nova The NMW survey discovered TCP J05415572-2308340 at 13.2 mag on 16 Oct. The counterpart is Gaia EDR3 2963574610161432960 G= 20.65(1) mag. https://vsx.aavso.org/index.php?view=detail.top&oid=10868112 http://www.cbat.eps.harvard.edu/unconf/followups/J05415572-2308340.html Josch Hambsh and Itoh-san have reported the time-resolved observations of TCP J05415572-2308340. After 23 Oct 2025, this shows the single-peaked superhumps with a mean period of 0.05496(2) d and an amplitude of 0.08 mag. Before this epoch, there were no clear modulations. Thus, this long waiting time before the appearance of ordinary superhumps, together with a large outburst amplitude and long outburst duration, suggests that TCP J05415572-2308340 is a new WZ Sge-type dwarf nova. Best regards, Yusuke -- ---------------------------------------------- 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 ----------------------------------------------

1 0

[vsnet-alert 28116] Possible bright missed supernova in ESO 157-27 galaxy
by Filipp Romanov 03 Nov '25

03 Nov '25

Hello to all! Today I found an interesting object when I blinked images from the DSS Plate Finder https://archive.stsci.edu/cgi-bin/dss_plate_finder with photos obtained on the remote telescope T75 of iTelescope.Net in Chile. This year I discovered SN 2025umq (Type Ia supernova https://ui.adsabs.harvard.edu/abs/2025ATel17361....1R/ in the galaxy SDSS J004819.14+075856.8) this way, but this time the object was not in new photographs, but in archival ones. I found a possible bright missed supernova in the ESO 157-27 galaxy on the POSS-II F plate (1994-12-28). I measured magnitude R = 12.3 compared to the R magnitudes of nearby stars from the ATLAS catalog (Tonry, et al., 2018). My measured J2000.0 position: 04:25:32.31 -56:51:20.09. GSC2.3 position = 04:25:32.2 -56:51:21.8; GSC2.3 magnitude R = 10.02; name GSC2.3 S12G005521. Now this is AT 1994au https://www.wis-tns.org/object/1994au (in the TNS). For comparison: 1994-12-28 DSS Red plate and image from DESI Legacy Surveys: https://www.wis-tns.org/system/files/uploaded/F.%20D.%20Romanov/tns_1994au_… No nearby minor planets found via Minor Planet Checker, there are no similar supernovae in the list http://www.cbat.eps.harvard.edu/lists/Supernovae.html and in the Transient Name Server. It does not look like a defect in the plate because the rays are similar to those of other stars. I have previously found similar astronomical transients - possible missed supernovae AT 1991bm in the galaxy UGC 11180 and AT 1992bw in the galaxy UGC 43 - in the images from the DSS Plate Finder (I mentioned this in my paper: https://ui.adsabs.harvard.edu/abs/2022arXiv221212543R ), like the possible dwarf nova Romanov V1 (on two POSS plates for 1958, more details about this: https://ui.adsabs.harvard.edu/abs/2018OEJV..190....1R/ ). But this is likely one of the brightest possible missed supernovae. With best regards, Filipp Romanov (AAVSO).

1 0

[vsnet-alert 28113] maintenance power outrage
by 保家大将 30 Oct '25

30 Oct '25

Dear, VSNET members, I'm Hiromasa Hoke, a master 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 1st (UTC: 07:00), and the system is scheduled to be restored at around 11:30 JST (UTC: 02:30) on November 4th. Thank you for your cooperation. Hiromasa Hoke

1 0