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

[vsnet-alert 28196] TCP J02191736+2857158: growing superhump
by Hiromasa Hoke 31 Aug '26

31 Aug '26

TCP J02191736+2857158: growing superhump Moriyama-san, Stephen, Funada-san, Peter Starr and Itoh-san reported the observation. According to the data from the last three days, the object has a superhump period of ~0.048(1)d. Further observations during this phase are very important. The current magnitude is ~14mag. best regard, Kyoto University master's grade 2 Hiromasa Hoke

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[vsnet-alert 28213] TCP J18030904+1218140= ZTF18absdcuk: large-amplitude CV outburst, possibly AM CVn-type?
by Yusuke Tampo 31 Aug '26

31 Aug '26

TCP J18030904+1218140= ZTF18absdcuk: large-amplitude CV outburst, possibly AM CVn-type? TCP J18030904+1218140 was discovered by Yuji Nakamura on 2026-08-19.5199 UT at 14.9 mag. Its previous outburst and log decline in 2018 were detected as ZTF18absdcuk. The VSX lists the r=21.1 mag star as the quiescent counterpart; thus the outburst amplitude is ~6 mag. https://alerce.online/object/ZTF18absdcuk https://vsx.aavso.org/index.php?view=detail.top&oid=10875986 Sano-san has reported the time-resolved observations for ~1.5 hours on 2026-08-20 UT. The light curve shows possible modulations with a period of 0.0288 d (41.5 min) with a double-peaked profile (early superhumps?). The optical spectrum obtained by the SAAO Lesedi telescope on 2026-08-19 UT shows a blue continuum with no prominent emission or absorption lines. Time-resolved photometry is strongly encouraged to confirm the periodicity and determine whether this is an AM CVn star or not. Best regards, Yusuke -- ---------------------------------------------- Yusuke TAMPO / 反保雄介 Postdoc fellow South African Astronomical Observatory / University of Cape Town EMAIL: tampo(a)kusastro.kyoto-u.ac.jp ALT. EMAIL: yusuke(a)saao.ac.za ----------------------------------------------

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[vsnet-alert 28219] SCOV390 brightening
by Tadashi Kojima 25 Aug '26

25 Aug '26

object YYYYMMDD(UT) mag SCOV390 20260615.677 137 SCOV390 20260810.447 129 SCOV390 20260825.437 120 Observer: Tadashi Kojima (Tsumagoi,Gunma, Japan) Instruments:fl=300mm lens+Canon EOS6D digital camera

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[vsnet-alert 28218] ATel #18008; Spectroscopic Observation of PNV J19450648+1822422: Likely a Classical Nova?
by Yusuke Tampo 25 Aug '26

25 Aug '26

ATel #18008; Spectroscopic Observation of PNV J19450648+1822422: Likely a Classical Nova? From ATel; https://www.astronomerstelegram.org/?read=18008 PNV J19450648+1822422 was originally discovered by the NMW-TexasTech survey. Its position coincides with a known eclipsing binary candidate in Gaia, with an orbital period of 9.9011 d. Thus, time-resolved observations may reveal eclipses during its decline as the photosphere recedes. http://www.cbat.eps.harvard.edu/unconf/followups/J19450648+1822422.html https://vsx.aavso.org/index.php?view=detail.top&oid=10762522 See also the case of U Sco and its eclipses during the nova eruption; Muraoka et al 2024 https://arxiv.org/abs/2402.06347 Best regards, Yusuke -- ---------------------------------------------- Yusuke TAMPO / 反保雄介 Postdoc fellow South African Astronomical Observatory / University of Cape Town EMAIL: tampo(a)kusastro.kyoto-u.ac.jp ALT. EMAIL: yusuke(a)saao.ac.za ----------------------------------------------

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[vsnet-alert 28212] ASASSN-26ew: new SU UMa-type dwarf nova, possibly WZ Sge-type
by Yusuke Tampo 24 Aug '26

24 Aug '26

ASASSN-26ew: new SU UMa-type dwarf nova, possibly WZ Sge-type ASASSN reported the discovery of ASASSN-26ew at 14.73 mag on 2026-08-13.82 UT. The archival ASASSN light curve shows that this had the outburst maximum on 2026-08-07.9 UT around 13.7 mag. The likely counterpart is the Bj=22.2 mag star in the GSC v2.4.2 catalogue; thus the outburst amplitude is ~8.5 mag. https://vsx.aavso.org/index.php?view=detail.top&oid=10875981 The SAAO Lesedi telescope observed ASASSN-26ew on 2026-08-18 and 2026-08-19. The light curve shows clear ordinary superhumps with a period of 0.05677(3) d and an amplitude of 0.15 mag. Thus ASASSN-26ew is a new SU UMa-type dwarf nova. Given its short superhump period and large outburst amplitude, this is a good candidate for a WZ Sge-type dwarf nova. The optical spectrum, also observed with the Lesedi telescope on 2026-08-18 UT, shows the Balmer absorption lines and superposed narrow emission core in Hα. Follow-up observations are encouraged. Best regards, Yusuke -- ---------------------------------------------- Yusuke TAMPO / 反保雄介 Postdoc fellow South African Astronomical Observatory / University of Cape Town EMAIL: tampo(a)kusastro.kyoto-u.ac.jp ALT. EMAIL: yusuke(a)saao.ac.za ----------------------------------------------

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[vsnet-alert 28201] DDE 196 outburst (WZ Sge-type dwarf nova candidate in Perseus)
by Denis Denisenko 21 Aug '26

21 Aug '26

Minrui Ning of the Chinese Daily CV Alert Project (DCAP) has informed me that this large-amplitude dwarf nova in Perseus is in outburst on ZTF images. See, for example, https://lasair-ztf.lsst.ac.uk/objects/ZTF26abngywk/ DDE 196 20260808.492 <20.31r ZTF 20260810.492 17.90r ZTF 20260811.493 13.23r ZTF I found this star in November 2021 from the PanSTARRS-1 data. Its previous outburst had started on 2013 Dec. 02 and lasted for at least 20 days, but somehow went unnoticed by ASAS-SN, MASTER and PanSTARRS themselves. The amplitude of 7.5 magnitudes (20.8-13.3), interval between (super)outbursts (13 years) and no-NO (the absence of normal outbursts in the archival survey data) strongly suggest the UGWZ-type nature of the object. The object is currently in morning visibility, so the observations from multiple longitudes are needed to determine the superhumps period. Position of the variable are as follows: DDE 196 = IPHAS J043920.40+500536.6 04 39 20.41 +50 05 36.6 Note of interest: Simbad image from PanSTARRS (combined from two bands, z and g) has a blue ring around DDE 196 with a diameter of 16". If this is not a processing artefact, it may be an expanding shell after the old, large-amplitude explosion (like a ring around the much brighter GK Per = Nova Persei 1901). 16 arc sec seems too large of FWHM for the 13.2 mag star on PS1 images. If this ring is real, DDE 196 may be an old classical Nova currently in dwarf nova regime. Best regards, Denis

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[vsnet-alert 28210] DDE 196: a new WZ Sge-type dwarf nova.
by Gianluca Masi 19 Aug '26

19 Aug '26

Dear Colleagues, tonight I managed to collect my fourth run in a row of time-resolved photometry on DDE 196, spotted in outburst by the ZTF survey last 10 Aug. Once again, I remotely used the 14”-f/6.8+STL-6303E robotic unit available as part of the Virtual Telescope Project facility in Manciano, Italy. Images were collected unfiltered. My 15, 16 and 17 Aug. photometry revealed the presence of small amplitude (0.02 mag.) early superhumps, revealing the WZ Sge nature of the source. Since I started observing, it faded of about 0.15/0.20 mag. per day. Tonight, the object is finally showing fully developed superhumps, having a full amplitude of 0.15 mag. Its average brightness is around CR=13.2. PDM analysis was performed on the first three nights, yielding an estimate for the early superhump period of 1.35(1) hours. The same analysis, performed on just the 4th night, the one showing regular superhumps - suggests Psh around 1.45 hours. So, DDE 196 is definitely a new WZ Sge dwarf nova. Further observations from different northern longitudes are strongly encouraged, being the variable in the morning sky, with a relatively short observing window. Data will be send to Kyoto for further analysis. Regards Gianluca Masi Virtual Telescope Project

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[vsnet-alert 28209] MAXI J1750-327: X-ray nova outburst
by Keisuke Isogai 17 Aug '26

17 Aug '26

MAXI J1750-327: X-ray nova outburst According to ATels, the X-ray nova MAXI J1750-327, a possible black hole binary, is undergoing an outburst. An optical counterpart has also been detected in outburst. https://www.astronomerstelegram.org/?read=17963 https://www.astronomerstelegram.org/?read=17974 The following ATel reports the magnitudes of g ~ 18.3 and i ~ 16.3 on Aug 14. And the coordinates are 17:50:03.038 -32:42:45.43. https://www.astronomerstelegram.org/?read=17971 Time-series photometry may reveal modulations. Thus, follow-up observations are strongly encouraged. Because of the high extinction toward this Galactic-plane target, Rc- or Ic-band observations are recommended for small telescopes.

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[vsnet-alert 28208] DDE 196 (IPHAS J043920.40+500536.6): new observations
by Gianluca Masi 17 Aug '26

17 Aug '26

Dear Colleagues, last night, I obtained my third set of data on this star, covering about 3.5 hours. I used the 14"-f/6.8 + ST-10XME robotic unit part of the Virtual Telescope Project installed in Manciano, Italy. The source continues to likely show early superhumps; using the three available datasets, I obtained for their period a value of 1.350 +/- 0.006 hours. Because of the position of this transient, just a few hours are available in the second part of the night to observe it, so coverage for different longitudes would be very precious. Data will be send to Kyoto for further analysis. All the best Gianluca Masi Virtual Telescope Project

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[vsnet-alert 28204] TCP J22571796+4707418: new SU UMa-type dwarf nova
by tonny.vanmunster＠gmail.com 16 Aug '26

16 Aug '26

Dear colleagues, The outburst of TCP J22571796+4707418 was discovered by the NMW-TexasTech survey team on 2026 Aug 09.3 UT at mag g = 14.4. The quiescent counterpart is a 21.4 g mag star, implying an outburst amplitude of ~7 mag. I have completed the analysis of my unfiltered CCD time-series observations of TCP J22571796+4707418, obtained on 5 nights between 2026 Aug 09/10 and 13/14 at CBA Extremadura & CBA Belgium Observatories. The data were acquired under clear skies with 0.40-m telescopes equipped with Moravian G2-4000 CCD and QHY-268M CMOS cameras. The last two nights of the combined light curve clearly show regular superhump modulations with an amplitude of 0.35 mag. A period analysis using ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0669 +/- 0.0002d. The object was measured at mag CV = 14.7 on Aug 14th. Over the course of those five nights, we see a stage A (low-amplitude onset) transition into stage B with growing and mature superhumps. Image calibration and photometry were carried out using the latest release of Phoranso, which enabled simultaneous photometry of additional variable stars in the same field of view. The detection of superhumps with a period of 0.0669 d securely establishes TCP J22571796+4707418 as an SU UMa-type dwarf nova. Continued monitoring is strongly 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

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