- vsnet-campaign-dn - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-campaign-dn 17536] ASASSN-25dc; a new candidate of a WZ Sge-type dwarf nova with the double superoutburst
by Yusuke Tampo 13 Aug '25

13 Aug '25

ASASSN-25dc; a new candidate of a WZ Sge-type dwarf nova with the double superoutburst ASASSN-25dc was discovered by ASAS-SN on 2025-07-13.09 UTC at g=13.07. This outburst is also observed by ATLAS, o~15.2 mag on 2025-07-07.8 UTC and o~13.5 mag on 2025-07-10.9 UTC. The likely counterpart is Gaia DR3 6129070308813533568 with G~21.0 mag, hence the outburst amplitude is ~7.0 mag. This system underwent a short dip on 16-17th July, around 14.5 mag, and is now recovering from the dip. Lesedi telescope at Sutherland, Josch Hambsh, and Berto Monard have reported the time-resolved observations of ASASSN-25dc. PDM analysis using the overall data yields a single-peaked modulation with a period of 0.05991(4) d and an amplitude of 0.03 mag. Combining the 1-mag dip feature on the light curve and short superhump period, ASASSN-25dc can be a similar system to double-superoutburst WZ Sge-type dwarf novae, especially the period-bouncer candidates ASASSN-15jd and ASASSN-16hg (see Kimura et al. 2016,2018). https://arxiv.org/abs/1604.06344 https://arxiv.org/abs/1803.03179 The ongoing second outburst should show the evolution of ordinary superhumps. The hint of ordinary superhumps is seen in the observations on 17th July. Further time-resolved observations are encouraged. 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 ----------------------------------------------

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[vsnet-campaign-dn 17542] ASASSN-25df; new SU UMa-type dwarf nova
by Yusuke Tampo 08 Aug '25

08 Aug '25

ASASSN-25df; new SU UMa-type dwarf nova ASASSN-25df was discovered by ASAS-SN on 2025-07-28.02 UTC at g=13.51 mag. The outburst amplitude is ~8.0 mag. ATLAS has also detected this outburst since 2025-07-25. https://vsx.aavso.org/index.php?view=detail.top&oid=10867883 Josch Hambsh reported the time-resolved observations. The observations after 2025-08-02 show strong variations with an amplitude of ~0.1 mag. Due to the short baselines because of its RA~12.5 hr, the superhump period is not well constrained; a possible period is ~0.067 d, but other aliases are equally possible. Thus, I conclude that ASASSN-25df is a new SU UMa-type dwarf nova. A waiting time of ~7 days before the appearance of ordinary superhumps suggests that ASASSN-25df can be a 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 ----------------------------------------------

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[vsnet-campaign-dn 17539] TCP J16271026-1030020: a new WZ Sge-type dwarf nova candidate possibly with large-amplitude early superhump
by Yusuke Tampo 05 Aug '25

05 Aug '25

TCP J16271026-1030020: a new WZ Sge-type dwarf nova candidate possibly with large-amplitude early superhump TCP J16271026-1030020 was discovered by T. Kojima on 2025-07-25.52 UTC at 13.8 mag (unfiltered). ATLAS force photometry and ASASSN also detect this outburst since 2025-07-22.3 UTC, peaking around g~12.6 mag. The Pan-STARRS1 counterpart is g=22.1(2) mag, giving the outburst amplitude of ~9.5 mag. http://www.cbat.eps.harvard.edu/unconf/followups/J16271026-1030020.html https://vsx.aavso.org/index.php?view=detail.top&oid=10867693 I have obtained the low-resolution spectrum with the Lesedi telescope at the SAAO Sutherland. This spectrum shows prominent Balmer, He II 4686, and other He I emission lines with no absorption features. Itoh-san also reported the time-resolved observations for ~45 min. The light curve shows a modulation of ~0.2 mag. These overall features suggest that TCP J16271026-1030020 is a new large-amplitude dwarf nova, most likely a WZ Sge-type, showing relatively large early superhump amplitude. Further time-resolved observations (with multiple bands, if possible) and time-resolved spectroscopy are encouraged. 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 ----------------------------------------------

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[vsnet-campaign-dn 17537] TCP J19181542+3158142: likely a new WZ Sge-type dwarf nova
by Yusuke Tampo 23 Jul '25

23 Jul '25

TCP J19181542+3158142: likely a new WZ Sge-type dwarf nova TCP J19181542+3158142 was discovered by the XOSS team on 18 July at 15.22 mag. The quiescence counterpart is a Pan-STARRS1 source with r=21.35(3) mag, indicating the outburst amplitude of ~6 mag. Itoh-san reported the time-resolved observations for three nights on 19-21 July. Although the scatter is large, PDM analysis yields a period of 0.05525(7) d, with an amplitude of ~0.1 mag and a double-peaked profile, probably early superhumps. Thus, TCP J19181542+3158142 is likely a new WZ Sge-type dwarf nova. This system is a bit faint for time-resolved observations (currently ~15.8 mag), but further observations are encouraged to confirm its superhump profile and evolution. 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 ----------------------------------------------

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[vsnet-campaign-dn 17534] TCP J19335406+4220008: new SU UMa-type dwarf nova
by tonny.vanmunster＠gmail.com 16 Jul '25

16 Jul '25

Dear colleagues, I have just completed the analysis of my unfiltered CCD observations of TCP J19335406+4220008, obtained on Jun 29/30 and Jun 30/Jul 01, 2025 at CBA Extremadura Observatory (Spain). The data was collected using a 0.40-m f/5.1 telescope and Moravian G2-4000 CCD camera under clear skies. The object was discovered by XOSS (Mi Zhang, Jianlin Xu, Guoyou Sun, Jiangao Ruan, et al.) on Jun 21st. The light curve clearly reveals the presence of regular superhumps with an amplitude of 0.13 mag, establishing TCP J19335406+4220008 as a new SU UMa-type dwarf nova. A period analysis, using the ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0615 +/- 0.0003d. The object was measured at mag CV = 14.9 on Jul 01st. Image calibration and photometry were performed using the latest release of Phoranso, allowing us to simultaneously collect observations of 4 additional interesting VSX stars in the same FOV. Further observations are encouraged to refine the superhump period. 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/>

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[vsnet-campaign-dn 17533] ASASSN-25cu: new SU UMa-type dwarf nova
by tonny.vanmunster＠gmail.com 29 Jun '25

29 Jun '25

Dear colleagues, I have just completed the analysis of my unfiltered CCD observations of ASASSN-25cu, obtained on Jun 27/28 and 28/29, 2025 at CBA Belgium Observatory. The data was collected using a 0.40-m f/10.0 telescope and QHY-268M CMOS camera under clear skies. The light curve clearly reveals the presence of regular superhumps with an amplitude of 0.25 mag, establishing ASASSN-25cu as a new SU UMa-type dwarf nova. A period analysis, using the ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0536 +/- 0.0014d. The object was measured at mag CV = 15.7 on Jun 29th. Image calibration and photometry were performed using the latest release of Phoranso. Further observations are encouraged to refine the superhump period. 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/>

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[vsnet-campaign-dn 17532] asassn-25ca, -25ce, -25ch at KKO
by Berto Monard 05 Jun '25

05 Jun '25

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[vsnet-campaign-dn 17531] TCP J20131357+1154031: new SU UMa-type dwarf nova, possibly WZ Sge-type
by Yusuke Tampo 03 Jun '25

03 Jun '25

TCP J20131357+1154031: new SU UMa-type dwarf nova, possibly WZ Sge-type K. Itagaki discovered TCP J20131357+1154031 on 2025-05-19 UTC at 14.7 mag (unfiltered). The outburst amplitude is ~8.4 mag. https://www.aavso.org/vsx/index.php?view=detail.top&oid=10848625 SAAO/Lesedi telescope, Josch Hambsch, and Sano-san have reported the time-resolved observations. Josch's observations after 28 May show single-peaked variation with a period of 0.05797(6) d, likely an ordinary superhump. No clear modulations were presented before this. Thus TCP J20131357+1154031 is a new SU UMa-type dwarf nova and a good candidate for a WZ Sge-type dwarf nova, given its late appearance of ordinary superhumps. 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 ----------------------------------------------

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[vsnet-campaign-dn 17530] ASASSN-25ce: new WZ Sge-type dwarf nova
by Yusuke Tampo 02 Jun '25

02 Jun '25

ASASSN-25ce: new WZ Sge-type dwarf nova ASAS-SN discovered ASASSN-25ce on 2025-05-28 UTC at 12.26 mag. The Gaia counterpart is G~20.7 mag thus the outburst amplitude is ~8.5 mag. The SAAO team and Berto Monard reported the time-resolved observations. These light curves show a double-peak modulation with an amplitude of ~0.1 mag and a period of ~0.05537(1) d. The 5-sec resolution observations by the SAAO/Lesedi telescope also show QPO-like modulation with 5--10 min. Hence, ASASSN-25ce is a new WZ Sge-type dwarf nova, possibly with a relatively higher inclination, while no clear eclipses are present. Further time-resolved observations are encouraged. 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 ----------------------------------------------

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[vsnet-campaign-dn 17529] asassn-25ca, -25ce on 31 May at KKO
by Berto Monard 01 Jun '25

01 Jun '25

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