August 2025 - vsnet-outburst - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-outburst 31534] 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-outburst 31547] Outbursts 11/08/2025
by Rod Stubbings 12 Aug '25

12 Aug '25

Outbursts detected on 11/08/2025 object YYMMDD(UT) mag code remarks ARAAT 250811.502 140 Stu.RASNZ outburst INDTU 250811.404 153 Stu.RASNZ outburst ASASSN-14IK 250811.407 143 Stu.RASNZ outburst LMC V3434 250811.384 144 Stu.RASNZ outburst -- Rod Stubbings Tetoora Road Observatory Victoria, Australia Honorary Associate member Astronomical Society of Australia Telescope: "Infinity" 22" f/3.8 stubbo(a)dcsi.net.au http://rodstubbingsobservatory.wordpress.com/

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[vsnet-outburst 31546] Outbursts 10/08/2025
by Rod Stubbings 10 Aug '25

10 Aug '25

Detected outbursts tonight. object YYMMDD(UT) mag code remarks AQLUU 250810.506 120 Stu.RASNZ outburst ARAV793 250810.519 149 Stu.RASNZ outburst CENV436 250810.387 123 Stu.RASNZ outburst CENV442 250810.386 126 Stu.RASNZ outburst CRABP 250810.377 144 Stu.RASNZ outburst DELHO 250810.501 137 Stu.RASNZ outburst SCOV598 250810.373 148 Stu.RASNZ outburst SERUZ 250810.384 134 Stu.RASNZ outburst SGRV729 250810.372 141 Stu.RASNZ outburst SGRV1830 250810.382 126 Stu.RASNZ outburst TRADV 250810.517 130 Stu.RASNZ outburst ASASSN-14FE 250810.601 138 Stu.RASNZ outburst ASASSN-19CT 250810.388 142 Stu.RASNZ outburst -- Rod Stubbings Tetoora Road Observatory Victoria, Australia Honorary Associate member Astronomical Society of Australia Telescope: "Infinity" 22" f/3.8 stubbo(a)dcsi.net.au http://rodstubbingsobservatory.wordpress.com/

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[vsnet-outburst 31545] 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-outburst 31539] 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-outburst 31543] Outbursts 2/08/2025
by Rod Stubbings 03 Aug '25

03 Aug '25

Outbursts detected 2/08/2025 object YYMMDD(UT) mag code remarks HYIWX 250802.575 140 Stu.RASNZ outburst PAVGS 250802.432 154 Stu.RASNZ outburst PEGHX 250802.386 146 Stu.RASNZ outburst NSV 35 250802.577 150 Stu.RASNZ outburst -- Rod Stubbings Tetoora Road Observatory Victoria, Australia Honorary Associate member Astronomical Society of Australia Telescope: "Infinity" 22" f/3.8 stubbo(a)dcsi.net.au http://rodstubbingsobservatory.wordpress.com/

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