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

[vsnet-outburst 31516] ASASSN-25ca: new SU UMa-type dwarf nova
by Yusuke Tampo 30 May '25

30 May '25

ASASSN-25ca: new SU UMa-type dwarf nova ASAS-SN reported ASASSN-25ca on 2025-05-20 at g=14.1. https://www.aavso.org/vsx/index.php?view=detail.top&oid=10848671 Berto Monard and Josch Hambsch reported the time-resolved observations of ASASSN-25ca. Their observations on 29 May show ordinary superhumps with a period of 0.0588(1) d. Observations on 27 May also show a hint of superhumps but the baseline was too short. Thus, ASASSN-25ca is a new SU UMa-type dwarf nova, and could be a WZ Sge-type based on its short superhump period, large outburst amplitude, and lack of previous outbursts. 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 31515] ASASSN-25bz: new SU UMa-type dwarf nova
by Yusuke Tampo 28 May '25

28 May '25

ASASSN-25bz: new SU UMa-type dwarf nova ASASSN-25bz (=AT 2025lkr) was discovered at 14.8 mag on 20 May by ASAS-SN. The suggested outburst amplitude is ~8 mag according to the VSX. ASAS-SN reported to the TNS that this could be a classical nova based on its low Galactic latitude b~-2.0 deg. https://www.aavso.org/vsx/index.php?view=detail.top&oid=10848672 I obtained the time-resolved observations of ASASSN-25bz with the SAAO/Lesedi telescope on 26 and 27 May. Its light curve shows a prominent ordinary superhump with an amplitude of 0.15 mag and a period of ~0.0561(1) d (1-d aliases are possible). The optical spectrum obtained on 23 May with the SAAO/Lesedi telescope is dominated by Balmer absorption lines. Thus, I conclude that ASASSN-25bz is a new SU UMa-type dwarf nova. The system is around 15.6 mag. 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 31513] TCP J18513997+3522412: large-amplitude modulation, possibly eclipsing WZ Sge-type dwarf nova?
by Yusuke Tampo 27 May '25

27 May '25

TCP J18513997+3522412: large-amplitude modulation, possibly eclipsing WZ Sge-type dwarf nova? TCP J18513997+3522412 was discovered by Y. Nakamura on 22nd May at 13.7 mag (unfiltered). The counterpart star in Pan-STARRS1 is r~20.5 mag, and thus the outburst amplitude is 6.8 mag. http://www.cbat.eps.harvard.edu/unconf/followups/J18513997+3522412.html https://www.aavso.org/vsx/index.php?view=detail.top&oid=10848644 Sano-san reported the time-resolved observations of this object. Although the baseline was just one hour, the light curve shows a large-amplitude modulation of ~0.35 mag. This is likely either an ordinary superhump in a SU UMa-type dwarf nova or even a large-amplitude early superhump + eclipse in an eclipsing WZ Sge-type dwarf nova. Further time-resolved observations with longer baselines are encouraged. Best regards, Yusuke -- ---------------------------------------------- South African Astronomical Observatory, Postdoc fellow 反保雄介 Yusuke TAMPO MAIL: tampo(a)kusastro.kyoto-u.ac.jp MAIL: yusuke(a)saao.ac.za ----------------------------------------------

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[vsnet-outburst 31512] TCP J02472889+6758170 = Gaia DR3 517539710877791488
by Yusuke Tampo 26 May '25

26 May '25

TCP J02472889+6758170 = Gaia DR3 517539710877791488 The NMW team discovered this transient at 13.0 mag (unfiltered), which is associated with the known variable star Gaia DR3 517539710877791488 with ~18.0 mag. They suggest that this could be an AM CVn star in outburst. Its blue color in the Pan-STARRS1 image also supports this suggestion, and TCP J02472889+6758170 is at least a CV in new outburst. http://www.cbat.eps.harvard.edu/unconf/followups/J02472889+6758170.html https://www.aavso.org/vsx/index.php?view=detail.top&oid=2841325 Time-resoved observations are encouraged. Best regards, Yusuke -- ---------------------------------------------- South African Astronomical Observatory, Postdoc fellow 反保雄介 Yusuke TAMPO MAIL: tampo(a)kusastro.kyoto-u.ac.jp MAIL: yusuke(a)saao.ac.za ----------------------------------------------

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[vsnet-outburst 31511] Outbursts 25/05/2025
by Rod Stubbings 25 May '25

25 May '25

Outbursts and selected activity. object YYMMDD(UT) mag code remarks AQLPQ 250525.623 153 Stu.RASNZ active CAPSY 250525.618 132 Stu.RASNZ active CAROQ 250525.547 148 Stu.RASNZ active CARV436 250525.415 146 Stu.RASNZ outburst CENV342 250525.557 144 Stu.RASNZ active CENV436 250525.559 134 Stu.RASNZ active CENV442 250525.558 125 Stu.RASNZ active CHAZ 250525.550 154 Stu.RASNZ active CHAST 250525.553 136 Stu.RASNZ outburst CMAWZ 250525.369 157 Stu.RASNZ active CMAHL 250525.363 119 Stu.RASNZ outburst CMISV 250525.357 130 Stu.RASNZ outburst CNCSY 250525.375 118 Stu.RASNZ active HYAV392 250525.517 148 Stu.RASNZ active LEOX 250525.379 130 Stu.RASNZ outburst LUPBR 250525.380 156 Stu.RASNZ outburst MICCM 250525.581 149 Stu.RASNZ active PAVGS 250525.576 148 Stu.RASNZ active PUPBV 250525.409 144 Stu.RASNZ outburst SCOV478 250525.506 151 Stu.RASNZ active SGRV730 250525.540 148 Stu.RASNZ outburst SGRV2276 250525.581 153 Stu.RASNZ active TRADV 250525.405 137 Stu.RASNZ active VIRTW 250525.521 143 Stu.RASNZ active ASASSN-14GR 250525.360 148 Stu.RASNZ outburst ASASSN-14KB 250525.392 149 Stu.RASNZ outburst ASASSN-15BI 250525.433 156 Stu.RASNZ active SSS 100511:061754-362655 250525.360 153 Stu.RASNZ active -- 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 31510] Activity (2025-05-25)
by Hiroyuki Maehara 25 May '25

25 May '25

Visual magnitude estimates by VSOLJ members object YYYYMMDD(UT) mag code HERAH 20250525.551 129 Mhh.VSOLJ UMASW 20250525.497 96 Mhh.VSOLJ Observer: Hiroyuki Maehara (Okayama, Japan) Instruments: 30cmL

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[vsnet-outburst 31509] Outbursts 24/05/2025
by Rod Stubbings 25 May '25

25 May '25

Outbursts and selected activity. object YYMMDD(UT) mag code remarks ARABF 250524.496 151 Stu.RASNZ active ARAV793 250524.478 149 Stu.RASNZ outburst CAPSY 250524.593 146 Stu.RASNZ outburst CAROQ 250524.543 145 Stu.RASNZ active CENV342 250524.537 146 Stu.RASNZ outburst CENV436 250524.539 124 Stu.RASNZ outburst CENV442 250524.538 128 Stu.RASNZ outburst CHAZ 250524.585 150 Stu.RASNZ active CHAST 250524.588 142 Stu.RASNZ active HYAV392 250524.526 150 Stu.RASNZ outburst MICCM 250524.567 150 Stu.RASNZ active PAVGS 250524.561 154 Stu.RASNZ outburst SERUZ 250524.518 150 Stu.RASNZ outburst SGRV2276 250524.567 156 Stu.RASNZ outburst TRADV 250524.481 136 Stu.RASNZ outburst ASASSN-15BI 250524.506 153 Stu.RASNZ active ASASSN-20PV 250524.536 144 Stu.RASNZ outburst rebrightened! NSV 11274 250524.493 150 Stu.RASNZ active -- 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 31508] ASASSN-25bu: new SU UMa-type dwarf nova
by Yusuke Tampo 23 May '25

23 May '25

ASASSN-25bu: new SU UMa-type dwarf nova ASASSN-25b was discovered by ASAS-SN on 2025-05-12.06. The outburst amplitude is ~8.3 mag according to the VSX. This object is currently ~17.5 mag. https://www.aavso.org/vsx/index.php?view=detail.top&oid=10848624 Josch Hambsch and the SAAO team have reported the time-seeries observations of ASASSN-25bu. Lesedi/Mookodi observations on 22 May showed probable superhumps with a period of ~0.0574 d and an amplitude of ~0.15 mag. Thus ASASSN-25bu is a new SU UMa-type dwarf nova. Considering its short superhump period, large outburst amplitude, and no previous outbursts, ASASSN-25bu might be a WZ Sge-type. Best regards, Yusuke -- ---------------------------------------------- South African Astronomical Observatory, Postdoc fellow 反保雄介 Yusuke TAMPO MAIL: tampo(a)kusastro.kyoto-u.ac.jp MAIL: yusuke(a)saao.ac.za ----------------------------------------------

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[vsnet-outburst 31507] Outbursts 20/05/2025
by Rod Stubbings 21 May '25

21 May '25

Outbursts and selected activity observed. object YYMMDD(UT) mag code remarks APSDT 250520.606 154 Stu.RASNZ outburst AQLFO 250520.634 153 Stu.RASNZ active AQLPQ 250520.638 150 Stu.RASNZ outburst AQLV1047 250520.639 150 Stu.RASNZ outburst ARABF 250520.515 146 Stu.RASNZ active CAROQ 250520.590 140 Stu.RASNZ active CENV803 250520.619 154 Stu.RASNZ outburst CENV803 250520.653 153 Stu.RASNZ active CHAZ 250520.592 132 Stu.RASNZ active CHAST 250520.595 143 Stu.RASNZ active CMAWZ 250520.402 150 Stu.RASNZ active CMAHL 250520.395 126 Stu.RASNZ active INDTU 250520.561 143 Stu.RASNZ outburst MICCM 250520.571 149 Stu.RASNZ outburst ORICN 250520.362 126 Stu.RASNZ active ORIV1159 250520.362 137 Stu.RASNZ outburst PUPUY 250520.399 146 Stu.RASNZ active PUPBX 250520.446 144 Stu.RASNZ outburst PUPHO 250520.401 145 Stu.RASNZ active SCOV478 250520.517 152 Stu.RASNZ active SCOV598 250520.419 153 Stu.RASNZ active SERUZ 250520.540 150 Stu.RASNZ active SGRV729 250520.559 154 Stu.RASNZ active ASASSN-14DW 250520.620 150 Stu.RASNZ outburst ASASSN-15BI 250520.441 147 Stu.RASNZ outburst ASASSN-15BI 250520.522 150 Stu.RASNZ active ASASSN-15CL 250520.401 147 Stu.RASNZ active NSV 11274 250520.531 146 Stu.RASNZ active DDE 76 250520.460 148 Stu.RASNZ outburst LMC V3434 250520.387 143 Stu.RASNZ outburst SSS 100511:061754-362655 250520.391 150 Stu.RASNZ active MASTER OT J142023.47-485540.0 250520.412 130 Stu.RASNZ active CTCVJ1940-4724 250520.542 140 Stu.RASNZ active -- 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 31501] ZTF18acynctq = TCP J20402089+4915562 = ASASSN-25bt: new SU UMa star candidate
by Yusuke Tampo 20 May '25

20 May '25

ZTF18acynctq = TCP J20402089+4915562 = ASASSN-25bt: new SU UMa star candidate XOSS team via TOCP/TNS and ASAS-SN reported the 2025 outburst of this system, which is already known as ZTF18acynctq in its 2018 outburst. https://alerce.online/object/ZTF18acynctq http://www.cbat.eps.harvard.edu/unconf/followups/J20402089+4915562.html https://www.aavso.org/vsx/index.php?view=detail.top&oid=10848612 Its 2018 outburst lasted for ~15 days and showed a possible rebrightening in the ATLAS data. Thus the outburst cycle is ~2300 d. This system is currently ~16.0 mag, and time-resolved observations may detect superhumps. Best regards, Yusuke -- ---------------------------------------------- South African Astronomical Observatory, Postdoc fellow 反保雄介 Yusuke TAMPO MAIL: tampo(a)kusastro.kyoto-u.ac.jp MAIL: yusuke(a)saao.ac.za ----------------------------------------------

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vsnet-outburst May 2025