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

[vsnet-alert 28090] 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-alert 28089] ASASSN-25dc; a new candidate of a WZ Sge-type dwarf nova with the double superoutburst
by Yusuke Tampo 18 Jul '25

18 Jul '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-alert 28085] 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-alert 28087] Two bright nova candidates in M31
by FIDRICH Robert 08 Jul '25

08 Jul '25

Dear Friends, I managed to discover two bright nova candidates in M31 in the las few days: *Vend60 (AT 2025qdc = M31N 2025-07a)* https://vendegcsillagkereso.blogspot.com/2025/07/vend60-possible-nova-in-m3… https://www.wis-tns.org/object/2025qdc This star got significantly brighter over the weekend (~16.5-17.0 magnitudes) See my recent photos: https://vendegcsillagkereso.blogspot.com/2025/07/vend-60-uj-novajelolt-az-a… *Vend61 (AT 2025qmf)* https://vendegcsillagkereso.blogspot.com/2025/07/vend61-possible-nova-near-… https://www.wis-tns.org/object/2025qmf Located 2178" west and 281" south of the center of M31. (Source: Extracalactic Novae page, Rochesterastronomy) Follow-up photometry, spectroscopy of both nova candidates and precize astrometry of AT 2025qmf urgently needed. Clear skies, Robert

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[vsnet-alert 28086] ASASSN-25cn
by 保家大将 07 Jul '25

07 Jul '25

ASASSN-25cn : new SU UMa-type dwarf nova,and possibly WZ Sge-type ASAS-SN discovered ASASSN-25cn on 2025-06-15.77 UTC at g=13.5 mag. According to VSX, this object's quiescence magnitude is B~22.0 thus the outburst amplitude is ~8.5 mag. VSX : Detail for ASASSN-25cn Josch Hambsch, Berto Monard, Itoh-san reported the time-resolved observations. These light curves (after 2025-6-26 UTC) show ordinary superhumps with an amplitude of ~0.2 mag and a period of 0.0567233(294)d. Hence, ASASSN-25cn is a new SU UMa-type dwarf nova. Due to the sparse coverage before June 19, we cannot judge if ASASSN-25cn showed early superhumps. Given the large outburst amplitude and short superhump period, it can be a WZ Sge-type dwarf nova. Best regards, Hiromasa

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[vsnet-alert 28084] 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-alert 28083] Re: [baavss-alert] PNV J10251200-5331109: possible nova in Vela at 5.7 mag
by walcom77 25 Jun '25

25 Jun '25

Hi All, Following the posting on the Central Bureau's Transient Object Confirmation Page regarding a possible nova in Vela (TOCP Designation: TCP PNV J10251200-5331109), we performed follow-up observations of this object using a 0.35-m f/3.0 reflector telescope equipped with a CMOS camera, located near Perth, Western Australia, and operated by SPACEFLUX company. In images taken on June 25.57, 2025, we confirm the presence of an optical counterpart with an unfiltered CMOS magnitude of approximately +7 (this value is a lower limit due to strong saturation in the 1-second exposure, indicating the object is likely significantly brighter), at coordinates R.A. = 10 25 13.89, Decl. = -53 31 21.0 (equinox 2000.0; astrometry based on Gaia DR2 catalogue reference stars). An animation showing a comparison between our image and an archive POSS plate (1996) is available at the following url: https://tinyurl.com/novavela Kind Regards, Ernesto Guido & Marco Rocchetto (SPACEFLUX) On Wed, Jun 25, 2025 at 3:50 PM Gary Poyner via groups.io <garypoyner=gmail.com(a)groups.io> wrote: > > ---------- Forwarded message --------- > From: Yusuke Tampo <tampo(a)kusastro.kyoto-u.ac.jp> > Date: Wed, 25 Jun 2025 at 14:43 > Subject: [vsnet-alert 28082] PNV J10251200-5331109: possible nova in Vela at 5.7 mag > To: vsnet-alert(a)ooruri.kusastro.kyoto-u.ac.jp <vsnet-alert(a)ooruri.kusastro.kyoto-u.ac.jp> > > > PNV J10251200-5331109: possible nova in Vela at 5.7 mag > > In TOCP, John Seach (and independently Andrew Pearce) reported the possible > nova PNV J10251200-5331109 in Vela at 5.7 mag on 2025 06 25, possibly > another naked-eye nova! > http://www.cbat.eps.harvard.edu/unconf/followups/J10251200-5331109.html > > Classification spectroscopy is highly encouraged. > Unfortunately, the weather in Sutherland seems bad for the next few days. > > 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 > > ---------------------------------------------- > > > _._,_._,_ > ________________________________ > Groups.io Links: > > You receive all messages sent to this group. > > View/Reply Online (#1134) | Reply to Group | Reply to Sender | Mute This Topic | New Topic > Your Subscription | Contact Group Owner | Unsubscribe [walcom77(a)gmail.com] > > _._,_._,_

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[vsnet-alert 28082] PNV J10251200-5331109: possible nova in Vela at 5.7 mag
by Yusuke Tampo 25 Jun '25

25 Jun '25

PNV J10251200-5331109: possible nova in Vela at 5.7 mag In TOCP, John Seach (and independently Andrew Pearce) reported the possible nova PNV J10251200-5331109 in Vela at 5.7 mag on 2025 06 25, possibly another naked-eye nova! http://www.cbat.eps.harvard.edu/unconf/followups/J10251200-5331109.html Classification spectroscopy is highly encouraged. Unfortunately, the weather in Sutherland seems bad for the next few days. 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-alert 28081] ASASSN-25ci
by 保家大将 20 Jun '25

20 Jun '25

ASASSN-25ci: new SU UMa-type dwarf nova,and possibly WZ Sge-type ASAS-SN discovered ASASSN-25ci on 2025-06-5.31 UTC at g=13.51 mag. According to VSX, this object's quiescence magnitude is B~21.0 thus the outburst amplitude is ~7.5 mag. https://vsx.aavso.org/index.php?view=detail.top&oid=10848701 Berto Monard and Josch Hambsch reported the time-resolved observations. These light curves (after 2025-6-11 UTC) show ordinary superhumps with an amplitude of ~0.3 mag and a period of 0.0535(1)d. Hence, ASASSN-25ci is a new SU UMa-type dwarf nova. Due to the sparse coverage before June 11, we cannot judge if ASASSN-25ci showed early superhumps. Given the large outburst amplitude and short superhump period, it can be a WZ Sge-type dwarf nova. Best regards, Hiromasa kyoto university hiromasa hoke / 保家大将 email: hoke(a)kusastro.kyoto-u.ac.jp

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[vsnet-alert 28074] ASASSN-25cm - 8.7 mag transient in Lupus
by Kirill Sokolovsky 17 Jun '25

17 Jun '25

The ASAS-SN team has posted a bright transient on the TNS: ASASSN-25cm = AT 2025nlr 15:08:03.274 -40:08:29.58 g=8.7 https://www.wis-tns.org/object/2025nlr with the following comment: "Very bright, young transient, possibly a Galactic Nova; photometry likely uncertain as the object is close to/above saturation limit". The extinction in this direction is relatively low A(V) = 0.345, so a typical classical nova peaking at absolute magnitude M_V= -7.0 at 8 kpc distance would rise to V=7.9. Confirmation imaging, astrometry, filter photometry and classification spectroscopy are all highly desirable. Best wishes, Kirill

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