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

[vsnet-campaign-dn 17551] 1eRASS J072044.9-402838 = PNV J07204545-4028357 = ASASSN-25ee: new SU UMa-type dwarf nova, likely WZ Sge-type
by Yusuke Tampo 05 Nov '25

05 Nov '25

1eRASS J072044.9-402838 = PNV J07204545-4028357 = ASASSN-25ee: new SU UMa-type dwarf nova, likely WZ Sge-type 1eRASS J072044.9-402838 was originally identified as a CV candidate in Rodriguez et al. (2025), G = 19.2 mag at ~267 pc, hence its absolute magnitude of ~12 mag. https://vsx.aavso.org/index.php?view=detail.top&oid=10868116 https://ui.adsabs.harvard.edu/abs/2025PASP..137a4201R/abstract ASASSN and John Seach discovered its 2025 outburst, peaking at ~11.0 mag around 20th October. https://www.astronomy.ohio-state.edu/asassn/transients.html http://www.cbat.eps.harvard.edu/unconf/followups/J07204545-4028357.html We, the SAAO team, obtained the time-resolved photometries and a snapshot spectrum of 1eRASS J072044.9-402838 on 3rd Nov. The light curve shows likely superhumps with a rough period of ~0.059 d. The spectrum shows Balmer absorption lines from the accretion disk and a superposed narrow emission component in Hα. Hence, 1eRASS J072044.9-402838 is now confirmed as (at least) a SU UMa-type dwarf nova, and probably a WZ Sge-type dwarf nova, considering its large outburst amplitude, long outburst duration, and short superhump period. Further time-resolved observations are encouraged to establish its superhump period and changes. 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 ----------------------------------------------

1 1

[vsnet-campaign-dn 17552] TCP J05415572-2308340: new WZ Sge-type dwarf nova
by Yusuke Tampo 04 Nov '25

04 Nov '25

TCP J05415572-2308340: new WZ Sge-type dwarf nova The NMW survey discovered TCP J05415572-2308340 at 13.2 mag on 16 Oct. The counterpart is Gaia EDR3 2963574610161432960 G= 20.65(1) mag. https://vsx.aavso.org/index.php?view=detail.top&oid=10868112 http://www.cbat.eps.harvard.edu/unconf/followups/J05415572-2308340.html Josch Hambsh and Itoh-san have reported the time-resolved observations of TCP J05415572-2308340. After 23 Oct 2025, this shows the single-peaked superhumps with a mean period of 0.05496(2) d and an amplitude of 0.08 mag. Before this epoch, there were no clear modulations. Thus, this long waiting time before the appearance of ordinary superhumps, together with a large outburst amplitude and long outburst duration, suggests that TCP J05415572-2308340 is a new 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 ----------------------------------------------

1 0

[vsnet-campaign-dn 17550] TCP J20522886+1637203: a likely new WZ Sge-type dwarf nova
by tonny.vanmunster＠gmail.com 19 Oct '25

19 Oct '25

Dear colleagues, TCP J20522886+1637203 was discovered by XOSS (Xingming Observatory Sky Survey) on 2025 Oct 08.6 at mag 12.73 CV. The quiescent counterpart is a 22.1 r mag object, implying an outburst amplitude of ~9 mag. I have been observing this object on a very regular basis since Oct 08th with no periodic modulations visible in the light curves - until last night (Oct 17/18). I have just completed the analysis of my unfiltered CCD observations of TCP J20522886+1637203, obtained on 2025 Oct 17/18 at CBA Extremadura Observatory. The data were acquired under clear skies with a 0.40-m f/5.1 telescope and a Moravian G2-4000 CCD. The light curve now shows clear ordinary superhumps with an amplitude of 0.20 mag. Given their late onset (9 dyas after detection) and the large outburst amplitude, we conclude that TCP J20522886+1637203 is a new WZ Sge-type dwarf nova. A period analysis, using ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0567 +/- 0.0004d. The object was measured at mag CV = 15.0 on Oct 18th. Image calibration and photometry were performed with the latest release of Phoranso, which enabled simultaneous photometry of several additional variable stars within the same frames. Continued monitoring is strongly encouraged to study the superhump profile and evolution. 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/>

1 0

[vsnet-campaign-dn 17549] TCP J03173646+7459318: a likely new WZ Sge-type dwarf nova
by tonny.vanmunster＠gmail.com 23 Sep '25

23 Sep '25

Dear colleagues, TCP J03173646+7459318 was discovered by XOSS (Xingming Observatory Sky Survey) on 2025 Sep 21.8 at mag 13.78C. The quiescent counterpart is a 20.9 V mag object, implying an outburst amplitude of ~8 mag. I have just completed the analysis of my unfiltered CCD observations of TCP J03173646+7459318, obtained on 2025 Sep 22/23 at CBA Extremadura Observatory. The data were acquired under clear skies with a 0.40-m f/5.1 telescope and a Moravian G2-4000 CCD. The light curve clearly reveals double-peaked modulations consistent with early superhumps, with an amplitude of 0.09 mag. A period analysis, using ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0600 +/- 0.0006d. The object was measured at mag CV = 13.6 on Sep 23rd. Image calibration and photometry were performed with the latest release of Phoranso, which enabled simultaneous photometry of several additional variable stars within the same frames. These findings strongly suggest that TCP J03173646+7459318 is a new WZ Sge-type dwarf nova. Continued monitoring is strongly encouraged to study the superhump profile and evolution. 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/>

1 0

[vsnet-campaign-dn 17548] TCP J20143906+0352503: new SU UMa-type dwarf nova
by tonny.vanmunster＠gmail.com 23 Sep '25

23 Sep '25

Dear colleagues, TCP J20143906+0352503 was discovered by XOSS (Xingming Observatory Sky Survey) on 2025 Sep 16.7 at mag 15.72C. The quiescent counterpart is possibly a 21.1 V mag star 2" to the W, implying an outburst amplitude of ~5 mag. I have just completed the analysis of my unfiltered CCD observations of TCP J20143906+0352503, obtained on 2025 Sep 22/23 at CBA Extremadura Observatory. The data were acquired under clear skies with a 0.40-m f/5.1 telescope and a Moravian G2-4000 CCD. The light curve clearly exhibits superhump modulations with an amplitude of 0.25 mag. Period analysis with ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0641 +/- 0.0006d. The object was measured at mag CV = 16.4 on Sep 23rd. Additional observations obtained on earlier nights (e.g. Sep 21/22) also showed superhump activity; however, the data sets were too short due to clouds to permit a reliable period determination. Image calibration and photometry were performed with the latest release of Phoranso, which enabled simultaneous photometry of several additional variable stars within the same frames. These results establish TCP J20143906+0352503 as a new SU UMa-type dwarf nova. Follow-up observations are 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 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/>

1 0

[vsnet-campaign-dn 17547] ASASSN-25dt: new SU UMa-type dwarf nova
by tonny.vanmunster＠gmail.com 12 Sep '25

12 Sep '25

Dear colleagues, ASASSN-25dt was discovered by the ASAS-SN Survey (Ohio State University) on 2025 Sep 05.3 at mag 14.5 V/g. The quiescent counterpart is a 20.1 g mag Pan-STARRS1 object, implying an outburst amplitude of ~5-6 mag. I have just completed the analysis of my unfiltered CCD observations of ASASSN-25dt, obtained on 2025 Sep 10/11 and Sep 11/12 at CBA Extremadura Observatory. The data were acquired under (mostly) clear skies with a 0.40-m f/5.1 telescope and a Moravian G2-4000 CCD. The Sep 10/11 light curve showed only irregular, small-amplitude variability. However, the Sep 11/12 light curve clearly exhibits superhump modulations with an amplitude of 0.27 mag. Period analysis with ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0605 +/- 0.0008d. The object was measured at mag CV = 15.9 on Sep 12th. Image calibration and photometry were carried out with the latest release of Phoranso. These results establish ASASSN-25dt as a new SU UMa-type dwarf nova. Follow-up observations are 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 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/>

1 0

[vsnet-campaign-dn 17546] TCP J21091443-0917104 (=ASASSN-25dq): new SU UMa-type dwarf nova
by Yusuke Tampo 08 Sep '25

08 Sep '25

TCP J21091443-0917104 (=ASASSN-25dq): new SU UMa-type dwarf nova NMW Survey discovered TCP J21091443-0917104 at 12.4 mag on 2025 08 22.8877 UCT. They suspected it could be a new UV Cet star based on its coincidence with the bright Gaia object (Gaia DR3 6896395696896704000; G=14.44, Plx=3.12 +/-0.04 mas). https://vsx.aavso.org/index.php?view=detail.top&oid=10867963 http://www.cbat.eps.harvard.edu/unconf/followups/J21091443-0917104.html S. Brincat and J. Hambsch have reported the time-resolved observations. Combining the observations by W. Goltz on AAVSO, I obtained a single-peak variation with a period of 0.05887(3) d, from the outburst maximum. ZTF light curve also shows a slow decline over the last two weeks, which is unlike a UV Cet star but agrees with a dwarf nova outburst. https://alerce.online/object/ZTF21abtlwbr Thus TCP J21091443-0917104 is most likely a new SU UMa-type dwarf nova. Considering its relatively short superhump period and expected large amplitude of outburst, the Gaia object can be a foreground star. The object is currently g=14.2 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 ----------------------------------------------

1 0

[vsnet-campaign-dn 17545] TCP J22135399+3015357: a likely new WZ Sge-type dwarf nova
by Tonny Vanmunster 21 Aug '25

21 Aug '25

Dear colleagues, TCP J22135399+3015357 was discovered by the NMW survey at the Astroverty astrofarm in Russia on 2025 Aug 19.8 at mag 13.6 CR. Archival images show that the object was already in outburst one day earlier. The quiescent counterpart is listed at 22.8 r mag, implying an outburst amplitude of ~9 mag. I have just completed the analysis of my unfiltered CCD observations of TCP J22135399+3015357, obtained on 2025 Aug 20/21 at CBA Extremadura Observatory. The data were acquired under clear skies with a 0.40-m f/5.1 telescope and a Moravian G2-4000 CCD. The light curve reveals clear double-peaked modulations consistent with early superhumps, with an amplitude of 0.11 mag. A period analysis, using ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0612 +/- 0.0012d. The object was measured at mag CV = 14.2 on Aug 20th. Image calibration and photometry were performed with the latest release of Phoranso. These findings strongly suggest that TCP J22135399+3015357 is a new WZ Sge-type dwarf nova. Continued monitoring is strongly encouraged to study the superhump profile and evolution. 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.com PERANSO : The Light Curve and Period Analysis Software http://www.peranso.com PHORANSO: Photometric Reduction and Analysis Software http://www.phoranso.com

1 0

[vsnet-campaign-dn 17544] TCP J21382907+4146190 (aka AT 2025sss): new WZ Sge-type dwarf nova
by tonny.vanmunster＠gmail.com 13 Aug '25

13 Aug '25

Dear colleagues, I have just completed the analysis of my unfiltered CCD observations of TCP J21382907+4146190 (aka AT 2025sss), obtained on 2025 Aug 12/13 at CBA Extremadura Observatory. The data were collected under clear skies using a 0.40-m f/5.1 telescope and a Moravian G2-4000 CCD. I have been observing this object nightly since Aug 02nd with only one night missed. TCP J21382907+4146190 was discovered by Yuji Nakamura (Japan) on Aug 01.55 UT. It has a g=22.6 mag counterpart, implying an outburst amplitude of ~8.5 mag. Until last night, no clear modulations were visible in the light curves. The Aug 12/13 light curve now shows clear ordinary superhumps with an amplitude of 0.16 mag. Given their late onset (11 days after detection) and the large outburst amplitude, we conclude that TCP J21382907+4146190 is a new WZ Sge-type dwarf nova. A period analysis, using ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0640 +/- 0.0012d. The object was measured at mag CV = 14.9 on Aug 12th. Image calibration and photometry were performed with the latest release of Phoranso. Further observations are strongly 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/>

1 0

[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 ----------------------------------------------

1 3

2025

2024

2023

2022

2021

vsnet-campaign-dn