September 2025 - vsnet-campaign-dn - ooruri.kusastro.kyoto-u.ac.jp

[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/>

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[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/>

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[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/>

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

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