April 2026 - vsnet-campaign-dn - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-campaign-dn 17579] ATLAS26dqo: new WZ Sge-type dwarf nova
by tonny.vanmunster＠gmail.com 19 Apr '26

19 Apr '26

Dear colleagues, ATLAS26dqo (aka TCP J16163603+4452289) was discovered by the ATLAS survey (J. Tonry et al.) on 2026 Mar 31.5 at mag 18.8. The object subsequently reached a peak of mag 14.0. The quiescent counterpart is a 22.8 g mag star, implying an outburst amplitude of ~9 mag. I have completed the analysis of my unfiltered CCD time-series observations of ATLAS26dqo, obtained on 2026 Apr 14/15 (CBA Belgium Observatory), and Apr 15/16 (CBA Extremadura Observatory, Spain). The data were acquired under mostly clear skies with 0.40-m telescopes. Key findings: * Superhump evolution: the Apr 14/15 light curve shows the emergence of Stage A superhumps with an amplitude of 0.07 mag. By Apr 15/16, the system transitioned into fully developed Stage B common superhumps with an amplitude of 0.14 mag. Note that I observed this object on multiple nights before Apr 15/16, but no obvious modulations were seen. * Period analysis: using multiple methods (ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM via Peranso 3.1), I derive a combined superhump period of 0.0608 +/- 0.0004d for the night of Apr 15/16. * Magnitude: the object was measured at mag CV = 15.5 on Apr 15th. Conclusion: The extreme outburst amplitude (almost 9 mag) and the remarkably long delay (~15 days) between initial discovery and the onset of common superhumps strongly confirm that ATLAS26dqo is a new WZ Sge-type dwarf nova. Image calibration and photometry were carried out using Phoranso, which enabled simultaneous photometry of additional variable stars in the same field of view. 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/>

2 2

[vsnet-campaign-dn 17578] ASASSN-26ck: new SU UMa-type dwarf nova
by tonny.vanmunster＠gmail.com 07 Apr '26

07 Apr '26

Dear colleagues, ASASSN-26ck was discovered by the ASAS-SN team on 2026 Mar 26.3 at mag g = 14.6. The quiescent counterpart is a 21.9 g mag star or a ~23.5 mag star, implying an outburst amplitude of ~7 to 9 mag. I have just completed the analysis of my unfiltered CCD time-series observations of ASASSN-26ck, obtained on 2026 Apr 04/05 and 05/06 at CBA Extremadura Observatory, and Apr 06/07 at CBA Belgium Observatory. The CBA Belgium data were acquired under clear skies with a 0.40-m f/10.0 telescope and a QHY-268M CMOS camera. No obvious modulations were seen on the nights of Apr 04/05 and 05/06. However, the Apr 06/07 light curve clearly shows regular superhump modulations with an amplitude of 0.15 mag. A period analysis using ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0601 +/- 0.0014d. The object was measured at mag CV = 16.1 on Apr 06th. Image calibration and photometry were carried out using the latest release of Phoranso, which enabled simultaneous photometry of additional variable stars in the same field of view. These results establish ASASSN-26ck as a new SU UMa-type dwarf nova. Further follow-up observations are encouraged to refine the superhump period and study its 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

1 0

[vsnet-campaign-dn 17577] TCP J08460573+1047397: new SU UMa-type dwarf nova
by tonny.vanmunster＠gmail.com 03 Apr '26

03 Apr '26

Dear colleagues, TCP J08460573+1047397 was discovered by the NMW-TexasTech transient survey (K. Sokolovsky et. al.) on 2026 Mar 21.2 at mag CV = 14.5. The quiescent counterpart is a 22.5 g mag star, implying an outburst amplitude of ~8 mag. I have just completed the analysis of my unfiltered CCD time-series observations of TCP J08460573+1047397, obtained on 2026 Mar 31/Apr 01 at CBA Belgium Observatory. The data were acquired under mostly clear skies with a 0.40-m f/10.0 telescope and a QHY-268M CMOS camera. I have observed this object on several nights between Mar 21st and Apr 01st but no obvious modulations were seen. However, the Mar 31/Apr 01 light curve clearly shows regular superhump modulations with an amplitude of 0.18 mag. A period analysis using ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0643 +/- 0.0008d. The object was measured at mag CV = 15.6 on Apr 01st. Image calibration and photometry were carried out using the latest release of Phoranso, which enabled simultaneous photometry of additional variable stars in the same field of view. These results establish TCP J08460573+1047397 as a new SU UMa-type dwarf nova. Further follow-up observations are encouraged to refine the superhump period and study its 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

1 0