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