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@kusastro.kyoto-u.ac.jp