AT 2025aeum (M31N 2025-11d) is the seventh reported eruption of the recurrent nova M31N 1963-09c

ATel #17506; Jingyuan Zhao, Jianlin Xu, Mi Zhang, Hualin Li, Ziyang Mai, Yanxi Li, Wenjie Zhou, Guoyou Sun, Jiangao Ruan, Xing Gao (Xingming Obsevatory), A. W. Shafter (SDSU), K. Hornoch (Astronomical Institute, Ondrejov, Czech Republic), R. Fidrich (HAA/VSS)
on 27 Nov 2025; 05:31 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Allen W. Shafter (ashafter@sdsu.edu)

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The M31 nova candidate AT 2025aeum (aka M31N 2025-11d; PNV J00425774+4108126; PSP25U; Vend76) was discovered through a citizen science program called the Popular Supernova Project (PSP). The position of the nova led the PSP group to conclude that AT 2025aeum (hereafter M31N 2025-11d) was a likely recurrence of the known recurrent nova M31N 1963-09c (Shafter et al. 2015, ApJS, 216, 34).

A careful registration of a single 200-s Clear-filter CMOS image taken on 2025 Nov. 25.8076 UT using the 0.43-m f/6.8 Corrected Dall-Kirkham telescope at Alnitak Remote Observatories with an image of the 1963 eruption of M31N 1963-09c (Henze et al. 2008, A&A 477 67) reveals that the transients are spatially coincident to better than 1" (see the link to the comparison image below).

We conclude that M31N 2025-11d is indeed the seventh observed eruption of the recurrent nova M31N 1963-09c, which was observed to subsequently erupt in 1968, 2001, 2010, 2015, 2020, and now 2025. The most recent four eruptions firmly establish a recurrence time of ~5 years. M31N 1963-09c now has more recorded eruptions than any other recurrent nova in M31, except for M31N 2008-12a -- the remarkable system with an unprecedentedly short 1-year recurrence interval.

Spectroscopic classification and additional photometric observations to better characterize the light curve of M31N 2025-11d are strongly encouraged.

Comparison image (1963-09c, black; 2025-11d, white)