M31N 2013-10c (= AT 2023yoa) is a Recurrent Nova in M31

ATel #16354; A. W. Shafter (SDSU), K. Hornoch (Astronomical Institute, Ondrejov, Czech Republic), Jianlin Xu, Mi Zhang, Leiming Tang, Wenjie Zhou, Jingyuan Zhao, Guoyou Sun, Jiangao Ruan, Xing Gao (Xingming Observatory)
on 29 Nov 2023; 19:07 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Allen W. Shafter (ashafter@sdsu.edu)

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The M31 nova AT 2023yoa = PNV J00430932+4115416 = PSP23N was discovered by J. Xu et al. on 2023 Nov. 27.831 UT at the Xingming observatory. J. Zhao alerted one of us (AWS) that the object was located near the position of M31N 2013-10c and that it was likely the second eruption of this earlier nova. The relatively fast evolution of M31N 2013-10c (t2 = 10.4 d; Soraisam et al. 2017, A&A, 599, A48) and the broad H-alpha emission observed for AT 2023yoa are consistent with this interpretation.

Follow-up observations of AT 2023yoa (designated by us as M31N 2023-11f) taken on 2023 Nov. 29.151 UT with the 40-in reflector at SDSU's Mount Laguna Observatory (MLO) yielded R = 17.05 +/- 0.06. The object was not detected at MLO on Nov. 26.094 UT to a limit of R > 19.8.

In order to confirm the association of M31N 2023-11f with the M31N 2013-10c, we have carefully registered the image of M31N 2023-11f taken at MLO on 2023 Nov. 29.151 UT with an archival Sloan r'-band image of M31N 2013-10c taken (during fading of the nova) with the 2.54-m Isaac Newton Telescope on 2013 Oct. 21.906 UT (see ATel #5503 for reference and confirmation of a nova nature of the object). The images of the nova are spatially coincident to better than 0.3" as shown in the registered comparison image linked below.

Given that the probability of a chance positional coincidence this far from the center of M31 is extremely remote, we conclude that M31N 2023-11f is a subsequent eruption of the newly-identified recurrent nova M31N 2013-10c.

Additional observations of this most recent eruption of M31N 2013-10c are strongly encouraged.

Comparison Image