Identification of AT2020xyv (PNV J00423733+4120519, M31N 2020-10e) as a likely recurrence of M31N 1998-10b, and thus a recurrent nova in M31
ATel #14117; K. Hornoch, H. Kucakova (Astronomical Institute, Ondrejov, Czech Republic), A. W. Shafter (SDSU)
on 25 Oct 2020; 21:36 UT
Credential Certification: Allen W. Shafter (ashafter@sdsu.edu)
Subjects: Optical, Nova, Transient
Referred to by ATel #: 14143
A new M31 nova candidate was independently discovered on 2020 Oct. 21.741 and 22.550 UT by K. Hornoch and H. Kucakova and by M. Zhang and X. Gao, respectively, and designated as AT2020xyv = PNV J00423733+4120519 = M31N 2020-10e (ATel #14114). Subsequently, the object was classified spectroscopically by L. Izzo et al. (ATel #14116) as a broad-line Fe IIb nova in M31.
Using the updated online catalogue of all historical optical novae and nova candidates in M31 (Pietsch et al. 2007), we found that our measured position of nova AT2020xyv = PNV J00423733+4120519 = M31N 2020-10e is very close (1.2") to that reported for a nova, M31N 1998-10b, previously discovered as part of the Research-Based Science Education (RBSE) project (Rector et al. 1999). Based on the position of the nova, which is located at an isophotal radius of 8.2' from the center of M31, we compute the probability of a chance positional coincidence between these two novae to be less than 0.01% (e.g., see Shafter et al. 2015). We conclude that the two observed eruptions were very likely produced by the same progenitor system, and therefore that this system is likely a recurrent nova. A recurrent nova identification is consistent with the fast rise of the M31N 2020-10e: G > 20.5 mag on Oct. 21.550, R = 18.1 on 21.741, V = 17.7 on 21.92, and G = 16.9 on 22.550 UT (ATels #14114 and #14116) as well as with its broad-line Fe IIb spectroscopic type. A precise astrometric comparison between the positions of the two eruptions from discovery images will be necessary to confirm that the object is a recurrent nova.
We also provide additional R-band magnitudes of M31N 2020-10e obtained using a 0.65-m telescope at Ondrejov:
2019 Oct. 24.702 UT, 17.83 ± 0.08; 24.752, 17.73 ± 0.09.
