Confirmation of M31N 2005-10a as a Recurrent Nova in M31

ATel #15545; K. Hornoch, H. Kucakova (Astronomical Institute, Ondrejov, Czech Republic), and A. W. Shafter (SDSU)
on 9 Aug 2022; 18:02 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Allen W. Shafter (ashafter@sdsu.edu)

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R. Belligoli et al. have reported that the position of the recent M31 transient AT 2022qpg = M31N 2022-08a appears "in the same position" as the known M31 nova TSS J004420.7+412311 = M31N 2005-10a.

To confirm beyond any reasonable doubt the association between these two objects, on 2022 Aug. 8.080 UT we obtained a co-added 1350-s R-band CCD image of the field surrounding M31N 2022-08a using the 0.65-m telescope at Ondrejov. The image shows the nova at R-band magnitude 17.21 ± 0.03.

A careful registration of our image with the discovery image of M31N 2005-10a obtained by the ROTSE-IIIb telescope at the McDonald Observatory 17 years ago (see ATel #627) reveals that the transients are spatially coincident to better than 1" (see the link to the comparison image below). The probability of a chance positional coincidence (Δ x < 1") of two unrelated novae at this location (~19.4 arcmin from the nucleus of M31) is vanishingly small. We conclude that M31N 2005-10a is indeed a recurrent nova in M31.

Additional observations of M31N 2005-10a as it fades from its latest eruption are encouraged.

We thank P. Schmeer and D. Bishop for bringing this recent eruption to our attention.

Comparison image: M31N 2005-10a [black]; M31N 2022-08a [white]