M31N 1923-12c is a recurrent nova in M31
ATel #3914; A. W. Shafter (SDSU), M. J. Darnley, M. F. Bode (Liverpool JMU, UK), R. Ciardullo (PSU), F. Schweizer (Carnegie Observatories)
on 6 Feb 2012; 23:40 UT
Credential Certification: Allen W. Shafter (firstname.lastname@example.org)
Subjects: Optical, Nova, Transient
A spectrum of PNV J00423804+4108417 (tentatively designated M31N 2012-01b) recently reported by Shafter et al. (ATel #3877) revealed the object to be a He/N nova in M31. A subsequent comparison of its position (R.A. = 00h 42m 38.04s; Decl. = 41deg 08' 41.7", J2000) with the ~900 novae in W. Pietsch's M31 nova catalog (http://www.mpe.mpg.de/~m31novae/opt/m31/M31_table.html) revealed that PNV J00423804+4108417 was apparently located ~6" from the cataloged position of M31N 1923-12c, a nova discovered by Edwin Hubble on December 11, 1923. Given that the positions of M31 novae from early photographic surveys were typically reported to a precision of only 0.1', and that He/N spectra are often associated with recurrent novae, we considered the possibility that M31N 1923-12c and PNV J00423804+4108417 represented two outbursts arising from the same nova progenitor. To explore this possibility further, one of us (F. Schweizer) located Hubble's original plate in the Carnegie Observatories archives and performed a comparison by eye of the position of Hubble's nova with that of PNV J00423804+4108417, finding that they appeared to be spatially coincident to within ~1.5" (see the comparison by following the link below). A digital scan of Hubble's plate then allowed us to estimate the position of the nova relative to those of three nearby USNO reference stars. The analysis revealed that M31N 1923-12c was located at R.A. = 00h 42m 38.06s; Decl. = 41deg 08' 41.0" (J2000), with an estimated uncertainty of 1" in each coordinate. We conclude that M31N 1923-12c and PNV J00423804+4108417 are coincident to within 1", and that PNV J00423804+4108417 represents the second recorded outburst of the recurrent nova M31N 1923-12c.
We are grateful to K. Nishiyama and F. Kabashima (Miyaki-Argenteus Observatory, Japan) for providing a finding chart and coordinates for PNV J00423804+4108417. A.W.S. thanks the NSF for support through AST-1009566.
Images of PNV J00423804+4108417 and M31N 1923-12c