Follow-up Photometry and Astrometric Confirmation of PNV J00423807+4108423 (AT 2021rno) as a recurrence of M31N 1923-12c

ATel #14755; A. W. Shafter (SDSU), K. Hornoch, H. Kucakova (Astronomical Institute, Ondrejov, Czech Republic)
on 5 Jul 2021; 23:08 UT
Credential Certification: Allen W. Shafter (ashafter@sdsu.edu)

Tweet

The recent M31 nova candidate PNV J00423807+4108423 (AT 2021rno), discovered on 2021 Jul 02.758 UT by Mi Zhang and Xing Gao at the Xingming Observatory, has been suspected to be the second recurrence of M31N 1923-12c (the first being M31N 2012-01b, ATel #3914; Shafter et al., 2015, ApJS, 216, 34). Recent spectroscopic observations of the nova are fully consistent with this interpretation (ATel #14750).

Direct images of the recent nova taken between 2021 Jul 03.913 and 04.070 UT with the 0.65-m telescope at Ondrejov have provided the photometric measurements given below and have allowed us to establish conclusively that the recent transient is indeed the second recorded recurrence of M31N 1923-12c. A careful alignment of our recent image (co-added from 36 individual VRI CCD frames with 3240-s of total exposure time) with Nishiyama's discovery image from the 2012 eruption (M31N 2012-01b) has confirmed that the two novae are spatially coincident to within 0.5 arcsec (see the link below, where the stars from our image are black and those from Nishiyama's image are white). The position of the nova as determined from our most recent images is: R.A. = 00h 42m 38.03s; Decl. = +41deg 08' 41.3" (equinox 2000.0).

The following V, R, and I magnitudes of the recurrent nova were obtained using the 0.65-m telescope at Ondrejov:

2021 Jul 4.002 UT, 18.22 ± 0.05 (V-band); 3.917, 17.52 ± 0.06 (R-band); 3.991, 17.59 ± 0.04 (R-band); 4.064, 17.61 ± 0.04 (R-band); 4.014, 17.25 ± 0.08 (I-band).

Comparison image