Independent Discovery of a Probable Nova in M31

ATel #16758; K. Hornoch (Astronomical Institute, Ondrejov, Czech Republic), M. Zejda (DTPA, Masaryk University, Brno, Czech Republic), H. Kucakova and M. Wolf (Charles University, Prague, Czech Republic), A. W. Shafter (SDSU)
on 7 Aug 2024; 20:09 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Allen W. Shafter (ashafter@sdsu.edu)

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We report the independent discovery of a probable rising nova found during our survey of the central region of M31. The object was discovered on a co-added 1620-s Sloan g CMOS frame taken on 2024 Aug. 7.054 UT with the 0.8-m telescope at Zdanice. The object is visible also on a co-added 1620-s Sloan r and Sloan i CMOS frames taken with the same instrumentation on Aug. 7.056 and 7.057 UT, respectively, and also on three prediscovery co-added R-band CCD frames taken on Aug. 6.924, 6.936, and 6.946 UT with the 0.65-m telescope at Ondrejov. The object was subsequently found barely visible also on a prediscovery CCD frames taken on Aug. 5.891 and 5.896 UT with the 0.65-m telescope at Ondrejov.

The object was independently discovered on Aug. 7.142 UT by J. Zhao and designated as PNV J00424486+4115420 = AT 2024rnm.

The object was designated by us as M31N 2024-08b and is located at R.A. = 0h42m44s.87, Decl. = +41o15'41".7 (equinox 2000.0), which is 6.2" east and 26.8" south of the center of M31 (see link to discovery image below).

The following magnitudes were obtained using the 0.65-m telescope at Ondrejov (D65) and the 0.8-m telescope at Zdanice (D80):

 
  Date [UT]    |  Mag   | Err  | Filter  | Telescope 
 
2024-08-01.062 | >19.7  |      | Sloan g | D80 
2024-08-03.845 | >19.4  |      | R       | D65 
2024-08-05.891 |  19.0  | 0.4  | R       | D65 
2024-08-05.896 |  19.2  | 0.4  | R       | D65 
2024-08-06.924 |  18.4  | 0.3  | R       | D65 
2024-08-06.936 |  18.2  | 0.25 | R       | D65 
2024-08-06.946 |  18.3  | 0.25 | R       | D65 
2024-08-07.054 |  18.43 | 0.10 | Sloan g | D80 
2024-08-07.056 |  18.6  | 0.15 | Sloan r | D80 
2024-08-07.057 |  18.4  | 0.2  | Sloan i | D80 
 

As with all extragalactic novae, follow-up spectroscopic and photometric observations to confirm the nova's nature and determine its spectroscopic class and rate of decline (speed class) are encouraged.

Discovery image