Discovery of a Probable Nova in M31, M31N 2026-05a

ATel #17797; K. Hornoch (Ondrejov), M. Myslivec (HVBO, Czech Republic), H. Kucakova (Ondrejov), A. W. Shafter (SDSU)
on 12 May 2026; 21:58 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Allen W. Shafter (ashafter@sdsu.edu)

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We report the discovery of a probable nova in M31 on a co-added 7800-s H_alpha CMOS frame taken on 2026 May 10.030 UT with the 0.4-m telescope at Belec nad Orlici (HVBO). Subsequently, we found the new object faintly visible also on several prediscovery H_alpha and R-band images taken at the HVBO and with the 0.65-m telescope at Ondrejov (D65), respectively. There is nothing visible at the position of the object down to H_alpha = 19.0 mag on a high-quality image taken on 2021 Dec. 22.772 UT at the HVBO.

The object was designated as M31N 2026-05a = PNV J00424745+4116585 and is located at R.A. = 0h42m47s.45, Decl. = +41o16'58".5 (equinox 2000.0), which is 35.2" east and 50.0" north of the center of M31 (see link to discovery image below).

The following magnitudes were obtained using the 0.4-m telescope (HVBO) and the 0.65-m telescope (D65):

 
  Date [UT]    |  Mag   | Err  | Filter  | Telescope 
 
2021-12-22.772 | >19.0  |      | Ha      | HVBO 
2026-04-10.095 |  16.5  | 0.3  | Ha      | HVBO 
2026-04-30.061 |  16.6  | 0.15 | Ha      | HVBO 
2026-05-01.080 |  18.6  | 0.3  | R       | D65 
2026-05-02.075 |  18.7  | 0.2  | R       | D65 
2026-05-10.030 |  16.8  | 0.1  | Ha      | HVBO 
 

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