Discovery of an Apparent Nova Positionally Coincident with G170 in M31, M31N 2026-06c

ATel #17857; K. Hornoch, H. Kucakova (Ondrejov), A. W. Shafter (SDSU)
on 28 Jun 2026; 11:34 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 an apparent nova found during our survey of the central region of M31. The object was discovered on a co-added 1800-s H_alpha CMOS frame taken on 2026 Jun. 26.059 UT with the 0.65-m telescope at Ondrejov. Subsequently, we found a prediscovery detection of the new object on a co-added R-band 600-s CCD frame taken on Jun. 13.442 UT with the Danish 1.54-m telescope at La Silla.

The object was designated as M31N 2026-06c = PNV J00423204+4110283 and is located at R.A. = 0h42m32s.04, Decl. = +41o10'28".3 (equinox 2000.0), which is 138.6" west and 340.2" south of the center of M31 (see link to discovery image below).

The nova is positionally coincident with a metal-rich globular cluster G170 (see the discovery and comparison image below) and looks as apparent "elongation" of the globular cluster (GC) in WNW direction. Up to now, only a few novae spatially coincident with a GC was discovered in M31 making this nova potentially interesting.

The following magnitudes were obtained using the 0.65-m telescope (D65) and the Danish 1.54-m telescope (DK154):

 
  Date [UT]    |  Mag   | Err  | Filter  | Telescope 
 
2026-06-04.036 | >17.8  |      | H_alpha | D65 
2026-06-13.442 |  17.8  | 0.2  | R       | DK154 
2026-06-26.059 |  16.6  | 0.3  | H_alpha | D65 
2026-06-26.957 | >19.1  |      | R       | D65 
2026-06-27.009 |  17.3  | 0.3  | H_alpha | D65 
 

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. This work is based (in part) on data collected with the Danish 1.54-m telescope at the ESO La Silla Observatory.

Discovery and comparison image: top left pre-outburst H_alpha; top right discovery H_alpha; bottom left pre-outburst R-band; bottom right prediscovery R-band