Independent Discovery of a Second Probable Nova in M81
ATel #17066; K. Hornoch (Ondrejov), H. Kucakova (Charles University), A. W. Shafter (SDSU)
on 6 Mar 2025; 22:58 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Allen W. Shafter (ashafter@sdsu.edu)
Subjects: Optical, Nova, Transient
We report the independent discovery of another probable nova in M81 on a co-added 3600-s unfiltered CCD frame taken on 2025 Mar. 6.138 UT with the 0.65-m telescope at Ondrejov. Additionally, we found the new object visible also on a prediscovery co-added CCD frame taken on Mar. 5.160 UT with the same instrumentation. Since the new object is laying on top of a brighter spot in the M81 background it was missed during initial search of the 5.160 UT frame (see ATel #17064), also due to its intrinsic faintness at that time.
The object was independently discovered on Mar. 5.827 UT by F. Castellani et al. and designated as PNV J09551261+6902462 = AT 2025dkp.
The object designated by us as M81N 2025-03b is located at R.A. = 9h55m12s.69, Decl. = +69o02'46".3 (equinox 2000.0), which is 109.8" west and 68.8" south of the center of M81 (see link to discovery image below).
Here we list the observing dates and corresponding photometry:
Date [UT] | Mag | Err | Filter | Telescope
2025-03-04.063 | >21.0 | | C | OND
2025-03-05.160 | 20.9 | 0.25 | C | OND
2025-03-06.138 | 19.2 | 0.1 | C | OND
As with all extragalactic novae, follow-up spectroscopic and photometric observations to determine the nova's spectroscopic class and rate of decline (speed class) are encouraged. The OND 0.65-m is a reflecting telescope at the Ondrejov observatory operated jointly by the Astronomical Institute of ASCR and the Astronomical Institute of the Charles University of Prague, Czech Republic. It uses a Moravian Instruments G2-3200 MkII CCD camera (with a Kodak KAF-3200ME sensor and standard BVRI photometric filters) mounted at the prime focus. The unfiltered OND photometry was calibrated against R-band comparison stars from
Perelmuter & Racine (1995).
Discovery image