Independent Discovery of a Probable Luminous Nova in M81

ATel #11527; K. Hornoch, H. Kucakova (Ondrejov), S. C. Williams (Lancaster), M. Henze (SDSU), G. Sala, J. Jose (UPC-IEEC), H. Meusinger (TLS), M. J. Darnley (LJMU), A. Kaur (PSU), D. H. Hartmann (Clemson), A. W. Shafter (SDSU)
on 11 Apr 2018; 18:08 UT
Credential Certification: Martin Henze (henze@ice.cat)

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The M81 nova monitoring collaboration reports the independent discovery of a probable luminous nova in M81 on a co-added 4410-s unfiltered CCD frame taken on 2018 Apr. 9.044 UT with the 0.65-m telescope at Ondrejov.

The object was first announced and designated AT2018asx by Z. Xu and X. Gao (see here) and is located at R.A. = 9h55m52s.59, Decl. = +68o58'40".6 (equinox 2000.0), which is 104.3" east and 314.5" 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 
 
2018-04-04.957 | <21.4  |      | C       | OND  
2018-04-08.127 | <20.6  |      | C       | OND  
2018-04-09.044 |  20.2  | 0.15 | C       | OND 
2018-04-10.102 |  19.3  | 0.1  | C       | OND 
2018-04-10.832 |  18.18 | 0.10 | C       | OND 
 

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 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