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Independent Discovery of an Apparent Nova in M81

ATel #11325; 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, D. H. Hartmann (Clemson), A. W. Shafter (SDSU)
on 20 Feb 2018; 21:15 UT
Credential Certification: Martin Henze (henze@ice.cat)

Subjects: Optical, Nova, Transient

The M81 nova monitoring collaboration reports the independent discovery of an apparent nova in M81 on a co-added 2700-s unfiltered CCD frame taken on 2018 Feb. 19.039 UT with the 0.65-m telescope at Ondrejov (OND). Additional R-band photometry is provided from a co-added 4000-s image obtained with the 0.80-m telescope Joan Oro (TJO).

The object was first announced and designated AT2018xb by Z. Xu and X. Gao (see here) and is located at R.A. = 9h54m52s.40, Decl. = +69o04'08".5 (equinox 2000.0), which is 218.5" west and 13.4" north 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 
2018-02-14.056 | <22.1 |      | C       | OND  
2018-02-19.039 |  20.4 | 0.2  | C       | OND 
2018-02-19.936 |  19.4 | 0.1  | C       | OND 
2018-02-19.972 |  19.9 | 0.4  | R       | TJO 
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 Telescopi Joan Oro (TJO) is a 80-cm Ritchey-Chretien F/9.6 telescope at the Observatori Astronomic del Montsec, owned by the Catalan Government and operated by the Institut d'Estudis Espacials de Catalunya, Spain. It uses a Finger Lakes PL4240-1-BI CCD Camera with a Class 1 Basic Broadband coated 2k x 2k chip with 13.5 microns square pixels. The unfiltered OND photometry was calibrated against R-band comparison stars from Perelmuter & Racine (1995). The TJO photometry is based on the SDSS DR7 photometry catalogue.

Discovery image