Discovery , photometry , and astrometry of 49 classical nova candidates in M 81 galaxy ⋆

Aims. This paper reports on a search for new classical nova candidates in the M81 galaxy based on archival, as well as recent, new images. Methods. We used images from 1999–2007 to search for optical transients in M81. The positions of the identified classical nova candidates were used to study their spatial distribution. Kolmogorov-Smirnov test (KS) and bottom-to-top (BTR) ratio diagnostic were used to analyze the nova candidate distribution and differentiate between the disk and the bulge populations. Results. In total, 49 classical nova candidates were discovered. In this study, we present the precise positions and photometry of these objects, plus the photometry of an additional 9 classical nova candidates found by Neill & Shara (2004). With our large sample, we find a different spatial distribution of classical nova candidates when compared to the results of earlier studies. Also, an extraordinarily bright nova was found and studied in detail.