PNV J01340288+3035111 is Likely a Nova in M33
In order to search for a known counterpart of the PNV J01340288+3035111 (see ATel #6331), we obtained additional images of M33 at higher spatial resolution using the Danish 1.54-m telescope at La Silla and the 0.65-m telescope at Ondrejov. These data also allowed us to determine color index and brightness evolution of the object. Our search for a counterpart was facilitated by the use of the Survey of Local Group Galaxies Currently Forming Stars: I. UBVRI Photometry of Stars in M31 and M33 by Massey et al. (2006, AJ, 131, 2478), which provided deep comparison images.
The following magnitudes were obtained using the 1.54-m (D) and the 0.65-m (O) telescopes:
2014 Jul. 21.047 UT, R = 18.9 ± 0.15 (O); 23.060, R = 19.1 ± 0.15 (O); 23.071, I = 18.8 ± 0.2 (O); 24.074, V = 18.8 ± 0.15 (O); 24.085, R = 18.6 ± 0.15 (O); 24.416, R = 18.82 ± 0.10 (D); 24.427, I = 18.58 ± 0.10 (D); 25.021, R = 19.5 ± 0.2 (O); 26.027, R = 19.7 ± 0.25 (O); 27.008, R = 20.1 ± 0.3 (O).
R-band and I-band images obtained around July 24.42 UT with the Danish 1.54-m telescope under ~1.3" seeing show that the PNV J01340288+3035111 is located ~ 0.5" away from the closest object visible on R-band and I-band Massey's images (i.e., no counterpart is visible there down to ~ 23rd magnitude). It confirms the suspicion from ATel #6331, that the nova candidate is not connected to the 21st magnitude variable No. 236977 listed in Hartman et al. (2006, MNRAS, 371, 1405). The lack of an optical counterpart brighter than ~ 23 mag at the location of the PNV J01340288+3035111, along with the observed color indicies [(V-R) ~ 0.2; (R-I) ~ 0.3 mag] and brightness evolution, is consistent with the nova nature of the object. Taken together, these findings strongly suggest that the PNV J01340288+3035111 is a nova in M33, discovered probably a few days after outburst.
This work is based (in part) on data collected with the Danish 1.54-m telescope at the ESO La Silla Observatory.