PNV J01330150+3033363 is a Likely Red LPV in M33

ATel #6388; K. Hornoch (Astronomical Institute, Ondrejov, Czech Republic)
on 14 Aug 2014; 18:33 UT
Credential Certification: Allen W. Shafter (aws@nova.sdsu.edu)

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Information about a discovery of possible nova in M33 by the Lick Observatory Supernova Search (LOSS) was recently posted here.

A search for known variable sources close to the position of the PNV J01330150+3033363 reveals a variable object (having amplitude of brightness changes > 2.5 mag in Sloan i'-band) designated No. 251341 in the Deep Canada-France-Hawaii Telescope photometric survey of the entire M33 galaxy - I. Catalogue of 36000 variable point sources, Hartman et al. (2006, MNRAS, 371, 1405). The variable object is located at R.A. = 1h33m01s.51, Decl. = +30o33'36".4 which is only 0.16" from the position of the PNV J01330150+3033363.

The object is also found in 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) where is designated as J013301.55+303336.7 having the following V, (U-B), (B-V), (V-R), and (R-I) magnitudes, respectively: 22.395 ± 0.056, -1.136 ± 0.052, 0.206 ± 0.076, 1.301 ± 0.058, 1.888 ± 0.015. Since Massey's magnitudes are averages of different numbers of measurements obtained in different epochs in each band, they are influenced by the variability of the object. A comparison of archival Massey's I-band and R-band images available through the link below clearly shows the object and its significantly red color.

The existing counterpart showing large amplitude brightness changes and a red color is consistent with classification of the PNV J01330150+3033363 as a Red LPV in M33, not a nova. This object appears to be another case of the "discovery" of a known variable object around its maximum brightness masquerading as a possible nova, e.g., see ATel #4314, #4315, #4341, and #6359.

Comparison image