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PNV J01335049+3035559 is a Likely Red LPV in M33

ATel #6697; K. Hornoch (Astronomical Institute, Ondrejov, Czech Republic)
on 14 Nov 2014; 05:59 UT
Credential Certification: Allen W. Shafter (aws@nova.sdsu.edu)

Subjects: Optical, Nova, Transient, Variables

Referred to by ATel #: 6703, 6716

A search for known variable sources close to the position of the PNV J01335049+3035559 reveals a variable object (having amplitude of the brightness changes > 1.4 mag in Sloan i'-band) designated No. 233761 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. = 1h33m50s.51, Decl. = +30o35'56".3 which is only 0.48" from the position of the PNV J01335049+3035559.

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 J013350.51+303556.4 having the following V, (U-B), (B-V), (V-R), and (R-I) magnitudes, respectively: 21.579 ± 0.062, 1.403 ± 0.224, 0.241 ± 0.343, 1.477 ± 0.064, 1.769 ± 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 large amplitude variability of the object and its significantly red color.

The existing counterpart showing large amplitude brightness changes and a red color suggests that the likely classification of the PNV J01335049+3035559 should be 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 extragalactic nova, e.g., see ATel #4314, #4315, #4341, #6359, and #6388.

Comparison image