A fourth observed outburst of a Galactic flare star in the field of M31
G. Carey (UK Nova/Supernova Patrol, BAA), K. Hornoch (Astronomical Institute, Ondrejov, Czech Republic), A. W. Shafter (SDSU)
We report the discovery of an optical transient in the field of M31 using a 0.20-m telescope at Bromsgrove, UK. The object, which is located at R.A. = 0h41m23s.70, Decl.= +41o14'59".6 (equinox 2000.0), is spatially coincident with the former recurrent nova candidate M31N 1966-08a = M31N 1968-10c = PNV J00412371+4114594.

M31N 1966-08a was initially thought to be either a very fast M31 recurrent nova or a foreground Galactic dwarf nova. However, a recent spectroscopic study of the quiescent counterpart of the object (see Shafter et al. 2017) suggested that it is in fact a foreground Galactic flare star. Shortly thereafter, on 2017 Dec. 20th, E. Conseil (see here) discovered another bright (15.5 mag) eruption of the object designated PNV J00412371+4114594. The outburst faded rapidly during 1.5 hr of observation, confirming the flare star nature of the object.

During the current flare, the object likely reached a fainter peak brightness, but faded rapidly as illustrated by the following photometry (luminance filter and R-band magnitudes used from comparison stars):
optical,nova,star,transient,variables