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SNHunt275 in NGC 2770 Is Brightening

ATel #7541; J. Vinko (U Szeged, UT Austin), K. Sarneczky, K. Vida (Konkoly Observatory)
on 20 May 2015; 19:22 UT
Credential Certification: Jozsef Vinko (vinko@astro.as.utexas.edu)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 7543

We observed SNHunt275 (iPTF13efv, PSN J09093496+3307204, see ATEL#7042, #7409, #7514 #7515, #7517) with the 60/90 cm Schmidt telescope at Konkoly Observatory, Piszkesteto, Hungary on May 16, 18 and 19, 2015. Photometry through Johnson-Cousins B,V,R,I filters was performed using local comparison stars selected from the SDSS DR12 catalog. The following preliminary (Vega-) magnitudes have been obtained for the transient:

 
  MJD       B     eB     V    eV     R     eR     I     eI 
57158.85 16.110 0.089 15.693 0.031 15.364 0.038 15.097 0.048 
57160.87 15.794 0.089 15.494 0.027 15.153 0.026 14.924 0.038 
57161.84 15.720 0.087 15.369 0.036 15.142 0.029 14.869 0.036 
These preliminary data suggest that the transient is still brightening in all observed optical bands. Adopting the mean distance for the host galaxy, NGC 2770, from NED as D = 30 +/- 3 Mpc, the observed magnitudes correspond to M ~ -17 mag absolute. This is at least ~3 mag brighter than the usual peak brightness of SN impostors, confirming the suggestion by de Ugarte Postigo et al. (ATel #7514) that the impostor may have finally exploded as a supernova. Follow-up observations are continuing.