ASAS-SN Discovery of a Probable Supernova in UGC 01395

ATel #5193; K. Z. Stanek, B. J. Shappee, C. S. Kochanek, J. Jencson, U. Basu, J. F. Beacom (Ohio State), J. L. Prieto (Princeton), D. Szczygiel, G. Pojmanski (Warsaw University Observatory), M. Dubberley, M. Elphick, S. Foale, E. Hawkins, D. Mullens, W. Rosing, R. Ross, Z. Walker (Las Cumbres Observatory)
on 4 Jul 2013; 17:55 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Krzysztof Stanek (stanek.32@osu.edu)

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During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"; ATel #5110, #5138, #5168, #5177, #5181, #5183, #5186), using data from the double 14-cm "Brutus" telescope in Haleakala, Hawaii, we discovered a new transient source, likely a supernova:

 
Object       RA (J2000)    DEC (J2000)     Disc. UT Date   Approx. Disc. V mag 
 
ASASSN-13bb  01:55:20.71 +06:36:35.28      2013 July 4.56  16.1 

No source is detected on 6/27 or in earlier images (V>17 mag), with detection in two images on 7/04 and very likely detection on 7/01. See the ASAS-SN discovery image, top left panel shows the reference image, top right shows the DSS image on the same angular scale, lower left is one of the 90-sec V-band images on 07/04 and lower right is the image subtraction residual image on 07/04. Circle with the 15" radius has the same position.

The new source is approximately 7" South and 19" West of the center of z=0.017405 (69 Mpc) spiral galaxy UGC 01395, giving it an absolute magnitude of approximately M_V=-18.3 (m-M=34.2, A_V=0.20, Schlafly & Finkbeiner 2011) and a projected distance from the galaxy center of approximately 7.0 kpc.

Finally we note that UGC 01395 is a Seyfert 2 galaxy and subject of many previous observations, including with the HST.

For more information about the ASAS-SN project, see this link and also ASAS-SN Transients page.

Happy Fourth of July!