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ASAS-SN Discovery of a Likely Supernova in NGC 1954

ATel #5303; J. Brimacombe (Coral Towers Observatory), J. L. Prieto (Princeton), K. Z. Stanek, B. J. Shappee, C. S. Kochanek, T. W-S. Holoien, J. Jencson, U. Basu, J. F. Beacom (Ohio State), 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 20 Aug 2013; 20:49 UT
Credential Certification: Jose L. Prieto (jose@obs.carnegiescience.edu)

Subjects: Optical, Supernovae, Transient

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the double 14-cm "Brutus" telescope in Haleakala, Hawaii, we discovered a new transient source, most likely a supernova:

 
Object        RA (J2000)    DEC (J2000)   Disc. UT Date    Disc. V mag   
ASASSN-13cc   05:32:46.62  -14:02:45.41     Aug. 19.62         15.6 
No source is detected on 08/14 or earlier images (V > 17 mag). The source is seen weakly in images obtained 08/17, although there are strong residuals in our subtractions due to a nearby bright star.

The transient is approximately 60.6" North and 24.7" West of the Sbc galaxy NGC 1954 (z=0.01044, d=41 Mpc from Virgo-corrected velocity, via NED), giving it an absolute V mag of approx. -17.8 (m-M=33.05, A_V=0.39, Schlafly & Finkbeiner 2011) and an offset from the host galaxy of approximately 13 kpc. We note that this galaxy also hosted two SNe previously: SN 2010ko (Type Ia; CBET #2569, #2575) and SN 2011fi (Type II; CBET #2800, #2815).

A confirmation image (4 x 900sec) in the IR filter (close to I-band) was obtained on Aug. 20.77 with a 16-inch RCOS telescope at Coral Towers Observatory (Cairns, Australia). This figure shows the discovery and confirmation image, which shows a new source at the location consistent with the ASAS-SN position.

For more information about the ASAS-SN project ASAS-SN Homepage and also ASAS-SN Transients page.