ASAS-SN Discovery of A Supernova in 2MASX J00443129-0301012

ATel #7841; Subo Dong (KIAA-PKU), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), K. Z. Stanek, C. S. Kochanek, J. S. Brown, A. B. Danilet, T. W.-S. Holoien, G. Simonian, U. Basu, J. F. Beacom, T. A. Thompson (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), E. Falco (CfA), P. R. Wozniak (LANL), D. Szczygiel, G. Pojmanski (Warsaw University Observatory)
on 25 Jul 2015; 21:34 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Subo Dong (dongsubo@pku.edu.cn)

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During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the double 14-cm "Cassius" telescope in Cerro Tololo, Chile, we discovered a new transient source in the galaxy 2MASX J00443129-0301012. It is confirmed spectroscopically as a supernova.

Object      RA (J2000)     DEC (J2000)       Disc. UT Date   Disc. V mag 
ASASSN-15nh  00:44:31.28    -03:01:01.45     2015-07-21.3     17.2

ASASSN-15nh was discovered in images obtained on UT 2015-07-21.25 at V~17.2 mag. It was also detected at V~17.1 on UT 2015-07-19.34. We do not detect (V>17.2) the object in images taken on UT 2015-07-14.54 and before.

The position of ASASSN-15nh is consistent with the center of the galaxy 2MASX J00443129-0301012 (z=0.054097, d_L=243 Mpc, via NED), shown in the SDSS image. ASASSN-15nh has an absolute V-band magnitude of approximately -19.8 (m-M=36.9, A_V=0.07).

We obtained a spectrum of ASASSN-15nh on UT 2015-07-25.24 with FLOYDS spectrograph on the 2-m LCOGT telescope at Haleakala. Classification performed with SNID (Blondin and Tonry 2007, ApJ, 666, 1024) suggests ASASSN-15nh to be a type Ia supernovae around 1 week after maximum light (best match: SN 2005hf +8 days). If ASASSN-15nh is a SN Ia, its luminosity (~-19.8) puts it at the luminous end of luminosity distribution of SNe Ia (see e.g., Hamuy et al., 1996, AJ, 112, 2391).

We thank LCOGT and its staff for their continued support of ASAS-SN. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.