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ASAS-SN Discovery of A Probable Supernova near 2MASX J11083863-1014456

ATel #6921; J. Brimacombe (Coral Towers Observatory), T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, A. B. Davis, G. Simonian, U. Basu, N. Goss, J. F. Beacom (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Subo Dong (KIAA-PKU), P. R. Wozniak (LANL), D. Szczygiel, G. Pojmanski (Warsaw University Observatory), E. Conseil (Association Francaise des Observateurs d'Etoiles Variables), J. M. Fernandez (Pontifica Universidad Catolica), S. Kiyota (Variable Star Observers League in Japan), R. A. Koff (Antelope Hills Observatory), B. Nicholls (Mt. Vernon Obs., New Zealand)
on 14 Jan 2015; 20:08 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@astronomy.ohio-state.edu)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 6925

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Brutus" telescope in Haleakala, Hawaii, we discovered a new transient source, most likely a supernova, near the galaxy 2MASX J11083863-1014456:

Object       RA (J2000)     DEC (J2000)      Disc. UT Date   Disc. V mag 
ASASSN-15az  11:08:37.60   -10:14:57.85      2015-01-14.46    16.7 

ASASSN-15az was discovered in images obtained on UT 2015-01-14.46 at V~16.7 mag. We also detect the object in images obtained on UT 2015-01-12.22 (V~17.1). We do not detect (V>16.6) the object in images taken on UT 2015-01-03.27 and before. An image obtained by J. Brimacombe on UT 2015-01-14.71 with the RCOS 41-cm telescope near Siding Spring Observatory confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the J. Brimacombe confirmation image (right). The red circle has a radius of 4" and is centered on the position of the transient in the J. Brimacombe image.

The position of ASASSN-15az is approximately 19" from the center of the galaxy 2MASX J11083863-1014456 (z=0.028323, d=124 Mpc, via NED), but is also located approximately 5" South of what appears to be a nearby uncatalogued dwarf galaxy. Taking the redshift of 2MASX J11083863-1014456 as the host redshift gives an absolute V-band magnitude of approximately -18.9 (m-M=35.4, A_V=0.171). Follow-up observations are encouraged.

ASASSN-15az is (most likely) the 100th supernova discovered by ASAS-SN project (83rd since May 1st, 2014). We thank LCOGT and its staff for their continued support of ASAS-SN. ASAS-SN is supported in part by Mt. Cuba Astronomical Foundation. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.