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ASAS-SN Discovery of A Probable Supernova in 2MASX J05235186-2442081

ATel #7061; S. Kiyota (Variable Star Observers League in Japan), T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, A. B. Danilet, 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), E. Falco (CfA), J. Brimacombe (Coral Towers Observatory), D. Szczygiel, G. Pojmanski (Warsaw University Observatory), R. A. Koff (Antelope Hills Observatory), B. Nicholls (Mt. Vernon Obs., New Zealand), W. Wiethoff (University of Minnesota, Duluth)
on 13 Feb 2015; 23:14 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 #: 7064

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, most likely a supernova, in the galaxy 2MASX J05235186-2442081:

Object       RA (J2000)     DEC (J2000)      Disc. UT Date   Disc. V mag 
ASASSN-15da  05:23:51.88   -24:42:08.38       2015-02-12.15    17.3 

ASASSN-15da was discovered in images obtained on UT 2015-02-12.15 at V~17.3 mag. We do not detect (V>16.8) the object in images taken on UT 2015-02-08.19 and before. An image obtained by S. Kiyota on UT 2014-02-13.09 using a Planewave CDK 0.61-m telescope located at Sierra Remote Observatory confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the S. Kiyota confirmation image (right). The red circle has a radius of 3.0" and is centered on the position of the transient in the S. Kiyota image.

The position of ASASSN-15da is approximately 0.5" South and 0.3" East from the center of the galaxy 2MASX J05235186-2442081, which has no spectroscopic redshift available in NED. The nearby galaxy 2MASX J05235106-2442201 has a redshift of 0.039207, corresponding to a distance of 167 Mpc. Assuming the same redshift for 2MASX J05235186-2442081 would give ASASSN-15da an absolute V-band magnitude of approximately -18.9 (m-M=36.11, A_V=0.098). Follow-up observations are encouraged.

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.