ASAS-SN Discovery of A Probable Supernova in ESO 113-G018

ATel #7502; J. Brimacombe (Coral Towers Observatory), K. Z. Stanek, T. W.-S. Holoien C. S. Kochanek, J. S. Brown, A. B. Danilet, G. Simonian, U. Basu, N. Goss, J. F. Beacom, T. A. Thompson (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Subo Dong (KIAA-PKU), E. Falco (CfA), P. R. Wozniak (LANL), D. Szczygiel, G. Pojmanski (Warsaw University Observatory), J. M. Fernandez (Observatory Inmaculada del Molino), S. Kiyota (Variable Star Observers League in Japan), B. Nicholls (Mt. Vernon Obs., New Zealand)
on 13 May 2015; 19:54 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"), using data from the double 14-cm "Cassius" telescope in Cerro Tololo, Chile, we discovered a new transient source, most likely a supernova, near the core of an edge-on galaxy ESO 113-G018.

ASASSN-15ja was discovered in images (two chips) obtained on UT 2015-05-13.43 at V~16.3 mag. It was also marginally detected in images taken during twilight on UT 2015-05-12.43. Before that, due to seasonal gap, this field was last observed on UT 2015-02-23.02. Image obtained by J. Brimacombe on UT 2015-05-13T17:35 using a 41-cm telescope at Warrumbungle Observatory, Siding Spring, Australia, confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the 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-15ja is approximately 1.5" from the center of the galaxy ESO 113- G 018 (z=0.026321, d=109 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.95 (m-M=35.18, A_V=0.06). Properties of the new sources and photometry are summarized in the tables below:

 
Object       RA (J2000)     DEC (J2000)    Disc. UT Date   Disc. V mag  Approx. Abs. Mag   Offset from Host (") 
ASASSN-15ja  01:09:39.033   -61:19:58.33   2015-05-13.43    16.3           -18.95               1.5 

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.