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ASAS-SN Discovery of A Probable Supernova in ESO 569-G009

ATel #7493; T. W.-S. Holoien, K. Z. Stanek, 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), P. R. Wozniak (LANL), E. Falco (CfA), J. Brimacombe (Coral Towers Observatory), D. Szczygiel, G. Pojmanski (Warsaw University Observatory)
on 11 May 2015; 20:13 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@astronomy.ohio-state.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 "Cassius" telescope in Cerro Tololo, Chile, we discovered a new transient source, most likely a supernova, in the galaxy ESO 569-G009.

ASASSN-15ir was discovered in images obtained on UT 2015-05-08.02 at V~17.0 mag. We also detect the object in images obtained on UT 2015-05-11.14 (V~16.6). We do not detect (V>16.2) the object in images taken on UT 2015-05-06.17 and before. An image obtained on UT 2015-05-11.70 with the LCOGT 1-m robotic telescope in Sutherland, South Africa confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the LCOGT g-band confirmation image (right). The red circle has a radius of 4" and is centered on the position of the transient in the LCOGT image.

The position of ASASSN-15ir is approximately 3.0" South and 12.1" East from the center of the galaxy ESO 569-G009 (z=0.012742, d=57.9 Mpc, via NED), giving an absolute V-band magnitude of approximately -17.0 (m-M=33.81, A_V=0.173). Properties of the new source 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-15ir  10:48:30.30   -21:38:07.95      2015-05-08.02      17.0          -17.0               12.47 
 
Obs. UT Date         V mag 
2015-05-06.17        >16.2 
2015-05-08.02         17.0 
2015-05-11.14         16.6 

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.