ASAS-SN Discovery of A Probable Supernova in MCG -02-16-004

ATel #8273; J. S. Brown, C. S. Kochanek (Ohio State), Subo Dong (KIAA-PKU), T. W.-S. Holoien, K. Z. Stanek, D. Godoy-Rivera, U. Basu (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Ping Chen (KIAA-PKU), J. Brimacombe (Coral Towers Observatory), S. Kiyota (Variable Star Observers League in Japan), G. Masi (Virtual Telescope Project, Ceccano, Italy), B. Nicholls (Mt. Vernon Obs., New Zealand)
on 11 Nov 2015; 17:04 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Jonathan Brown (brown@astronomy.ohio-state.edu)

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During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Cassius" telescope in Cerro Tololo, Chile, we discovered a new transient source, most likely a supernova, in the galaxy MCG -02-16-004.

ASASSN-15ss was discovered in images obtained on UT 2015-11-11.31 at V~17.1 mag. We do not detect (V>17.2) the object in images taken on UT 2015-11-09.24 and before. An image obtained on 2015-11-11 with the LCOGT 1-m robotic telescope at Siding Spring Observatory confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the LCOGT V-band confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the LCOGT image.

The position of ASASSN-15ss is approximately 1.06" North and 21.99" West from the center of the galaxy MCG -02-16-004 (z=0.035558, d=152 Mpc, via NED), giving an absolute V-band magnitude of approximately -19.4 (m-M=35.90, A_V=0.636). 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-15ss  06:12:33.398   -14:15:26.94     2015-11-11.31      17.1          -19.4               22.02 

 
Obs. UT Date         V mag 
2015-11-09.24        >17.2 
2015-11-11.31         17.1 

Follow-up observations are encouraged.

We thank LCOGT and its staff for their continued support of ASAS-SN. ASAS-SN is supported by NSF grant AST-1515927, the Mt. Cuba Astronomical Foundation, the Center for Cosmology and AstroParticle Physics (CCAPP) at OSU, and the Robert Martin Ayers Sciences Fund. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.