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ASAS-SN Discovery of A Probable Supernova in 2MASX J19320827-6226340

ATel #8237; J. S. Brown (Ohio State), Subo Dong (KIAA-PKU), K. Z. Stanek, T. W.-S. Holoien, C. S. Kochanek, 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), B. Nicholls (Mt. Vernon Obs., New Zealand)
on 2 Nov 2015; 20:37 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Jonathan Brown (brown@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 quadruple 14-cm "Cassius" telescope in Cerro Tololo, Chile, we discovered a new transient source, most likely a supernova, in the galaxy 2MASX J19320827-6226340.

ASASSN-15sh was discovered in images obtained on UT 2015-11-02.01 at V~16.6 mag. We also detect the object in images taken as early as UT 2015-10-18.02 (V~16.8). We do not detect (V>17.4) the object in images taken on UT 2015-10-13.08 and before. An image obtained on 2015-11-02 with the LCOGT 1-m robotic telescope in Southerland, South Africa 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-15sh is approximately 4.01" North and 18.80" West from the center of the galaxy 2MASX J19320827-6226340 (no redshift information available from NED). 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-15sh  19:32:07.007  -62:26:29.99      2015-11-02.01      16.6         N/A               19.22 
 
Obs. UT Date         V mag 
2015-10-13.08        >17.4 
2015-10-18.02         16.8 
2015-10-22.00         16.6 
2015-10-24.12         16.9 
2015-10-27.08         16.3 
2015-10-29.02         16.7 
2015-11-02.01         16.6 

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.