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ASAS-SN Discovery of A Probable Supernova in 2MASX J14250783+6253235

ATel #7645; T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, J. S. Brown, A. B. Danilet, G. Simonian, U. Basu, 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), J. Brimacombe (Coral Towers Observatory), E. Falco (CfA), P. R. Wozniak (LANL), D. Szczygiel, G. Pojmanski (Warsaw University Observatory)
on 17 Jun 2015; 02:11 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 quadruple 14-cm "Brutus" telescope in Haleakala, Hawaii, we discovered a new transient source, most likely a supernova, in the galaxy 2MASX J14250783+6253235.

ASASSN-15li was discovered in images obtained on UT 2015-06-16.34 at V~16.1 mag. We also detect the object in images obtained on UT 2015-06-11.33 (V~16.6), and UT 2015-06-08.28 (V~16.1). We do not detect (V>16.9) the object in images taken on UT 2015-06-06.35 and before. This figure shows the ASAS-SN V-band reference image (top-left), the ASAS-SN V-band discovery image (top-right), the archival DSS image of the host (bottom-left) and the ASAS-SN V-band discovery subtraction image (bottom-right). The red circle has a radius of 5" and is centered on the position of the transient in the subtraction image.

The position of ASASSN-15li is approximately 6.1" North and 1.2" West from the center of the galaxy 2MASX J14250783+6253235, which has no redshift available in 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-15li  14:25:07.69    +62:53:29.7      2015-06-16.34      16.1          N/A                  6.22 
Obs. UT Date         V mag 
2015-06-06.35        >16.9 
2015-06-08.28         16.1 
2015-06-11.33         16.6 
2015-06-16.34         16.1 

Follow-up observations, particularly spectroscopy, 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.