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ASAS-SN Discovery of A Probable Bright Supernova in UGC 00546

ATel #7670; 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 19 Jun 2015; 16:06 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@astronomy.ohio-state.edu)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 7712

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 bright transient source, most likely a supernova, in the galaxy UGC 00546.

ASASSN-15ln was discovered in images obtained on UT 2015-06-19.58 at V~16.0 mag. We also detect the object in images obtained on UT 2015-06-15.58 (V~16.5). We do not detect (V>16.7) the object in images taken on UT 2015-06-05.60 and before. This figure shows the archival DSS image of the host (left), the ASAS-SN V-band reference image of the host (center), and the ASAS-SN 2015-06-19 discovery subtraction image (right). The red circle has a radius of 10" and is centered on the position of the transient in the ASAS-SN image.

The position of ASASSN-15ln is approximately 31.2" North and 9.1" West from the center of the galaxy UGC 00546 (z=0.015014, d=57.8 Mpc, via NED), giving an absolute V-band magnitude of approximately -17.9 (m-M=33.81, A_V=0.13). 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-15ln  00:53:41.40    +18:05:29.0      2015-06-19.58      16.0          -17.9               32.5 
Obs. UT Date         V mag 
2015-06-05.60        >16.7 
2015-06-15.58         16.5 
2015-06-19.58         16.0 

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.