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ASAS-SN Discovery of A Probable Bright Supernova in UGC 04883

ATel #7593; 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 5 Jun 2015; 16:18 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 #: 7609

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 bright supernova, in the galaxy UGC 04883.

ASASSN-15kk was discovered in images obtained on UT 2015-06-05.28 at V~14.7 mag. We also detect the object in images obtained on UT 2015-06-04.31 (V~14.9), UT 2015-06-02.33 (V~14.6), and UT 2015-05-30.26 (V~16.2). We do not detect (V>16.6) the object in images taken on UT 2015-05-29.29 and before. This figure shows the archival DSS image of the host (top-left), the ASAS-SN V-band reference image (top-right), the ASAS-SN V-band 2015-06-05 discovery image (bottom-left), and the ASAS-SN V-band discovery subtraction image (bottom-right). The red circle has a radius of 10" and is centered on the position of the transient in the ASAS-SN subtraction image.

The position of ASASSN-15kk is approximately 1.6" South and 4.4" West from the center of the galaxy UGC 04883 (z=0.009893, d=41.6 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.5 (m-M=33.09, A_V=0.089). 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-15kk  09:18:31.05    +74:19:07.0      2015-06-05.28      14.7          -18.5               4.68 
Obs. UT Date         V mag 
2015-05-29.29        >16.6 
2015-05-30.26         16.2 
2015-06-02.33         14.6 
2015-06-04.31         14.9 
2015-06-05.28         14.7 

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.