ASAS-SN Discovery of A Probable Supernova in UGC 09108 NED02

ATel #7775; J. Nicolas (Groupe SNAUDE, France), G. Masi, P. Catalano (Virtual Telescope Project, Ceccano, Italy), J. M. Fernandez (Observatory Inmaculada del Molino), J. S. Brown, K. Z. Stanek, T. W.-S. Holoien, C. S. Kochanek, 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 8 Jul 2015; 18:13 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Krzysztof Stanek (stanek.32@osu.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 "Brutus" telescope in Haleakala, Hawaii, we discovered a new transient source, most likely a supernova, in the galaxy UGC 09108 NED02.

ASASSN-15mf was discovered in images obtained on UT 2015-07-07.32 at V~16.8 mag. We do not detect (V>16.8) the object in images taken on UT 2015-07-05.34 and before. Images obtained on 2015-07-07 by J. Nicolas, G. Masi, and J. M. Fernandez confirm the discovery of the transient. This figure shows the archival SDSS g-band image of the host (left) and the G. Masi confirmation image (right). The red circle has a radius of 3" and is centered on the position of the transient in the G. Masi image.

The position of ASASSN-15mf is approximately 0.21" South and 2.59" West from the center of the galaxy UGC 09108 NED02 (z=0.026, d=113 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.6 (m-M=35.26, A_V=0.101). 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-15mf  14:14:22.80    +02:58:31.0      2015-07-07.32      16.8          -18.6               2.6 

 
Obs. UT Date         V mag 
2015-07-05.34        >16.8 
2015-07-07.32         16.8 

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.