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ASAS-SN Discovery of A Probable Supernova in 2MASX J03305920-1833266

ATel #7948; J. Brimacombe (Coral Towers Observatory), T. W.-S. Holoien (Ohio State), J. L. Prieto (Diego Portales; MAS), K. Z. Stanek, C. S. Kochanek, J. S. Brown, G. Simonian, U. Basu, J. F. Beacom, T. A. Thompson (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), D. Bersier (LJMU), Subo Dong (KIAA-PKU), E. Falco (CfA), P. R. Wozniak (LANL), G. Pojmanski (Warsaw University Observatory), I. Cruz (Cruz Observatory), S. Kiyota (Variable Star Observers League in Japan), G. Masi (Virtual Telescope Project, Ceccano, Italy)
on 24 Aug 2015; 18:04 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 double 14-cm "Cassius" telescope in Cerro Tololo, Chile, we discovered a new transient source, most likely a supernova, in the galaxy 2MASX J03305920-1833266.

ASASSN-15ov was discovered in images obtained on UT 2015-08-24.39 at V~17.1 mag. We do not detect (V>18.1) the object in images taken on UT 2015-08-22.26 and before. An image obtained by J. Brimacombe on UT 2014-08-24.63 with the CDK 43-cm telescope at Savannah Skies Observatory confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the J. Brimacombe confirmation image (right). The red circle has a radius of 3" and is centered on the position of the transient in the J. Brimacombe image.

The position of ASASSN-15ov is approximately 3.4" North and 0.7" West from the center of the galaxy 2MASX J03305920-1833266 (z=0.025451, d=105 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.1 (m-M=35.10, A_V=0.107). 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-15ov  03:30:59.15    -18:33:23.19      2015-08-24.39      17.1          -18.1               3.47 
Obs. UT Date         V mag 
2015-08-22.26        >18.1 
2015-08-24.39         17.1 

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 NSF grant AST-1515927 and by the 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.