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ASAS-SN Discovery of A Probable Supernova in LSBG F418-058

ATel #7961; J. Brimacombe (Coral Towers Observatory), J. S. Brown, K. Z. Stanek, T. W.-S. Holoien, C. S. Kochanek, 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), E. Falco (CfA), P. R. Wozniak (LANL), G. Pojmanski (Warsaw University Observatory), B. Nicholls (Mt. Vernon Obs., New Zealand), S. Kiyota (Variable Star Observers League in Japan)
on 27 Aug 2015; 20:14 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Jonathan Brown (brown@astronomy.ohio-state.edu)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 8031

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 LSBG F418-058.

ASASSN-15ox was discovered in images obtained on UT 2015-08-27.36 at V~17.1 mag. We do not detect (V>17.6) the object in images taken on UT 2015-08-22.27 and before. An image obtained on 2015-08-27 by J. Brimacombe 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-15ox is approximately 3.95" North and 17.7" West from the center of the low surface brightness galaxy LSBG F418-058 (z=0.046499, d=196 Mpc, via NED), giving an absolute V-band magnitude of approximately -19.4 (m-M=36.46, A_V=0.035). 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-15ox  03:20:39.266    -32:11:54.74      2015-08-27.36      17.1          -19.4               18.14 
Obs. UT Date         V mag 
2015-08-22.27        >17.6 
2015-08-27.36         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.