ASAS-SN Discovery of A Probable Supernova in 2MASX J20390918-3045201
ATel #7910; J. Brimacombe (Coral Towers Observatory), J. S. Brown, T. W.-S. Holoien, K. Z. Stanek, 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), D. Szczygiel, G. Pojmanski (Warsaw University Observatory), S. Kiyota (Variable Star Observers League in Japan), G. Masi (Virtual Telescope Project, Ceccano, Italy)
on 14 Aug 2015; 20:08 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Jonathan Brown (firstname.lastname@example.org)
Subjects: Optical, Supernovae, Transient
Referred to by ATel #: 7945
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 J20390918-3045201.
ASASSN-15oi was discovered in images obtained on UT 2015-08-14.20 at V~16.2 mag. We do not detect (V>17.2) the object in images taken on UT 2015-07-26.26 and before. An image obtained on 2015-08-14 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-15oi is approximately 0.05" North and 0.072" West from the center of the galaxy 2MASX J20390918-3045201 (no redshift information available from NED). 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-15oi 20:39:09.096 -30:45:20.71 2015-08-14.20 16.2 N/A 0.09
Obs. UT Date V mag
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.