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ASAS-SN Discovery of A Probable Supernova in 2MASX J22090684+0144384

ATel #8028; G. Bock (Runaway Bay Observatory, Australia), J. S. Brown, K. Z. Stanek, T. W.-S. Holoien, C. S. Kochanek, Diego Godoy Rivera, 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, Ping Chen (KIAA-PKU), J. Brimacombe (Coral Towers Observatory), E. Falco (CfA), P. R. Wozniak (LANL), G. Pojmanski (Warsaw University Observatory), E. Conseil (Association Francaise des Observateurs d'Etoiles Variables), I. Cruz (Cruz Observatory), S. Kiyota (Variable Star Observers League in Japan), G. Masi (Virtual Telescope Project, Ceccano, Italy), B. Nicholls (Mt. Vernon Obs., New Zealand)
on 9 Sep 2015; 16:03 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 #: 8060

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 2MASX J22090684+0144384.

ASASSN-15ph was discovered in images obtained on UT 2015-09-09.48 at V~17.5 mag. We also detect the object in images obtained on UT 2015-09-06.24 (V~17.6). We do not detect (V>17.7) the object in images taken on UT 2015-09-05.34 and before. An image obtained on 2015-09-09 by G. Bock confirms the discovery of the transient. This figure shows the archival SDSS g-band image of the host (left) and the G. Bock confirmation image (right). The red circle has a radius of 3" and is centered on the position of the transient in the G. Bock image.

The position of ASASSN-15ph is approximately 2.3" North and 1.6" East from the center of the galaxy 2MASX J22090684+0144384 which has no available redshift in 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-15ph  22:09:06.986    01:44:40.79      2015-09-09.48      17.5          N/A               2.8 
Obs. UT Date         V mag 
2015-09-05.34        >17.7 
2015-09-06.24         17.6 
2015-09-09.48         17.5 

Follow-up observations are encouraged.

We thank LCOGT and its staff for their continued support of ASAS-SN. ASAS-SN is supported by NSF grant AST-1515927, the Mt. Cuba Astronomical Foundation, and the Center for Cosmology and AstroParticle Physics (CCAPP) at OSU. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.