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ASASSN-16aw: Discovery of A Probable Supernova in ESO 306-G016

ATel #8607; S. Kiyota (Variable Star Observers League in Japan), J. S. Brown, T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, D. Godoy-Rivera, U. Basu (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), G. Bock (Runaway Bay Observatory, Australia), R. A. Koff (Antelope Hills Observatory), G. Masi (Virtual Telescope Project, Ceccano, Italy)
on 29 Jan 2016; 15:11 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 #: 8613

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Cassius" telescope in Cerro Tololo, Chile, we discovered a new transient source, most likely a supernova, in the galaxy ESO 306-G016.

ASASSN-16aw (AT 2016yr) was discovered in images obtained on UT 2016-01-29.27 at V~17.0 mag. We do not detect (V>16.6) the object in images taken on UT 2016-01-23.27 and before. An image obtained on 2016-01-29 by S. Kiyota confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the S. Kiyota confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the S. Kiyota image.

The position of ASASSN-16aw is approximately 12.5" South and 59.5" East from the center of the galaxy ESO 306-G016 (z=0.037279, d=159 Mpc, via NED), giving an absolute V-band magnitude of approximately -19.0 (m-M=35.92, A_V=0.088). ASASSN-16aw is located close to an uncatalogued dwarf galaxy, which may in fact be the host of the transient. 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-16aw  05:39:57.452  -40:30:57.84      2016-01-29.27      17.0          -19.0               61.53 
Obs. UT Date         V mag 
2016-01-23.27        >16.6 
2016-01-29.27         17.0 

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 Center for Cosmology and AstroParticle Physics (CCAPP) at OSU, the Mt. Cuba Astronomical Foundation, George Skestos, and the Robert Martin Ayers Sciences Fund. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.