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ASASSN-16ah: Discovery of A Supernova in an Uncatalogued Galaxy

ATel #8539; J. Brimacombe (Coral Towers Observatory), R. A. Koff (Antelope Hills Observatory), D. Bersier (LJMU), J. L. Prieto (Diego Portales; MAS), 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), Subo Dong, Ping Chen (KIAA-PKU), E. Conseil (Association Francaise des Observateurs d'Etoiles Variables), S. Kiyota (Variable Star Observers League in Japan), G. Krannich (Roof Observatory Kaufering)
on 13 Jan 2016; 16:22 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Jonathan Brown (brown@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 quadruple 14-cm "Brutus" telescope in Haleakala, Hawaii, we discovered a new transient source, most likely a supernova, in an uncatalogued galaxy.

ASASSN-16ah was discovered in images obtained on UT 2016-01-11.34 at V~16.8 mag. We also detect the object in images obtained on UT 2016-01-08.34 (V~17.2). We do not detect (V>17.4) the object in images taken on UT 2016-01-04.46 and before. Images obtained on 2016-01-12 by J. Brimacombe and R. Koff confirm 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 5" and is centered on the position of the transient in the J. Brimacombe image.

We obtained a spectrum of ASASSN-16ah on UT 2016-01-12 with the SPRAT spectrograph on the Liverpool Telescope. Classification performed with SNID (Blondin and Tonry 2007, ApJ, 666, 1024) suggests ASASSN-16ah to be a type Ia supernovae around 1 week before maximum light (best match: SN 2004ef at -6 days) at a redshift of z=0.034 (m-M=35.78).

The position of ASASSN-16ah is approximately 7.9" North and 4.7" East from the center of an uncatalogued galaxy (no host 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-16ah  05:47:45.380  +53:36:32.26      2016-01-11.34      16.8          -19.0                9.19 
Obs. UT Date         V mag 
2016-01-04.46        >17.4 
2016-01-08.34         17.2 
2016-01-11.34         16.8 

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.