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ASASSN-16at: Discovery of A Probable Nearby Supernova in UGC 08041

ATel #8566; G. Bock (Runaway Bay Observatory, Australia), B. J. Shappee (Hubble Fellow, Carnegie Observatories), K. Z. Stanek (Ohio State), J. L. Prieto (Diego Portales; MAS), C. S. Kochanek, T. W.-S. Holoien, J. S. Brown, D. Godoy-Rivera, U. Basu (Ohio State), D. Bersier (LJMU), Subo Dong, Ping Chen (KIAA-PKU), J. Brimacombe (Coral Towers Observatory), G. Masi (Virtual Telescope Project, Ceccano, Italy), S. Kiyota (Variable Star Observers League in Japan)
on 20 Jan 2016; 17:20 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Benjamin Shappee (bshappee@obs.carnegiescience.edu)

Subjects: Optical, Supernovae

Referred to by ATel #: 8567, 8584, 8588

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 UGC 8041.

ASASSN-16at (AT 2016X) was discovered in images obtained on UT 2016-01-20.586 at V~15.1 mag. We also detect the object in images obtained on UT 2016-01-19.487 (V~16.6+/-0.3) and UT 2016-01-19.495 (V~17.0+/-0.3). We do not detect (V>18.0) the object in images taken on UT 2016-01-18.351 and before. An image obtained on 2016-01-20 by G. Bock confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the G. Bock confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the G. Bock image.

The position of ASASSN-16at is approximately 60” South and 42” East from the center of the galaxy UGC 08041 (d=15.8 Mpc, Tully-Fisher distance via NED), giving an absolute V-band magnitude of approximately -15.9 (m-M=30.98, A_V=0.061). 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-16at  12:55:15.5    +00:05:59.7      2016-01-20.586      15.1          -15.9               73 
Obs. UT Date         V mag  
2016-01-18.351      >18.0          
2016-01-19.487       16.6  0.3         
2016-01-19.495       17.0  0.3         
2016-01-20.586       15.1  0.1    

Rapid 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.