Pac-Man in Space? ASAS-SN Discovery of A Probable Supernova in Galaxy Pair CGCG 314-006

ATel #8409; Zhen Guo (KIAA-PKU), T. W.-S. Holoien (Ohio State), Subo Dong (KIAA PKU), K. Z. Stanek, C. S. Kochanek, J. S. Brown, D. Godoy-Rivera, U. Basu (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Ping Chen (KIAA-PKU), J. Brimacombe (Coral Towers Observatory)
on 14 Dec 2015; 19:35 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@astronomy.ohio-state.edu)

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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 middle of the Pac-Man-shaped galaxy pair CGCG 314-006.

ASASSN-15ub was discovered in images obtained on UT 2015-12-14.55 at V~16.6 mag. We also detect the object in images obtained on UT 2015-12-11.55 (V~17.0) and UT 2015-12-09.58 (V~17.2). We do not detect (V>17.4) the object in images taken on UT 2015-12-06.60 and before. An image obtained on 2015-12-14.73 by Zhen Guo confirms the discovery of the transient. This figure shows the archival SDSS g-band image of the host (left) and the Zhen Guo confirmation image (right). The red circle has a radius of 3" and is centered on the position of the transient in the Zhen Guo image.

The position of ASASSN-15ub is approximately 5.0" North and 2.8" West from the center of the more southern galaxy in the pair, CGCG 314-006 NED01 (z=0.032046, d=137 Mpc, via NED), giving an absolute V-band magnitude of approximately -19.1 (m-M=35.68, A_V=0.043). 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-15ub  11:07:13.07    +65:05:58.21      2015-12-14.55      16.6          -19.1               5.73 

 
Obs. UT Date         V mag 
2015-12-06.60        >17.4 
2015-12-09.58         17.2 
2015-12-11.55         17.0 
2015-12-14.55         16.6 

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, the Center for Cosmology and AstroParticle Physics (CCAPP) at OSU, 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.