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ASASSN-16bc: Discovery of A Probable Supernova in 2MASX J12052488-2123572

ATel #8628; J. M. Fernandez (Observatory Inmaculada del Molino), S. Kiyota (Variable Star Observers League in Japan), J. S. Brown, K. Z. Stanek, T. W.-S. Holoien, 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), R. A. Koff (Antelope Hills Observatory), G. Masi (Virtual Telescope Project, Ceccano, Italy)
on 3 Feb 2016; 14:44 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 #: 8634

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 2MASX J12052488-2123572.

ASASSN-16bc (AT 2016zd) was discovered in images obtained on UT 2016-02-02.28 at V~17.0 mag. We also detect the object in images obtained on UT 2016-02-03.27 (V~16.9). We do not detect (V>17.3) the object in images taken on UT 2016-01-31.56 and before. Images obtained on 2016-02-03 by J. M. Fernandez confirm the discovery of the transient. This figure shows the archival DSS image of the host (left) and the J. M. Fernandez confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the J. M. Fernandez image.

The position of ASASSN-16bc is approximately 4.1" South and 13.89" East from the center of the galaxy 2MASX J12052488-2123572 (z=0.031939, d=140 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.8 (m-M=35.65, A_V=0.152). 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-16bc  12:05:25.826  -21:24:01.20      2016-02-02.28      17.0          -18.8               14.48 
Obs. UT Date         V mag 
2016-01-31.56        >17.3 
2016-02-02.28         17.0 
2016-02-03.27         16.9 

Follow-up observations are encouraged.

As a reminder to the community, the proper, IAU registered name of any ASAS-SN transient is the "ASASSN-16??" name. We are presently participating in the TNS system, and recommend the format ASASSN-16?? (AT 2016??) to indicate the secondary TNS name.

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.