ASASSN-16jc: Discovery of A Probable Supernova in NGC 6942

ATel #9393; P. Marples (Leyburn Observatory, Australia), J. S. Brown (Ohio State), Subo Dong (KIAA-PKU), T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, J. Shields, U. Basu (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), S. Bose, Ping Chen (KIAA-PKU), J. Brimacombe (Coral Towers Observatory), P. Cacella (DogsHeaven Observatory), S. Kiyota (Variable Star Observers League in Japan), R. S. Post (Post Astronomy), G. Stone (Sierra Remote Observatories)
on 22 Aug 2016; 15:46 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Jonathan Brown (brown@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 "Cassius" telescope in Cerro Tololo, Chile, we discovered a new transient source, most likely a supernova, in the galaxy NGC 6942. The transient was independently detected by P. Marples on 2016-08-22.44.

ASASSN-16jc (AT 2016fej) was discovered in images obtained on UT 2016-08-22.17 at V~17.0 mag. We do not detect (V>17.3) the object in images taken on UT 2016-08-20.18 and before. An image obtained on 2016-08-22 by P. Marples confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the P. Marples confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the P. Marples image.

The position of ASASSN-16jc is approximately 28.0" South and 17.8" East from the center of the galaxy NGC 6942 (z=0.010914, d=43.4 Mpc, via NED), giving an absolute V-band magnitude of approximately -16.3 (m-M=33.16, A_V=0.130). 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-16jc  20:40:39.878   -54:18:38.96     2016-08-22.17      17.0          -16.3               33.18 

 
Obs. UT Date         V mag 
2016-08-20.18        >17.3 
2016-08-22.17         17.0 

Follow-up observations are encouraged.

While we are participating in the TNS system to minimize potential confusion, ASAS-SN will continue using ASASSN-16xx transient names as our primary nomenclature (including supernovae, but also other classes of transients), and we encourage others to do the same. We prefer merging the names as ASASSN-16xx (AT2016xyz) to preserve, rather than anonymize, the origin of the transient.

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, and the Mt. Cuba Astronomical Foundation. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.