ASASSN-17ad: Discovery of A Probable Supernova in CGCG 314-011

ATel #9944; R. S. Post (Post Astronomy), J. Shields (OSU), Subo Dong (KIAA-PKU), K. Z. Stanek, C. S. Kochanek, T. W.-S. Holoien, J. S. Brown, T. A. Thompson (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), S. Kiyota (Variable Star Observers League in Japan), J. M. Fernandez (Observatory Inmaculada del Molino), G. Masi (Virtual Telescope Project, Ceccano, Italy), P. Marples (Leyburn Observatory, Australia), G. Bock (Runaway Bay Observatory, Australia)
on 5 Jan 2017; 21:15 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Krzysztof Stanek (stanek.32@osu.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 galaxy CGCG 314-011.

ASASSN-17ad (AT 2017ah) was discovered in images obtained on UT 2017-01-04.55 at V~17.3 mag. We do not detect (V>17.6) the object in images taken on UT 2017-01-03.59 and before. An image obtained on 2017-01-04 by R. Post confirms the discovery of the transient. This figure shows the archival SDSS image of the host (left) and the R. Post confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the R. Post image.

The position of ASASSN-17ad is approximately 3.16" North and 2.138" West from the center of the galaxy CGCG 314-011 (z=0.032863, d=140 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.5 (m-M=35.73, A_V=0.032). 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-17ad  11:10:01.955   63:38:34.16     2017-01-04.55      17.3          -18.5               3.82 

 
Obs. UT Date         V mag 
2017-01-03.59        >17.6 
2017-01-04.55         17.3 

Follow-up observations are encouraged.

While we are participating in the TNS system to minimize potential confusion, ASAS-SN will continue using ASASSN-17xx 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-17xx (AT 2017xyz) to preserve, rather than anonymize, the origin of the transient.

We thank Las Cumbres Observatory 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 Chinese Academy of Sciences South America Center for Astronomy (CASSACA), 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.