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ASASSN-16ek: Discovery of A Probable Supernova in a Bright, Uncatalogued Spiral Galaxy

ATel #8944; I. Cruz (Cruz Observatory), J. S. Brown, T. W.-S. Holoien, K. Z. Stanek, 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), G. Bock (Runaway Bay Observatory, Australia), E. Conseil (Association Francaise des Observateurs d'Etoiles Variables), S. Kiyota (Variable Star Observers League in Japan), R. A. Koff (Antelope Hills Observatory), G. Masi (Virtual Telescope Project, Ceccano, Italy)
on 13 Apr 2016; 09:02 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 #: 8992, 9836, 10298, 10344, 10391, 10554, 10823, 11305

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 GALEXASC J072024.60+325058.8.

ASASSN-16ek (AT 2016bmd) was discovered in images obtained on UT 2016-04-12.29 at V~16.5 mag. We do not detect (V>17.6) the object in images taken on UT 2016-04-09.27 and before. An image obtained on 2016-04-13 by I. Cruz confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the I. Cruz confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the I. Cruz image.

The position of ASASSN-16ek is approximately 3.9" North and 5.6" West from the center of the galaxy GALEXASC J072024.60+325058.8 (no redshift information available on NED). 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-16ek  07:20:24.158  +32:51:02.58      2016-04-12.29      16.5             N/A               6.82 
Obs. UT Date         V mag 
2016-04-09.27        >17.6 
2016-04-12.29         16.5 

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, 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.