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ASASSN-16eh: Discovery of A Probable Supernova in SDSS J154029.29+005437.4

ATel #8930; J. S. Brown (Ohio State), Subo Dong (KIAA-PKU), 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), Ping Chen (KIAA-PKU), J. Brimacombe (Coral Towers Observatory), G. Bock (Runaway Bay Observatory, Australia), E. Conseil (Association Francaise des Observateurs d'Etoiles Variables), J. M. Fernandez (Observatory Inmaculada del Molino), S. Kiyota (Variable Star Observers League in Japan), B. Nicholls (Mt. Vernon Obs., New Zealand)
on 10 Apr 2016; 15:50 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Jonathan Brown (brown@astronomy.ohio-state.edu)

Subjects: Optical, Supernovae, Transient

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 SDSS J154029.29+005437.4.

ASASSN-16eh (AT 2016blz) was discovered in images obtained on UT 2016-04-10.44 at V~16.4 mag. We do not detect (V>17.8) the object in images taken on UT 2016-04-04.54 and before. An image obtained on 2016-04-10 with the LCOGT 1.0-m robotic telescope at Siding Spring Observatory confirms the discovery of the transient. This figure shows the archival SDSS g-band image of the host (left) and the LCOGT confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the LCOGT image.

The position of ASASSN-16eh is approximately 0.3" South and 0.2" West from the center of the galaxy SDSS J154029.29+005437.4 (z=0.011730, d=50.6 Mpc, via NED), giving an absolute V-band magnitude of approximately -17.4 (m-M=33.49, A_V=0.281). 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-16eh  15:40:29.233  +00:54:36.38      2016-04-10.44      16.4          -17.4               0.36 
Obs. UT Date         V mag 
2016-04-04.54        >17.8 
2016-04-10.44         16.4 

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.