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ASASSN-16oz: Discovery of A Probable Supernova in an Uncatalogued Galaxy

ATel #9887; G. Stone (Sierra Remote Observatories), J. Brimacombe (Coral Towers Observatory), T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, J. S. Brown, J. Shields (Ohio State), T. A. Thompson, B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Subo Dong, S. Bose, Ping Chen (KIAA-PKU), J. M. Fernandez (Observatory Inmaculada del Molino), S. Kiyota (Variable Star Observers League in Japan), P. Marples (Leyburn Observatory, Australia), G. Masi (Virtual Telescope Project, Ceccano, Italy), R. S. Post (Post Astronomy)
on 20 Dec 2016; 17:07 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@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 "Cassius" telescope in Cerro Tololo, Chile, we discovered a new transient source, most likely a supernova, near the the UV source GALEXASC J090013.19-133803.5.

ASASSN-16oz (AT 2016iyv) was discovered in images obtained on UT 2016-12-20.11 at V~16.8 mag. We also detect the object in images obtained on UT 2016-12-19.35 (V~16.5). We do not detect (V>17.0) the object in images taken on UT 2016-12-15.47 and before. An image obtained on UT 2016-12-20 by G. Stone confirms the discovery of the transient. This figure shows the archival Pan-STARRS r-band image of the host (left) and the G. Stone confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the G. Stone image.

The position of ASASSN-16oz is approximately 1.4" North and 2.6" East from the center of the UV source GALEXASC J090013.19-133803.5, which appears to be an uncatalogued galaxy. The host has no known redshift in 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-16oz  09:00:13.38   -13:38:02.23     2016-12-20.110      16.8          N/A               2.95 
Obs. UT Date         V mag 
2016-12-15.47        >17.0 
2016-12-19.35         16.5 
2016-12-20.11         16.8 

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 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.