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ASASSN-16db: Discovery of A Probable Supernova in UGC 06198

ATel #8813; S. Kiyota (Variable Star Observers League in Japan), J. Brimacombe (Coral Towers 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. M. Fernandez (Observatory Inmaculada del Molino), G. Masi (Virtual Telescope Project, Ceccano, Italy), B. Nicholls (Mt. Vernon Obs., New Zealand)
on 14 Mar 2016; 15:10 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 #: 8833, 8837

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 UGC 06198.

ASASSN-16db (AT 2016bcy) was discovered in images obtained on UT 2016-03-13.44 at V~16.9 mag. We also detect the object in images obtained on UT 2016-03-11.37 (V~17.6). We do not detect (V>17.9) the object in images taken on UT 2016-03-08.37 and before. An image obtained on 2016-03-14 by S. Kiyota confirms the discovery of the transient. This figure shows the archival SDSS g-band image of the host (left) and the S. Kiyota confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the S. Kiyota image.

The position of ASASSN-16db is approximately 14.3" North and 0.6" West from the center of the galaxy UGC 06198 (z=0.034787, d=151 Mpc, via NED), giving an absolute V-band magnitude of approximately -19.0 (m-M=35.82, A_V=0.072). 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-16db  11:09:25.757  +29:34:23.61      2016-03-13.44      16.9          -19.0               14.31 
Obs. UT Date         V mag 
2016-03-08.37        >17.9 
2016-03-11.37         17.6 
2016-03-13.44         16.9 

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.