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ASAS-SN Discovery of A Probable Supernova in 2MASX J03344211-2050502

ATel #8380; G. Masi (Virtual Telescope Project, Ceccano, Italy), I. Cruz (Cruz Observatory), J. Brimacombe (Coral Towers Observatory), G. Bock (Runaway Bay Observatory, Australia), S. Kiyota (Variable Star Observers League in Japan), T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, J. S. Brown, 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), G. Krannich (Roof Observatory Kaufering), W. Wiethoff (University of Minnesota, Duluth)
on 7 Dec 2015; 18:35 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@astronomy.ohio-state.edu)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 8390

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, in the galaxy 2MASX J03344211-2050502.

ASASSN-15ts was discovered in images obtained on UT 2015-12-06.27 at V~17.3 mag. We do not detect (V>17.9) the object in images taken on UT 2015-12-03.33 and before. Images obtained by multiple observers on 2015-12-06 and 2015-12-07 confirm the discovery of the transient. This figure shows the archival DSS image of the host (left) and the S. Kiyota 2015-12-07 confirmation image (right). The red circle has a radius of 3" and is centered on the position of the transient in the S. Kiyota image.

The position of ASASSN-15ts is approximately 3.3" North and 1.4" West from the center of the galaxy 2MASX J03344211-2050502 (z=0.059978, d=256 Mpc, via NED), giving an absolute V-band magnitude of approximately -19.8 (m-M=37.04, A_V=0.077). 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-15ts  03:34:42.02    -20:50:47.04      2015-12-06.27      17.3          -19.8               3.58 
Obs. UT Date         V mag 
2015-12-03.33        >17.9 
2015-12-06.27         17.3 

Follow-up observations are encouraged.

We thank LCOGT and its staff for their continued support of ASAS-SN. ASAS-SN is supported by NSF grant AST-1515927, the Mt. Cuba Astronomical Foundation, the Center for Cosmology and AstroParticle Physics (CCAPP) at OSU, 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.