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ASAS-SN Discovery of A Probable Supernova in LCRS B123822.1-062502

ATel #8329; J. Brimacombe (Coral Towers Observatory), S. Kiyota (Variable Star Observers League in Japan), J. S. Brown, 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), Subo Dong, Ping Chen (KIAA-PKU), G. Bock (Runaway Bay Observatory, Australia), J. M. Fernandez (Observatory Inmaculada del Molino)
on 24 Nov 2015; 15:18 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 #: 8356

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 LCRS B123822.1-062502.

ASASSN-15tb was discovered in images obtained on UT 2015-11-23.65 at V~16.5 mag. We do not detect (V>15.9) the object in images taken on UT 2015-11-18.65 and before. An image obtained on 2015-11-24 by J. Brimacombe confirms the discovery of the transient. This figure shows the archival SDSS g-band image of the host (left) and the J. Brimacombe confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the J. Brimacombe image.

The position of ASASSN-15tb is approximately 5.65" South and 14.96" East from the center of the galaxy LCRS B123822.1-062502 (z=0.024614, d=108 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.7 (m-M=35.17, A_V=0.068). 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-15tb  12:40:58.187  -06:41:34.85      2015-11-23.65      16.5          -18.7               15.99 
Obs. UT Date         V mag 
2015-11-18.65        >15.9 
2015-11-23.65         16.5 

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.