ASASSN-16hz: Discovery of A Probable Supernova in 2MASX J23154564-0120135

ATel #9332; J. Brimacombe (Coral Towers Observatory), R. S. Post (Post Astronomy), S. Kiyota (Variable Star Observers League in Japan), T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, J. S. Brown, J. Shields, 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, S. Bose, Ping Chen (KIAA-PKU), I. Cruz (Cruz Observatory), G. Stone (Sierra Remote Observatories)
on 6 Aug 2016; 17:21 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@astronomy.ohio-state.edu)

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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 J23154564-0120135.

ASASSN-16hz (AT 2016eqb) was discovered in images obtained on UT 2016-08-01.35 at V~16.8 mag. We also detect the object in images obtained on UT 2016-08-06.18 (V~16.5), UT 2016-08-05.31 (V~16.5), and UT 2016-08-03.27 (V~16.2). We do not detect (V>16.2) the object in images taken on UT 2016-07-31.24 and before. An image obtained on UT 2016-08-06 by the LCOGT 1-m telescope at Cerro Tololo confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the LCOGT V-band confirmation image (right). The red circle has a radius of 3" and is centered on the position of the transient in the LCOGT image.

The position of ASASSN-16hz is approximately 9.0" South and 2.4" West from the center of the galaxy 2MASX J23154564-0120135 (z=0.025308, d=101 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.3 (m-M=35.02, A_V=0.099). 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-16hz  23:15:45.48   -01:20:22.73     2016-08-01.35      16.8          -18.3               9.31 

 
Obs. UT Date         V mag 
2016-07-31.24        >16.2 
2016-08-01.35         16.8 
2016-08-03.27         16.2 
2016-08-05.31         16.5 
2016-08-06.18         16.5 

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.