ASASSN-16kz: Discovery of A Probable Supernova in ESO 555-G029

ATel #9568; T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, J. S. Brown, J. Shields (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), J. Brimacombe (Coral Towers Observatory)
on 29 Sep 2016; 18:41 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 ESO 555-G029.

ASASSN-16kz (AT 2016gsb) was discovered in images obtained on UT 2016-09-29.28 at V~15.9 mag. We also detect the object in images obtained on UT 2016-09-28.28 (V~16.3), and UT 2016-09-27.28 (V~16.4). We do not detect (V>17.4) the object in images taken on UT 2016-09-24.32 and before. This figure shows the archival DSS image of the host (left), the ASAS-SN V-band reference image of the host (center), and the ASAS-SN V-band discovery image (right). The red circle has a radius of 7" and is centered on the position of the transient in the ASAS-SN image.

The position of ASASSN-16kz is approximately 48.9" North and 9.6" East from the center of the galaxy ESO 555-G029 (z=0.009650, d=41.2 Mpc, via NED), giving an absolute V-band magnitude of approximately -17.4 (m-M=33.08, A_V=0.187). 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-16kz  06:04:28.14   -20:20:24.95     2016-09-29.28      15.9          -17.4               49.83 

 
Obs. UT Date         V mag 
2016-09-24.32        >17.4 
2016-09-27.28         16.4 
2016-09-28.28         16.3 
2016-09-29.28         15.9 

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, 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.