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ASASSN-16kk: Discovery of A Supernova in LSBG F156-039

ATel #9484; J. S. Brown, K. Z. Stanek, T. W.-S. Holoien, C. S. Kochanek, 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 10 Sep 2016; 16:07 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Jonathan Brown (brown@astronomy.ohio-state.edu)

Subjects: Optical, Supernovae, Transient

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 LSBG F156-039.

ASASSN-16kk (AT 2016gdu) was discovered in images obtained on UT 2016-09-09.25 at V~16.9 mag. We also detect the object in images obtained on UT 2016-09-06.33 (V~17.1) and UT 2016-09-05.32 (V~17.1). We do not detect (V>17.5) the object in images taken on UT 2016-09-04.36 and before. This figure shows the archival DSS image of the host (left), the ASAS-SN reference image (middle), and the ASAS-SN subtraction image (right). The red circle has a radius of 10" and is centered on the position of the transient in the subtraction image.

The position of ASASSN-16kk is approximately 3.1" South and 7.8" West from the center of the galaxy LSBG F156-039 (z=0.043707, d=185 Mpc, via NED), giving an absolute V-band magnitude of approximately -19.4 (m-M=36.25, A_V=0.037). The classification of the transient in ATEL #9483 indicate that ASASSN-16kk is a Type Ia SN near maximum light. 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-16kk  04:10:31.49    -54:41:06.72     2016-09-09.25      16.9          -19.4               8.39 
 
Obs. UT Date         V mag 
2016-09-04.36        >17.5 
2016-09-05.32         17.1 
2016-09-06.33         17.1 
2016-09-09.25         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, 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.