ASASSN-16lg: Discovery of A Probable Supernova in ARK 530

ATel #9601; 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 7 Oct 2016; 16:23 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Jonathan Brown (brown@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 "Brutus" telescope in Haleakala, Hawaii, we discovered a new transient source, most likely a supernova, in the galaxy ARK 530.

ASASSN-16lg (AT 2016gye) was discovered in images obtained on UT 2016-10-06.20 at V~16.2 mag. We also detect the object in images obtained on UT 2016-10-07.21 (V~16.0). We do not detect (V>17.8) the object in images taken on UT 2016-09-30.23 and before. This figure shows the archival DSS image of the host (left) and 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-16lg is approximately 0.7" North and 1.6" East from the center of the galaxy ARK 530 (z=0.021171, d=87.4 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.7 (m-M=34.71, A_V=0.215). 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-16lg  17:48:12.378   +17:37:31.57     2016-10-06.20      16.2          -18.7               1.75 

 
Obs. UT Date         V mag 
2016-09-30.23        >17.8 
2016-10-06.20         16.2 
2016-10-07.21         16.0 

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.