ASASSN-16ll: Discovery of A Probable Supernova in IRAS F18594+5429

ATel #9602; 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; 19:35 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 IRAS F18594+5429.

ASASSN-16ll (AT 2016gyt) was discovered in images obtained on UT 2016-09-26.29 at V~17.1 mag. We also detect the object in images obtained on UT 2016-10-07.26 (V~16.8) and UT 2016-09-30.28 (V~17.0). We do not detect (V>17.1) the object in images taken on UT 2016-09-25.28 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-16ll is approximately 9.3" South and 2.9" East from the center of the galaxy IRAS F18594+5429 (no redshift information available from NED). 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-16ll  19:00:32.43   +54:34:09.70     2016-09-26.29      17.0              N/A               9.74 

 
Obs. UT Date         V mag 
2016-09-25.28        >17.1 
2016-09-26.29         17.1 
2016-09-30.28         17.0 
2016-10-07.26         16.8 

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.