ASASSN-16la: Discovery of A Probable Supernova in 2MASXi J0229172+180515
ATel #9571; 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 29 Sep 2016; 23:57 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 "Brutus" telescope in Haleakala, Hawaii, we discovered a new transient source, most likely a supernova, in the galaxy 2MASXi J0229172+180515.
ASASSN-16la (AT 2016gsn) was discovered in images obtained on UT 2016-09-29.46 at V~16.3 mag. We also detect the object in images obtained on UT 2016-09-25.210 (V~17.5). We do not detect (V>17.6) the object in images taken on UT 2016-09-23.24 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-16la is approximately 0.3" North and 4.0" East from the center of the galaxy 2MASXi J0229172+180515 (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-16la 02:29:17.480 +18:05:16.35 2016-09-29.46 16.3 N/A 4.01
Obs. UT Date V mag
2016-09-23.24 >17.6
2016-09-25.21 17.5
2016-09-29.46 16.3
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.
