ASASSN-16lm: Discovery of A Probable Supernova in 2MASX J09033461+4142367

ATel #9611; J. Nicolas (Groupe SNAUDE, France), J. Shields, K. Z. Stanek, C. S. Kochanek, J. S. Brown, T. Holoien (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 Oct 2016; 17:41 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Krzysztof Stanek (stanek.32@osu.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 2MASX J09033461+4142367.

ASASSN-16lm (AT 2016haa) was discovered in images obtained on UT 2016-10-09.61 at V~17.4 mag, and we also detect the transient on UT 2016-09-27 14:52:48 at V~17.7 We do not detect (V>18.0) the object in images taken on UT 2016-05-04 06:43:12 and before. An image obtained on 2016-10-09 by J. Nicolas confirms the discovery of the transient. This figure shows the archival SDSS image of the host (left) and the J. Nicolas confirmation image (right.. The red circle has a radius of 5" and is centered on the position of the transient in the J. Nicolas image.

The position of ASASSN-16lm is approximately 9.0" North and 1.14" West from the center of the galaxy 2MASX J09033461+4142367 (z=0.040476, d=174 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.9 (m-M=36.21, A_V=0.049). 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-16lm  135.89374   +41:42:45.5     2016-10-09.61      17.4          -18.9               9.1 

 
Obs. UT Date          V mag 
2016-05-04.28         >18.0 
2016-09-27.62          17.7 
2016-10-09.61           17.4 

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.