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ASAS-SN Discovery of A Probable Supernova in GALEXASC J021558.44+121415.2

ATel #8212; J. S. Brown, K. Z. Stanek, T. W.-S. Holoien, C. S. Kochanek, D. Godoy-Rivera, U. Basu (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Subo Dong, Ping Chen (KIAA-PKU), J. Brimacombe (Coral Towers Observatory)
on 24 Oct 2015; 19:02 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Jonathan Brown (brown@astronomy.ohio-state.edu)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 8239, 8249

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 GALEXASC J021558.44+121415.2.

ASASSN-15rw was discovered in images obtained on UT 2015-10-24.49 at V~16.0 mag. We also detect the object in images obtained on UT 2015-10-23.28 (V~16.4). We do not detect (V>16.7) the object in images taken on UT 2015-10-21.43 and before. This figure shows the ASAS-SN V-band reference image (left), the ASAS-SN discovery image (middle), and the archival SDSS g-band image of the host (right). The red circle has a radius of 5" and is centered on the position of the transient in the discovery image.

The position of ASASSN-15rw is approximately 0.70" South and 4.35" West from the center of the galaxy GALEXASC J021558.44+121415.2 (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-15rw  02:15:58.15    +12:14:14.60      2015-10-24.49      16.0         N/A              4.41

 
Obs. UT Date         V mag 
2015-10-21.43        >16.7 
2015-10-23.28         16.4 
2015-10-24.49         16.0

Follow-up observations are encouraged.

We thank LCOGT and its staff for their continued support of ASAS-SN. ASAS-SN is supported by NSF grant AST-1515927, the Mt. Cuba Astronomical Foundation, the Center for Cosmology and AstroParticle Physics (CCAPP) at OSU, and the Robert Martin Ayers Sciences Fund. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.