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ASASSN-16hn: Discovery of A Probable Supernova in GALEXASC J000403.88-344851.6

ATel #9262; J. Brimacombe (Coral Towers Observatory), J. S. Brown, K. Z. Stanek, T. W.-S. Holoien, C. S. Kochanek, J. Shields, 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, S. Bose, Ping Chen (KIAA-PKU), S. Kiyota (Variable Star Observers League in Japan), J. Nicolas (Groupe SNAUDE, France), R. S. Post (Post Astronomy), G. Stone (Sierra Remote Observatories)
on 25 Jul 2016; 00:53 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 "Cassius" telescope in Cerro Tololo, Chile, we discovered a new transient source, most likely a supernova, in the galaxy GALEXASC J000403.88-344851.6.

ASASSN-16hn (AT 2016egz) was discovered in images obtained on UT 2016-07-24.32 at V~16.6 mag. We also detect the object in images taken on UT 2016-07-21.26 (V~16.1). We do not detect (V>17.4) the object in images taken on UT 2016-07-17.23 and before. An image obtained on 2016-07-24 by J. Brimacombe confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the J. Brimacombe confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the J. Brimacombe image.

The position of ASASSN-16hn is approximately 0.9" North and 0.3" West from the center of the galaxy GALEXASC J000403.88-344851.6 (z=0.023200, d=93.2 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.2 (m-M=34.80, A_V=0.042). 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-16hn  00:04:03.854   -34:48:51.87     2016-07-24.32      16.6          -18.2               0.95 
Obs. UT Date         V mag 
2016-07-17.23        >17.4 
2016-07-21.26         16.1 
2016-07-24.32         16.6 

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, the Mt. Cuba Astronomical Foundation, George Skestos, 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.