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ASAS-SN Discovery of A Bright Probable Supernova in GALEXASC J044353.08-094205.8

ATel #7895; S. Kiyota (Variable Star Observers League in Japan), T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, J. S. Brown, A. B. Danilet, G. Simonian, U. Basu, J. F. Beacom, T. A. Thompson (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Subo Dong (KIAA-PKU), J. Brimacombe (Coral Towers Observatory), E. Falco (CfA), P. R. Wozniak (LANL), D. Szczygiel, G. Pojmanski (Warsaw University Observatory), G. Masi (Virtual Telescope Project, Ceccano, Italy), W. Wiethoff (University of Minnesota, Duluth)
on 9 Aug 2015; 17:23 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@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 bright new transient source, most likely a supernova, in the galaxy GALEXASC J044353.08-094205.8.

ASASSN-15nx was discovered in images obtained on UT 2015-08-08.63 at V~15.6 mag. We also detect the object in images obtained on UT 2015-08-09.62 (V~16.0), UT 2015-07-21.41 (V~16.3), and UT 2015-07-19.42 (V~16.6). We do not detect (V>16.3) the object in images taken on UT 2015-07-01.44 and before. An image obtained by S. Kiyota on UT 2015-08-09.51 using a Planewave CDK 0.61-m telescope located at Sierra Remote Observatory confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the S. Kiyota confirmation image (right). The red circle has a radius of 3" and is centered on the position of the transient in the S. Kiyota image.

The position of ASASSN-15nx is approximately 5.3" South and 1.6" East from the center of the galaxy GALEXASC J044353.08-094205.8, which has no available redshift in 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-15nx  04:43:53.19    -09:42:11.22     2015-08-08.63      15.6            N/A                  5.54 
 
Obs. UT Date         V mag 
2015-07-01.44        >16.3 
2015-07-19.42         16.6 
2015-07-21.41         16.3 
2015-08-08.63         15.6 
2015-08-09.62         16.0 

Follow-up observations are encouraged.

We thank LCOGT and its staff for their continued support of ASAS-SN. ASAS-SN is supported in part by 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.