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ASAS-SN Discovery of A Probable Supernova in 2MFGC 08437

ATel #7548; J. Nicolas (Groupe SNAUDE, France), T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, J. S. Brown, A. B. Danilet, G. Simonian, U. Basu, N. Goss, 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), J. G. Carballo (Observatorio Cerro del Viento MPC 184), J. M. Fernandez (Observatory Inmaculada del Molino), S. Kiyota (Variable Star Observers League in Japan), B. Nicholls (Mt. Vernon Obs., New Zealand), W. Wiethoff (University of Minnesota, Duluth)
on 21 May 2015; 23:39 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@astronomy.ohio-state.edu)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 7609

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 2MFGC 08437.

ASASSN-15js was discovered in images obtained on UT 2015-05-21.210 at V~16.8 mag. We do not detect (V>16.4) the object in images taken on UT 2015-05-21.210 and before. An image obtained by J. Nicolas on UT 2015-05-21.91 using a 0.41-m telescope at Observatoire Chante-Perdrix-Dauban, France, confirms the discovery of the transient. This figure shows the archival SDSS g-band image of the host (left) and the J. Nicolas confirmation image (right). The red circle has a radius of 6" and is centered on the position of the transient in the J. Nicolas image.

The position of ASASSN-15js is approximately 2.9" North and 0.8" East from the center of the galaxy 2MFGC 08437 (z=0.021059, d=92.9 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.1 (m-M=34.84, A_V=0.07). 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-15js  10:50:38.35   +12:17:49.19      2015-05-21.210      16.8          -18.1               3.01 
Obs. UT Date         V mag 
2015-05-21.210        >16.4 
2015-05-21.210         16.8 

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.