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ASAS-SN Discovery of A Probable Supernova in ESO 561-G012

ATel #7157; J. Brimacombe (Coral Towers Observatory), T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, 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), P. R. Wozniak (LANL), E. Falco (CfA), D. Szczygiel, G. Pojmanski (Warsaw University Observatory), J. M. Fernandez (Observatory Inmaculada del Molino), S. Kiyota (Variable Star Observers League in Japan), G. Krannich (Roof Observatory Kaufering), W. Wiethoff (University of Minnesota, Duluth)
on 27 Feb 2015; 19:44 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 #: 7180

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 ESO 561-G012:

 
Object       RA (J2000)     DEC (J2000)      Disc. UT Date   Disc. V mag 
ASASSN-15eb  08:06:07.40   -22:33:48.86      2015-02-26.33    16.0 

ASASSN-15eb was discovered in images obtained on UT 2015-02-26.33 at V~16.0 mag. We also detect the object in images obtained on UT 2015-02-27.34 (V~15.8). We do not detect (V>16.8) the object in images taken on UT 2015-02-08.41 and before. ESO 561-G012 is located close to the Galactic plane (b=5.1 degrees), in a field that is less frequently observed than our regular 2-3 day cadence. An image obtained by J. Brimacombe on UT 2015-02-27.66 with the RCOS 41-cm telescope near Siding Spring Observatory 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 lines indicate the position of the transient in the J. Brimacombe image.

The position of ASASSN-15eb is approximately 0.4" North and 1.1" West from the center of the galaxy ESO 561-G012 (z=0.016481, d=72.1 Mpc, via NED), giving it an absolute V-band magnitude of approximately -18.8 (m-M=34.29, A_V=0.534). 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.