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ASAS-SN Discovery of A Possible Supernova Near 2MASXi J0909234-044327

ATel #7426; S. Kiyota (Variable Star Observers League in Japan), 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. G. Carballo (Observatorio Cerro del Viento MPC 184), J. M. Fernandez (Observatory Inmaculada del Molino), R. A. Koff (Antelope Hills Observatory), G. Krannich (Roof Observatory Kaufering), L. A.G. Monard (Klein Karoo Observatory), B. Nicholls (Mt. Vernon Obs., New Zealand), J. Nicolas (Groupe SNAUDE, France), W. Wiethoff (University of Minnesota, Duluth)
on 21 Apr 2015; 18:43 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 #: 7432

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the double 14-cm "Cassius" telescope in Cerro Tololo, Chile, we discovered a new transient source, possibly a supernova, near the extended source 2MASXi J0909234-044327.

ASASSN-15ho was discovered in images obtained on UT 2015-04-19.06 at V~16.9 mag. We also detect the object in images obtained on UT 2015-04-18.06 (V~17.1), UT 2015-04-14.13 (V~16.7), and UT 2015-04-10.29 (V~17.3). We do not detect (V>17.4) the object in images taken on UT 2015-04-09.15 and before. Images obtained by S. Kiyota on UT 2015-04-21.15 using a Planewave CDK 0.43-m telescope located near Mayhill, New Mexico and by J. Brimacombe on UT 2015-04-21.15 with the RCOS 51-cm telescope in New Mexico and confirm 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 4.0" and is centered on the position of the transient in the J. Brimacombe image.

The position of ASASSN-15ho is approximately 3.3" South and 7.1" East from the center of the extended source 2MASXi J0909234-044327, which is not labelled as a galaxy in NED (see here). As the nature of the potential host is unknown, the nature of the transient cannot be determined without a spectrum, but if the extended source is a galaxy, ASASSN-15ho is likely a new supernova. Properties of the 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-15ho  09:09:23.89   -04:43:30.98      2015-04-19.06      16.9          N/A                    7.83 
Obs. UT Date         V mag 
2015-04-09.15        >17.4 
2015-04-10.29         17.3 
2015-04-14.13         16.7 
2015-04-18.06         17.1 
2015-04-19.06         16.9 

Follow-up observations, particularly spectroscopy, 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.