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ASAS-SN Discovery of Two Probable Supernovae in SDSS J110204.81+033003.1 and 2MASX J15570808-1240252

ATel #7491; J. Brimacombe (Coral Towers Observatory), T. W.-S. Holoien (Ohio State), D. Bersier (LJMU), 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), 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), L. A.G. Monard (Klein Karoo Observatory)
on 11 May 2015; 16:10 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 #: 7497, 7531

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 two new transient sources, most likely supernovae, in the galaxies SDSS J110204.81+033003.1 and 2MASX J15570808-1240252.

ASASSN-15ik was discovered in images obtained on UT 2015-05-11.24 at V~16.7 mag. We also detect the object in images obtained on UT 2015-05-06.28 (V~17.1). We do not detect (V>16.6) the object in images taken on UT 2015-05-05.38 and before. An image obtained by J. Brimacombe on UT 2015-05-11.51 with the RCOS 51-cm telescope in New Mexico 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 3" and is centered on the position of the transient in the J. Brimacombe image.

The position of ASASSN-15ik is approximately 0.4" South and 1.4" West from the center of the galaxy SDSS J110204.81+033003.1, which, while clearly a galaxy, has no redshift available in NED.

ASASSN-15il was discovered in images obtained on UT 2015-05-11.310 at V~16.7 mag. We also detect the object in images obtained on UT 2015-05-10.28 (V~16.6). We do not detect (V>16.0) the object in images taken on UT 2015-05-08.54 and before. An image obtained by J. Brimacombe on UT 2015-05-11.53 with the RCOS 51-cm telescope in New Mexico 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 3" and is centered on the position of the transient in the J. Brimacombe image.

The position of ASASSN-15il is approximately 1.7" North and 0.5" East from the center of the galaxy 2MASX J15570808-1240252 (z=0.023316, d=99.3 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.8 (m-M=34.98, A_V=0.477). Properties of the new sources 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-15ik  11:02:04.75   +03:30:02.66      2015-05-11.24      16.7            N/A               1.46 
ASASSN-15il  15:57:08.15   -12:40:23.93      2015-05-11.31      16.7          -18.8               1.77 

ASASSN-15ik photometry:

 
Obs. UT Date         V mag 
2015-05-05.38        >16.6 
2015-05-06.28         17.1 
2015-05-11.24         16.7 

ASASSN-15il photometry:

 
Obs. UT Date         V mag 
2015-05-08.54        >16.0 
2015-05-10.28         16.6 
2015-05-11.31         16.7 

Follow-up observations of both objects 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.