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ASAS-SN Discovery of Two Possible Supernovae in Hosts with Unknown Redshifts

ATel #7450; 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), J. Brimacombe (Coral Towers Observatory), D. Szczygiel, G. Pojmanski (Warsaw University Observatory)
on 27 Apr 2015; 04:31 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 #: 7458

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 two new transient sources, possibly supernovae, both near potential hosts with unknown redshifts.

ASASSN-15hy was discovered in images obtained on UT 2015-04-25.210 at V~16.4 mag. We also detect the object in images obtained on UT 2015-04-26.210 (V~16.2). We do not detect (V>16.8) the object in images taken on UT 2015-04-21.34 and before. An image obtained on UT 2015-04-27.09 with the LCOGT 1-m robotic telescope in Sutherland, South Africa confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the LCOGT g-band confirmation image (right). The red circle has a radius of 4" and is centered on the position of the transient in the LCOGT image.

The position of ASASSN-15hy is approximately 6.4" North and 11.2" West from what appears to be a galaxy in archival DSS images, but the potential host is not listed in NED.

ASASSN-15hz was discovered in images obtained on UT 2015-04-26.38 at V~17.2 mag. We do not detect (V>17.5) the object in images taken on UT 2015-04-19.310 and before. An image obtained on UT 2015-04-27.13 with the LCOGT 1-m robotic telescope in Sutherland, South Africa confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the LCOGT g-band confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the LCOGT image.

The position of ASASSN-15hz is approximately 3.3" South and 1.4" East from the center of the galaxy APMUKS(BJ) B222606.49-654315.6, which has no available redshift in NED. (See here.) 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-15hy  20:10:02.35    -00:44:21.31      2015-04-25.21      16.4          N/A                  12.9 
ASASSN-15hz  22:29:38.08    -65:27:56.24      2015-04-26.38      17.2          N/A                  3.58 

ASASSN-15hy photometry:

 
Obs. UT Date         V mag 
2015-04-21.34         >16.8 
2015-04-25.210         16.4 
2015-04-26.210         16.2 

ASASSN-15hz photometry:

 
Obs. UT Date         V mag 
2015-04-19.310        >17.5 
2015-04-26.38          17.2 

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.