ASAS-SN Discovery of A Probable Supernova Near Unknown Redshift Galaxy SDSS J142443.90+260255.4

ATel #7816; T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, J. S. Brown, A. B. Danilet, G. Simonian, U. Basu, 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)
on 20 Jul 2015; 14:57 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@astronomy.ohio-state.edu)

Tweet

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 SDSS J142443.90+260255.4.

ASASSN-15mx was discovered in images obtained on UT 2015-07-19.31 at V~16.8 mag. We also detect the object in images obtained on UT 2015-07-13.32 (V~17.1) and UT 2015-07-07.31 (V~17.2). We do not detect (V>17.2) the object in images taken on UT 2015-07-05.33 and before. This figure shows the archival DSS image of the host (left), the ASAS-SN V-band reference image (center), and the ASAS-SN 2015-07-19.31 V-band discovery image (right). The red circle has a radius of 5" and is centered on the position of the transient in the ASAS-SN image.

The position of ASASSN-15mx is approximately 3.4" South and 8.8" East from the center of the galaxy SDSS J142443.90+260255.4, which has no available redshift in NED. 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-15mx  14:24:44.55    +26:02:52.1      2015-07-19.31      16.8            N/A               9.43 

 
Obs. UT Date         V mag 
2015-07-05.33        >17.2 
2015-07-07.31         17.2 
2015-07-13.32         17.1 
2015-07-19.31         16.8 

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.