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ASAS-SN Discovery of A Probable Supernova in ESO 534-G024

ATel #8118; T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, J. S. Brown, D. Godoy-Rivera, U. Basu (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Subo Dong, Ping Chen (KIAA-PKU), J. Brimacombe (Coral Towers Observatory)
on 4 Oct 2015; 16:18 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@astronomy.ohio-state.edu)

Subjects: Optical, Supernovae, Transient

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Cassius" telescope in Cerro Tololo, Chile, we discovered a new transient source, most likely a supernova, in the galaxy ESO.

ASASSN-15qh was discovered in images obtained on UT 2015-10-04.11 at V~16.5 mag. We also detect the object in images obtained on UT 2015-10-02.18 (V~16.8) and UT 2015-09-30.18 (V~16.2). We do not detect (V>16.5) the object in images taken on UT 2015-09-28.05 and before. An image obtained on UT 2015-10-04.61 with the LCOGT 1-m robotic telescope at Siding Springs Observatory confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the LCOGT r-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-15qh is approximately 11.0" North and 21.1" West from the center of the galaxy ESO 534-G024 (z=0.010207, d=37.8 Mpc, via NED), giving an absolute V-band magnitude of approximately -16.5 (m-M=32.89, A_V=0.083). 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-15qh  22:45:13.22    -22:43:39.82      2015-10-04.11      16.5          -16.5               23.8 
Obs. UT Date         V mag 
2015-09-28.05        >16.5 
2015-09-30.18         16.2 
2015-10-02.18         16.8 
2015-10-04.11         16.5 

Follow-up observations are encouraged.

We thank LCOGT and its staff for their continued support of ASAS-SN. ASAS-SN is supported by NSF grant AST-1515927, the Mt. Cuba Astronomical Foundation, the Center for Cosmology and AstroParticle Physics (CCAPP) at OSU, and the Robert Martin Ayers Science Fund. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.