ASAS-SN Discovery and Spectroscopic Confirmation of A Supernova in GALEXASC J000337.23-343323.1
ATel #8199; T. W.-S. Holoien (Ohio State), J. L. Prieto (Diego Portales; MAS), B. Madore, B. J. Shappee (Carnegie Observatories), J. C. Munoz-Mateos (ESO), K. Z. Stanek, C. S. Kochanek, J. S. Brown, D. Godoy-Rivera, U. Basu (Ohio State), D. Bersier (LJMU), Subo Dong, Ping Chen (KIAA-PKU), J. Brimacombe (Coral Towers Observatory)
on 21 Oct 2015; 02:31 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 supernova near the UV source GALEXASC J000337.23-343323.1.
ASASSN-15rp was discovered in images obtained on UT 2015-10-02.03 at V~17.4 mag. It is also detected in images taken on UT 2015-10-08.15 at V~17.1 mag. We do not detect (V>16.5) the object in images taken on UT 2015-09-30.20 and before. An image obtained on UT 2015-10-11.00 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 V-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-15rp is approximately 1.0" South and 0.2" East from the center of the UV source GALEXASC J000337.23-343323.1, which is unresolved in POSS images. We obtained a follow-up optical spectrum (range 370-910 nm) of the transient obtained on 2015-10-17 with the du Pont 2.5-m telescope (+ WFCCD) at Las Campanas Observatory. This spectrum shows a good match to a normal type II supernova and narrow H-alpha in emission at redshift z=0.02894. Assuming this redshift for the host gives an absolute V-band magnitude of approximately -18.2 (m-M=35.53, A_V=0.043). 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-15rp 00:03:37.25 -34:33:24.23 2015-10-02.03 17.4 -18.2 1.02
Obs. UT Date V mag
2015-09-30.20 >16.5
2015-10-02.03 17.4
2015-10-08.15 17.1
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.
