ASASSN-16eo: Discovery of A Supernova in an Uncatalogued Galaxy
ATel #8965; J. Strader, L. Chomiuk, L. Shishkovsky (MSU), 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 18 Apr 2016; 03:13 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 in an uncatalogued galaxy.
ASASSN-16eo (AT 2016bro) was discovered in images obtained on UT 2016-04-03.09 at V~17.0 mag. We also detect the object in images obtained on UT 2016-04-07.08 (V~17.5), UT 2016-03-30.06 (V~17.4), UT 2016-03-29.010 (V~16.9), and UT 2016-03-24.06 (V~16.6). We do not detect (V>16.5) the object in images taken on UT 2016-03-23.12 and before. An image obtained 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 confirmation image (right). The red circle has a radius of 3" and is centered on the position of the transient in the LCOGT image.
The position of ASASSN-16eo is approximately 0.1" South and 0.0" West from the center of the host. While the host is visible in DSS images, the nearest source listed in NED, GALEXASC J054310.28-413132.9, is roughly half an arcminute away from the transient. An optical spectrum of ASASSN-16eo was obtained on 2016-04-16 by J. Strader, L. Chomiuk, L. Shishkovsky using the Goodman spectrograph on the SOAR 4.1-m telescope. Classification with SNID (Blondin and Tonry 2007, ApJ, 666, 1024) indicates that the transient is a normal type Ia supernova roughly 22 days after maximum light, at a redshift of z=0.037 (d=136.9 Mpc), giving an absolute V-band magnitude of approximately -19.2 (m-M=36.07, A_V=0.12). 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-16eo 05:43:12.78 -41:31:15.76 2016-04-03.09 17.0 -19.2 0.1
Obs. UT Date V mag
2016-03-23.12 >16.5
2016-03-24.06 16.6
2016-03-29.01 16.9
2016-03-30.06 17.4
2016-04-03.09 17.0
2016-04-07.08 17.5
Follow-up observations are encouraged.
While we are participating in the TNS system to minimize potential confusion, ASAS-SN will continue using ASASSN-16xx transient names as our primary nomenclature (including supernovae, but also other classes of transients), and we encourage others to do the same. We prefer merging the names as ASASSN-16xx (AT2016xyz) to preserve, rather than anonymize, the origin of the transient.
We thank LCOGT and its staff for their continued support of ASAS-SN. ASAS-SN is supported by NSF grant AST-1515927, the Center for Cosmology and AstroParticle Physics (CCAPP) at OSU, the Mt. Cuba Astronomical Foundation, George Skestos, and the Robert Martin Ayers Sciences Fund. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.
