ASASSN-16fm: Discovery of A Probable Supernova with no Apparent Host Galaxy
ATel #9080; S. Villanueva Jr., J. S. Brown, K. Z. Stanek, T. W.-S. Holoien, C. S. Kochanek, 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 25 May 2016; 17:17 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Jonathan Brown (brown@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 "Brutus" telescope in Haleakala, Hawaii, we discovered a new transient source, most likely a supernova, with no apparent host galaxy.
ASASSN-16fm (AT 2016cny) was discovered in images obtained on UT 2016-05-13.59 at V~16.9 mag. We also detect the object in images obtained on UT 2016-05-19.47 (V~16.7) and UT 2016-05-22.58 (V~17.1). We do not detect (V>17.9) the object in images taken on UT 2016-05-03.58 and before. An image obtained on 2016-05-25 by S. Villanueva with the DEMONEXT robotic telescope confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the DEMONEXT confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the DEMONEXT image.
There is no apparent host galaxy within the vicinity of ASASSN-16fm, which could be indicative of an unusually luminous transient. However, the transient is relatively close to the Galactic plane (l,b=63.7532,-8.2003; A_V=1.2), making a less luminous, local transient a plausible alternative. 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-16fm 20:22:50.125 +22:42:09.66 2016-05-13.59 16.9 N/A N/A
Obs. UT Date V mag
2016-05-03.58 >17.9
2016-05-13.59 16.9
2016-05-19.47 16.7
2016-05-22.58 17.1
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.
Data taken during commissioning of the DEdicated MONitor of EXotransits and Transients (DEMONEXT), a robotic and automated 20 inch telescope located at Winer Observatory in Sonoita, AZ. DEMONEXT is a PlaneWave CDK20 telescope on a Mathis Instruments MI750/1000 equatorial mount, and has a Finger Lakes Instruments 2048x2048 CCD, with a 0.9"/pixel scale and 30.7'x30.7' field-of-view.
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.