ASASSN-16do: Discovery of A Probable Supernova in an Uncatalogued Galaxy

ATel #8888; B. Nicholls (Mt. Vernon Obs., New Zealand), J. S. Brown, K. Z. Stanek (Ohio State), Subo Dong (KIAA-PKU), 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), Ping Chen (KIAA-PKU), J. Brimacombe (Coral Towers Observatory), S. Kiyota (Variable Star Observers League in Japan), G. Masi (Virtual Telescope Project, Ceccano, Italy)
on 31 Mar 2016; 22:51 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Jonathan Brown (brown@astronomy.ohio-state.edu)

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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 an uncatalogued galaxy.

ASASSN-16do (AT 2016blf) was discovered in images obtained on UT 2016-03-30.12 at V~16.1 mag. We also detect the object in images obtained on UT 2016-03-29.12 (V~16.0) and UT 2016-03-24.06 (V~16.4). We do not detect (V>17.1) the object in images taken on UT 2016-03-23.14 and before. An image obtained on 2016-03-31 with the LCOGT 1.0-m robotic telescope at SAAO 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 5" and is centered on the position of the transient in the LCOGT image.

There are no catalogued galaxies within 2' of ASASSN-16do, but inspection of DSS plates reveal a potential host galaxy 0.1" South and 1.3" West of the position of the transient. We also note the possibility that ASASSN-16do is a CV, but consider this to be unlikely given the light curve. ASASSN-16do could plausibly be a super-luminous supernova, given SN-host magnitude difference. 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-16do  06:34:12.716  -32:59:49.62      2016-03-30.12       16.1           N/A                  1.3 

 
Obs. UT Date         V mag 
2016-03-23.14        >17.1 
2016-03-24.06         16.4 
2016-03-29.12         16.0 
2016-03-30.12         16.1 

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.

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.