ASASSN-16fn and ASASSN-16fo: Discovery of Two Probable Supernovae

ATel #9081; B. Nicholls (Mt. Vernon Obs., New Zealand), 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), I. Cruz (Cruz Observatory), S. Kiyota (Variable Star Observers League in Japan), R. A. Koff (Antelope Hills Observatory)
on 26 May 2016; 16:31 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 two new probable supernovae, one in an uncatalogued galaxy, and a second in 2MASX J13323577-0516218.

ASASSN-16fn (AT 2016coa) was discovered in images obtained on UT 2016-05-26.21 at V~16.2 mag. We do not detect (V>16.6) the object in images taken on UT 2016-05-21.12 and before. An image obtained on 2015-05-26 by B. Nicholls confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the B. Nicholls confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the B. Nicholls image.

The position of ASASSN-16fn is approximately 0.1" North and 0.8" West of a small, uncatalogued host galaxy (no redshift information available from NED).

ASASSN-16fo (AT 2016cob) was discovered in images obtained on UT 2016-05-26.23 at V~16.6 mag. We also detect the transient in images taken on UT 2016-05-21.33 (V~16.6). We do not detect (V>17.9) the object in images taken on UT 2016-05-12.36 and before. An image obtained on 2016-05-26 by B. Nicholls confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the B. Nicholls confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the B. Nicholls image.

The position of ASASSN-16fo is approximately 0.3" North and 0.5" East from the center of the galaxy 2MASX J13323577-0516218 (z=0.029610, d=129 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.8 (m-M=35.48, A_V=0.086). Properties of the new source and photometry are summarized in the tables below: Properties of the new sources 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-16fn  12:56:58.887   -15:32:10.51     2016-05-26.21      16.2           N/A                0.8 
ASASSN-16fo  13:32:35.812   -05:16:21.33     2016-05-26.23      16.6          -18.8               0.6 

ASASSN-16fn photometry:

 
Obs. UT Date         V mag 
2016-05-21.12        >16.6 
2016-05-26.21         16.2 

ASASSN-16fo photometry:

 
Obs. UT Date         V mag 
2016-05-12.36        >17.9      
2016-05-21.33         16.6     
2016-05-26.23         16.6 

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.