ASASSN-16dx: Discovery of A Probable Supernova in APMUKS(BJ) B032028.93-441621.0

ATel #8898; J. Brimacombe (Coral Towers Observatory), T. W.-S. Holoien (Ohio State), Subo Dong (KIAA-PKU), 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), Ping Chen (KIAA-PKU), I. Cruz (Cruz Observatory), J. M. Fernandez (Observatory Inmaculada del Molino), S. Kiyota (Variable Star Observers League in Japan), P. Marples (Leyburn Observatory, Australia)
on 3 Apr 2016; 21:16 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@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 the galaxy APMUKS(BJ) B032028.93-441621.0.

ASASSN-16dx (AT 2016blk) was discovered in images obtained on UT 2016-04-02.98 at V~16.3 mag. We also detect the object in images obtained on UT 2016-03-28.01 (V~16.9). We do not detect (V>16.6) the object in images taken on UT 2016-03-23.02 and before. Images obtained on UT 2016-04-03 by J. Brimacombe and with the LCOGT 1-m robotic telescope at Siding Spring Observatory confirm 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 3" and is centered on the position of the transient in the LCOGT image.

The position of ASASSN-16dx is approximately 0.3" North and 1.7" East from the center of the galaxy APMUKS(BJ) B032028.93-441621.0 (z=0.02997, d=132.1 Mpc, via VIZIER), giving an absolute V-band magnitude of approximately -19.3 (m-M=35.60, A_V=0.036). 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-16dx  03:22:12.85    -44:05:40.74      2016-04-02.98      16.3          -19.3               1.73 

 
Obs. UT Date         V mag 
2016-03-23.02        >16.6 
2016-03-28.01         16.9 
2016-04-02.98         16.3 

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.