ASASSN-16gu: Discovery of A Probable Supernova in NGC 4725

ATel #9211; J. Brimacombe (Coral Towers Observatory), Subo Dong(KIAA-PKU), C. S. Kochanek, K. Z. Stanek, J. S. Brown, T. W.-S. Holoien, 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. M. Fernandez (Observatory Inmaculada del Molino), R. A. Koff (Antelope Hills Observatory), R. S. Post (Post Astronomy), G. Stone (Sierra Remote Observatories), W. Wiethoff (University of Minnesota, Duluth)
on 5 Jul 2016; 11:03 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Subo Dong (dongsubo@pku.edu.cn)

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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, in the galaxy NGC 4725.

ASASSN-16gu (AT 2016cyu) was discovered in images obtained on UT 2016-07-05.27 at V ~ 17.0 mag. We do not detect (V>18.4) the object in images taken on UT 2016-06-26.30 and before. An image obtained on UT 2016-07-05.39 by J. Brimacombe confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the J. Brimacombe confirmation image (right). The red circle has a radius of 10" and is centered on the position of the transient in the J. Brimacombe image.

The position of ASASSN-16fq is approximately 324" from the center of the galaxy NGC 4725 (z=0.004023, d~13 Mpc, via NED), giving an absolute V-band magnitude of approximately -13.6 (m-M~30.6, A_V=0.03). 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-16gu  12:50:50.09    +25:31:13.82      2016-07-05.27      17.0          -13.6               324 

   
Obs. UT Date         V mag   
2016-06-26.30        >18.4   

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.