ASASSN-16gz and ASASSN-16ha: Discovery of Two Probable Supernovae

ATel #9222; 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 7 Jul 2016; 17:30 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 transient sources, most likely supernovae, in the galaxies APMUKS(BJ) B043218.28-211910.3 and Fairall 0673.

ASASSN-16gz (AT 2016cyz) was discovered in images obtained on UT 2016-07-06.42 at V~16.6 mag. We do not detect (V>16.8) the object in images taken on UT 2016-04-07.97 and before. An image obtained on 2016-07-07 with the 1.0-m LCOGT 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.

The position of ASASSN-16gz is approximately 5.3" North and 4.2" West from the center of the galaxy APMUKS(BJ) B043218.28-211910.3 (no redshift information available from NED).

ASASSN-16ha (AT 2016cza) was discovered in images obtained on UT 2016-07-07.37 at V~16.3 mag. We also detect the object in images obtained on UT 2016-06-28.36 (V~17.2). We do not detect (V>17.0) the object in images taken on UT 2016-06-21.33 and before. This figure shows the DSS reference image (left), the ASAS-SN reference image (middle), and the ASAS-SN subtraction image (right). The red circle has a radius of 20" and is centered on the position of the transient in the subtraction image.

The position of ASASSN-16ha is approximately 0.7" South and 14.6" West from the center of the galaxy FAIRALL 0673 (z=0.022529, d=91.5 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.5 (m-M=34.76, A_V=0.033).

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-16gz  04:34:27.549   -21:12:55.11     2016-07-06.42      16.6           N/A                6.8 
ASASSN-16ha  01:03:30.273   -47:01:27.58     2016-07-07.37      16.3           -18.5              14.6 

ASASSN-16gz photometry:

 
Obs. UT Date         V mag 
2016-04-07.97        >16.8 
2016-07-06.42         16.6 

ASASSN-16ha photometry:

 
Obs. UT Date         V mag 
2016-06-21.33        >17.0 
2016-06-28.36         17.2 
2016-07-07.37         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.