ATLAS detection of the bright, fast rising supernova candidate AT2016gkg in NGC 613

ATel #9526; J. Tonry, L. Denneau, B. Stalder, A. Heinze, A. Sherstyuk (IfA, University of Hawaii), A. Rest (STScI), K. W. Smith, S. J. Smartt (Queen's University Belfast)
on 21 Sep 2016; 18:21 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Ken Smith (k.w.smith@qub.ac.uk)

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ATLAS is a twin 0.5m telescope system on Haleakala and Mauna Loa (see Tonry et al. ATel #8680). The first unit is operational on Haleakala is robotically surveying the sky. Two filters are used, cyan and orange (denoted c and o, all mags in AB system), more information is on http://www.fallingstar.com. We report detection and photometry of AT2016gkg discovered by S. Otero & V. Buso (TNS Astronomical Transient Report No. 5381) at 9hrs after the discovery and confirmed by ASAS-SN in ATel #9521 (Nicholls et al.). ATLAS detection details are as follows, which confirm the fast rise and very likely young SN nature.

 
Name      | ATLAS Name | RA (J2000)  | Dec (J2000) | Disc. MJD | Disc. Date  | Disc Mag |   z 
AT2016gkg | ATLAS16cvu | 01:34:14.40 | -29:26:24.2 | 57651.54  | 20160920.54 |  15.94 o | 0.004940 

As reported by ASAS-SN, the SN candidate is 92.3" from the centre of NGC 0613, with spectroscopic redshift z=0.004940. The distance is likely in the range 25 +/- 5Mpc (all data from NED). Assuming A_o=0.04 the object is M_o = -16.1 in the ATLAS images and rising fast. The published data to date indicate the following rise (our last non-detection is on 2016-09-12):

 
Date            Mag             Source 
2019-09-12.61  o<18.5           ATLAS  
2019-09-20.16    17.6           Otero & Buso 
2016-09-20.16   >17.3           ASASSN 
2016-09-20.54  o=15.94 +/- 0.13 ATLAS 
2016-09-20.55  o=15.78 +/- 0.08 ATLAS 
2016-09-21.29    15.0           ASASSN