ATLAS18bcde (AT2018kpo) : discovery of young transient in MCG-01-10-019 (70 Mpc)

ATel #12326; S. J. Smartt, K. W. Smith, A. McCormack (Queen's University Belfast), L. Denneau, H. Flewelling, A. Heinze, J. Tonry, H. Weiland (IfA, University of Hawaii), B. Stalder (LSST) A. Rest (STScI), P. Clark, M. Fulton, O. McBrien, M. Magee, K. Maguire, D. O'Neill, S. Prentice, D. R. Young (Queen's University Belfast), D. E. Wright (University of Minnesota)
on 24 Dec 2018; 19:44 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Stephen Smartt (s.smartt@qub.ac.uk)

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ATLAS is a twin 0.5m telescope system on Haleakala and Mauna Loa which is robotically surveying the sky above declination -40 with a cadence of 2 days (Tonry et al. 2018, PASP, 13, 064505). Two filters are used, cyan and orange (denoted c and o; all mags quoted are in the AB system). While carrying out the primary mission for Near Earth Objects, we search for and publicly report stationary transients to the IAU Transient Name Server. More information is on http://www.fallingstar.com. We are submitting Astronomer's Telegrams for transients that are either within 100 Mpc, or have some other interesting feature to bring to the community's attention, such as bright nuclear transients, slowly rising or rapidly fading objects.

We report a new, young transient source, most likely a supernova in the galaxy MCG-01-10-019. We discovered ATLAS18bcde (AT2018kpo) on MJD 58476.37 == 2018 December 24.37 UT, at m_o = 18.1 +/- 0.2. ATLAS18bcde is offset by 29.58 arcsec south, 1.03 arcsec east from MCG-01-10-019, which is at z=0.018 or d=70 +/- 5 Mpc (from NED). Implying an absolute magnitude of M =-16.2 (assuming m-M = 34.2 and A_o = 0.1).

An upper limit of o < 19.3 was measured 24hrs earlier, implying a rise of > 1 mag in the first day. A summary of the transient's properties are summarised below. Follow up observations are encouraged.

 
Name        | ATLAS Name | RA (J2000)  | Dec (J2000) | Disc. Date | Disc Mag | Offset from host    
ATLAS18bcde | AT2018kpo  | 03:40:43.05 | -06:25:24.1 |  58476.37  | 18.1 o   | 30 arcsec 
 
 
This work has made use of data from the Asteroid Terrestrial-impact 
Last Alert System (ATLAS) project. ATLAS is primarily funded to search 
for near earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, 
and 80NSSC18K1575; byproducts of the NEO search include images and 
catalogs from the survey area. The ATLAS science products have been 
made possible through the contributions of the University of Hawaii 
Institute for Astronomy, the Queen's University Belfast, and the Space 
Telescope Science Institute.