AstroNote 2019-105

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DRAFT
2019-10-17 16:04:50
Type: Object/s-Discovery/Classification
ATLAS19yhi (AT2019spl): discovery of a candidate SN in NGC 3042 (56 Mpc)
Authors: K. W. Smith, S. Srivastav, O. McBrien, S. J. Smartt, J. Gillanders (Queen's University Belfast), T.-W. Chen (MPE), L. Denneau, H. Flewelling, A. Heinze, J. Tonry, H. Weiland (IfA, University of Hawaii), B. Stalder (LSST) A. Rest (STScI), P. Clark, M. Fulton, D. O'Neill, D. R. Young (Queen's University Belfast), D. E. Wright (University of Minnesota)
Source Group: ATLAS
Keywords: Supernova
Abstract:
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). Here we report the discovery of a transient ATLAS19yhi (AT2019spl) in galaxy NGC 3042 at 56 Mpc.

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.  Data processing is carried out at Queen's University which combines automated source parameter filtering, machine learning image recognition, and spatial cross-matching with astronomical catalogues. More information is on the ATLAS homepage. We are submitting AstroNotes 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 transient source, most likely a supernova in the galaxy NGC 3042. We discovered ATLAS19yhi (AT2019spl) on MJD 58764.63 == 2019-10-08.63, at m_o = 18.28 +/- 0.1. ATLAS19yhi is offset by 1.70 arcsec south, 15.20 arcsec east from NGC 3042, which is at z = 0.013 or d = 56 Mpc (from NED), implying an absolute magnitude of M = -15.3 (assuming m-M = 33.73 and A_r = 0.13 and A_i = 0.09). The object has just emerged from behind the sun and appears to have declined by 0.2 magnitudes 8 days later (MJD 58772 == 2019-10-16), implying an old supernova. Followup observations are encouraged. 

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. 

Show current TNS values
CatalogNameReported RAReported DECReported Obj-TypeReported RedshiftHost NameHost RedshiftRemarksTNS RATNS DECTNS Obj-TypeTNS Redshift
TNS2019spl [ATLAS19yhi]09:53:21.233+00:41:50.02SN0.01309:53:21.270+00:41:48.60