AstroNote 2020-249

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DRAFT
2020-12-10 15:59:03
Type: Object/s-Discovery/Classification
ATLAS20bhfe (AT2020acat): discovery of a supernova in PGC 037027 (38 Mpc)
Authors: S. Srivastav, K. W. Smith, O. McBrien, S. J. Smartt, J. Gillanders, M. Fulton, D. R. Young, L. Shingles, M. McCollum (Queen's University Belfast), T.-W. Chen (Stockholm), J. Anderson (ESO), L. Denneau, A. Heinze, J. Tonry, H. Weiland (IfA, University of Hawaii), B. Stalder (LSST), A. Rest (STScI), D. E. Wright (University of Minnesota)
Source Group: ATLAS
Keywords: Supernova
Abstract:
Here we report the ATLAS discovery of the young supernova ATLAS20bhfe (AT2020acat) in galaxy PGC 037027 at magnitude o = 18.48 +/- 0.14. At a distance of 38 Mpc, the transient was discovered on MJD = 59192.63 (2020-12-09.63) with an absolute magnitude of M = -14.5 +/- 0.2. ATLAS20bhfe was promptly classified as a young SN IIb by ePESSTO+ with an NTT spectrum obtained on MJD 59193.31. The last non-detection through forced photometry was on MJD = 59190.61. Further follow-up is encouraged.

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,130:064505). 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 (Smith et al. 2020, PASP, 132:085002). 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 supernova in the galaxy PGC 037027. We discovered ATLAS20bhfe (AT2020acat) on MJD 59192.63 == 2020-12-09.63, at m_o = 18.48 +/- 0.14. There was no detection by ATLAS on MJD 59190.61 == 2020-12-07.61. ATLAS20bhfe is offset by 26.7 arcsec south, 19.9 arcsec west from its likely host galaxy PGC 037027, which is at z = 0.0079 or d = 38 Mpc (from NED), implying an absolute magnitude of M = -14.5 (assuming m-M = 32.89 and A_r = 0.05 and A_i = 0.04). ATLAS20bhfe was classified as a young IIb supernova by ePESSTO+ with a NTT spectrum obtained on MJD 59193.31 = 2020-12-10.31 (Pessi et al. AstroNote 2020-248). A finder and forced photometry plot are attached, 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 catalogues 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
TNS2020acat [ATLAS20bhfe]11:50:41.209-10:13:38.7211:50:41.225-10:13:38.92SN IIb0.0079