AstroNote 2020-189

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DRAFT
2020-10-09 15:24:08
Type: Object/s-Discovery/Classification
ATLAS20bcmt (AT2020uzq): discovery of a candidate nuclear transient in MCG -02-60-001 (43 Mpc)
Authors: L. J. Shingles, K. W. Smith, S. Srivastav, O. McBrien, S. J. Smartt, J. Gillanders, P. Clark, M. Fulton, D. O'Neill, D. R. Young, 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 transient ATLAS20bcmt (AT2020uzq) in the core of galaxy MCG -02-60-001 at magnitude m_o = 17.6 +/- 0.1. At a distance of 43 Mpc, the transient was discovered on MJD = 59126.43 (2020-10-04.43) with an absolute magnitude of M = -15.64 +/- 0.09. The last non-detection through forced photometry was on MJD = 59125.51. This is coincidence with the core of MCG -02-60-001. While the image subtraction may lead to spurious residuals at times, there are 5 epochs of consistently positive flux in the difference images since 59125, indicating this most likely real. It appears to have risen slowly to m_o = 17.3. Spectroscopic classification is encouraged, but will be challenging due to the bright host.

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 transient source, coincident with the nucleus of the galaxy MCG -02-60-001. We discovered ATLAS20bcmt (AT2020uzq) on MJD 59126.43 == 2020-10-04.43, at m_o = 17.58 +/- 0.09. There was no detection by ATLAS on MJD 59125.51 == 2020-10-03.51. ATLAS20bcmt is offset by 1.2 arcsec south, 0.4 arcsec east from MCG -02-60-001, which is at z = 0.0115 or d = 43 Mpc (from NED), implying an absolute magnitude of M = -15.64 (assuming m-M = 33.16 and A_r = 0.07 and A_i = 0.05).

This is coincidence with the core of MCG -02-60-001. While the image subtraction may lead to spurious residuals at times, there are 5 epochs of consistently positive flux in the difference images since 59125, indicating this most likely real. It appears to have risen slowly to m_o = 17.3. Spectroscopic classification is encouraged, but will be challenging due to the bright host. 

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
TNS2020uzq [ATLAS20bcmt]23:34:00.199-11:46:59.210.011523:34:00.190-11:46:59.06SN II0.0117