AstroNote 2020-111

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2020-05-24 11:10:04
Type: Object/s-Discovery/Classification
Rapid fading of ATLAS20njy (AT2020krl) from ATLAS and ZTF observations
Authors: S. Srivastav, S. J. Smartt, K. W. Smith, O. McBrien, 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, H. Flewelling, 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
We report rapid fading of the transient AT2020krl from ATLAS and ZTF observations. The spectrum is blue and featureless.

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 (Smith et al. 2020, arXiv:2003.09052). 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 rapid fading of the transient ATLAS20njy (AT2020krl). The transient declined from o = 18.14 +/- 0.10 mag (orange-band) on MJD 58990.47 to  c = 18.72 +/- 0.10 mag (cyan-band) on MJD 58992.48. It was also detected by ZTF at g = 18.17 +/- 0.06, r = 18.44 +/- 0.07 on MJD 58991.43.  The ZTF g+r photometry implies a synthetic cyan-band mag of c = 18.3, which  would mean a decline of 0.4 mag in the cyan band in 24hrs. 

The discovery Astronote 2020-109 (Smith et al.) points at M = -16.5 if it is associated with UGC 11262 (81 Mpc) and it is offset by a projected distance of 17 kpc. 

A spectrum obtained using LT/SPRAT on MJD 58991.96 shows a blue, featureless continuum.  This is either a fast declining faint transient (and a kilonova candidate) or a foreground CV. Further observations are planned and 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
TNS2020krl [ATLAS20njy]18:30:32.022+42:41:15.7718:30:32.021+42:41:15.78CV