AstroNote 2022-164

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DRAFT
2022-08-12 12:16:02
Type: Object/s-Discovery/Classification
ATLAS22zpf (AT2022qzr): discovery of a fast fading transient at 73 Mpc
Authors: S. Srivastav, K. W. Smith, D. R. Young, S. J. Smartt, J. Gillanders, M. Fulton, M. McCollum, T. Moore (Queen's University Belfast), L. Shingles (GSI/QUB), L. Denneau, J. Tonry, H. Weiland, A. Lawrence, R. Siverd (IfA, University of Hawaii), N. Erasmus, W. Koorts (South African Astronomical Observatory), J. Anderson (ESO), A. Jordan, V. Suc (UAI, Obstech), D. Pacheco (PUC), A. Rest (STScI), T.-W. Chen (Stockholm), M. Nicholl (Birmingham), C. Stubbs (Harvard), S. Rest (JHU/QUB)
Source Group: ATLAS
Keywords: Supernova
Abstract:
Here we report the ATLAS discovery of the nearby fast fading transient ATLAS22zpf (AT2022qzr) at magnitude o = 18.12 +/- 0.10. At a distance of 73 Mpc, the transient was discovered on MJD = 59800.43 (2022-08-09.43) with an absolute magnitude of M = -16.3 +/- 0.2. The last non-detection was a day before discovery on MJD = 59799.28. The transient shows a rapid rise to peak within 2 days of last non-detection, and a fast fade of 0.7 +/- 0.2 mag/day. At a peak magnitude of -16.7, the transient could be a AT2018kzr like fast transient, or a IIb caught during shock breakout. The rapid fade is similar to the kilonova AT2017gfo, but it is 1.5 mag brighter at peak. Spectroscopic classification is encouraged.

ATLAS is a quadruple 0.5m telescope system with two units in Hawaii (Haleakala and Mauna Loa), and one each in Chile (El Sauce) and South Africa (Sutherland), see  Tonry et al. 2018, (PASP,130:064505). With the installation of the two southern units, we are robotically surveying the whole sky with a cadence of 1 day between -50 and +50 and 2 days in the polar regions, weather permitting. 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 fast fading transient discovered by ATLAS. We discovered ATLAS22zpf (AT2022qzr) on MJD 59800.43 == 2022-08-09.43, at m_o = 18.12 +/- 0.10. There was no detection by ATLAS a day prior on MJD 59799.28 == 2022-08-08.28. Within 2 days, the transient rose to a peak magnitude of m_o = 17.64 (M_o = -16.7) and then faded rapidly to m_o = 18.51 +/- 0.22 at a rate of 0.72 +/- 0.22 mag/day. A ZTF detection on MJD 59801.42 at g = 17.42 implies a relatively blue colour. The likely host galaxy SDSS J000955.08-050115.5 is at z = 0.019 or d = 73 Mpc (from NED), we assume m-M = 34.32 and A_r = 0.07 and A_i = 0.06. A finder and forced photometry plot are attached, followup observations are encouraged.

The ATLAS  four telescope system provided dense time sampling with 5 detections over 2.5 days in survey mode. The fading rate is similar to the kilonova AT2017gfo, but the peak luminosity is approximately 1.5 mag brighter. It bears some resemblence to the transient AT2018kzr, proposed as a WD+BH merger (McBrien et al. 2019, ApJL, 885, 23; Gillanders et al 2020, MNRAS, 497, 246). A rapid shock cooling signature is also possible, in which case the brightness should rise again within 24-48hrs. 

A finder and forced photometry plot are attached, followup observations are encouraged as soon as possible, given its fast fading nature. 

The Asteroid Terrestrial-impact Last Alert System (ATLAS) project 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. This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889, and STFC grants ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen's University Belfast, the Space Telescope Science Institute, the South African Astronomical Observatory, and The Millennium Institute of Astrophysics (MAS), Chile. 

Show current TNS values
CatalogNameReported RAReported DECReported Obj-TypeReported RedshiftHost NameHost RedshiftRemarksTNS RATNS DECTNS Obj-TypeTNS Redshift
TNS2022qzr [ATLAS22zpf]00:09:55.009-05:01:16.07SDSS J000955.08-050115.50.01870500:09:55.001-05:01:16.09SN IIb0.019