{
  "bibcode": "2023GCN.33226....1W",
  "body": "Kailai Wang (Cornell), Anna Y. Q. Ho (Cornell), Daniel Perley (LJMU) on\nbehalf of the Zwicky Transient Facility (ZTF) collaboration:\n\nWe report the discovery of a fast-evolving red transient in Zwicky\nTransient Facility (ZTF) partnership data and Liverpool Telescope (LT) data.\n\nZTF23aaarlti (AT2023avj) was discovered at the position (J2000) of:\nRA = 09:39:20.82 (144.83673 deg)\nDec = +58:08:12.52 (58.13681 deg)\n\non 2023 January 22 by ZTF at i = 19.27 +/- 0.27 (MJD=59966.29) and g =\n 20.02 +/- 0.20 (MJD=59966.32).  Forced photometry on P48 images revealed\nan additional r-band detection (r=20.14+/-0.19; MJD 59966.39) as well as\nlimits the previous night of g > 20.18 mag (MJD 59965.37) and r > 21.14 mag\n(MJD 59965.35). The rise rate (>1 mag/day in r-band) of AT2023avj was\ntherefore very fast.\n\nThe Galactic latitude of AT2023avj is 45 degrees, and the Galactic\nextinction towards the direction of AT2023avj is low: E(B-V)=0.01 from\nSchlafly & Finkbeiner (2011). There is no counterpart within several\narcseconds in Legacy Survey DR9 imaging.\n\nThe red color, fast rise rate, and lack of a stellar counterpart or bright\nhost galaxy motivated us to trigger follow-up observations.\n\nLT griz imaging at 4.7 days after the first ZTF detection confirmed the red\ncolors. With a detection at r=23.08 +/- 0.25 (MJD=59971.05), the implied\naverage fading rate is 0.46 mag/day in r-band.\n\nThe fast rise, fast decay, red color, and lack of archival optical\ncounterpart of AT2023avj make it a strong candidate afterglow. However, we\ndid not identify any GRBs coincident with this position during the time\nwindow between the last non-detection and the first detection.\n\nZTF is supported by the National Science Foundation under Grant No.\nAST-2034437 and a collaboration including Caltech, IPAC, the Weizmann\nInstitute for Science, the Oskar Klein Center at Stockholm University, the\nUniversity of Maryland, Deutsches Elektronen-Synchrotron and Humboldt\nUniversity, the TANGO Consortium of Taiwan, the University of Wisconsin at\nMilwaukee, Trinity College Dublin, Lawrence Livermore National\nLaboratories, and IN2P3, France. Operations are conducted by COO, IPAC, and\nUW.",
  "circularId": 33226,
  "createdOn": 1674785408000,
  "email": "annayqho@berkeley.edu",
  "subject": "ZTF and LT Observations of AT2023avj, a Candidate Optical Afterglow",
  "submitter": "Anna Ho at UC Berkeley  <annayqho@berkeley.edu>"
}