{
  "bibcode": "2019GCN.25492....1R",
  "body": "J. Ruan (McGill U.), N. Vieira (McGill U.),\nD. Haggard (McGill U.), M. R. Drout (U. of Toronto),\nN. Asfari (U. of Toronto), R. Carlberg (U. of Toronto),\nR. Doyon (U. de Montreal), R. Fernandez (U. of Alberta),\nB. Gaensler (U. of Toronto), D. Lafreniere (U. de Montreal),\nC. Matzner (U. of Toronto), D-S. Moon (U. of Toronto),\nC. Ni (U. of Toronto), M. Nynka (MIT),\nA. L. Piro (Carnegie Obs.), S. Safi-Harb (U. of Manitoba),\nK. Spekkens (RMC/Queen's U.)\n\nWe report upper-limits from our CFHT non-detections of the\noptical counterpart to AT2019osy, including deep g-band\nimaging within a few hours of the DECam detection.\n\nAT2019osy was originally reported as a rising radio source in ASKAP\nobservations (GCN 25487), lying within the 95% localization volume\nof LIGO/Virgo S190814bv (GCN 25333). An optical counterpart was\nsubsequently reported in DECam observations at MJD 5816.26\n(GCN 25488), with a preliminary magnitude of i=22.3.\n\nPreviously, we used the MegaPrime/MegaCam instrument on CFHT to\ntile the localization region of LIGO/Virgo S190814bv. Our imaging\ncovered AT2019osy multiple times, including deep g-band observations\nwithin hours of the DECam observations that discovered the optical\ncounterpart with i=22.3 mag on MJD 58716. We do not detect\nAT2019osy in our images, and report the following upper limits:\n\nMJD, days post-merger, band, mag\n58711.5,   1.7 days,   g,   >21.85\n58713.5,   3.6 days,   i,   >22.50\n58716.5,   6.6 days,   g,   >23.50\n\nWe thank the CFHT queued service observing team and the telescope\nstaff for their help in obtaining these observations.",
  "circularId": 25492,
  "createdOn": 1566924064000,
  "email": "jjr2125@gmail.com",
  "subject": "LIGO/Virgo S190814bv: Optical non-detection of radio source AT2019osy from CFHT",
  "submitter": "John J. Ruan at McGill U  <jjr2125@gmail.com>",
  "eventId": "LIGO/Virgo S190814bv"
}