{
  "createdOn": 1714057251093,
  "submittedHow": "email-legacy",
  "submitter": "Paul Groot at Radboud University Nijmegen <p.groot@astro.ru.nl>",
  "bibcode": "2024GCN.36304....1G",
  "subject": "S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection",
  "body": "P.J. Groot (Radboud, UCT, SAAO), H. Tranin (Barcelona), H. Wichern\n(DTU), G. Leloudas (DTU), F. Stoppa (Radboud), I. Arcavi (Tel Aviv),\nS. Bloemen (Radboud), P.M. Vreeswijk (Radboud), D. Pieterse (Radboud)\nreport on behalf of the BlackGEM/MeerLICHT Consortium:\n\nFollowing the LVK Alert S240422ed the 0.6m BlackGEM/MeerLICHT\ntelescope array located at the ESO La Silla, Chile and SAAO\nSutherland, South Africa observatories observed the error box with the\nML1/BG2/BG4 telescopes using a predefined sky-grid tiling that covers\nthe accessible part of the error region using the ranked-tiling method\nas outlined in Ghosh et al. (2016). Observations were obtained in the\nq band, spanning 440-720nm, using a 2x10-tile strategy. Starting with\nthe highest probability tiles a set of 10-tiles was observed in the\nq-band filter using 60s exposures each, which was repeated directly\nafter the first 10 tiles were observed. Subsequently tiles 11-20 were\nobserved in the same two-visit manner, etc.\n\nObservations on the Updated error region of S240422ed (Biscoveanu et\nal., GCN Circular 36240) were repeated on the nights of 2024-04-23 and\n2024-04-24 following the same tiling pattern.\n\nTransient candidates were extracted using the BlackBOX/ZOGY pipeline,\nwhere astrophotometric calibrations are performed using Gaia DR3\nphotometry and astrometry. Possible asteroids are filtered using the\ndaily-updated lists of known asteroids from the Minor Planet\nCenter. All coordinates are given in the ICRS, epoch J2016.0\nastrometric frame and magnitudes quoted are on the AB system.\n\nWe report the following detections on the candidate AT2024hfx, which\nwas reported to the Transient Name Server by the PanSTARRS\ncollaboration (Chambers et al. 2024, TNS alert 208432). \n\nName                   RA (ICRS) Dec(ICRS) Filter AB-Mag   Date-UT\nMLTJ081941.58-172807.2 124.92321 -17.46874 q 18.243+/-0.06 2024-04-24\n19:10:16 \nMLTJ081941.58-172807.2 124.92321 -17.46874 q 18.311+/-0.07 2024-04-24\n19:24:26 \nBGEMJ081941.57-172807.4 124.92323 -17.46869 q 18.546+/-0.07 2024-04-25\n00:08:05 \nBGEMJ081941.57-172807.4 124.92323 -17.46869 q 18.497+/-0.07 2024-04-25\n00:23:14\n\nThe last non-detection at this position was obtained on 2024-04-07\n00:38:21 in the i-band with a 5-sigma point-source transient limiting\nmagnitude at the position of the source of i>18.91\n\nIt was pointed out to us by G. Hosseinzadeh that at the position of\nAT2024hfx, there is a single, but clear archival detection in ZTF as\nZTF21aawlmgc on 2021-04-19 03:52:10 at g=19.035 +/- 0.165. Although\nclassified as 'bogus' in the ZTF Stamp Classifier the position\ncoincides with AT2024hfx.\n\nThe BlackGEM/MeerLICHT telescopes are designed, installed and operated\nby a consortium of the following universities and institutions:\nRadboud University, Netherlands Research School for Astronomy NOVA, KU\nLeuven, Armagh Observatory and Planetarium, Hebrew University of\nJerusalem, South African Astronomical Observatory, Technical\nUniversity of Denmark, Tel Aviv University, Texas Tech University,\nUniversity of Amsterdam, University of Barcelona, University of\nCalifornia at Davis, University of Cape Town, University of Durham,\nUniversity of Hamburg, University of Manchester, University of Oxford,\nUniversity of Potsdam, University of Valparaiso, University of\nWarwick, Weizmann Institute\n\nReferences:\nGhosh et al., 2016, A&A 592, 82\n\n",
  "circularId": 36304
}