{
  "bibcode": "2020GCN.27317....1A",
  "body": "K. Ackley (1); Y.-L. Mong (1); D. K. Galloway (1); D. Steeghs (2); V. \nDhillon (3); P. O'Brien (4); G. Ramsay (5); D. Pollacco (2); E. Thrane \n(1); S. Poshyachinda (6); R. Kotak (7); L. Nuttall (8); E. Pall\\'e (9); \nK. Ulaczyk (2); J. Lyman (2); R. Cutter (2); A. Levan (2); T. Marsh (2); \nR. West (2); E. Stanway (2); B. Gompertz (2); K. Wiersema (2); T. \nKillestein (2); A. Casey (1); M. Brown (1); B. Muller (1); M. Dyer (3); \nJ. Mullaney (3); E. Daw (3); S. Littlefair (3); J. Maund (3); L. \nMakrygianni (3); U. Burhanudin (3); R. Starling (4); R. Eyles (4); S. \nTooke (4); S. Aukkaravittayapun (6); U. Sawangwit (6); S. Awiphan (6); \nD. Mkrtichian (6); P. Irawati (6); S. Mattila (7); T. Heikkil\\\"a (7); E. \nRol (1)\n\n((1) Monash University, (2) Warwick University, (3) University of \nSheffield, (4) University of Leicester, (5) Armagh Observatory & \nPlanetarium, (6) National Astronomical Research Institute of Thailand, \n(7) University of Turku, (8) University of Portsmouth, (9) Instituto de \nAstrofisica de Canarias)\n\nreport on behalf of the GOTO collaboration:\n\nWe report on optical observations with the Gravitational-wave Optical \nTransient Observer prototype in response to S200225q (GCN #27193). \nTargeted observations started shortly after the preliminary event \nnotification was received. These spanned 64 unique tile pointings, with \nimage subtraction, containing 81.6% of the source location probability \n(based on the initial BAYESTAR skymap) and were acquired between 21:46 \nUT Feb 25 2020 and 00:30 UT Feb 26 2020 (starting 15.6 hours after the \nevent trigger). No new transients that could be credibly associated with \nS200225q were detected.\n\nEach pointing spans 4.9x3.7 square degrees and consisted of 3x60s \nexposures in our L-band filter (400-700nm passband similar to g+r) with \na median 5-sigma photometric depth equivalent to g=19.3 for an \nindividual pointing. Limits are based on a photometric calibration \nagainst PS1 sources. Most pointings were observed multiple times, \ntypically 2-3 times.\n\nImages are processed immediately after acquisition using the GOTOphoto \npipeline. Difference imaging was performed on the median of each triplet \nof exposures using recent survey observations of the same pointings. \nSource candidates were initially filtered using a classifier and \ncross-matched against a variety of catalogs, including the MPC and PS1. \nHuman candidate vetting was performed following data acquisition and \nautomated classifier cuts.\n\nGOTO is operated at the La Palma observing facilities of the University \nof Warwick on behalf of a consortium including the University of \nWarwick, Monash University, Armagh Observatory, the University of \nLeicester, the University of Sheffield, the National Astronomical \nResearch Institute of Thailand (NARIT), The University of Portsmouth, \nthe University of Turku and the Instituto de Astrofisica de Canarias \n(IAC) (https://goto-observatory.org/)",
  "circularId": 27317,
  "createdOn": 1583416658000,
  "email": "b.gompertz@warwick.ac.uk",
  "subject": "LIGO/Virgo S200225q: No notable candidates in GOTO imaging",
  "submitter": "Ben Gompertz at U of Warwick  <b.gompertz@warwick.ac.uk>",
  "eventId": "LIGO/Virgo S200225q"
}