{
  "bibcode": "2022GCN.32640....1B",
  "body": "Eric Broens (Mol, Belgium) reports:\n\nFollowing the detection of the bright hard X-ray and optical transient\nSwift J1913.1+1946 (Dichiara et al., GCN 32632; Lipunov et al., GCN 32634),\nwhich is possibly a GRB (Kennea & Williams, GCN 32635; Veres et al.,\nGCN 32636), photometric observations were obtained using a 0.28-meter SCT\ntelescope equiped with a Moravian G2-1600 CCD camera and Astrodon\nJohnson-Cousins BVRcIc filters. \nThe observations started at 19:13:48 UT on 2022-10-09.\n\nFive 180 s exposures were average combined for each filter.\nThe following magnitudes were measured using three APASS DR9 field stars.\nThe APASS DR9 r' and i' magnitudes were transformed to Cousins Rc and Ic\nusing the Jester et al. (2009, AJ 130, 873) relations.\nThe afterglow was not detected in the B filter with a 5-sigma upper limit\nof B = 17.8. \n\n\nDate [UT]            Filter   mag\n-------------------  ------  ---------------\n2022-10-09 19:21:21   B      >17.8 (5-sigma)\n2022-10-09 19:36:30   V       17.48 +/- 0.02\n2022-10-09 19:51:40   Rc      16.60 +/- 0.05\n2022-10-09 20:06:50   Ic      15.76 +/- 0.06\n\nThese magnitudes are not corrected for galactic extinction.",
  "circularId": 32640,
  "createdOn": 1665361862000,
  "email": "eric.broens@skynet.be",
  "subject": "Swift J1913.1+1946: Optical photometry",
  "submitter": "Eric Broens at Vereniging Voor Sterrenkunde  <eric.broens@skynet.be>"
}