{
  "circularId": 39796,
  "body": "WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and\n\nAlexei V. Filippenko (UCB) report on behalf of the KAIT GRB team:\n\n\nThe 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at\n\nLick Observatory, observed the field of EP250226a/GRB 250226A\n\n(Fermi GBM team, GCN 39479; Jiang et al., GCN 39482; Jiang et al.,\n\nGCN 39513; Zhang et al., GCN 39492; Thakur et al., GCN 39518;\n\nPathak et al., GCN 39530; Svinkin et al., GCN 39542; Ronchini\n\net al., GCN 39672) on Feb 26 at 09:27:20 (~2.88 hours after GBM\n\ntrigger) and lasted for 4 hours. A set of 160x60s images were\n\nobtained in the clear (roughly R) filters. We detect the optical\n\nafterglow (An et. al, GCN 39486; Zhu et. al, GCN 39487; Magnani\n\net. al, GCN 39488; Li et. al, GCN 39489; Aryan et. al, GCN 39509;\n\nZou et al., GCN 39511; Li et. al, GCN 39514; Jiang et al., GCN 39515;\n\nPoidevin et al., GCN 39524; Tanasan et al., GCN 39554) in our single\n\nimages. We measure the OT brightness to be 19.6 +/- 0.1 mag (Vega)\n\nat 2.88 hours after GBM trigger. We observed the OT again on the\n\nfollowing night with 60x60s exposures and detected the OT in the\n\ncoadd image with 22.2 +/- 0.2 mag (Vega) at a mid time of 1.17 days.\n\nThis gives a decay index of -1.04 between the two nights.\n",
  "createdOn": 1742540047902,
  "eventId": "EP250226a",
  "submitter": "Weikang Zheng at UC Berkeley <weikang@berkeley.edu>",
  "submittedHow": "email",
  "bibcode": "2025GCN.39796....1Z",
  "subject": "EP250226a/GRB 250226A: KAIT optical observations"
}