{
  "subject": "GRB240418A: YAHPT Upper Limits",
  "submittedHow": "web",
  "createdOn": 1713525310725,
  "circularId": 36177,
  "eventId": "GRB 240418A",
  "submitter": "Tianrui Sun at Purple Mountain Obs,CAS <trsun@pmo.ac.cn>",
  "body": "Tian-Rui Sun, Jin-Jun Geng, Jian Chen, Yan-Long Hua  and Lei Hu report on behalf of the YAHPT team:\n\nFollowing the detection of GRB 240418A by SWIFT (Siegel et al., GCN 36162; Evans et al., GCN 36166), \nwe use the Yaoan High Precision Telescope at Yaoan Astronomy Observation Station (Yunnan province, China) to search and follow up its afterglow at XRT position.\n\nWe observed the target position with 180s exposure in V-band starting from 2024-04-18T20:32:14.600 about 486.6 seconds after the burst.\nWe took 25 images with total exposure time of 4500 seconds from 20:32:14 to 21:48:29.4. \nWe did not detect any object up to V = 22.2 with the stacked images within the Enhanced Swift XRT position \nThis non-detection results of the gamma-ray bursts is in agreement with the previous circulars \n(Lipunov et al., GCN 36163; Odeh et al., GCN 36165; Malesani et al., GCN 36167; Pozanenko et al. GCN 36168;).\n\nWe used the UCAC4 catalog (Vmag) as the magnitude reference for calibration.",
  "bibcode": "2024GCN.36177....1S"
}