{
  "circularId": 37546,
  "subject": "EP240918a: YAHPT Optical Upper Limit",
  "bibcode": "2024GCN.37546....1S",
  "createdOn": 1726675201879,
  "submittedHow": "web",
  "submitter": "Tianrui Sun at Purple Mountain Obs,CAS <trsun@pmo.ac.cn>",
  "body": "Tian-Rui Sun, Jin-Jun Geng, Jian Chen, Yan-Long Hua, Yi-Fang Liang (Purple Mountain Observatory, CAS) and Lei Hu (CMU) report on behalf of the YAHPT team:\n\n\nFollowing the detection of EP240918a by Einstein Probe (Zhang et al., GCN 37541), \nwe use the Yaoan High Precision Telescope at Yaoan Astronomy Observation Station (Yunnan province, China) to search and follow up.\n\n​\nWe observed the target position in both Rc and Ic starting from 2024-09-18T13:13:31 with 180s exposure.\nWe did not detect any possible new optical counterpart with an uncertainty of 20 arcsec in the coadded image.\n\n\nUT (start)         |5 sigma Upper Limit| Exposure Time | Filter \n2024-09-18T13:13:31| 20.3              | 180*5s        | Rc \n2024-09-18T13:16:34| 19.1              | 180*5s        | Ic \n\nThis non-detection result of the transient is in agreement with the previous circulars (Wang et al., GCN 37544).\n\nWe used the USNO B1.0 catalogue (R2mag and Imag) as the magnitude reference for calibration.",
  "eventId": "EP240918a",
  "format": "text/plain"
}