{
  "subject": "LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations",
  "bibcode": "2025GCN.39261....1C",
  "body": "Ce Cai (HEBNU), Shao-Lin Xiong, Yan-Qiu Zhang, Wen-Jun Tan, Chen-Wei Wang, Yue Wang and\nJin-Peng Zhang (IHEP) report on behalf of the GECAM team:\n\nAt the event time 2025-02-06T21:25:30.439 (UTC) of S250206dm (GCN 39175; GCN 39178; GCN 39231), GECAM-C was observing normally and monitored 66.9% of the localization probability region of this GW event, while GECAM-A and GECAM-B detectors were turned off. \n\nThere was no GECAM-C in-flight trigger around the event time of S250206dm. The routine blind search of GECAM-C data also found no burst candidate. Thus, we implemented a targeted search [1] within +/-30 s around the event time, and identified no candidate above 3 sigma.\n\nConsidering three typical GRB spectral models (i.e. soft, normal and hard Band functions), three timescales and the center region of GW localization (RA= 38.21°, Dec = 53.47°), the 3 sigma upper limits of the GRB energy flux (10 keV-1000 keV, in units of 10^-7 erg/s/cm^2) are reported below:\n\nTimescale (s)    Soft    Normal    Hard\n0.1            \t 1.84    2.33      4.10\n1          \t 0.58    0.73      1.29\n10       \t 0.18    0.23      0.41\n\nWith the median luminosity distance of 373 Mpc from the GW detection (GCN 39231), we further calculate the following upper limits of the GRB intrinsic luminosity (1 keV-10 MeV, in units of 10^49 erg/s):\n\nTimescale (s)    Soft    Normal    Hard\n0.1     \t 0.46    0.55      3.39\n1                0.14    0.17      1.06\n10               0.05    0.05      0.33\n\nWe note that all these results are preliminary and refined analysis will be reported.\n\nGravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) \nmission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in \nDec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard \nSATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese \nAcademy of Sciences (CAS).\n\n[1] C. Cai et al. MNRAS 508, 3910–3920 (2021) https://doi.org/10.1093/mnras/stab2760\n",
  "submittedHow": "web",
  "format": "text/plain",
  "circularId": 39261,
  "createdOn": 1739157589929,
  "submitter": "yqzhang_cl@163.com",
  "eventId": "LIGO/Virgo/KAGRA S250206dm"
}