{
  "bibcode": "2021GCN.29783....1Z",
  "body": "C. Zheng, X. Y. Song, S. L. Xiong, X. Y. Zhao, D. Y. Guo, Y. Huang, S. Xiao,\nC. Cai, Y. Zhao, J. C. Liu, Q. B. Yi, Y. Q. Zhang, W. C. Xue, Z. W. Guo,  \nP. Wang, X. B. Li, W. X. Peng, R. Qiao, C. W. Wang,\nZ. H. An, C. Chen, G. Chen, W. Chen, M. Gao, K. Gong, D. Y. Guo, J. J. He,\nB. Li, C. Li, C. Y. Li, J. H. Li, Q. X. Li, X. Q. Li, Y. G. Li, X. H. Liang,\nJ. Y. Liao, J. C. Liu, X. J. Liu, Y. Q. Liu, F. J. Lu, Q. Luo, X. Ma,\nG. Ou,  D. L. Shi, J. Y. Shi, L. M. Song, G. X. Sun, X. L. Sun, Y. L. Tuo,\nJ. Z. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu, S. Yang, M. Yao, B. X. Zhang,\nC. Y. Zhang, D. L. Zhang, Fan Zhang, Fei Zhang, H. M. Zhang, K. Zhang,\nP. Zhang, S. N. Zhang, Z. Zhang, S. Y. Zhao, S. J. Zheng, X. Zhou (IHEP),\nreport on behalf of GECAM team:\n\nDuring the commissioning phase, GECAM-B triggered a long burst,\nGRB 210409A, at 2021-04-09T21:28:07.950 UTC (T0) from the ground search.\nThere is a weak precursor, by which the ground search found this burst,\n~20 s before the main burst, which triggered GECAM-B in-flight as well.\n\nAccording to the GECAM-B light curves in about 8 keV - 500 keV, \nthis burst mainly consists of multiple pulses with duration of about 37 s.\nSpectral evolution is clearly seen during the burst, and the emissions\nin low energies last longer than that in high energies.\n\nAlthough the in-flight calibration of energy response and localization\nhas not been finalized yet, GECAM-B localized this burst to the \nfollowing position (J2000):\nRa: 70.9 deg \nDec: -58.3 deg \nErr: 2.9 deg (1-sigma, statistical only) \n\nThe current systematic error of location is estimated to be several degrees\nwhich could be minimized by the ongoing calibration. \n\nThe GECAM light curve could be found here: \nhttp://twiki.ihep.ac.cn/pub/GECAM/GRBList/multiLCvsE_tn210409_212807.pdf\n\nThe GECAM preliminary location could be found here:  \nhttp://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_skymap_bdm_71702907_V01.png\n\nPlease note that all GECAM results here are preliminary. The final analysis\nwill be published in journal papers or GECAM online catalog.\n\nGravitational wave high-energy Electromagnetic Counterpart All-sky Monitor\n(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in\nLow Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),\nwhich was funded by the Chinese Academy of Sciences (CAS).",
  "circularId": 29783,
  "createdOn": 1618058774000,
  "email": "zhengchao97@ihep.ac.cn",
  "subject": "GRB 210409A: GECAM detection",
  "submitter": "Chao Zheng at IHEP  <zhengchao97@ihep.ac.cn>",
  "eventId": "GRB 210409A"
}