{
  "createdOn": 1781709921193,
  "eventId": "GRB 260616B",
  "subject": "GRB 260616B: CALET Gamma-Ray Burst Monitor detection",
  "format": "text/plain",
  "submitter": "Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp>",
  "circularId": 44966,
  "submittedHow": "web",
  "bibcode": "2026GCN.44966....1A",
  "body": "Y. Asaoka (ICRR), A. Yoshida, T. Sakamoto, S. Sugita, Y. Kawakubo (AGU),\nK. Yamaoka (Nagoya U), S. Nakahira (JAXA), S. Torii, Y. Akaike, \nK. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),\nN. Cannady (GSFC), M. L. Cherry (LSU), S. Ricciarini (U of Florence),\nP. S. Marrocchesi (U of Siena),\nand the CALET collaboration:\n\nThe CALET Gamma-ray Burst Monitor (CGBM) detected GRB 260616B\nat 07:05:24.65 UTC on 16 June 2026 (trigger #1465628601;\nhttps://cgbm.calet.jp/cgbm_trigger/flight/1465628601/index.html).\nA CGBM Notice was distributed in near real time.\nThis event was also reported by Fermi GBM (Preis et al., GCN #44951;\nMalacaria et al., GCN #44953).\n\nThe burst signal was seen by HXM2 and SGM.  The burst light curve shows a double-peaked structure starting\nat T-7.7 s, peaking at T+2.6 s, and ending at T+4.1 s.\nThe T90 and T50 durations measured with the SGM data are 11.2 +/- 0.3 s\nand 8.1 +/- 0.2 s in the 40-1000 keV band, respectively.\n\nEinstein Probe/WXT detected an X-ray transient, EP 260616a\n(Li et al., GCN #44956), about 9 s before the CGBM trigger.\nThe position of EP 260616a was marginally above the Earth horizon\nas seen from CALET/ISS at the trigger time, at an incident angle\nof 110 degrees.\n\nThe ground-processed light curve is available at:\nhttps://cgbm.calet.jp/cgbm_trigger/ground/1465628601/\nThe CALET data used in this analysis were provided by\nthe Waseda CALET Operation Center located at Waseda University.\n"
}