{
  "bibcode": "2023GCN.33466....1L",
  "body": "M.J. Liu, Y.L. Wang, Y. Liu, C. Zhang, Z.X. Ling, H.Q. Cheng, C.Z. Cui, D.W. Fan, \nH.B. Hu, J.W. Hu, M.H. Huang, C.C. Jin, D.Y. Li, J.Q. Li, H.Y. Liu, H. Sun, H.W. Pan, \nW.X. Wang, Q.Y. Wu, X.P. Xu, Y.F. Xu, H.N. Yang, M. Zhang, W.D. Zhang, Z. Zhang, \nD.H. Zhao, and W. Yuan (NAOC, CAS), report on behalf of the LEIA and Einstein Probe team:\n\nThe prompt emission of the extremely bright long-duration GRB 230307A (Fermi/GBM \ndetection: GCN 33405, 33407, 33411, 33414; GECAM-B detection: GCN 33406; \nSolar Orbiter STIX detection: GCN 33410; AGILE/MCAL detection: GCN 33412, 33444; \nIPN triangulation: GCN 33413; AstroSat detection: GCN 33415; BALROG\nlocalization: GCN 33416; GRBAlpha detection: 33418, VZLUSAT-2: GCN 33424,\nKonus-Wind GCN 33427, AstroSat CZIT: 33415, Swift/BAT upper limits: GCN 33431, \nAstroSat LAXPC detection: GCN 33437, ASO-S/HXI detection: GCN 33438, MAXI/GSC \nupper limit: GCN 33448) was detected by LEIA (Lobster Eye Imager for Astronomy) \nin the soft X-ray 0.5-4 keV band during one of its monitoring observations of \nthe Large Magellanic Cloud. \n\nThe observation was conducted from 2023-03-07T15:43:41 (25 s earlier than the \nFermi GBM trigger time at 2023-03-07T15:44:06) to 2023-03-07T16:02:00 with \na net exposure of 761 s. The GRB was detected within the extended FoV \n(about 0.6 deg outside the nominal 18.6deg x 18.6deg FoV) of LEIA, and the \non-ground calculated position is RA=60.6, Dec=-75.4, with an estimated 3-sigma \nerror of 10 arcmin, which is consistent with the IPN localizaition (GCN 33461). \nThe lightcurve shows a burst profile which peaked at 2023-03-07T15:44:13 \nin 0.5 - 4.0 keV, and droped quickly to a level comparable to the detection \nsensitivity within about 200 s. Given that the source is outside the nominal FoV, \nthe estimation of the source flux is complex and subject to further \ninvestigation and will be published later.  \n\nLEIA also conducted follow-up observations in 6 successive orbits covering \nthe entire IPN error box from 2023-03-09UT00:47:26 to 2023-03-09UT10:32:34. \nThe total good exposure is around 4000 s and no significant emission was detected. \nThe derived upper limit of the LEIA is around 1e-11 erg/cm^2/s \nin the energy band of 0.5 - 4.0 keV.\n \nLEIA (Zhang et al, ApJL, 941, 2) is a soft X-ray monitor (0.5 - 4.0 keV)\nwith a FoV of 340 square degrees aboard the SATech-01 satellite of the CAS,\nlaunched on July 27, 2022. The above result is preliminary and the final\nresult will be published elsewhere.",
  "circularId": 33466,
  "createdOn": 1678706695000,
  "email": "ep_ta@bao.ac.cn",
  "subject": "GRB 230307A: soft X-ray detection with LEIA",
  "submitter": "LEIA Team at NAOC/CAS  <ep_ta@bao.ac.cn>",
  "eventId": "GRB 230307A"
}