TITLE: GCN CIRCULAR NUMBER: 36028 SUBJECT: Konus-Wind detection of LXT 240402A/GRB 240402B DATE: 24/04/04 15:59:11 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru> A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long-duration GRB 240402B (GECAM-C detection: Xue et al., GCN 36017) associated with the LEIA fast X-ray transient LXT 240402A (Xu et al., GCN 36016) triggered Konus-Wind at T0=31668.797 s UT (08:47:48.797). The burst light curve shows a multipeaked structure which starts at ~T0-0.2 s and has a total duration of ~5.1 s. The emission is seen up to ~3 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB240402_T31668/ As observed by Konus-Wind, the burst had a fluence of 7.56(-0.43,+0.50)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0+2.704 s, of 5.07(-0.66,+0.68)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 4 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.71(-0.17,+0.19), the high energy photon index beta = -3.58(-1.30,+0.44), the peak energy Ep = 86(-4,+5) keV (chi2 = 57/68 dof). This spectrum is nearly-well fitted by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.78(-0.15,+0.16) and Ep = 88(-4,+4) keV (chi2 = 61/69 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/36028. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...