TITLE: GCN CIRCULAR NUMBER: 36583 SUBJECT: IPN triangulation of the initial episode of GRB 240529A DATE: 24/05/31 22:31:27 GMT FROM: Dmitry Svinkin at Ioffe Institute svinkin@mail.ioffe.ru

A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars Odyssey team,

D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko, and T. Cline on behalf of the Konus-Wind team,

E. Burns, on behalf of the IPN,

S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report:

The long-duration GRB 240529A (Swift-BAT detection: Eyles-Ferris et al., GCN 36556; AstroSat-CZTI detection: Joshi et al., GCN 36560; Insight-HXMT/HE detection: Tan et al., GCN 36578) was detected by Swift (BAT), Konus-Wind, AstroSat (CZTI), Insight-HXMT (HE), and Mars-Odyssey (HEND). The burst triggered Swift-BAT at T0(BAT) = 10710.788 s UT (02:58:30.788).

The Konus-Wind lightcurve shows two emission episodes at ~T0(BAT)-400 s and ~T0(BAT)-300 s. These episodes was also detected by Swift (BAT), probably outside the coded FoV, and Mars-Odyssey (HEND).

We have triangulated the most intense episode (at ~T0(BAT)-400 s) to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 336.181 (22h 24m 43s) +52.215 (+52d 12' 55") Corners: 341.510 (22h 46m 02s) +56.219 (+56d 13' 07") 331.787 (22h 07m 09s) +47.993 (+47d 59' 34") 332.038 (22h 08m 09s) +47.767 (+47d 46' 02") 341.743 (22h 46m 58s) +55.982 (+55d 58' 54") --------------------------------------------- The error box area is 2.61 sq. deg, and its maximum dimension is 10.2 deg (the minimum one is 15 arcmin). The Sun distance was 73 deg.

Triangulation of the less intense episode (at ~T0(BAT)-400 s) is consistent with this IPN localization.

This localization is consistent with the Swift localization of GRB 240529A, implying the episodes belong to GRB 240529A and extending the burst duration up to ~600 s.

A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB240529_T10304/IPN The HEALPix triangulation map is the multi-order HEALPix in units of probability density.

The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.

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