TITLE: GCN CIRCULAR NUMBER: 29909 SUBJECT: IPN triangulation of GRB 210424B (short/hard) DATE: 21/04/28 16:20:26 GMT FROM: Dmitry Svinkin at Ioffe Institute K. Hurley, on behalf of the IPN, I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, D. Svinkin, S. Golenetskii, D. Frederiks, A. Ridnaia, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report: The short-duration, very bright GRB 210424B was detected by Konus-Wind, INTEGRAL (SPI-ACS), CALET (GBM), and Mars-Odyssey (HEND) at about 28916 s UT (08:01:56). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 284.716 (18h 58m 52s) +16.172 (+16d 10' 20") Corners: 284.892 (18h 59m 34s) +16.078 (+16d 04' 42") 284.882 (18h 59m 32s) +16.153 (+16d 09' 09") 284.540 (18h 58m 10s) +16.265 (+16d 15' 55") 284.550 (18h 58m 12s) +16.191 (+16d 11' 28") --------------------------------------------- The error box area is 84 sq. arcmin, and its maximum dimension is 23 arcmin (the minimum one is 4 arcmin). The Sun distance was 102 deg. This box may be improved. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB210424_T28916/IPN The time history and spectrum will be given in forthcoming GCN Circulars.