TITLE: GCN CIRCULAR NUMBER: 30890 SUBJECT: IPN triangulation of GRB 210925B DATE: 21/09/27 18:08:46 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru> 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, A. Ridnaia, S. Golenetskii, D. Frederiks, D. Svinkin, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, A. Goldstein, M. S. Briggs, and C. Wilson-Hodge on behalf of the Fermi-GBM team, A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, 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, and R. Starr, on behalf of the GRS-Odyssey GRB team, report: The long-duration GRB 210925B was detected by Fermi (GBM trigger 654225613), Konus-Wind, Mars-Odyssey (HEND), INTEGRAL (SPI-ACS), and Swift-BAT at about 4809 s UT (01:20:09). The burst was outside the coded field of view of the BAT. We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 48.817 (03h 15m 16s) -52.863 (-52d 51' 45") Corners: 47.551 (03h 10m 12s) -53.723 (-53d 43' 21") 50.006 (03h 20m 01s) -52.058 (-52d 03' 29") 50.027 (03h 20m 06s) -51.978 (-51d 58' 41") 47.579 (03h 10m 19s) -53.644 (-53d 38' 39") --------------------------------------------- The error box area is 335 sq. arcmin, and its maximum dimension is 2.3 deg (the minimum one is 2.5 arcmin). The Sun distance was 113 deg. This box may be improved. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB210925_T04810/IPN/ The time history and spectrum will be given in forthcoming GCN Circulars.