TITLE: GCN CIRCULAR NUMBER: 23388 SUBJECT: IPN Triangulation of GRB 181028A (long) DATE: 18/10/29 17:45:10 GMT FROM: Dmitry Svinkin at Ioffe Institute K. Hurley, on behalf of the IPN, I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova 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, 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 181028A (Fermi-LAT detection: Axelsson et al., GCN Circ. 23386; Fermi-GBM detection: Bissaldi et al., GCN Circ. 23387) was detected by Fermi (GBM trigger 562428587), Konus-Wind, INTEGRAL (SPI-ACS), and Mars-Odyssey (HEND), at about 50982 s UT (14:09:42). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 88.889 (05h 55m 33s) -21.163 (-21d 09' 49") Corners: 89.470 (05h 57m 53s) -21.496 (-21d 29' 47") 89.355 (05h 57m 25s) -22.345 (-22d 20' 42") 88.311 (05h 53m 15s) -20.824 (-20d 49' 27") 88.431 (05h 53m 43s) -19.956 (-19d 57' 23") --------------------------------------------- The error box area is about 1.0 sq. deg, and its maximum dimension is 2.539 deg (the minimum one is 33.12 arcmin). The Sun distance was about 114 deg. This box intersects the Fermi-LAT 90% CL error circle (Axelsson et al., GCN Circ. 23386) to form an error box whose area is about 4 times smaller than that of the LAT error circle. This box may be further improved. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB181028_T50984/IPN The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.