TITLE: GCN CIRCULAR NUMBER: 37538 SUBJECT: IPN triangulation of GRB 240913С / EP 240913a DATE: 24/09/17 20:48:24 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, A. Goldstein, M. S. Briggs, C. Wilson-Hodge, and E. Burns on behalf of the Fermi GBM team, 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, G. Waratkar, V. Jethwani, J.Joshi, V. Bhalerao, D. Bhattacharya, and S. Vadawale, on behalf of the Astrosat-CZTI 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 240913C (AstroSat-CZTI detection: Dasgupta et al., GCN 37505; ETJASMIN Joint location: Zhang et al., GCN 37507; Fermi-GBM detection: Bissaldi and Meegan, GCN 37509; INTEGRAL-SPI-ACS detection: Pawar et al., GCN 37510) was detected by AstroSat (CZTI), Fermi (GBM trigger 747920561), Konus-Wind, INTEGRAL (SPI-ACS), Swift (BAT), and Mars-Odyssey (HEND) at about 42156 s UT (11:42:36). The burst was outside the coded field of view of the BAT. We have triangulated it to the following annuli: --------------------------------------------------- annulus R.A. Dec. R dR (3sigma) (deg) (deg) (deg) (deg) --------------------------------------------------- Konus-GBM 333.897 -8.566 50.692 1.965 Konus-SPI-ACS 334.296 -2.846 47.219 3.486 GBM-SPI-ACS 56.462 86.015 62.390 17.278 GBM-HEND 95.231 23.495 73.181 0.024 --------------------------------------------------- The Konus-GBM, GBM-SPI-ACS and GBM-HEND annuli intersect to form a long box, whose area is 3075 sq. arcmin, and its maximum dimension is 20.8 deg (the minimum one is 3.2 arcmin). The Sun distance was 142 deg. This localization may be improved. The IPN localization is consistent with, but reduces the area of, the Fermi-GBM and ETJASMIN joint localizations. The position of the fast X-ray transient EP240913a (Li et al., GCN 37492; Jiang et al., GCN 37497) is inside the IPN localization, strengthening the association of GRB 240913C with the EP240913a initially suggested by Dasgupta et al. (GCN 37505) and Zhang et al. (GCN 37507). A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB240913_T42159/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. View this GCN Circular online at https://gcn.nasa.gov/circulars/37538. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...