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GCN Circular 33843

IPN triangulation of GRB 230518A (short)
2023-05-21T13:50:51Z (18 days ago)
Dmitry Svinkin at Ioffe Institute <>
D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko, on behalf of the IPN, 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, and S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team, report: The short-duration GRB 230518A (Fermi-GBM detection: The Fermi GBM team, GCN Circ. 33822; Swift-BAT/GUANO detection: Ronchini, GCN Circ. 33825) has been detected by Fermi (GBM trigger 706142972), Swift (BAT), and INTEGRAL (SPI-ACS), so far, at about 82168 s UT (22:49:28). The burst was outside the coded field of view of the BAT. We have triangulated it to a GBM-SPI-ACS annulus centered at RA(2000)=19.521 deg (01h 18m 05s) Dec(2000)=-66.594 deg (-66d 35' 40") whose radius is 88.662 +/- 2.786 deg (3 sigma). The annulus combined with the Fermi-GBM final position (GCN 33822; glg_healpix_all_bn230518951_v00) gives 480 sq. deg (3 sigma) localization region. The localization is inconsistent with the localization of the NSBH merger event candidate S230518h (LVK Collaborations, GCN Circ. 33813, 33816). A triangulation map and HEALPix FITS file are posted at
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