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--- main:nonbruce_instrument_info [2021/05/07 23:16]
bruce [Launches]
+++ main:nonbruce_instrument_info [2022/01/15 01:37] (current)
bruce [GBM Localization]
@@ Line 49: / Line 49: @@
+====== Fermi GBM ======
+Fermi GBM is like a smaller version of BATSE; scintillators on the corners of cube geometry give all-sky (with earth occulting a LOT of the sky) coverage and rough localization.
+===== GBM Localization =====
+The reference here is Connaughton+15 ApJS https://iopscience.iop.org/article/10.1088/0067-0049/216/2/32#apjs506206s6.
+Ground-Automated GCN NOtices 30-60 s after trigger give 68% probability within (+/- or radius) 7.6 deg; there is a much larger tail for like 90% probability. BRIGHT SUB-SAMPLE: GRBs reported with only 1 deg.  statistical uncertainty, 68% radius=2.9 deg.
+one degree radius looks like it would get you about 10% of the Bright Sub-sample.  for a square FOV, that's 1.7 deg on a side - yuk.  two deg on a side gets you radius = 1.13 deg and around 17.5% of Bright sample events. So, that helps.
+HiTL (Human in the Loop) positions are available ~ 1 hr later. 68% prob. radius=5.3 deg.  BRIGHT SUB-SAMPLE: for For GRBs reported with only 1 deg. statistical uncertainty, 68% radius=3.4 deg (yes, worse than automated).

Bruce GRB Wiki