TITLE: GCN CIRCULAR NUMBER: 20570 SUBJECT: GRB 170131A detected in Swift/BAT ground processing DATE: 17/02/01 19:19:04 GMT FROM: David Palmer at LANL GRB 170131A detected in Swift/BAT ground processing David Palmer (LANL), on behalf of the Swift team, reports: At 23:15:13 UT on 2017-01-31, the Swift Burst Alert Telescope (BAT) detected a marginal peak in a rate-triggered image (Swift Trigger #736107). Because it was below the image significance threshold, it did not yield a GRB follow-up. However, ground analysis shows that it is at the same location as a Fermi/GBM trigger (#507597304). KONUS/WIND also reported a trigger at the same time. The BAT on-board calculated location is RA, Dec 341.447, 64.006, which is RA(J2000) = 22h 45m 55s Dec(J2000) = +64d 00' 22" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a ~30 s long FRED structure starting at ~T-20 (consistent with the Fermi/GBM trigger time) superimposed with a ~5 second peak near the BAT trigger time. The peak count rate was ~3000 counts/sec (15-350 keV), at ~3 sec after the BAT trigger. A Swift ToO observation has been scheduled.