TITLE: GCN CIRCULAR NUMBER: 18421 SUBJECT: Trigger 659734: Swift detection of SAX J1750.8-2900 or other source near Galactic center DATE: 15/10/16 01:48:57 GMT FROM: David Palmer at LANL J. R. Cummings (NASA/UMBC), K. L. Page (U Leicester) and T. Sakamoto (AGU) report on behalf of the Swift Team: At 01:25:59 UT, the Swift Burst Alert Telescope (BAT) triggered and located a burst with a position consistent with SAX J1750.8-2900 (trigger=659734). Swift did not slew immediately to the location due to higher priority observations. The BAT on-board calculated location is RA, Dec 267.600, -29.018 which is RA(J2000) = 17h 50m 24s Dec(J2000) = -29d 01' 04" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single soft FRED structure with a duration of about 8 sec. The peak count rate was ~1300 counts/sec (15-350 keV), at ~1 sec after the trigger. Although this BAT detection was consistent in position with SAX J1750.8-2900 (within 71 arcseconds) the location near the Galactic center (lon,lat = 0.47,-0.94 degrees) has a high density of known and unknown sources, so the identification cannot be confirmed. Follow-up observations with the XRT are planned to determine the origin of the burst.