GCN Circular 21849
S. D. Barthelmy (GSFC), C. Gronwall (PSU) and K. L. Page (U Leicester) report on behalf of the Swift Team: At 08:13:48 UT, the Swift Burst Alert Telescope (BAT) triggered and located MAXI J1535-571 (trigger=771371). The BAT on-board calculated location is RA, Dec 233.847, -57.233, which is RA(J2000) = 15h 35m 23s Dec(J2000) = -57d 13' 59" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows several small peaks with a total duration of about 60 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~20 sec after the trigger. Swift did not automatically slew to the trigger because of a higher merit planned observation. However, about 100 s later, pre-planned observations of MAXI J1735-571 began, and data from that observation will be available when downlinked.