NASA Swift: GRB 060502: Swift detection of a burst with an optical counterpart
TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 5047
SUBJECT: GRB 060502: Swift detection of a burst with an optical counterpart
DATE: 06/05/02 03:55:38 GMT
FROM: Scott Barthelmy at NASA/GSFC Scott@lheamail.gsfc.nasa.gov
V. La Parola (INAF-IASFPA), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), P. Romano (INAF-OAB), T. Sakamoto (NASA/ORAU), E. Troja (INAF-IASFPA) and D. E. Vanden Berk (PSU) report on behalf of the Swift Team:
At 03:03:32 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 060502 (trigger=208169). Swift slewed immediately to the burst. The BAT on-board calculated location is RA,Dec 240.858, +66.595 {16h 03m 26s, +66d 35′ 42″} (J2000) with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a roughly triangular shaped single peak starting at ~T-8 sec and lasting until ~T+20 sec. The peak count rate was ~2500 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 03:04:48 UT, 76 seconds after the BAT trigger. Ground analysis of the initial XRT data found a bright, uncatalogued, fading X-ray source located at RA(J2000) = 16h 03m 42.9s, Dec(J2000) = +66d 35′ 57.4″, with an estimated uncertainty of 3.9 arcseconds (90% confidence radius). This location is 98 arcseconds from the BAT on-board position, within the BAT error circle. The initial flux in the 2.5s image was 1.3e-09 erg/cm2/s (0.2-10 keV).
UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 85 seconds after the BAT trigger. There is an 18.4 magnitude source that is not visible in the Digitized Sky Survey images, at J2000 coordinate 16h 03m 42.48s, +66d 36′ 02.5″ (240.9270, +66.6007). The position is 5.7 arcseconds from the center of the XRT error circle.
This burst triggered BAT at the beginning of a Malindi telemetry downlink session and so the downlink of the TDRSS notices was delayed until the end of the pass (~18 min).
