J. K. Cannizzo (NASA/UMBC), A. P. Beardmore (U Leicester),
N. Gehrels (NASA/GSFC), H. A. Krimm (CRESST/GSFC/USRA),
D. Malesani (DARK/NBI), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester) and T. N. Ukwatta (LANL) report on behalf of
the Swift Team:
At 13:46:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150201A (trigger=629302). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 11.832, -37.625 which is
RA(J2000) = 00h 47m 20s
Dec(J2000) = -37d 37' 29"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a double-peaked
structure with a duration of about 20 sec. The peak count rate
was ~21500 counts/sec (15-350 keV), at ~2 sec before the trigger.
The XRT began observing the field at 13:48:26.8 UT, 87.2 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 11.8325, -37.6193 which is equivalent to:
RA(J2000) = +00h 47m 19.80s
Dec(J2000) = -37d 37' 09.5"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This
location is 20 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy.
The initial flux in the 2.5 s image was 3.03e-09 erg cm^-2 s^-1 (0.2-10
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 92 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
Burst Advocate for this burst is J. K. Cannizzo (cannizzo AT milkyway.gsfc.nasa.gov).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)