GCN Circular 22020
Subject
Trigger 779351: Swift detection of Swift J0243.6+6124
Date
2017-10-16T08:25:52Z (7 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
A. P. Beardmore (U Leicester), A. A. Breeveld (UCL-MSSL),
J.D. Gropp (PSU), K. L. Page (U Leicester), T. Sakamoto (AGU) and
B. Sbarufatti (PSU) report on behalf of the Swift Team:
At 07:53:29 UT, the Swift Burst Alert Telescope (BAT) triggered and
located Swift J0243.6+6124 (trigger=779351). Swift slewed immediately to the
location. The BAT on-board calculated location is RA, Dec 40.908, +61.433
which is
RA(J2000) = 02h 43m 38s
Dec(J2000) = +61d 25' 59"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The light-curve shows the known 9.86 s periodicity,
as was noted in GCN 22017.
The XRT began observing the field at 07:54:27.1 UT, 57.6 seconds after
the BAT trigger. XRT found a bright X-ray source located
at RA, Dec 40.9175, 61.4328 which is equivalent to:
RA(J2000) = +02h 43m 40.20s
Dec(J2000) = +61d 25' 58.1"
with an uncertainty of 5.6 arcseconds (radius, 90% containment),
consistent with the location of Swift J0243.6+6124. No event data are
yet available to determine the column density using X-ray spectroscopy.
The XRT light-curve also shows the 9.86 s periodicity.
Swift J0243.6+6124 was first detected by Swift/BAT on October 3, 2017
(GCN 21960; ATel 10809). It has since been brightening in the
gamma-rays. The daily light curve from the BAT transient monitor is
available at
https://swift.gsfc.nasa.gov/results/transients/weak/SwiftJ0243.6p6124/