TITLE:   GCN CIRCULAR
NUMBER:  10771
SUBJECT: Swift Trigger 422437 is probably not a GRB
DATE:    10/05/18 06:37:06 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

J. L. Racusin (NASA/GSFC), V. D'Elia (ASDC),
P. A. Evans (U Leicester), C. B. Markwardt (CRESST/GSFC/UMD),
D. M. Palmer (LANL), T. A. Pritchard (PSU),
M. Stamatikos (OSU/NASA/GSFC) and T. N. Ukwatta (GSFC/GWU) report on
behalf of the Swift Team:

At 06:18:20 UT, the Swift Burst Alert Telescope (BAT) located 
trigger 422437.  Swift slewed immediately to the location. 
The BAT on-board calculated location is RA, Dec 311.162, +40.170 which is 
   RA(J2000) = 20h 44m 39s
   Dec(J2000) = +40d 10' 12"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The raw light curve showed a rise of count
rate as the spacecraft passed into the South Atlantic Anomaly (SAA). 

The XRT began observing the field at 06:19:41.1 UT, 80.3 seconds after
the BAT trigger. No source was detected in the promptly available XRT
data. We are waiting for the full dataset to detect and localise the
XRT counterpart. 

Due to the passage through the SAA at the time of  the trigger, no
UVOT data is available at this time. 

Due to the effect of the SAA, the marginal detection (6.6 sigma)
in the BAT image, and the lack of a detection in the XRT,
we believe that this is probably not an astrophysical event. 
Further determination of the reality of this object will
require the downlinked Malindi data. 

Burst Advocate for this burst is J. L. Racusin (judith.racusin AT 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.)