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GCN Circular 36604

GRB 240603B: Swift detection of a possible burst
2024-06-03T07:29:50Z (a month ago)
K.L. Page at U Leicester <>

A. P. Beardmore (U Leicester), A. Y. Lien (U Tampa) and
K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 06:57:43 UT, the Swift Burst Alert Telescope (BAT) triggered 
and located on a possible GRB 240603B (trigger=1232755).  
Swift did not slew immediately to the location. 
The BAT on-board calculated location is 
RA, Dec 36.054, -50.944 which is 
   RA(J2000) = 02h 24m 13s
   Dec(J2000) = -50d 56' 38"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve did not show any 
significant structures, despite the light curve fluctuated greatly 
from ~4000 ct/s to ~10000 ct/s. Also, the source was detected with
marginal significance (7.0 sigma) in the image, but the source is
no longer detected in the scaled map from ground analysis. 
Therefore, the trigger may be due to a noisy detector. However,
further ground data and XRT/UVOT observation is required to confirm
the nature of the trigger. 

Due to an observing constraint, Swift will not slew until T0+54.8
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is A. P. Beardmore (apb AT 
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:

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