TITLE:   GCN CIRCULAR
NUMBER:  33921
SUBJECT: GRB 230606A: Swift detection of a burst
DATE:    23/06/06 01:15:46 GMT
FROM:    David Palmer at LANL <palmer@lanl.gov>


A. Y. Lien (U Tampa), J.D. Gropp (PSU), J. A. Kennea (PSU),
D. M. Palmer (LANL), T. M. Parsotan (GSFC/UMBC/CRESSTII) and
B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 00:14:37 the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230606A (trigger=1173731).  Due to communications problems
from a recent typhoon in Guam, only limited real-time data is
available and notices are being delayed. Swift had a delayed slew
to the burst, presumably due to observing constraints. 
The ground-calculated BAT location based on available data is
RA, Dec 166.7956  36.5090. 
There is no immediately-available BAT lightcurve data for
this GRB, however the BAT trigger duration was on the 2 second
timescale, suggesting a long GRB. 

Using promptly downlinked data we find an uncatalogued X-ray source
located at RA, Dec 166.81107, 36.48427 which is equivalent to:
   RA(J2000)  = 11h 07m 14.66s
   Dec(J2000) = +36d 29' 03.4"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
position may be improved as more data are received; the latest position
is available at https://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.32 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4
(+2.97/-2.57) x 10^21 cm^-2 (90% confidence). 

Further information will be available after the complete data
download at the next ground pass. 

Burst Advocate for this burst is A. Y. Lien (yarleen AT gmail.com). 
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/)