GRB 260122B

D. M. Palmer (LANL), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm
(NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
A. Mei (INAF-OAB), M. J. Moss (GSFC), T. Parsotan (GSFC), D. Sadaula
(GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team):

Using the data set from T-60 to T+243 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 260122B (trigger #1443066)
(Mei et al., GCN Circ. 43502
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 ).  The ground analysis confirms that this
event is indeed a GRB and not due to background fluctuations (Mei et al.,
GCN Circ. 43502
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 ). The BAT ground-calculated position is
RA, Dec = 336.096, -59.176 deg which is
   RA(J2000)  =  22h 24m 22.9s
   Dec(J2000) = -59d 10' 32.1"
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 57%.

The mask-weighted light curve shows a single-pulse structure that starts
~T-1 s, peaks at ~T+9 s, and ends at ~T+20 s. T90 (15-350 keV) is 16.59 +-
3.89 sec (estimated error including systematics).

The time-averaged spectrum from T+0.23 to T+19.51 sec is best fit by a
simple power-law model.  The power law index of the time-averaged spectrum
is 1.34 +- 0.17.  The fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-06
erg/cm2. The 1-sec peak photon flux measured from T+8.46 sec in the 15-150
keV band is 1.6 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90%
confidence level.

The results of the batgrbproduct analysis are available at
https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1443066

A. Mei (INAF-OAB), R. Brivio (INAF-OAB), R. Gupta (NASA GSFC),
A. Y. Lien (U Tampa) and M. H. Siegel (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 23:13:10 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 260122B (trigger=1443066).  Swift did not slew immediately 
to the burst due to observing constraint.
The BAT on-board calculated location is 
RA, Dec 336.079, -59.167 which is 
   RA(J2000) = 22h 24m 19s
   Dec(J2000) = -59d 10' 02"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 15 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger. 
We note that the burst occurred during the high background interval near
the SAA. Therefore, at this moment we cannot completely rule out the 
possibility that the event is due to background fluctuation. However, 
given that the image significance is 9.35 sigma, we believe this is 
likely a real burst. Further ground data is required to determine the 
nature of the burst.

Due to a Sun observing constraint, Swift cannot slew to the BAT 
position until 2026 February 16. There will thus be no XRT or UVOT
data for this trigger.

Burst Advocate for this burst is A. Mei (alessio.mei AT inaf.it).
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/)