GRB 220404A

S. B. Cenko (GSFC), V. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU),
J.D. Gropp (PSU), K. L. Page (U Leicester) and
T. M. Parsotan (GSFC/UMBC/CRESSTII) report on behalf of the Neil
Gehrels Swift Observatory Team:

At 11:54:30 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 220404A (trigger=1101133). 
The BAT on-board calculated location is 
RA, Dec 50.448, +10.005 which is 
   RA(J2000) = 03h 21m 47s
   Dec(J2000) = +10d 00' 16"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 10 sec.  The peak count rate
was ~1200 counts/sec (15-350 keV), at ~2 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 20:40 UT on 2022 June 28. There will thus be no XRT or
UVOT data for this trigger before this time. 

Burst Advocate for this burst is S. B. Cenko (brad.cenko 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/)

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), S. B. Cenko (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC),
T. Sakamoto (AGU), M. Stamatikos (OSU)
(i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 220404A (trigger #1101133)
(Cenko, et al., GCN Circ. 31828
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 ).  The BAT ground-calculated position is
RA, Dec = 50.413, 10.001 deg which is
   RA(J2000)  =  03h 21m 39.0s
   Dec(J2000) = +10d 00' 03.4"
with an uncertainty of 2.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 47%.

The mask-weighted light curve shows a weak peak starts at T0 and ends at
T+3 s.  There is a hint of a emission around T+5 s. T90 (15-350 keV) is
2.54 +- 0.66 sec (estimated error including systematics).

The time-averaged spectrum from T+0.26 to T+2.98 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.90 +- 0.36.  The fluence in the 15-150 keV band is 1.4 +- 0.3 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+1.15 sec in the 15-150 keV band
is 1.1 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1101133/BA/