GRB 230322B

S. B. Cenko (GSFC), J.D. Gropp (PSU), J. A. Kennea (PSU),
N. P. M. Kuin (UCL-MSSL), S. Laha (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), M. J. Moss (GWU), K. L. Page (U Leicester)
and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 21:10:37 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230322B (trigger=1161127).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 16.565, -47.729 which is 
   RA(J2000) = 01h 06m 16s
   Dec(J2000) = -47d 43' 42"
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 ~30 sec.  The peak count rate
was ~900 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 21:12:31.7 UT, 113.8 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 16.55359, -47.70106
which is equivalent to:
   RA(J2000)  = 01h 06m 12.86s
   Dec(J2000) = -47d 42' 03.8"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 104 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
https://www.swift.ac.uk/sper.  We cannot determine whether the source
is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.48 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.5
(+2.99/-2.59) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 118 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	01:06:12.85 =  16.55353
  DEC(J2000) = -47:42:02.8  = -47.70079
with a 90%-confidence error radius of about 0.62 arc sec. This position is 0.7
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.60 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.017. 

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/)

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, 
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov,  D.Cheryasov, Ya.Kechin
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez 
(INAOE, Guillermo Haro Astrophysics Observatory),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 230322B ( S. B. Cenko et al., GCN 33505
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 ) errorbox  22856 sec after notice time and 22880 sec after trigger time at 2023-03-23 03:31:58 UT, with upper limit up to  15.7 mag. Observations started at twilight.  The observations began at zenith distance = 85 deg. The sun  altitude  is -15.9 deg. 

The galactic latitude b = -69 deg., longitude l = 295 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2205479

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   22970 |         MASTER-SAAO |   C |   180 | 15.7 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 957 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 230322B, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 16.55333, -47.70077 which is equivalent
to:

RA (J2000): 01h 06m 12.80s
Dec (J2000): -47d 42' 02.8"

with an uncertainty of 2.3 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.

J. D. Gropp (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), A.P. Beardmore (U. Leicester), B. Sbarufatti (INAF-OAB), A.
D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR), S. Dichiara (PSU), J.A.
Kennea (PSU) and S.B. Cenko report on behalf of the Swift-XRT team:

We have analysed 7.8 ks of XRT data for GRB 230322B (Cenko et al. GCN
Circ. 33505
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 ), from 123 s to 24.7 ks after the  BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Evans et al. (GCN Circ. 33507
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 ).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.61 (+/-0.05).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.09 (+0.21, -0.19). The
best-fitting absorption column is  8.7 (+5.1, -4.4) x 10^20 cm^-2, in
excess of the Galactic value of 2.5 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.1 x 10^-11 (3.8 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     8.7 (+5.1, -4.4) x 10^20 cm^-2
Galactic foreground: 2.5 x 10^20 cm^-2
Excess significance: 2.3 sigma
Photon index:	     2.09 (+0.21, -0.19)

If the light curve continues to decay with a power-law decay index of
0.61, the count rate at T+24 hours will be 0.015 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.8 x
10^-13 (5.9 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01161127.

This circular is an official product of the Swift-XRT team.

S. R. Oates (U. of Birmingham) and S. B. Cenko (GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230322B
119 s after the BAT trigger (Cenko et al., GCN Circ. 33505
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 ).
A source consistent with the XRT position
(Evans et al. GCN Circ. 33507
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 )
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  01:06:12.84 =  16.55350 (deg.)
    Dec (J2000) = -47:42:02.8  = -47.70079 (deg.)
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white              119          269          147         17.60 +/- 0.04
v                  661         1061           58        >18.3
b                  758          778           19         18.55 +/- 0.36
u                  332          581          246         17.63 +/- 0.08
w1                 710         1095           19         16.90 +/- 0.28
m2                1064         1084           19         17.17 +/- 0.35
w2                 635          655           19         17.36 +/- 0.32

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.017 in the direction of the burst
(Schlegel et al. 1998).

S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC),
S. B. Cenko (GSFC), H. A. Krimm (NSF),
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-826 to T+962 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 230322B (trigger #1161127)
(Cenko et al., GCN Circ. 33505
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 ).  The BAT ground-calculated position is
RA, Dec = 16.550, -47.709 deg which is
   RA(J2000)  =  01h 06m 12.1s
   Dec(J2000) = -47d 42' 31.2"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 92%.

The mask-weighted light curve shows a single-peaked FRED-like structure
that starts at ~T-3 s, peaks at ~T0, and ends at ~T+11 s.
T90 (15-350 keV) is 11.61 +- 2.17 sec (estimated error including
systematics).

The time-averaged spectrum from T-2.41 to T+11.12 sec is best fit by a
simple
power-law model.  The power law index of the time-averaged spectrum is
2.07 +- 0.26.  The fluence in the 15-150 keV band is 3.7 +- 0.6 x 10^-7
erg/cm2.
The 1-sec peak photon flux measured from T+0.02 sec in the 15-150 keV band
is 1.1 +- 0.2 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/1161127/BA/