GRB 080123

T. N. Ukwatta (GSFC/GWU), W. H. Baumgartner (GSFC/UMBC),
M. M. Chester (PSU), N. Gehrels (NASA/GSFC),
S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU),
S. Immler (CRESST/GSFC/UMD), J. A. Kennea (PSU),
V. Mangano (INAF-IASFPA), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL), T. Sakamoto (NASA/UMBC),
B. Sbarufatti (INAF-IASFPA) and D. E. Vanden Berk (PSU) report on
behalf of the Swift Team:

At 04:21:57 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 080123 (trigger=301578).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 338.929, -64.890 which is 
   RA(J2000) = 22h 35m 43s
   Dec(J2000) = -64d 53' 23"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a double-peaked
structure with a duration of about 0.5 sec.  The peak count rate
was ~6000 counts/sec (15-350 keV), at ~0.1 sec after the trigger. 

The XRT began observing the field at 04:23:38 UT, 102 seconds after the
BAT trigger. Using prompt downlinked data, we find a bright, fading X-ray 
source located at RA, Dec 338.9446, -64.9011 which is
  RA(J2000)  = 22h 35m 46.71s
  Dec(J2000) = -64d 54' 04.0"
with an uncertainty of 1.6 arcsec (radius, 90% containment). 
This location is 46 arcseconds from the BAT on-board position,
outside the BAT error circle. 

UVOT took a finding chart exposure of nominal 100 seconds with the
White (160-650 nm) filter starting 111 seconds after the BAT trigger. 
No afterglow candidate has been found in the initial data products. 
Image catalog data are not available at this time. The 8'x8' region
for the list of sources generated on-board covers 100% of the BAT
error circle. The list of sources is typically complete to about 18
mag. No correction has been made for the expected extinction
corresponding to E(B-V) of 0.03. 

Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta 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/too.html.)

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

Using 390 s of overlapping XRT Photon Counting mode and UVOT
V-band data for GRB 080123, 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 = 338.94226, -64.90090 which is equivalent
to:

RA (J2000): 22h 35m 46.1s
Dec (J2000): -64d 54' 3.24"

with an uncertainty of 2.1 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, astro-ph/0708.0986
http://www.swift.ac.uk/xrt_positions/Goad.pdf).

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

J. Tueller (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC),
E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), T. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+962 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 080123 (trigger #301578)
(Ukwatta, et al., GCN Circ. 7203
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 ).  The BAT ground-calculated position is
RA, Dec = 338.974, -64.930 deg which is 
   RA(J2000)  =  22h 35m 53.8s 
   Dec(J2000) = -64d 55' 48" 
with an uncertainty of 4.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 20%.
 
The mask-weighted light curve shows two well-separated peaks.  The first
starts at ~T+0.3 sec and is no wider than 64 msec.  The second peak
starts at ~T+0.6 sec with a FRED-like shape and a duration of ~256 msec.
There is soft extended emission lasting ~120 sec.  T90 (15-350 keV) is
115 +- 30 sec (estimated error including systematics).
 
The time-averaged spectrum from T+0.3 to T+122.2 sec (SHB plus extended
emmission) is best fit by a simple power-law model.  The power law index
of the time-averaged spectrum is 2.15 +- 0.54.  The fluence in the
15-150 keV band is 5.7 +- 1.7 x 10^-7 erg/cm2.  The 1-sec peak photon flux
measured from T-0.05 sec in the 15-150 keV band is 1.8 +- 0.4 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/301578/BA/

A. Cucchiara (PSU), T. N. Ukwatta (GSFC/GWU)
report on behalf of the Swift-UVOT team:

The Swift/UVOT observed the field of GRB080123 (trigger #301578)
starting 111 seconds after the BAT trigger (Ukwatta et al. 2008, GCN
Circ. 7203
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 ). We do not find any new source in any of the UVOT
single or coadded observations inside the XRT enhanced error
circle (Osborne et al., GCN Circ. 7204
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 ).
The XRT position is not covered by the V ,U and B
images.

The 3-sigma upper limits (in the UVOT photometric system,
Breeveld et al., GCN Circ. 6614
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 ) are listed:

Filter           Tstart   Tstop     Exp    Magnitude  
                   (s)     (s)      (s)   

white              112     211      100    >20.48
(finding chart)

uvw1               651    8022      577    >20.86
uvm2               626    7817      578    >20.70
uvw2               731   14026     1188    >21.56

The values quoted above are not corrected for the expected Galactic
extinction corresponding to a reddening of E_{B-V} = 0.03  mag in the
direction of the burst (Schlegel et al. 1998).

V. Mangano, B. Sbarufatti (INAF-IASF PA), T. N. Ukwatta (GSFC/GWU),
and D. N. Burrows (PSU) report on behalf of the Swift XRT team:

We have analyzed the XRT data collected during the first three
orbits of observation of GRB 080123 (Ukwatta et al., GCN Circ. 7203
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 ).
We have 124 s of exposure in WT mode (from T+108 to T+224 s)
and 7.1 ks in PC mode.

The initial XRT on-board position was centered on a cosmic ray hit. 
This position was retracted.  The XRT position reported in GCN Circ. 
7203
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  was obtained from the first downlinked data, but we note that the 
error circle given in this circular erroneously  ignored the systematic 
component and was therefore much too small.  The new, refined position 
of the XRT afterglow is

22h 35m 46.6s, -64d 54' 03.8" (J2000)

with an error circle radius of 3.9" (90% confidence).
As reported by Osborne et al. (GCN Circ. 7204
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 ), the UVOT-enhanced
astrometric position is RA, Dec = 338.94226, -64.90090 which is
equivalent to:

RA (J2000):   22h 35m 46.1s
Dec (J2000): -64d 54' 03.24"

with an uncertainty of 2.1 arcsec (radius, 90% confidence).

The X-ray light curve of the source shows a doubly broken
power law behaviour, with an initial decay with slope 1.7 +/- 0.2,
a first break at T+203 +/- 10 s, a second decay phase with
slope 6.9 +/- 0.4, a second break at T+436 +/- 250 s
and a third decay phase with slope 1.2 +/- 0.3.
If decaying at this rate the source will be at the level of
9.0e-5 counts/s at T+24 hr.

The WT spectrum is well fitted by an absorbed power law with
photon index 1.64 +/- 0.09, while the PC spectrum can be
fitted by a power law with photon index of 2.1 +/- 0.2.
Both spectra are consistent with an absorption column
of (8.1 +/- 2.4)e20 cm^-2, in excess with respect to the
Galactic absorption along the line of sight (2e20 cm^-2,
Kalberla et al. 2005).
The observed (unabsorbed) flux in the 0.3-10 keV band
is 7.0e-10 (7.9e-10) erg cm^-2 s^-1 for the WT spectrum
and 1.1e-12 (1.4e-12) erg cm^-2 s^-1 for the PC spectrum.

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

T. Uehara, M. Ohno, T. Takahashi, Y. Fukazawa, C. Kira, Y. Hanabata (Hiroshima U.),
T. Tamagawa (RIKEN), K. Yamaoka, Y. E. Nakagawa,
S. Sugita (Aoyama Gakuin U.), M. Tashiro, Y. Terada, Y. Urata, A. Endo,
K. Onda, M. Suzuki, N. Kodaka, K. Morigami (Saitama U.),
T. Enoto, R. Miyawaki, K. Nakazawa, K. Makishima (Univ. of Tokyo),
E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara (Univ. of Miyazaki),
M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), S. Hong (Nihon U.),
on behalf of the Suzaku WAM team, report:

The short GRB 080123 (Swift/BAT trigger #301578 ; Ukwatta et al., GCN 7203
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 )
triggered the Suzaku Wide-band  All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 2008-01-22 04:21:57 UT (=T0).

The observed light curve shows a double-peaked structure 
starting at T0 s, ending at T0+0.4 s with a duration (T90) of about 0.40 seconds. 
The fluence in 100 - 1000 keV was 3.1 (+/- 0.5) x 10^-7 erg/cm^2.
The 1-s peak flux measured from T0 s was 1.2 (+/- 0.2) photons/cm^2/s 
in the same energy range.

Preliminary result shows that the time-averaged spectrum from T0 s to
T0+0.5 s is well fitted by a single power-law with a photon index
of 1.22 (+0.21, -0.52) (chi^2/d.o.f = 10/13).

All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.
 
The light curves for this burst are available at:

 http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html

A. Copete, J. Grindlay, B. Allen, J. Hong (Harvard)
S. Barthelmy, C. Markwardt, N. Gehrels (GSFC)

We report the independent detection of early afterglow (or post prompt- 
emission flaring) emission from the short GRB 080123 (GCN#7203
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 ). The  
BATSS pipeline processed the BAT data from the initial automatic slew  
to the burst, which started at 04:22:09 UT (T+12sec), and was  
completed within 5 hours of the BAT trigger. A 6.2-sigma image
detection (from stacked 0.2sec slew images throughout the 68sec slew)  
in the 15-50 keV energy band yielded a position of:
  RA(J2000) = 22h 35m 08s
  Dec(J2000) = -64d 57' 24"
with an uncertainty of 6 arcmin (90% confidence radius), consistent  
with the XRT reported position of GRB080123 (GCN# 7208). Preliminary  
lightcurve analysis shows the BATSS image detection is due to an  
inital ~4sec duration flare at T+20, followed by two possible broader  
(~10-15sec) peaks at T+49 and T+72. The total estimated fluence is  
2.1E-7 erg/cm2  (15-50keV; derived for a PL model with photon index 2)  
over the 68.8sec duration of the slew. This fluence is a factor of  
0.36 times that reported in the 15-150keV band (GCN Report 111.1) for T 
+0.3 to T+122.2 and is likely dominated by the soft flare emission  
after the prompt hard emission of the short GRB.

BATSS pipeline processing is in the final stages of development  
following our first preliminary tests, which discovered GRB070326  
(GCN# 6653). Full BATSS results will begin to be available soon from a  
website
to be announced.