GRB 100213A

D. Grupe (PSU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),
E. A. Hoversten (PSU), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), C. B. Markwardt (CRESST/GSFC/UMD),
D. M. Palmer (LANL), T. Sakamoto (NASA/UMBC),
B. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU),
M. C. Stroh (PSU), T. N. Ukwatta (GSFC/GWU) and L. Vetere (PSU) report
on behalf of the Swift Team:

At 22:27:48 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 100213A (trigger=412217).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 349.428, +43.383 which is 
   RA(J2000)  =  23h 17m 43s
   Dec(J2000) = +43d 23' 00"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows two main spikes
with a total duration of about 4 sec (we can not reject a short burst). 
The peak count rate was ~6000 counts/sec (15-350 keV), at ~2 sec
after the trigger. 

The XRT began observing the field at 22:29:00.8 UT, 72.7 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 349.3917, 43.3796 which
is equivalent to:
   RA(J2000)  = 23h 17m 34.01s
   Dec(J2000) = +43d 22' 46.4"
with an uncertainty of 3.2 arcseconds (radius, 90% containment). This
location is 95 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 http://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 consistent with the Galactic value of
1.11e+21 cm^-2 (Kalberla et al. 2005). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 76 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 16% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT 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
0.31. 

Burst Advocate for this burst is D. Grupe (grupe AT astro.psu.edu). 
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.)

D. Grupe (PSU) reports on behalf of the Swift-XRT team:

We have analyzed 274 s of XRT data for GRB 100213A (Grupe et al.
GCN Circ. 10411
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 ), from 86 s to 361 s after the BAT trigger. The
data are entirely in  Photon Counting (PC) mode. At this point only
data of the first orbit are available. Further observations have
been delayed due to the detection of GRB 100213B (Vetere et al., GCN
Circ. 10412
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 ). Therefore no prediction of the future light curve is
possible at this time.

A spectrum formed from the PC mode data can be fitted with an
absorbed  power-law with a photon spectral index of 2.04
(+0.45, -0.56) with the absorption column density fixed to the
Galactic value of 1.1 x 10^21 cm^-2 (Kalberla et
al. 2005). The counts to observed  (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum is  4.5 x 10^-11
(5.9 x 10^-11) erg cm^-2 count^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00412217.

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

Adria C. Updike (Clemson University), Gary D. Henson (ETSU), and Dieter H.
Hartmann (Clemson University) report:

We observed the field of GRB 100213A (Grupe et al., GCN 10411
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 ) with the
0.9m SARA telescope located on Kitt Peak in Arizona beginning 4 hours and
11 minutes after the trigger at high airmass under good conditions.  In 20
minutes of stacked exposures, we detect no new sources in the XRT error
circle down to a limiting magnitude of R ~ 20 (as compared to USNO B1.0
field stars).

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

Using 273 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 100213A, 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 = 349.39183, +43.37892 which is equivalent
to:

RA (J2000): 23h 17m 34.04s
Dec (J2000): +43d 22' 44.1"

with an uncertainty of 2.2 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.

P.A. Curran (MSSL-UCL) and D. Grupe (PSU) report on behalf of the
Swift/UVOT team:


The Swift/UVOT began settled observations of the field of GRB 100213A
77s after the BAT trigger (Grupe et al., GCN 10411
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 ). No optical
afterglow consistent with the XRT position (Beardmore et al., GCN 10418
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 ) 
is detected in the initial UVOT exposures.

Preliminary 3-sigma upper limits using the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627) for the first exposures are:

Filter    T_start(s)   T_stop(s)  Exp(s)  Mag
------------------------------------------------
white     77           227        147     >20.20
v         59           68         9       >17.19
u         289          366        75      >19.7


The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.31 in the direction of the burst
(Schlegel et al. 1998).

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), D. Grupe (PSU), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-61 to T+242 sec from telemetry downlinks,
we report further analysis of BAT GRB 100213A (trigger #412217)
(Grupe, et al., GCN Circ. 10411
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 ).  The BAT ground-calculated position is
RA, Dec = 349.379, 43.370 deg which is 
   RA(J2000)  =  23h 17m 31.0s 
   Dec(J2000) = +43d 22' 13.1" 
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 59%.
 
The mask-weighted light curve shows four spikes between ~T-0.7 and ~T+2.5 sec
plus a low level tail out to ~T+40 sec.  T90 (15-350 keV) is 2.4 +- 0.4 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-0.7 to T+2.2 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.34 +- 0.15.  The fluence in the 15-150 keV band is 2.7 +- 0.3 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+1.01 sec in the 15-150 keV band
is 2.1 +- 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/412217/BA/

T. Sakamoto (UMBC/GSFC), D. Donato (ORAU/GSFC), N. Gehrels (GSFC),
T. Okajima (JHU/GSFC), Y. Urata (NCU), C.A. Wallace (FGCU)

We observed the field of GRB 100213A detected by Swift
(trigger #412217; Grupe et al., GCN Circ. 10411
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 ) with the 14-inch
Goddard Robotic Telescope (GRT) located at the Goddard Geophysical
and Astronomical Observatory (http://cddisa.gsfc.nasa.gov/ggao/).

Total 49 images of 60 sec exposures were taken in the R filter 
starting from February 13 23:42:02 (UT) about 1.2 hours after 
the trigger and stopped on February 14 01:28:00 (UT).  We do 
not detect the optical afterglow both in the individual images 
and the combined image inside the XRT position 
(Beardmore et al., GCN #10418
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 ).  The estimated three sigma upper 
limit of the combined image (total exposure of 1800 sec; excluding 
bad quality images) is ~17.5 mag using the USNO-B1 catalog.

J. P. Norris (U. Denver), S. D. Barthelmy (GSFC), 
N. Gehrels (GSFC), and D. Grupe (PSU) report:
 
Temporal analysis of BAT data for GRB 100213A suggests
that the burst is likely a member of the short, hard class:

Structures in the burst's most intense pulse complex
are as short as ~ 10-25 ms, typical of most short bursts.

Spectral lag analysis of this most intense pulse complex
indicate a lag between BAT channels 4 (100-350 keV) and
2 (25-50 keV) of ~ 5 ms +- 15 ms.  For the whole event,
the lag between these same channels is ~ 15 ms +- 15 ms.

A Bayesian Block analysis reveals no significant emission
after the T90 duration of 2.4 s (reported in GCN circ. 10424
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 ,
Barthelmy et al.) for ~ 400 s following the BAT trigger time.
This is inconsistent only at the 2-sigma level with the finding
in Circ 10424 that there was "low level emission out to T+40 sec",
and we further note that this emission is only in the 15-25 keV band.