GRB 100522A

E. Troja (NASA/GSFC/ORAU), A. P. Beardmore (U Leicester),
M. M. Chester (PSU), J. M. Gelbord (PSU),
S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), C. Pagani (U Leicester),
D. M. Palmer (LANL), R. L. C. Starling (U Leicester),
T. N. Ukwatta (GSFC/GWU) and L. Vetere (PSU) report on behalf of the
Swift Team:

At 03:45:52 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 100522A (trigger=422783).  Swift slewed immediately to 
the burst.  The BAT on-board calculated location is 
RA, Dec 6.983, +9.417 which is 
   RA(J2000) = 00h 27m 56s
   Dec(J2000) = +09d 25' 03"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a first pair of peaks near T0 with a duration of 
about 5 sec and a second fainter and softer pair of peaks near T+30 s.  
The peak count rate was ~15,000 counts/sec (15-350 keV), at ~0 sec 
after the trigger. 

The XRT began observing the field at 03:46:57.7 UT, 65.4 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
6.9867, 9.4023 which is equivalent to:
   RA(J2000)  = 00h 27m 56.82s
   Dec(J2000) = +09d 24' 08.1"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 54 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. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (3.98e+20
cm^-2, Kalberla et al. 2005), with an excess column of 2.7
(+2.46/-2.10) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 2.40e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 73 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 100% of  the XRT error circle. The 3-sigma
upper limit at the XRT position is 18.5 mag. No  correction has been
made for the expected extinction corresponding to E(B-V) of  0.06. 

Burst Advocate for this burst is E. Troja (eleonora.troja 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/too.html.)

M. Jelínek (IAA-CSIC Granada), P. Kubánek (IPL Valencia, IAA-CSIC) and 
A. J. Castro-Tirado (IAA-CSIC), on behalf of a larger collaboration,

report:

"The 0.6m TELMA robotic telescope at the BOOTES-2 astronomical
station in Málaga (Spain) reacted to the Swift GRB 100522A
(Troja et al., GCNC10784), starting 10m25s after the trigger
(15s after receiving the delayed trigger). A set of 10s
unfiltered images was obtained, however the progressing
twillight degraded the images (already taken at high airmass).
The 120s coadded image with an exposure mean time 735s after
the GRB provides a limit R>15.5 at the XRT position reported
by Troja et al."

This message can be quoted.

A. de Ugarte Postigo (OAB-INAF), A.J. Castro-Tirado (IAA-CSIC),
A. Guijarro and M. Alises (CAHA) report on behalf of a larger
collaboration:

"We have observed the field of GRB 100522A (Troja et al. GCNC
10784) with the 3.5m CAHA telescope (+Omega2000) in J and Ks
bands. The observations were obtained during twilight, with a
very high background. In a preliminary analysis we do not detect
any source within the XRT error circle in any of the images. The
3x60s combined J-band exposure, has a mean time  04:20:27 UT
and a 3-sigma limiting magnitude of 17.9. The 4x60s combined
K-band exposure has a mean time of 04:31:50 and a limiting
magnitude of 16.3."

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

Using 3778 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 100522A, 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 = 6.98662, +9.40184 which is equivalent
to:

RA (J2000): 00h 27m 56.79s
Dec (J2000): +09d 24' 06.6"

with an uncertainty of 1.5 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.

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL),
T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU),
E. Troja (NASA/GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(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 100522A (trigger #422783)
(Troja, et al., GCN Circ. 10784
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 ).  The BAT ground-calculated position is
RA, Dec = 6.990, +9.397 deg which is
   RA(J2000)  =  00h 27m 57.6s
   Dec(J2000) = +09d 23' 50.1"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 71%.

The mask-weighted light curve shows a complex structure.  There are two 
main
episodes of emission, starting at T-0.5 sec and T+25 sec, respectively.  
The
first episode starts with a broad multi-peaked structure 2.5 sec long 
followed
by three short (~0.3 sec long) peaks.  Then the emission returns to
background levels before rising in a second, less intense and softer two 
peak
structure approximately 15 sec long. T90 (15-350 keV) is 35.3 +- 1.8 sec
(estimated error including systematics).

The time-averaged spectrum from T-0.5 to T+40.2 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.89 +- 0.08.  The fluence in the 15-150 keV band is 2.1 +- 0.1 x 10-6 
erg/cm2.
The 1-sec peak photon flux measured from T+0.04 sec in the 15-150 keV band
is 7.1 +- 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/422783/BA/

R.L.C. Starling, A.P. Beardmore (U. Leicester) and E. Troja (NASA/GSFC/ORAU) 
report on behalf of the Swift-XRT team:

We have analysed 5.4 ks of XRT data for GRB 100522A (Troja et al. GCN 
Circ. 10784
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 ), from 56 s to 13.6 ks after the BAT trigger. The data 
comprise 87 s in Windowed Timing (WT) mode (the first 7 s were taken while 
Swift was slewing) with the remainder in Photon Counting (PC) mode. The 
enhanced XRT position for this burst was given by Osborne et al. (GCN. 
Circ 10787).

The light curve can be modelled with a series of power-law decays. The 
initial decay index is alpha = 4.8 (+/-0.4). At T+130 s the decay flattens 
to an alpha of 0.53 (+0.04, -0.09) before breaking again at T+7830 s to a 
final decay with index alpha = 1.2 (+2.8, -0.4).

A spectrum formed from the WT mode data can be fitted with an absorbed 
power-law with a photon spectral index of Gamma = 2.82 (+0.32, -0.28). The 
best-fitting absorption column is 4.0 (+0.8, -0.7) x 10^21 cm^-2, in 
excess of the Galactic value of 4.0 x 10^20 cm^-2 (Kalberla et al. 2005). 
The PC mode spectrum has a photon index of 2.14 (+0.30, -0.28) and a 
best-fitting absorption column of 4.0 (+1.2, -1.0) x 10^21 cm^-2. The 
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced 
from this spectrum is 4.4 x 10^-11 (8.1 x 10^-11) erg cm^-2 count^-1.

If the light curve continues to decay with a power-law decay index of 1.2, 
the count rate at T+24 hours will be 0.011 count s^-1, corresponding to an 
observed (unabsorbed) 0.3-10 keV flux of 4.8 x 10^-13 (8.9 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/00422783.

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

S. McBreen (UCD/MPE)
reports on behalf of the Fermi GBM Team:

"At 03:45:52.29 UT on 22 May 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 100522A (trigger 296192754 / 100522157)
which was also detected by the Swift-BAT (Troja et al. 2010, GCN 10784
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 ).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 81 degrees.

The GBM light curve consists of two of pulses with
substructure from T0 to T0+5 s followed by two softer pulses
lasting from T0+25 s to about T0+40 sec.  The burst
has a duration (T90) of about 35.0 +/-1.5 s (50-300 keV).
The time-averaged spectrum from T0-0.003 s to T0+40.385 s is
adequately fit by a simple power law function
with index -1.81 (+/-0.03)(CSTAT 544 for 481 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(5.2 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.25 s in the 8-1000 keV band
is 11.0 +/- 0.3 ph/s/cm^2.

A power law function with an exponential high energy cutoff
fits the spectrum equally well (CSTAT 538 for 480 d.o.f).
The power law index is -1.62 (+0.10/-0.09) and
the cutoff energy, parameterized as Epeak, is 138 (+82/-32) keV.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

M. De Pasquale (MSS-UCL) and Eleonora Troja (NASA/GSFC/ORAU)
report on behalf of the Swift/UVOT team:

Swift/UVOT began settled observations of GRB100522A (Troja et al.
GCN Circ. 10784
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 ) starting 73 seconds after trigger. No optical afterglow
within the enhanced XRT position (Osborne et al. GCN Circ. 10787
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 ) is
detected in the UVOT exposures. Preliminary 3-sigma upper limits using
the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for
the first finding chart (FC) exposure and subsequent summed exposures are:

Filter   T_start(s)  T_stop(s)   Exp(s)   Mag
-----------------------------------------------------------
white       73         223         147      >20.1 (FC)
white       73        7223         569      >20.9
v          614        6199         352      >19.0
b          541        7018         352      >19.9
u          285       13630        1243      >20.1
uw1        663       12939        1242      >20.5
m2         639        7838         549      >20.2
w2         590        7429         363      >20.1


The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.06 in the direction of the burst
(Schlegel et al. 1998).

P. Afonso (MPE Garching), S. Klose (TLS Tautenburg), and J. Greiner (MPE 
Garching), report on behalf of the GROND team:

GROND (Greiner et al. 2008, PASP 120, 405), the 7-channel imager mounted 
at the 2.2m ESO/MPI telescope on La Silla, started follow-up observations 
of the Swift/Fermi burst GRB 100522A (Troja et al. 2010, GCN 10784
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 ; 
McBreen 2010, GCN 10790
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 ) on May 23 at 09:18 UT (about 29.5 hrs after the 
burst), and continued for about 1 hour.

Within the enhanced XRT 1.5 arcsec error circle reported by Osborne et al. 
(GCN 10787
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 ) we do not find any afterglow candidate. Based on 50 min of 
total exposures in g'r'i'z' and 40 min in JHK, preliminary measured upper 
limits are (in the AB system, 3 sigma):

g' > 24.8,
r' > 24.4,
i' > 23.6,
z' > 23.3,
J  > 21.7,
H  > 20.9,
K  > 20.6,

using GROND zeropoints and the 2MASS catalog.

A. Daikyuji, N. Ohmori, Y. Nishioka, M. Yamauchi (Univ. of Miyazaki),
K. Yamaoka (Aoyama Gakuin U.), S. Sugita (Nagoya U.),
Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa (Hiroshima U.),
Y. Terada, M. Tashiro, W. Iwakiri, K. Takahara, T. Yasuda (Saitama U.),
M. Ohno, M. Suzuki, M. Kokubun, T. Takahashi (ISAS/JAXA),
Y. E. Nakagawa, T. Tamagawa (RIKEN), N. Vasquez (Tokyo Tech.), Y. Urata,
H. M. Lin (NCU), T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo),
S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report:

The long GRB100522A (Swift/BAT trigger #422783 ; Troja et al., GCN 10784
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 )
was detected by the the Suzaku Wide-band All-sky Monitor (WAM) which
covers an energy range of 50 keV - 5 MeV at 2010-05-22 03:45:52 UT (=T0).

The observed light curve shows a single peak starting at T0, ending
at T0+4s with a duration (T90) of about 3 seconds.
The WAM detected only the first bright peak observed by
Swift/BAT (Barthelmy et al., GCN 10788
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 ) and Fermi/GBM(McBreen et al.,
GCN 10790
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 ).
The fluence in 100 - 1000 keV was 1.39 (-0.18, +0.15) x10-6 erg/cm2.
The 1-s peak flux measured from T0+1s was 1.50 (-0.27, +0.24)
photons/cm2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from T0 to
T0+4s is well fitted by a single power-law with a photon index
of 2.26 (-0.18, +0.21) (chi2/d.o.f = 26.8/35).

All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.

The light curves with 1-sec time resolution for this burst will be
appeared at:

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

S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:

The long GRB 100522A (Swift-BAT trigger=422783;
Troja et al., GCN 10784
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 ; Barthelmy et al., GCN 10788
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 )
triggered Konus-Wind at T0=13549.843s UT (03:45:49.843)

The burst light curve shows a single pulse
with a total duration of ~6 s.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB100522_T13549/

As observed by Konus-Wind the burst
had a fluence of 1.7(-0.5, +0.3)x10-6 erg/cm2,
and a 256-ms peak flux measured from T0-0.256s
of 0.7(-0.2, +0.1)x10-6 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).

The time-integrated spectrum of the burst (from T0 to T0+8.848 s)
is best fit in the 20 keV - 2 MeV range by a single power-law
model with a photon index of 2.9 (-/+0.5), chi2 = 78/69 dof.

All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level.