GRB 100619A

J. K. Cannizzo (NASA/UMBC), N. Gehrels (NASA/GSFC),
J. M. Gelbord (PSU), S. T. Holland (CRESST/USRA/GSFC),
J. Mao (INAF-OAB), R. Margutti (INAF-OAB), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/IASFPA),
M. H. Siegel (PSU), M. A. Stark (PSU) and T. N. Ukwatta (GSFC/GWU)
report on behalf of the Swift Team:

At 00:21:07 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 100619A (trigger=424998).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 84.615, -27.001 which is 
   RA(J2000) = 05h 38m 28s
   Dec(J2000) = -27d 00' 02"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed two well-separated
peaks about 90 seconds apart with an overall duration of about 120 sec. 
The peak count rate was ~4000 counts/sec (15-350 keV), at ~0 sec after
the trigger for the first peak, and 5000 counts/sec (15-350 keV) at
~95 sec after the trigger for the second peak. 

The XRT began observing the field at 00:22:23.7 UT, 76.4 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
84.6227, -27.0049 which is equivalent to:
   RA(J2000)  = 05h 38m 29.46s
   Dec(J2000) = -27d 00' 17.8"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 27 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 (2e+20
cm^-2, Kalberla et al. 2005), with an excess column of 3.8
(+1.95/-1.69) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 0.1 s image was 5.61e-08 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White
filter starting 87 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 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 0.03. 

Burst Advocate for this burst is J. K. Cannizzo (cannizzo AT milkyway.gsfc.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. Stamatikos (GSFC/ORAU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. K. Cannizzo (NASA/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), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC),
G. Sato (ISAS), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 100619A (trigger #424998)
(Cannizzo, et al., GCN Circ. 10863
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 ).  The BAT ground-calculated position is
RA, Dec = 84.618, -27.012 deg which is 
   RA(J2000)  =  05h 38m 28.3s 
   Dec(J2000) = -27d 00' 42.2" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 75%.
 
The mask-weighted light curve shows two well separated peaks.  The first
s compsed of several overlapping pulses which starts at ~T-3 sec, peaks at
~T_10 sec, and returns to background at ~T+20 sec.  The second peak starts
~T+55 sec, peaks at ~T=85 sec, and ends at ~T+120 sec.  T90 (15-350 keV)
is 97.5 +- 3 sec (estimated error including systematics).
 
The time-averaged spectrum from T-2.9 to T+105.7 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.83 +- 0.06.  The fluence in the 15-150 keV band is 4.5 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+87.22 sec in the 15-150 keV band
is 4.8 +- 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/424998/BA/

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

Using 4927 s of XRT Photon Counting mode data and 8 UVOT
images for GRB 100619A, 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 = 84.62214, -27.00534 which is equivalent
to:

RA (J2000): 05h 38m 29.31s
Dec (J2000): -27d 00' 19.2"

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.

J. Mao (INAF-OAB) and J. K. Cannizzo (NASA/UMBC) report on behalf of the
Swift-XRT team:

We have analysed 6.6 ks of XRT data for GRB 100619A (Cannizzo  et al.
GCN Circ. 10863
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 ), from 80 s to 13.2 ks after the  BAT trigger. The data
comprise 492 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The light curve initially shows a flare feature
at the time 90s, then it has a power-law decay with an index 0.88, after 
that,
the light curve shows a clear flare feature with the peak at 1000s. 
Then, the
light cure has a power-law decay with an index of alpha=0.85 (+/-0.02).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.41 (+/-0.03). The
best-fitting absorption column is  3.4 (+/-0.1) x 1021 cm^-2, in
excess of the Galactic value of 2.0 x 1020 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 2.16 (+0.20, -0.19)
and a best-fitting absorption column of 3.7 (+/-0.6) x 1021 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 6.7 x 10^-11 (9.6 x 10^-11) erg cm^-2
count^-1. If the light curve continues to decay with a power-law decay 
index
of 0.85, 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 1.0 x
10^-12 (1.4 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00424998.

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

P.A. Curran (MSSL-UCL) and J. K. Cannizzo (NASA/UMBC) report on behalf
of the Swift/UVOT team:


The Swift/UVOT began settled observations of the field of GRB 100619A 87 
s after the BAT trigger (Cannizzo et al., GCN Circ. 10863
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 ). No optical 
afterglow consistent with the enhanced  XRT position (Beardmore et al., 
GCN Circ. 10865
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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 finding chart (FC) and subsequent 
exposures are:


Filter   T_start(s)  T_stop(s)  Exp(s)   Mag
-----------------------------------------------
white    87          237        147      >21.2 (FC)
u        300         549        246      >20.5 (FC)

white    87          6773       785      >22.0
v        630         7184       510      >20.2
b        556         13220      1161     >21.5
u        300         19002      2089     >21.6
w1       679         18300      2128     >21.7
m2       654         17394      1396     >21.4
w2       606         6978       510      >20.9


The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).

P. N. Bhat (UAH) 
reports on behalf of the Fermi GBM Team:

"At 03:55:23.71 UT on 19 June 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 100619A (trigger 298612525 / 100619015).
which was also detected by the SWIFT-BAT (Cannizzo et al. 2008, GCN 10863
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 )
The GBM on-ground location is consistent with the Swift position.
 
The angle from the Fermi LAT boresight is 117 degrees.

The GBM light curve shows 2 well separated pulses
with a duration (T90) of about 96.8 s (50-300 keV).
The time-averaged spectrum from T0-9.216 s to T0+101.378 s is
well fit by a power law function with an exponential
high energy cutoff.  The power law index is -1.61 +/- 0.05 and
the cutoff energy, parameterized as Epeak, is 143.2 +/- 24.8 keV

(C-stat 419 for 241 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(1.71 +/- 0.1)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+83 s in the 10-1000 keV band is 1.88 +/- 0.04 ph/s/cm^2.

A Band function fits the spectrum equally well (C-stat 419 for 240 d.o.f.)
with Epeak= 135.3 +/- 37.1 keV, alpha = -1.60 +/- 0.07 and beta = -2.36 +/-
0.69. 


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

P. N. Bhat (UAH) 
reports on behalf of the Fermi GBM Team:

"The trigger time of GRB 100619A reported in GCN 10868
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  as 03:55:23.71 UT is
in error. The actual trigger time is 00:21:07.03 UT."