GRB 070419B

A. M. Parsons (GSFC), D. N. Burrows (PSU), M. Capalbi (ASDC),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), C. Gronwall (PSU),
C. Guidorzi (Univ Bicocca&INAF-OAB), W. B. Landsman (NASA/GSFC),
C. B. Markwardt (GSFC/UMD), F. E. Marshall (NASA/GSFC),
P. T. O'Brien (U Leicester), D. M. Palmer (LANL), M. Perri (ASDC),
P. Romano (Univ. Bicocca & INAF-OAB), E. Troja (INAF-IASFPA) and
H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team:

At 10:44:05 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070419B (trigger=276212).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 315.719, -31.267 which is 
   RA(J2000) = 21h 02m 52s
   Dec(J2000) = -31d 15' 59"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows multiple peaks,
with a duration of about 160 seconds. The peak count rate was 
~2500 counts/sec (15-350 keV), at ~0 sec after the trigger.  
We note that this burst is distinct from GRB 070419A (trigger 276206). 

The XRT began observing the field at 10:45:26 UT, 81 seconds after the
BAT trigger. XRT found a bright, fading and uncatalogued X-ray source
located at RA, Dec 315.7067, -31.2635 which is
   RA(J2000)  =  21h 02m 49.6s
   Dec(J2000) = -31d 15' 48.6"
with an uncertainty of 5 arcseconds (radius, 90% containment). 
This location is 40 arcseconds from the BAT on-board position,
within the BAT error circle. The initial flux in the 2.5s image
was 1.5e-08 erg/cm2/s (0.2-10 keV). 

UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)
filter starting 89 seconds after the BAT trigger. No 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 18.5 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 extinction.

P. Tristram (MOA, Univ. of Canterbury), A. J. Castro-Tirado,
A. de Ugarte Postigo (IAA-CSIC Granada), A. Gilmore,
P. Kilmartin (Univ. of Canterbury), J. Gorosabel, M. Jelínek
and R. Cunniffe (IAA-CSIC Granada),

report:

"Following the detection by Swift of the GRB 070419B
(Parson et al. GCNC 6305), we have obtained R & I -band
images at the 0.6m B&C telescope at the Mt. John Observatory
on Lake Tekapo, New Zealand. They were taken starting
on Apr 19.537 UT (i.e. 2.17 hr post-burst).

The single frames (300s in R) reveal a point-like source
with R ~ 20 consistent with the Swift/XRT error box which
is not present in the DSS-2 red. Preliminary coordinates
(+/- 1") yield:

AR(2000): 21:02:49.80
Dec(2000): -31:15:49.23

Observations are ongoing. More details will be given on
forthcoming GCN Circular."

P. Tristram (MOA, Univ. of Canterbury), A. J. Castro-Tirado,
A. de Ugarte Postigo (IAA-CSIC Granada), A. Gilmore,
P. Kilmartin (Univ. of Canterbury), J. Gorosabel, M. Jelínek
and R. Cunniffe (IAA-CSIC Granada),

report:

"Following the detection by Swift of the GRB 070419B
(Parson et al. GCNC 6305), we have obtained R & I -band
images at the 0.6m B&C telescope at the Mt. John Observatory
on Lake Tekapo, New Zealand. They were taken starting
on Apr 19.537 UT (i.e. 2.17 hr post-burst).

The single frames (360s in R) reveal a point-like source
with R ~ 20 consistent with the Swift/XRT error box which
is not present in the DSS-2 red. Preliminary coordinates
(+/- 1") yield:

AR(2000): 21:02:49.80
Dec(2000): -31:15:49.23

More details will be given on forthcoming GCN Circular."

This message can be quoted.

A. de Ugarte Postigo, M. Jelínek (IAA-CSIC Granada),
P. Tristram (MOA, Univ. of Canterbury),  I. Bond
(Massey Univ.), Ph. Yock (Univ. of Auckland),
J. Hearnshaw (Univ. of Christchurch) and A. J. Castro-
Tirado (IAA-CSIC), on behalf of a larger collaboration,

report:

"We have continued the BVRI optical monitoring of the proposed
optical afterglow (Tristram et al. GCNC 6312) to GRB 070419B
(Parson et al. GCNC 6305) with the 0.6m B&C telescope at the
Mt. John Observatory on Lake Tekapo. We confirm the detection
in the VRI -bands and a derive a complex lightcurve (preliminary
analysis shows a steep decline up to T0 + 0.2 days and a plateau
phase lasting until the end of our observations at T0 + 0.3 days
with R ~ 21.0).

A more accurated astrometry (+/- 0.5") yields:

AR(2000): 21:02:49.78
Dec(2000): -31:15:48.8

A finding chart is posted at:
http://www.iaa.es/~deugarte/GRBs/070419B/GRB070419B.gif

Spectroscopic and photometric observations are encouraged."

This message can be quoted.

We have analyzed the first 3 orbits of Swift-XRT data on GRB 070419B
(Parsons et al. GCN 6305
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 ), with a total exposure of 276 s in Windowed
Timing (WT) mode and of 4.5 ks in Photon Counting (PC) mode.
This provides a refined XRT position at RA,DEC=315.70654,-31.26381
which is:

RA(J2000)=21 02 49.57
Dec(J2000)=-31 15 49.7

with an estimated error radius of 3.5 arcseconds (90% confidence).
This position is 32 arcseconds from the BAT position
(Parsons et al. GCN 6305
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 ), 1.2 arcseconds from the initial XRT
position (Parsons et al. GCN 6305
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 ) and 3.0 arcseconds from the
optical candidate (Tristram et al. GCN 6314
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 ).

The 0.3-10 keV X-ray light curve presents a flaring behavior
starting from 88 s up to about 350 s after the burst, with three
flares. The second and third orbits data taken in PC mode show marginal
evidence of a flat decay between 3.8 ks and 6.0 ks after the trigger,
followed by a fading decay behavior that can be fit with a power law
model with decay index 1.3+/-0.1

The X-ray spectrum from the XRT/WT data from 88 s to about 350 s can
be fit by an absorbed power law with a photon index of 1.88+/-0.03
and a total column density of NH=(0.22+/-0.01)e22 cm**-2. We note that
the Galactic column density in the direction of the source is
6.7e20 cm**-2 (Dickey & Lockmann 1990).

Assuming the X-ray emission continues to decline at the same rate,
we predict a 0.3-10.0 keV XRT count rate of 7.5e-2 count/s at T+24h
and 3.1e-2 at T+48h.

This circular is an official product of the Swift Team.

B. Schmidt (ANU) and G. Mackie (Swinburne) report on behalf of a larger 
collaboration

We have obtained R and I photometry of GRB070419B  (Parson et al. GCN 
6305
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 ) with the
ANU 1m telescope + WFI at Siding Spring observatory. I images taken Apr 
19.737-19.748  and R images taken at Apr 19.753-19.757  confirm the 
source of Tristram et al. (GCN 6312
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 ) at a position

    RA  (2000):   21:02:49.82
    DEC(2000):  -31:15:49.3

 with a position uncertainty +/- 0.1" referenced to the UCAC2 catalog.

The R and I magnitudes are estimate to be ~ I=20.7, R=22.1 referenced to 
the UCAC2/2Mass star
located at 21:02:59.34 -31:18:13.4 with mag ~I=14.75, R=15.25. This is 
significantly fainter than observed by Tristram et al., and suggests 
strongly that this object is associated with GRB07419B.

D. Palmer (LANL), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), A. Parsons (GSFC),
T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS),
M. Stamatikos (GSFC/ORAU), and J. Tueller (GSFC)
on behalf of the Swift-BAT team:

Using the data set from T-239.9 to T+602.1 sec from the recent
telemetry downlink, we report further analysis of BAT GRB 070419
(trigger #276212)   (Parsons, et al., GCN Circ. 6305
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 ).  The BAT
ground-calculated position is RA, Dec = 315.709, -31.266 deg which is
     RA(J2000) = 21h 2m 50.2s
     Dec(J2000) = -31d 15' 58.3"
with an uncertainty of 1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 66%.

The mask-weighted light curve exhibits 4 main peaks at ~T+0 s,T+25s,
T+35s, and T+60s and its duration T90 (15-350 keV) is 236.5 +-12 sec
(estimated error including systematics).

The time-averaged spectrum from -11.7 to 314.8 s is best fit by
a simple power-law model.  The power law index of the time-averaged
spectrum is 1.70 +- 0.05. The fluence in the 15-150 keV band is
7.5 +- 0.2 x 10^-6 erg/cm2.The 1-sec peak photon flux measured from
T-0.28 sec in the 15-150 keV band is 1.4 +- 0.2 ph/cm2/sec.  All the
quoted errors are at the 90% confidence level.

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

The long GRB 070419B (Swift/BAT trigger #276212 ; Parsons et al.,
GCN 6305
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 ; Palmer et al., GCN 6327
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 ), was detected at 10:44:01 UT (=T0)
by the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy
range of 50 keV - 5 MeV. The observed light curve shows two separate
peak structures with a duration (T90) of about 71 seconds. The fluence
in 100-1000 keV was (1.1 +/-0.2) X 10^-5 erg/cm^2. The 1-s peak flux was
0.9 +/-0.1 photons/cm^2/s in the same energy range.

Preliminary result shows that time-averaged spectrum from T0-5 to
T0+83 sec is well fitted by a single power law with a photon index
of 1.7 +/-0.2.

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