GRB 070107
GCN Circular 5999
Subject
GRB 070107: Swift detection of a burst
Date
2007-01-07T13:10:10Z (18 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
M. Stamatikos (NASA/ORAU), S.D. Barthelmy (GSFC), M. M. Chester (PSU),
G. Cusumano (INAF-IASFPA), W. B. Landsman (NASA/GSFC),
T. Mineo (INAF-IASFPA), D. M. Palmer (LANL) and
P. Romano (Univ. Bicocca & INAF-OAB) report on behalf of the Swift Team:
At 12:05:18 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070107 (trigger=255029). Swift slewed immediately to the
burst. The BAT on-board calculated location is
RA, Dec 159.408, -53.208 which is
RA(J2000) = 10h 37m 38s
Dec(J2000) = -53d 12'
27" with an uncertainty of 3 arcmin (radius, 90% containment,
including systematic uncertainty). The BAT light curve showed a
broad peak lasting about 40 seconds with smaller structure. The peak
count rate was ~2500 counts/sec (15-350 keV), at ~6 sec after the
trigger.
The XRT began observing the field at 12:08:17.02 UT, 179 seconds after the
BAT trigger. XRT did not make an immediate localization. The lightcurve does not
show any time variability, however, the spectrum appears consistent
with that of a GRB. We are waiting for the full data set from the
next Malindi download data pass for futher analysis.
UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 181 seconds after the BAT trigger, and a
finding chart exposure of 400 seconds with the V filter starting 287
seconds after the BAT trigger. No afterglow candidate has been found
in the initial data products. The 2.7'x2.7' sub-image covers 25% of
the BAT error circle, and the 8'x8' region for the list of sources
generated on-board covers 100% of the BAT error circle. Because of
the density of catalogued stars, further analysis is required to
report an upper limit for any afterglow in the region. No correction
has been made for extinction.
GCN Circular 6000
Subject
GRB 070107: Swift/XRT position
Date
2007-01-08T03:42:36Z (18 years ago)
From
Jamie A. Kennea at PSU/Swift-XRT <kennea@astro.psu.edu>
J. A. Kennea (PSU) and M. Stamatikos (NASA/ORAU) report on behalf of the
Swift/XRT team:
At 12:08:17 UT, Swift XRT began observing GRB 070107. Although no X-ray
counterpart was found by the on-board software, analysis of downlinked
data reveals a bright, flaring, uncatalogued point source at the following
location:
RA(J2000) = 10h 37m 36.1,
Dec(J2000) = -53d 12m 46.9s,
with an estimated uncertainty of 10 arcseconds radius (90% contrainment).
This position lies 24 arcseconds from the BAT position reported in GCN
5999.
GCN Circular 6001
Subject
GRB 070107, Swift-BAT refined analysis
Date
2007-01-08T05:17:51Z (18 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), L. Barbier (GSFC), J. Cummings (GSFC/UMBC),
E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC), T. Ukwatta (GWU)
on behalf of 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 070107 (trigger #255029)
(Stamatikos, et al., GCN Circ. 5900). The BAT ground-calculated position
is RA, Dec = 159.422, -53.202 deg which is
RA(J2000) = 10h 37m 41.4s
Dec(J2000) = -53d 12' 08.4"
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 53%.
The analysis of this burst is complicated by the fact that the burst
started before it was in the BAT FOV. BAT was executing a preplanned
slew to the next planned target when the burst came into the FOV.
BAT triggered (a 96-sec imager trigger) on the tail end of the last
of 2 (or potentially more) peaks in the burst. The mask-weighted
lightcurve starts at ~T-32 sec with a rising flux, peaking at ~T-7 sec,
and then returning to almost background levels at ~T+80 sec. Then there is
a FRED-like peak starting at ~T+310 sec, peaking at ~T+320 sec, and returning
to background levels at ~T+400 sec. We are not quoting a T90 value
because the burst data was truncated at the beginning of the burst.
For the partial amount of time covered, the time-averaged spectrum
from T-19.7 to T+404.2 is best fit by a simple power-law model.
The power law index of the time-averaged spectrum is 1.34 +- 0.10.
The lower limit to the fluence in the 15-150 keV band is
5.2 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured
(for the portion of the burst BAT observed) from T-7.24 sec
in the 15-150 keV band is 1.9 +- 0.2 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.
GCN Circular 6002
Subject
GRB 070107: Possible UVOT Afterglow
Date
2007-01-08T20:05:22Z (18 years ago)
From
Padi Boyd at GSFC <padi@milkyway.gsfc.nasa.gov>
GRB 070107: Possible UVOT Afterglow
P. T. Boyd (GSFC), M. Chester (PSU), C. B. Markwardt (CRESST/GSFC/USRA)
and F. E. Marshall (GSFC) report on behalf of the Swift team:
In response to GRB 070107 (Stamatikos et al. GCN Circ. 5999)
UVOT took a 100-s finding chart exposure with the White filter (160-650 nm)
starting 183 seconds after the BAT trigger, followed by a 400-s V
finding chart exposure. A second set of finding chart
exposures was obtained starting 868s post-trigger. We detect a
new variable source inside the XRT error region (Kennea et al.
GCN Circ. 6000) in the first exposure at
RA(J2000) = 10 37 36.35
DEC(J2000) = -53 12 47.5
with a 1-sigma error radius of about 1 arcsec. However, we caution
that this source is in a crowded region at low galactic latitude,
and only 4.1 arcsec from a bright V=15.9 cataloged star, which
causes the afterglow and the star to be blended in the UVOT image,
and complicates the position, magnitude, and significance estimates.
We estimate a White magnitude of ~19.5 for the new source. The source
is detected at a ~4-sigma significance level. The same source is
detected at a level of 2.7 sigma in the subsequent 400-s V finding chart.
The new source is not significant in later White and V exposures.
We note that the extinction estimate in this region (whose galactic
latitude is 4.56 degrees) is large, and uncertain.
GCN Circular 6003
Subject
GRB070107: Swift/XRT refined analysis
Date
2007-01-08T22:12:04Z (18 years ago)
From
Teresa Mineo at INAF-IASFA <teresa.mineo@ifc.inaf.it>
T. Mineo, B. Sbarufatti, V. Mangano, G. Cusumano (INAF-IASF Pa)
report on behalf of the Swift XRT team:
We have analyzed the first ten orbits of Swift-XRT data on GRB 070107
(Stamatikos et al. GCN 5999), with a total exposure of 420 s seconds
in Window Timing (WT) mode and 15.8 ks seconds in Photon Counting (PC)
mode.
This provides a refined XRT position at RA,Dec=159.4016,-53.2131
which is:
RA (J2000) = 10h 37m 36.4s
Dec(J2000) = -53d 12m 47.3s
with an estimated error radius of 3.7 arcseconds (90% confidence). This
position is 59.4 arcseconds from the BAT refined position (Barthelmy et
al. GCN 6001), 2.6 arcseconds from the initial XRT position
(Kennea & Stamatikos, GCN 6000), and 0.4 arcseconds from the UVOT
optical candidate (Boyd et al., GCN 6002).
The 0.3-10 keV X-ray light curve presents a bright flare starting at
about 300 s from the trigger and coincident with the peak detected in
the BAT light curve (Barthelmy et al. GCN 6001). A second fainter peak
is also present at 1300 s and the light curve between 3 ks and 59 ks
can be fit with a simple power-law with a decay slope of 1.05 � 0.05.
The X-ray spectrum from the XRT/WT data, mainly covering the first
bright flare, is well fit by an absorbed power-law with a photon index
of 2.07�0.07 and column density of (3.8�0.2)e21 cm**-2, consistent
with the Galactic column density in the direction of the source
(3.6E21 cm**-2). The unabsorbed 0.3-10 keV flux for this spectrum is
1.3e-9 erg/cm**2/s. The XRT/PC data is modeled by an absorbed power law
with a photon index of 2.2�0.1 and column density of (4.3�0.4)e21 cm**-2
and the unabsorbed 0.3-10 keV flux is 2.48E-11 erg/cm**2/s.
Assuming the X-ray emission continues to decline at the same rate, we
predict a 0.3-10 keV XRT count rate of 1e-2 count/s at T+48hr, which
corresponds to an observed 0.3-10 keV flux of 1.4e-12 erg/cm**2/s.
This circular is an official product of the Swift XRT Team.
GCN Circular 6006
Subject
GRB070107 Swift/UVOT Observations of a Fading Optical Afterglow
Date
2007-01-10T17:04:52Z (18 years ago)
From
Padi Boyd at GSFC <padi@milkyway.gsfc.nasa.gov>
GRB 070107: UVOT Observations of a Fading Optical Afterglow
P. T. Boyd and F. E. Marshall (NASA/GSFC) report on behalf of the Swift team:
UVOT observed the field of GRB 070107 (Stamatikos et al. GCN Circ. 5999).
The complete data set through T=117,471s now available clearly shows a
fading source at the position reported by Boyd et al. (GCN Circ 6002).
This afterglow candidate is visible at early times in the White and
V filters, and probably also in the U filter.
The table below gives the measured magnitudes after correcting for
flux in the source aperture due to the bright (V=15.9 mag) nearby
star. Reported significance levels were calculated based on rates
in the source region, while magnitude errors include the contribution
from aperture correction.
Filter TSTART Exposure Mag Error Significance
White 181 98 19.5 0.3 5.6
White 5355 197 20.5 0.3 3.5
V 286 393 19.2 0.3 3.9
V 971 393 19.8 0.4 2.0
U 29220 590 20.6 0.4 2.8
B 5151 197 20.7 (3sigma UL)
W1 6174 197 20.0 (3sigma UL)
M2 16718 886 20.5 (3sigma UL)
W2 22501 886 20.8 (3sigma UL)
These magnitudes have not been corrected for the large and unreliable
Galactic extinction at this position.
GCN Circular 6016
Subject
GRB 070107: Suzaku WAM observation of the prompt emission
Date
2007-01-13T07:02:33Z (18 years ago)
From
Masanori Ohno at Hiroshima U <ohno@hirax7.hepl.hiroshima-u.ac.jp>
T. Takahashi, M. Ohno, T. Asano, T. Uehara, Y. Fukazawa (Hiroshima U.),
Y. Urata, M. Tashiro, K. Abe, K. Onda, Y. Sato, M. Suzuki (Saitama U.),
K. Yamaoka, S. Sugita (Aoyama Gakuin U.), T. Enoto, R. Miyawaki,
K. Makishima (Univ. of Tokyo), M. Suzuki, T. Tamagawa, Y. Terada (RIKEN),
K. Nakazawa, M. Kokubun, T. Takahashi, (ISAS/JAXA), S. Hong (Nihon U.),
on behalf of the Suzaku WAM team report:
The long GRB 070107 (Stamatikos et al., GCN 5999; Barthelmy et al.,
GCN 6001) triggered the Suzaku Wide-band All-sky Monitor (WAM),
which covers the energy range of 50 keV - 5 MeV, at 12:05:06 UT(=T0).
The light curve shows double peaks with a total duration of
about 92 seconds. The fluence in 100 - 1000 keV of the burst was
1.57 +- 0.13 x 10^-5 erg/cm2, while the 1-s peak flux was
1.18 (-0.13, +0.14) photons/cm2/s in the same energy range.
The time-averaged spectrum from T0-66 sec to T0+94 sec is well fitted
by a single power-law model. The power-law photon index of its spectrum
is 1.75 (-0.13,+0.15). All the quoted errors are at statistical 90%
confidence level, while systematic errors are not included.
The WAM light curve of this event is available at
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/grb_table.html