GRB 070208
GCN Circular 6074
Subject
GRB 070208: Swift detection of a burst
Date
2007-02-08T09:34:19Z (18 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
G. Sato (GSFC/ISAS), S. D. Barthelmy (GSFC), S. Campana (INAF-OAB),
M. L. Conciatore (ASDC), P. A. Evans (U Leicester),
N. Gehrels (NASA/GSFC), C. Gronwall (PSU),
C. Guidorzi (Univ Bicocca&INAF-OAB), V. Mangano (INAF-IASFPA),
P. T. O'Brien (U Leicester), J. P. Osborne (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
P. Romano (Univ. Bicocca & INAF-OAB), G. Stratta (ASDC),
G. Tagliaferri (INAF-OAB), S. D. Vergani (DIAS-DCU) and
H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team:
At 09:10:34 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070208 (trigger=259714). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 197.920, +61.959 which is
RA(J2000) = 13h 11m 41s
Dec(J2000) = +61d 57' 31"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a single peak structure
with a duration of about 2 sec. The peak count rate
was ~1200 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began taking data at 09:12:29 UT, 116 seconds after the BAT
trigger. XRT could not centroid onboard, however in a 222 s ground-processed
image, we found a previously uncatalogued X-ray source in the field of view at
the following coordinates:
RA(J2000) = 13h 11m 32.77s
Dec(J2000)= +61d 57' 55.17"
with an uncertainty of 5 arcseconds radius (90% containment).
This position lies 63 arcseconds from the center of the BAT error circle.
The approximate initial flux is 1.044e-11 erg/cm2/sec (0.2-10 keV).
UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 119 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 the expected extinction corresponding to
E(B-V) of 0.01.
GCN Circular 6075
Subject
GRB 070208: MDM Observations
Date
2007-02-08T10:00:30Z (18 years ago)
From
Nestor Mirabal at Columbia U <mirabal@astro.columbia.edu>
N. Mirabal and J. P. Halpern (Columbia U.) report on
behalf of the MDM Observatory GRB follow-up team:
"We have observed the Swift BAT localization of
GRB 070208 (Sato et al., GCN 6074) with the
MDM 1.3m telescope starting on February 8 09:25.
Within the XRT error box, we detect two extended
sources (also seen in the DSS plates), which should
be considered potential host galaxies for this short
burst. Observations are continuing to determine
optical variability.
This message may be cited."
GCN Circular 6076
Subject
GRB 070208: ROTSE-III Optical Limits
Date
2007-02-08T10:13:07Z (18 years ago)
From
Fang Yuan at ROTSE <yuanfang@umich.edu>
F. Yuan (U Mich), W. Rujopakarn (U Arizona), H. Swan (U Mich), E. S.
Rykoff (U Mich) report on behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB
070208 (Swift trigger 259714, GCN 6074, Sato, et al), producing images
beginning 5.8 s after the GCN notice time. An automated response took
the first image at 09:11:14.8 UT, 40.5 s after the burst, under fair
conditions. We took 10 5-sec, 10 20-sec and 20 60-sec exposures. These
unfiltered images are calibrated relative to USNO A2.0 (R).
Comparison to the DSS (second epoch) reveals no new sources within both
the BAT and the XRT error circles, for both single images and coadding
into sets of 10. We marginally detect one of the DSS objects detected by
Mirabal & Halpern (GCN 6075) in our deepest images. Individual images
have limiting magnitudes ranging from 15.9-17.0; we set the following
specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
09:11:14.8 09:11:19.8 5 16.0 40.5 N
09:11:14.8 09:12:21.9 67 17.5 40.5 Y
09:12:29.9 09:17:25.5 295 18.2 115.6 Y
GCN Circular 6077
Subject
GRB070208: Faulkes Telescope North Afterglow Identification
Date
2007-02-08T10:14:08Z (18 years ago)
From
Carole Mundell at ARI, JMU,Liverpool <cgm@astro.livjm.ac.uk>
C. Guidorzi, C.G. Mundell, A. Monfardini,A. Gomboc, I. A. Steele, C.J.
Mottram, R.J. Smith, M.F. Bode (Liverpool JMU), P. O'Brien, E. Rol, N.
Bannister (Leicester) report:
"The 2-m Faulkes Telescope North robotically followed up GRB070208
(SWIFT trigger 259714; GCN 6074 Sato et al) 2.33 min after the GRB
trigger time.
We identify a fading uncatalogued source at:
13:11:32.51
+61:57:54.5 (J2000)
This afterglow candidate is located close to but south-west of the
extended galaxy visible in the SDSS. The of the two sources identified by
Mirabal et al. (GCN 6075), we suggest the SW source is the afterglow.
Observations are ongoing."
GCN Circular 6078
Subject
GRB 070208: Afterglow confirmation from P60
Date
2007-02-08T10:37:30Z (18 years ago)
From
Derek Fox at PSU <dfox@astro.psu.edu>
D. B. Fox (PSU), E. Ofek (Caltech) and S. B. Cenko (Caltech) report
on behalf of a larger collaboration:
"We have imaged the localization region for the afterglow of GRB
070208 (Sato et al., GCN 6074) with the robotic Palomar 60-inch
telescope, in a series of exposures beginning at 09:15:33 UT, 5
minutes after the burst.
We confirm the point-like, fading nature of the afterglow candidate
reported by Guidorzi et al. (GCN 6077), although given the nearby
(candidate host) galaxy (Mirabel & Halpern, GCN 6075; Guidorzi et al.,
GCN 6077) we cannot exclude the presence of underlying diffuse
emission at this time.
In our images the afterglow has i'~22 mag at 09:18 UT and i'~23.4 mag
at 10:05 UT, corresponding to fading with power-law index alpha~-0.7
referenced to the burst epoch."
GCN Circular 6079
Subject
GRB 070208: Early IR detection and afterglow astrometry
Date
2007-02-08T11:00:33Z (18 years ago)
From
Josh Bloom at UC Berkeley <jbloom@astron.berkeley.edu>
J. S. Bloom (UC Berkeley) reports on behalf of a large group:
We began observing GRB 070208 (Sato et al. GCN 6074) with the robotic
IR telescope PAIRITEL at 2007-02-08 09:12:26 UTC, 1 minute 52 seconds
after the trigger. Consistent with the position of the fading source
reported by Guidorzi et al. (GCN 6077; see also Fox et al. 6078) we
find a new IR point source, offset from the nearby SDSS galaxy.
Astrometry of the afterglow position relative to 2MASS gives a
location of (J2000):
RA: 13:11:32.607
DEC: +61:57:54.37
(rms uncertainty of 350 mas in both coordinates). Adopting the
nominal SDSS position for the center of the putative host (Mirabal et
al. 6075), the afterglow is offset by 2.48" W, 2.77" S.
In a stacked exposure from 2007-02-08 09:12:26 to 09:28:44 we find a
preliminary magnitude of J=17.52 +/- 0.16, Ks=16.19+/-0.18.
A finder showing the XRT position (Sato et al. 6074; yellow circle),
SDSS sources (white squares), and the FTN optical afterglow position
may be found at:
http://lyra.berkeley.edu/~jbloom/grb070208.ps.gz
This message may be cited.
GCN Circular 6080
Subject
GRB070208 - SDSS Pre-Burst Observations
Date
2007-02-08T15:15:51Z (18 years ago)
From
Richard J. Cool at U.of AZ/Steward Obs <rcool@as.arizona.edu>
Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona), David W. Hogg
(NYU), Michael R. Blanton (NYU), David J. Schlegel (LBNL), J.
Brinkmann (APO),
Donald Q. Lamb (Chicago), Donald P. Schneider (PSU), and Daniel E.
Vanden Berk
(PSU) report:
The Sloan Digital Sky Survey (SDSS) imaged the field of burst GRB070208
prior to the burst. As these data should be useful as a pre-burst
comparison
and for calibrating photometry, we are supplying the images and
photometry
measurements for this GRB field to the community.
Data from the SDSS, including 5 FITS images, 3 JPGS, and
3 files of photometry and astrometry, are being placed at
http://mizar.as.arizona.edu/~grb/public/GRB070208
We supply FITS images in each of the 5 SDSS bands of a 8'x8' region
centered
on the GRB position (ra=197.887 (13:11:32.8), dec=61.9653
(61:57:55.2); GCN
6074), as well as 3 gri color-composite JPGs (with different
stretches). The
units in the FITS images are nanomaggies per pixel. A pixel is 0.396
arcsec
on a side. A nanomaggie is a flux-density unit equal to 10^-9 of a
magnitude
0 source or, to the extent that SDSS is an AB system, 3.631e-6 Jy.
The FITS
images have WCS astrometric information.
In the file GRB070208_sdss.calstar.dat, we report photometry and
astrometry
of 140 bright stars (r<20.5) within 15' of the burst location. The
magnitudes
presented in this file are asinh magnitudes as are standard in the
SDSS (Lupton
1999, AJ, 118, 1406). Beware that some of these stars are not well-
detected
in the u-band; use the errors and object flags to monitor data quality.
In the files GRB070208_sdss.objects_flux.dat and
GRB070208_sdss.objects_magnitudes.dat, we report photometry of 329
objects detected within 6' of the GRB position. We have removed
saturated
objects and objects with model magnitudes fainter than 23.0 in the r-
band.
The fluxes listed in GRB070208_sdss.objects_flux.dat are in nanomaggies
while the magnitudes listed in GRB070208_sdss.objects_magnitudes.dat are
asinh magnitudes.
All quantities reported are standard SDSS photometry, meaning that
they are
very close to AB zeropoints and magnitudes are quoted in asinh
magnitudes.
Photometric zeropoints are known to about 2% rms. None of the
photometry
is corrected for dust extinction. The Schlegel, Finkbeiner, and Davis
(1998) predictions for this region are A_U=0.084 mag, A_g=0.062 mag,
A_r =
0.045 mag, A_i=0.034 mag, and A_z=0.024 mag.
The file GRB070208_sdss.spectro.dat contains a list of the 3 objects
with
SDSS spectroscopy within 6 arcminutes of the GRB position. In
addition to
the redshift and 1-sigma error for each object, this file also lists the
object spectroscopic classification.
SDSS astrometry is generally better than 0.1 arcsecond per coordinate.
Users requiring high precision astrometry should take note that the SDSS
astrometric system can differ from other systems such as those used
in other
notices; we have not checked the offsets in this region.
More detailed information pertaining to our SDSS GRB releases can be
found
in our initial data release paper (Cool et al. 2006, PASP, 118, 733).
See the SDSS DR4 documentation for more details: http://www.sdss.org/
dr5.
These data have been reduced using a slightly different pipeline than
that
used for SDSS public data releases. We cannot guarantee that the
values here
will exactly match those in the data release in which these data are
included.
In particular, we expect the photometric calibrations to differ by of
order
0.01 mag.
This note may be cited, but please also cite the SDSS data release
paper,
Adelman-McCarthy et al. (2006, ApJS, 162, 38), when using the data or
referring to the technical documentation.
GCN Circular 6081
Subject
GRB 070208, Swift-BAT refined analysis
Date
2007-02-08T17:03:48Z (18 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
C. Markwardt (GSFC/UMD), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC)
on behalf of the Swift-BAT team:
Using the data set from T-239 to T+552 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 070208 (trigger #259714)
(Sato, et al., GCN Circ. 6074). The BAT ground-calculated position is
RA, Dec = 197.896, 61.946 deg which is
RA(J2000) = 13h 11m 35.0s
Dec(J2000) = 61d 56' 44.3"
with an uncertainty of 3.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 50%.
The mask-weighted lightcurve shows two peaks. The first (at T_zero) is
FRED-like with a duration of ~7 sec. The second starts at ~T+35 sec
and ends at ~T+50 sec. T90 (15-350 keV) is 48 +- 2 sec
(estimated error including systematics).
The time-averaged spectrum from T-1.0 to T+47.8 is best fit by a
simple power-law model. The power law index of the time-averaged
spectrum is 1.96 +- 0.37. The fluence in the 15-150 keV band
is 4.3 +- 1.0 x 10^-07 erg/cm2. The 1-sec peak photon flux measured
from T-0.26 sec in the 15-150 keV band is 0.9 +- 0.2 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.
Fitting the two peaks separately with a simple power law model,
-2 to 5 s: photon index = 2.17 -0.44 +0.53
25 to 50 s: photon index = 1.69 -0.34 +0.36
Given the widths of the two peaks and that the second peak is
spectrally harder than the first, we conclude that this burst
is a long GRB and is not a short hard burst with extended emission.
GCN Circular 6082
Subject
GRB 070208: MDM Optical Decay
Date
2007-02-08T19:56:55Z (18 years ago)
From
Jules Halpern at Columbia U. <jules@astro.columbia.edu>
J. P. Halpern & N. Mirabal (Columbia U.) report on behalf of the
MDM Observatory GRB follow-up team:
"Monitoring of the afterglow of GRB 070208 (GCNs 6077, 6078, 6079)
in the R-band on the MDM 1.3m telescope consisted of a series of
10-minute exposures beginning on Feb. 8 09:25 UT and ending at
13:12 UT, thus spanning the time 0.25-4 hours after the burst.
Partly cloudy conditions, together with bright moonlight,
resulted in images of highly variable quality. Nevertheless,
we see the fading optical transient within the Swift XRT error
circle (Sato et al., GCN 6074). In agreement with the GCNs
listed above, we find the OT 3.0" west and 3.3" south of the
center of a galaxy visible on the POSS (Mirabal & Halpern, GCN 6075)
and in pre-burst SDSS images (Cool et al., GCN 6080).
Preliminary magnitudes for the OT, calibrated with respect to
USNO B1.0 magnitudes of nearby stars, are R=20.04+/-0.08 for the
first exposure centered at 09:30 UT, and R=21.5+/-0.2 for a summed
30-minute exposure centered at 12:55 UT. Some contamination from
the nearby galaxy is possible in this analysis. Quoted uncertainties
are statistical only. This corresponds to a mean power-law decay
index of -0.55.
It is not yet clear from this collection of images, both SDSS
and MDM, if the visible galaxy is the host, or if we should wait
to see if a fainter galaxy underlies the OT of this judged long
burst (Markwardt et al., GCN 6081).
Images are posted at http://www.astro.columbia.edu/~jules/grb/070208/
This message may be cited."
GCN Circular 6083
Subject
GRB070208: Absorption and emission redshift from Gemini
Date
2007-02-08T20:55:39Z (18 years ago)
From
Antonino Cucchiara at PSU <cucchiara@astro.psu.edu>
A. Cucchiara (PSU), D. B. Fox (PSU), S. B. Cenko (Caltech) and
P. A. Price (Hawaii) report on behalf of a larger collaboration:
"We observed the optical afterglow (Guidorzi et al., GCN 6077, Fox et
al., GCN 6078) of GRB 070208 (Sato et al., GCN 6074) with the
Gemini-North telescope + Gemini Multi-Object Spectrograph in four
1800-s integrations with mean epoch 11:37 UT on 8 Feb 2007
(approximately 2.5 hours after the burst). Our spectral coverage is
4000-8300 A. The bright nearby galaxy seen in archival images (e.g.,
Mirabal & Halpern, GCN 6075) does not fall within our slit.
At the afterglow position we observe a strong [OII] (3727 A) emission
line at redshift z=1.165 superposed on the afterglow continuum, along
with multiple metal absorption features consistent with this redshift,
including: the MgII (2796.4 A, 2803.5 A) doublet, FeII (2600.5 A), and
MnII (2576.9 A).
We conclude that the redshift of GRB 070208 and its underlying host
galaxy is z=1.165."
GCN Circular 6084
Subject
GRB 070208: RAPTOR detection of early afterglow onset
Date
2007-02-08T23:35:08Z (18 years ago)
From
James Wren at LANL <jwren@nis.lanl.gov>
J. Wren, W.T. Vestrand, P.R. Wozniak, R. White, J. Pergande
of Los Alamos National Laboratory report:
Our Raptor-S telescope responded to Swift trigger 259714
(Sato et al., GCN 6074) at 09:11:17.10 UT, 42.8 s after the
trigger and 6.3 s after receiving the GCN packet. We clearly
detect the source at the location of the optical counterpart
identified by Guidorzi et al. (GCN 6077). Our first 5 second
exposure was obtained while the Swift BAT was still detecting
emission from the second GRB pulse (Markwardt et al., GCN 6081).
Our measurements show that the optical counterpart brightened
from fainter than magnitude 18.7 to 18.2 in the first 300
seconds after the trigger time and then began to fade steadily
after that. Our unfiltered magnitudes were calibrated using
the R-band magnitudes from the USNO B1.0 catalog.
GCN Circular 6085
Subject
GRB 070208: Swift XRT refined analysis
Date
2007-02-08T23:40:46Z (18 years ago)
From
Maria Laura Conciatore at ASDC <conciatore@asdc.asi.it>
M.L. Conciatore, G. Stratta, M. Perri (ASDC), G. Sato (GSFC/ISAS)
D. Burrows (PSU) report on behalf of the Swift/XRT team:
We have analysed the first seven orbits of XRT data GRB070208. A 11.7
ks photon counting mode image provides a refined XRT position:
RA(J2000) =13h 11m 32.73s,
Dec(J2000) =+61d 57m 55.20s
with an uncertainty of 3.7 arcsec (90% containment). This position is
0.3 arcsec from the XRT position quoted in Sato et el. (GCN
Circ. 6074), 72 arcsec from the ground-calculated BAT position
reported by Markwardt et al. (GCN Circ. 6081) and 1.7 arcsec from the
fading source reported by Guidorzi et al. (GCN Circ. 6077; see also
Fox et al., GCN Circ. 6078).
The 0.3-10 keV X-ray light-curve, after an initial slow rising phase,
shows a steep decay (alpha~-3.6) during the second orbit (from T+4.3ks
to T+6.7ks). Starting from the third orbit, the light-curve shows a
power-law decline with a decay index of 1.8+/-0.4.
The X-ray spectrum is well fitted by an absorbed power-law with a
photon index of 2.6 +/- 0.2 and column density of (2.6 +/-0.4 )e21
cm**-2. We note the Galactic column density in the direction of the
source is 1.7e20 cm**-2. The 0.3-10 keV observed flux was 1.5e-12
ergs cm**-2 s**-1, which corresponds to an unabsorbed flux of 3.5e-12
ergs cm**-2 s**-1.
If the burst continues decaying at the current rate we estimate an XRT
count rate of 0.002 counts/s at T + 24hr, which corresponds to an
observed 0.3-10 keV flux of 2.3e-13 ergs cm**-2 s**-1
This circular is an official product of the Swift XRT Team.
GCN Circular 6090
Subject
GRB 070208: MARGE Optical Observations
Date
2007-02-09T19:56:20Z (18 years ago)
From
Heather Swan at U.of Michigan/ROTSE <hflewell@umich.edu>
H. Swan (U. Michigan), I. Smith (Rice), M. Skinner (AMOS Observatory,
Boeing LTS), R. Russell, (Aerospace Corporation),
report on behalf of the MARGE collaboration:
The AEOS Burst Camera (ABC) on the AEOS telescope located at the Maui
Space Surveillance System on Haleakala Maui began imaging Swift
GRB070208 (GCN 6074 Sato et al) on Feb 8, 2007 at 09:22:38.11 UTC, ~12
minutes after the GRB was detected. These are unfiltered optical images.
After coadding our 10s images in sets of 10, we find the OT first
identified by Guidorzi et al. (GCN 6077). Using the SDSS data provided
by Cool et al (GCN 6080), we calibrate the OT to the r band magnitude of
the star located at RA=197.89688 Dec=61.97785. The approximate
statistical errors are 0.2 magnitudes. We report the following
magnitudes for the OT:
time ABC mag
09:22:38.11 UT mag= 20.3
09:35:10.03 UT mag= 20.3
09:59:46.08 UT mag= 20.9
10:02:53.99 UT mag= 20.8
The Rice University CCD Camera (RUCCD) on the AEOS telescope also
observed GRB 070208. Ic-band images were taken between 2007-02-08
09:49 UT and 10:35 UT. The results are consistent with the Palomar
observations of Fox et al. (GCN 6078).
GCN Circular 6093
Subject
GRB070208: optical observations
Date
2007-02-10T15:46:20Z (18 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Klunko (ISTP), V. Kouprianov (GAO), A. Pozanenko (IKI), V.Rumyantsev
(CrAO) on behalf of larger GRB follow up collaboration report:
We observed the error box of GRB070208 (Barthelmy et al., GCN 6074) with
1.5m telescope of Sayan Observatory (Mondy) in R-bands on Feb.08 between
(UT) 15:43 and 19:28. Series of 300 s exposures were taken under not optimal
weather conditions. We detect fading source (Guidorzi et al., GCN 6077, Fox
et al., GCN 6078, Bloom et al., GCN 6079) contaminated by nearby galaxy
(Mirabal & Halpern, GCN 6075). Detailed photometry will be done after
additional observation of the galaxy.
This message may be cited.
GCN Circular 6222
Subject
GRB070208: optical observations
Date
2007-03-23T19:07:45Z (18 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Klunko (ISTP), A. Shulga, A. Volnova (SAI MSU), V. Kouprianov (GAO), A.
Pozanenko (IKI) on behalf of larger GRB follow up collaboration report:
We observed the afterglow of GRB070208 (Guidorzi et al., GCN 6077, Fox et
al., GCN 6078, Bloom GCN 6079) in R-band on Feb.8 with 1.5m telescope of
Sayan observatory. A set of 300 s exposures was obtained between (UT) 15:43
and 19:28 (Klunko et al., GCN 6093). Best combined image of total exposure
4200 s is centered at Feb. 7.785. After mask subtraction of the nearby
galaxy in the best combined image we estimate OT magnitude as following:
Mid time (UT), Exposure, R_mag
Feb. 7.785 14x300 s 21.4 +/- 0.2
The photometry is based on USNO A2.0 stars. The mask subtracted image can
be found in http://grb.rssi.ru/GRB070208/
The message may be cited.