GRB 061126
GCN Circular 5985
Subject
erratum : SDSS Pre-burst Observations of GRB061126
Date
2006-12-30T04:01:42Z (19 years ago)
From
Richard J. Cool at U.of AZ/Steward Obs <rcool@as.arizona.edu>
It has come to our attention that the SDSS photometry released for
the burst GRB061126 was not calibrated with the correct photometric
zero-points measured for the runs associated with these images. We
have found the problem in the scripts use to generate our GRB
followup messages and it has been corrected so this will not affect
any other future bursts. We have also verified that this problem does
not affect any other data previously released for other bursts.
The photometry previously released for GRB061126 should not be used
for photometric calibration of new data. This includes both the
photometric zero-points in the catalogs we released for this burst as
well as the photometric zero-points of the associated images.
We would like to emphasize that this error occurred due to a mistake
in our GRB pre-burst scripts and is not due to a problem with the
SDSS reductions themselves.
At the URL:
http://mizar.as.arizona.edu/grb/public/GRB061126/
We have replaced our previously released data with the official SDSS
reduction of these data (which does not suffer from the same zero-
point error). This data is suitable for photometric calibration.
At this time, we have only included an updated version of the bright
star photometry and astrometry in the file
GRB061126_sdss.calstar_v2.dat. The format for this file is identical
to that of previous releases. We have also included images for this
field from SDSS. *These images have not been corrected for the
incorrect photometric zero-points, so no photometric measurements
should me made directly from the images*.
We regret this mistake and apologize for any confusion or
inconvenience it may have caused.
GCN Circular 5911
Subject
GRB 061126: Radio Observations
Date
2006-12-12T17:20:13Z (19 years ago)
From
Dale A. Frail at NRAO <dfrail@nrao.edu>
Dale A. Frail (NRAO) and P. Chandra (NRAO/UVA) report on behalf of a
larger collaboration:
"We used the Very Large Array to observe the field of view toward GRB
061126 (GCN 5854) at a frequency of 8.46 GHz on 2006 December 9.30 UT.
The peak radio brightness at the position of the UVOT detected
afterglow (GCN 5856) is -62 uJy � 36 uJy. No further observations
are planned.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
GCN Circular 5908
Subject
GRB 061126: a GRB detected off-axis by INTEGRAL
Date
2006-12-12T14:00:57Z (19 years ago)
From
Paolo Goldoni at SAp/CEA <paolo.goldoni@cea.fr>
M. Denis (CBK, Warsaw), R. Marcinkowski (IPJ, Swierk), T. Bulik (CAMK,
Warsaw), P. Goldoni, P. Laurent (APC, Paris; CEA Saclay) report:
The bright GRB061126 (Sbarufati et al. GCN 5854; Krimm et al., GCN 5860)
was at 90.4 degrees from the pointing axis of the INTEGRAL satellite
It was clearly detected by the SPI ACS.
In the INTEGRAL/IBIS telescope a measurable flux was detected by the ISGRI
instrument, the PICsIT instrument and in the coincidence Compton events.
The Compton image of this burst does not show excess at the source
position due to the high GRB off-axis angle (see Marcinkowski et al. 2006
A&A 452,113 for details of the analysis).
The ISGRI spectrum of the first peak,lasting 2.2 s, was fitted up to 900
keV with a single powerlaw with a photon index of 1.1 +/- 0.15, consistent
with the RHESSI results (Bellm et al. GCN 5867).
Plots of the light curves and ISGRI spectrum have been posted at
http://grb.cbk.waw.pl/061126/
This message can be cited.
GCN Circular 5903
Subject
Optical Afterglow observations of GRB 061126
Date
2006-12-08T21:20:19Z (19 years ago)
From
Kuntal Mishra at ARIES,Nainital,India <kuntal@aries.ernet.in>
Kuntal Misra (ARIES, Nainital) on behalf of a larger Indian GRB
collaboration
We observed the optical afterglow detected by SWIFT-UVOT (Vanden Berk et
al. GCN 5856) of GRB 061126
(swift trigger=240766, Sbarufatti et al. GCN 5854) in VRI bands using
the 1.0-m Sampurnanand Telescope
located at ARIES, Nainital on 26 November 2006. Several exposures in VRI
bands were taken and the
field was calibrated by imaging the Landolt Standard SA 95 region on the
same night. The R band magnitude
of the afterglow is the following:
#Days since burst Magnitude Exposure time
0.41 20.98 � 0.10 300
0.42 21.04 � 0.09 900
0.49 21.34 � 0.10 1800
0.56 21.49 � 0.10 1800
The observations between 0.41 to 0.56 d gives a power law decay index of
~ 1.4 which is different than the
power law index of ~ 1.0 mentioned by Rol et al. (GCN 5876) but
consistent with the power law decay index
of ~ 1.5 mentioned by Pozanenko et al. (GCN 5902).
This message may be cited.
GCN Circular 5902
Subject
GRB061126: optical observations
Date
2006-12-08T20:45:23Z (19 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Pozanenko (IKI), A. Shulga, A. Volnova (SAI MSU), M. Ibrahimov, R.
Karimov (MAO) on behalf of larger
GRB follow up collaboration report:
We observed optical afterglow (Vanden Berk et al., GCN 5856) of GRB061126
(Sbarufatti et al, GCN 5854) with 1.5m telescope of Maidanak observatory
(MAO). Several exposures of 300 s in R-band were obtained on Nov. 26
between (UT) 19:11 - 23:44. Preliminary photometry against USNO-A2.0 stars
of two combined images is following:
T0+ , Exposure, R_mag
0.454 d 9x300 21.16 +/- 0.04
0.593 d 14x300 21.65 +/- 0.08
A local power law decay index of the afterglow in our observations between
0.454 and 0.593 days is -1.5 +/-0.13, which is differ from global power-law
decay index of -1.0 (+/- 0.1) between 0.54 and 1.76 days after the burst
reported early (Rol et al., GCN5876).
GCN Circular 5900
Subject
GRB061126: update on the Swift-XRT afterglow light curve
Date
2006-12-06T09:01:40Z (19 years ago)
From
Boris Sbarufatti at INAF-IASF-Pa <sbarufatti@ifc.inaf.it>
B. Sbarufatti (INAF IASF Pa), G. Cusumano (INAF IASF Pa), T. Mineo (INAF
IASF Pa), V. Mangano (INAF IASF Pa) report on behalf of the SWIFT team
We have analyzed the afterglow light curve of GRB061126 (GCN 5854,
Sbarufatti et al.) observed with XRT.
The source is decaying as a simple power law with slope alpha=-1.31 +/-
0.01 since its first detection with XRT up to T+76ks.
We do not find evidence of the possible jet break reported by Kann et
al. (GCN 5875) - but not detected by Rol et al. (GCN 5876) - at 1.8 days
after the trigger.
A tentative fit with a broken powerlaw, albeit very poorly constrained,
showed a marginal compatibility with a flattening of the light curve
after T+1E5s, as opposed with the steepening expected from a jet break.
XRT observation of the afterglow (which shows a count rate 1.5E-3 c/s at
T+76 ks)are still ongoing.
This circular is an official product of the Swift XRT Team.
GCN Circular 5894
Subject
GRB061126 : NMSU 1.0m observations
Date
2006-12-03T18:32:57Z (19 years ago)
From
Jon Holtzman at New Mexico State U <holtz@nmsu.edu>
J. Holtzman, T. Harrison, B. Mcnamara of New Mexico State University report:
The robotic NMSU 1m telescope at Apache Point Observatory responded
to Swift trigger 240766 (Sbarufatti et al. GCN 5854) shortly after the
burst announcement. Our first 10s I band image was started 47s
after the trigger (31s after the notification). This was followed
by images in R, V, B, and U; an optical source at the location of
the optical counterpart was clearly detected in all of the images
with the following brightness:
filter | exptime | midtime after burst | magnitude +/- error
I 10s 52s 12.24 +/- 0.004
R 10s 97s 13.86 +/- 0.007
V 20s 149s 14.94 +/- 0.009
B 40s 213s 15.95 +/- 0.011
U 60s 303s 15.85 +/- 0.037
Our magnitudes were calibrated relative to a nearby star for which
transformed UBVRI magnitudes were obtained from the SDSS magnitudes
(Cool et al, GCN 5863) using transformations given on the SDSS web site,
http://www.sdss.org/dr5/algorithms/sdssUBVRITransform.html, which were
taken from a paper by Jester et al. (2005). Error bars are statistical
only and do not include uncertainties in the SDSS photometry, the adopted
SDSS to UBVRI transformations, nor internal transformations; systematic
errors are probably on the order of several percent.
Ten cycles of UBVRI observations were continued for about an hour after
the burst. Analysis of temporal and spectral evolution is underway. Late
epoch imaging is also continuing.
GCN Circular 5876
Subject
INT+WFC observations of GRB 061126
Date
2006-11-28T15:32:42Z (19 years ago)
From
Evert Rol at U.Leicester <er45@star.le.ac.uk>
E. Rol (U of Leicester), K. Wiersema (U of Amsterdam) and P. Prema
(Cambridge) report on behalf of a larger collaboration:
We observed the afterglow of GRB 061126 (Sbarufatti et al, GCN
Circ. 5854) on the nights of 26-27 and 27-28 November, with the Wide
Field Camera (WFC) on the 2.5m Isaac Newton Telescope at La Palma.
We detect the afterglow in r' and i' images on both nights. Photometry
relative to the SDSS data (Cool et al, GCN Circ. 5863) shows a steadily
declining light curve with a -1.0 (+/- 0.1) power-law decay between
0.54 and 1.76 days after the burst, with no evidence for a break. This
is in contrast to the report by Kann (GCN Circ. 5875).
The r'-band image at 1.76 days post burst shows the likely host galaxy
underneath the afterglow. The magnitude of the host + OT in a
seeing-matched aperture is 22.76 +/- 0.06. The image can be seen at
http://www.star.le.ac.uk/~er45/grb061126/ . The underlying host probably
means the light curve decay is somewhat steeper than our estimated
-1.0 decay, although not by too much, and would likely not explain the
discrepancy with the result reported by Kann.
The large field of view of the WFC, in combination with the SDSS
astrometry, allows for an accurate astrometric solution of the optical
afterglow position. Our best position is (J2000):
RA = 05 46 24.428
Dec = 64 12 38.78
with an estimated error of 0.12 arcseconds in both coordinates.
GCN Circular 5875
Subject
GRB 061126: Possible Jet Break
Date
2006-11-28T08:36:02Z (19 years ago)
From
Alexander Kann at TLS Tautenburg <kann@tls-tautenburg.de>
D. A. Kann (TLS Tautenburg) reports:
The afterglow of GRB 061126 (Sbarufatti et al., GCN 5854, Vanden Berk et
al., GCN 5856) was observed with the Tautenburg 1.34m Schmidt telescope
under good weather conditions.
Observations commenced at 4:14:15 UT on November 28, and consisted of 6 x
600 sec Rc band images.
The afterglow is detected in the stacked image. Comparing with the USNO-B1
catalog, I derive the following magnitude:
R = 23.69 +/- 0.17 at 1.83656 days after the burst.
This lies significantly beneath the extrapolation (with alpha = 0.99 +/-
0.03) of the data reported by Smith et al. (GCN 5857), Updike et al.
(GCN 5959) and Kann & Malesani (GCN 5866), by 0.85 magnitudes.
This may suggest that a jet break has occured and the decay has thus
become steeper.
This message may be cited.
GCN Circular 5873
Subject
GRB 061126: RAPTOR Optical Detection During Gamma-Ray Emission
Date
2006-11-27T20:48:42Z (19 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 autonomous Raptor-S telescope responded to Swift trigger
240766 (Sbarufatti et al. GCN 5854) at 08:48:17.29 UT, 20.87 s
after the trigger and 4.3 s after receiving the GCN packet.
Our first two images were obtained while the Swift BAT was still
detecting emission from the GRB. We clearly detect a fading
optical source at the location of the optical counterpart seen
by the UVOT (Vanden Berk et al. GCN 5856). Our measurements
show that the optical counterpart faded from magnitude R=12.3
to 14.4 over the first 90 seconds. Our unfiltered magnitudes
were calibrated using the R-band magnitudes from the USNO B1.0
catalog.
GCN Circular 5869
Subject
GRB 061126: Early Super-LOTIS Observations
Date
2006-11-27T04:21:25Z (19 years ago)
From
Grant Williams at Steward Observatory <ggwilli@mmto.org>
G. G. Williams (MMTO) and P. A. Milne (Steward Observatory), on behalf of
the Super-LOTIS Collaboration, report:
The robotic 0.6-m Super-LOTIS telescope began observing the error box of
GRB 061126 (Swift Trigger 240766, Sbarufatti et al. GCN 5854) at
08:48:30.7 UT, 35 seconds after the trigger. Our initial observations
include 5 x 10s exposures, 5 x 20s exposures, and 30 x 60s exposures, all
in the R-band.
Observations were hampered by high winds; most of the images are elongated
as a result of wind buffeting. Despite the poor image quality we clearly
detect the bright optical afterglow first reported by Vanden Berk (GCN
5856) in all our early images.
Using the single USNO-B1.0 star at RA=05:46:31.61, Dec=+64:11:59.7 with
R2MAG=12.80, we estimate the following R-band magnitude for the OT using
circular aperture photometry (despite elongated images):
t_start (UT) exp t (s) t_start-t_0 (s) R Mag
----------------------------------------------------------------
08:48:30.7 10.0 35 R = 12.93 +/- 0.2
Because of the elongated PSF the error bar is a conservative estimate.
Continued analysis is underway.
GCN Circular 5868
Subject
GRB 061126: optical observation
Date
2006-11-27T02:43:01Z (19 years ago)
From
Ken ichi Torii at Osaka U <torii@ess.sci.osaka-u.ac.jp>
K. Torii (Osaka U.) reports:
The error region of GRB 061126 (Sbarufatti et al. GCN 5854, 5855) was
observed with the 0.3m telescope in the New Mexico Skies Observatory.
Starting at 08:58:19 (623 s after the trigger time), ten frames of
120s exposure were acquired through Ic filter.
The optical afterglow (Vanden Berk, GCN 5856) is detected and the
preliminary photometry relative to USNO-B1.0 I2 magnitude gave the
following measurements.
------------------------------------------
StartUT Filter Mag Nframes
------------------------------------------
08:58:20 Ic 17.1 +/-0.2 1
09:01:20 Ic 17.0 +/-0.2 1
------------------------------------------
GCN Circular 5867
Subject
RHESSI Spectrum of GRB061126
Date
2006-11-27T01:07:48Z (19 years ago)
From
Kevin Hurley at UCBerkeley/SSL <khurley@ssl.berkeley.edu>
E. Bellm, M. Bandstra, S. Boggs, C. Wigger, W. Hajdas,
D. M. Smith, and K. Hurley on behalf of the RHESSI team report:
As observed by RHESSI, GRB061126 (Sbarufatti et al., GCN 5854; Krimm
et al., GCN 5860) had a duration of ~25s starting at about T0=8:47:54 UT.
A fit to the time-integrated RHESSI spectrum of the main period of emission
from T0+6s - T0+13s between 30 keV and 10 MeV gives a cutoff power law, with
alpha = -0.95 +0.29/-0.23
E0 = 890. +740/-370. keV
Epeak = 935. +/-360. keV
(90% confidence levels).
The 30 keV-2 MeV fluence is ~2 E-5 erg/cm^2.
This fit is preliminary and may be improved with ongoing analysis.
GCN Circular 5866
Subject
GRB 061126: Tautenburg afterglow observations
Date
2006-11-26T22:29:58Z (19 years ago)
From
Alexander Kann at TLS Tautenburg <kann@tls-tautenburg.de>
D. A. Kann (TLS Tautenburg) and D. Malesani (NBI/Dark) report:
We are observing the afterglow of GRB 061126 (Sbarufatti et
al., GCN 5854, Vanden Berk et al., GCN 5856) with the 1.34m
Schmidt telescope of the Thueringer Landessternwarte
Tautenburg in Germany. Sky conditions are variable, with
passing clouds.
Observations started at 18:20:41 UT and consist of 600 s R
band exposures. The initial airmass was 1.47, it is decreasing.
The afterglow is detected on most single frames.
From a raw image, we measure the following magnitude in
comparison to the USNO-B1 catalog (R1 magnitudes):
R = 21.5 +/- 0.25 at 0.49907 days after the burst.
(Errors are 0.2 mag statistical and 0.1 mag systematic.)
We find this agrees very well with an alpha = 1 extrapolation of
the data of Smith et al. (GCN 5857) and Updike et al. (GCN
5959).
Observations are continuing as weather permits.
Spectroscopy is encouraged.
This message may be cited.
GCN Circular 5865
Subject
GRB061126: Optical afterglow observations from MIRO
Date
2006-11-26T20:50:13Z (19 years ago)
From
Kiran S Baliyan at Physical Research Lab, Ahmedabad,India <baliyan@prl.res.in>
KS Baliyan, S Ganesh and UC Joshi (MIRO-PRL, Ahmedabad, India)
report:
We observed the field around position of the optical counterpart of
GRB061126 (Swift BAT trigger number 240766) beginning about 8 hours
after the burst. The 1296*1154 CCD mounted on the 1.2 M telescope of
Mt Abu IR Observatory, operated by Physical Research Laboratory,
Ahmedabad- India, was used to observe OT in RI bands and white light
with 180 and 120 secs exposures.
The visual inspection of the images shows a very faint source in
I band and white light images at the position mentioned in GCN 5856.
The results of detailed photometry will be reported later. The
monitoring of the source is going on.
This message may be cited.
GCN Circular 5864
Subject
GRB061126: Optical afterglow observations from MIRO
Date
2006-11-26T20:36:58Z (19 years ago)
From
Kiran S Baliyan at Physical Research Lab, Ahmedabad,India <baliyan@prl.res.in>
K.S. Baliyan, S. Ganesh, UC Joshi (MIRO-PRL, Ahmedabad, India) report:
We observed the field around position of the optical counterpart of
GRB061126 (Swift Burst Alert Telescope (BAT) trigger number 240766)
beginning about 8 hours after the burst. The 1296*1152 CCD mounted
on the 1.2 M telescope of Mt Abu IR Observatory, operated by Physical
Research Laboratory, Ahmedabad- India, was used to observe OT in RI
bands and white light. Several images with exposure times 120 secs
and 180 secs are taken.
A visible inspection of the images shows a very faint source in I
band and white light at the position reported by D. E. Vanden Berk,
B. Sbarufatti, and S. D. Barthelmy (GCN 5856). Results of the
detailed photometry will be reported later. The monitoring is on.
This message may be cited.
*****************************************************************
* Dr Kiran S. Baliyan * Residence: *
* Physical Research Laboratory * 61-Shreerang Villa Row House *
* Ahmedabad- 380 009 INDIA * Nr. LJ Commerce College *
* FAX: (091) 79 2630 1502 * Vastrapur, Ahmedabad-380 015 *
* 079 26314512(Th),26314757(PRL) * (079) 6542 6570 *
*****************************************************************
GCN Circular 5863
Subject
GRB 061126 : SDSS Pre-Burst Observations
Date
2006-11-26T20:34:24Z (19 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
GRB061126 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/GRB061126
We supply FITS images in each of the 5 SDSS bands of a 8'x8' region
centered on the GRB position (ra=86.6021 (05:46:24.5), dec=64.2104
(64:12:37.6); GCN 5854), 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 GRB061126_sdss.calstar.dat, we report photometry
and astrometry of 490 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 GRB061126_sdss.objects_flux.dat and
GRB061126_sdss.objects_magnitudes.dat, we report photometry of
433 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
GRB061126_sdss.objects_flux.dat are in nanomaggies while the
magnitudes listed in GRB061126_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=0.983 mag, A_g=0.723 mag, A_r = 0.525 mag, A_i=0.398
mag, and A_z=0.282 mag.
There are currently no objects within 6 arcminutes of the GRB
position in the SDSS spectroscopic database.
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,
astro-ph/0601218). 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 5862
Subject
GRB 061126: Swift-XRT refined analysis
Date
2006-11-26T19:35:02Z (19 years ago)
From
Boris Sbarufatti at INAF-IASF-Pa <sbarufatti@ifc.inaf.it>
B. Sbarufatti (INAF IASF-Pa), V. Mangano (INAF IASF-Pa), C. Guidorzi
(INAF OAB)
and D. N. Burrows, report on behalf of the Swift XRT team:
We have analyzed the first 3 orbits of Swift-XRT data obtained for
GRB 061126
(trigger=240766, GCN 5854). The data consist of 240 s in Windowed
Timing (WT) mode,
starting 1603 seconds after the trigger followed by 6 ks in Photon
Counting (PC) mode.
Using the PC data we obtain a refined position of:
RA(J2000) = 05h 46m 24.5s
Dec(J2000)= +64d 12m 37.6s
with an estimated uncertainty radius of 3.5 arcsec (90% containment).
This location is 1.62 arcsec from the first XRT position (GCN 5855)
and 0.95 arcsec
from the UVOT position (GCN 5856).
The light-curve shows a power-law decay with slope alpha=1.3 +/- 0.03
up to the end of
the third orbit.
The PC spectrum can be modeled with an absorbed power-law of photon
index
Gamma = 2.01 +/- 0.09 and NH= (2.7 +/- 0.3)E21 cm^-2 in excess with
respect to the
galactic absorption of 1.0E21 cm^-2. The average unabsorbed flux is
7.7E-11 ergs cm^-2 s^-1.
If decaying at the present rate, the source will reach a flux level of
1.7e-12 erg cm^-2 s^-1 (2.6E-2 c/s) at 24 h after the trigger.
All errors are quoted at 90% confidence level.
This circular is an official product of the Swift-XRT team.
GCN Circular 5861
Subject
GRB 061126: Swift/UVOT Observations
Date
2006-11-26T19:28:23Z (19 years ago)
From
Patricia Schady at MSSL/Swift <ps@mssl.ucl.ac.uk>
P. Schady (MSSL/UCL) and B. Sbarufatti (INAF-IASFPA) report on behalf of the
Swift/UVOT team:
The Swift/UVOT began observing the field of GRB 061121 at 09:14:41 on
2006-11-26, 27.6 minutes after the BAT trigger (Sbarufatti et al., GCN 5854).
An optical counterpart is detected in the V, B, U, UVW1 and UVM2 filters, as
well as in the White-band filter (160-650 nm) at a position consistent with
that reported by Vanden Berk et al. (GCN 5856). We can, therefore, put a
photometric upper limit on the redshift of GRB 061126 of z < ~1.5.
The photometry results for each UVOT filter are given below where Tmid is
the average time of the exposure, in seconds, since the BAT trigger. For those
filters in which the afterglow is detected we report the magnitude of the
afterglow in the first and last exposures taken before the spacecraft slewed to
another target 4.3hrs after the BAT trigger. The upper limit (3 sigma) reported
for the UVW2 filter is taken from a co-added exposure and for all detections
that are less than 3-sigma above background, the significance of the detection
is given. The quoted errors do not include the 0.1 mag systematic uncertainty
in the photometric zero points.
Filter Tmid Exposure Mag Err
(s) (s)
==========================================
V 3423 197 19.29 0.58 (1.9 sigma)
9178 295 19.86 0.78 (1.4 sigma)
B 2809 197 19.75 0.24
7097 197 21.04 0.75 (1.5 sigma)
U 7702 197 19.54 0.27
15331 110 > 18.72
UVW1 5664 279 19.34 0.37
14515 886 > 20.04
UVM2 3627 197 19.79 0.56
13608 886 21.38 0.85 (1.3 sigma)
UVW2 5767 393 > 20.00
White 1655 98 18.50 0.12
8111 197 19.72 0.22
==========================================
The values quoted above are not corrected for the expected Galactic
extinction of E_{B-V} = 0.18 mag (Schlegel et al. 1998).
GCN Circular 5860
Subject
GRB 061126, Swift-BAT refined analysis
Date
2006-11-26T17:09:43Z (19 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
H. Krimm (GSFC/USRA), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), B. Sbarufatti (INAF-IASFPA),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
on behalf of the Swift-BAT team:
Using the data set from T-239 to T+574 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 061126 (trigger #240766)
(Sbarufatti, et al., GCN Circ. 5854). The BAT ground-calculated position
is RA,Dec = 86.615, 64.201 deg {5h 46m 27.6s, 64d 12' 3.0"} (J2000)
+- 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 49%.
The mask-weighted lightcurve starts at T-10 sec with four main overlapping peaks.
The brightest peak occurs at T+7 sec. The last peak ends at ~T+25 sec
with an on-going low level emission out to ~T+200 sec. T90 (15-350 keV)
is 191 +- 10 sec (estimated error including systematics).
The time-averaged spectrum from T-6.0 to T+411.0 is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.34 +- 0.08. The fluence in the 15-150 keV band is 7.2 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+6.66 sec in the 15-150 keV band
is 9.8 +- 0.4 ph/cm2/sec. All the quoted errors are at the 90%
confidence level.
GCN Circular 5859
Subject
GRB 061126: SARA Observations
Date
2006-11-26T15:08:28Z (19 years ago)
From
Adria C. Updike at Clemson U <aupdike@clemson.edu>
A. C. Updike, D. H. Hartmann (Clemson University) and T. D. Oswalt, M.
Rudkin (FIT) report on behalf of the Clemson GRB Follow-Up Team:
We began R-band observations with the SARA 0.9m of the burst 47 minutes
after the trigger (240766). Our observations consisted of 3 sets of 10 x
300 sec (stacked) images. We detect a fading source at the UVOT position
(Vanden Berk, GCN 5856).
------------------------------------------------------------------- time
after burst (m) exp length (s) R-band mag and error
-------------------------------------------------------------------
47 3000 18.8 +/- 0.2
98 3000 19.3 +/- 0.5
149 3000 19.4 +/- 0.3
-------------------------------------------------------------------
The Clemson Unversity GRB Response Site may be found at:
http://people.clemson.edu/~kgarime/burst/index.php
The SARA Homepage can be found at:
http://saraobservatory.org
This message may be cited.
GCN Circular 5858
Subject
GRB 061126: Early Detection of the IR Afterglow
Date
2006-11-26T11:44:30Z (19 years ago)
From
Josh Bloom at UC Berkeley <jbloom@astron.berkeley.edu>
GRB 061126: Early Detection of the IR Afterglow
J. S. Bloom (UC Berkeley), on behalf of a larger collaboration, reports:
"We began observing the field of GRB 061126 (GCN 5854) with the
Peters Automated Infrared Imaging Telescope (PAIRITEL) starting at
2006-11-26 08:48:54.3 UTC, after an automated trigger. This is 58
seconds after the GRB trigger and 42 seconds after the BAT Position
Notice was issued. In individual 7.8 sec exposures, we detect a
transient source simultaneously in JHKs at position of (J2000):
RA 05:46:24.475
DEC +64:12:38.46
(+- 250 mas), consistent with the position of the X-ray transient
(GCN 5855) and optical transient (GCN 5866). In a stack of 39
exposures ending at 08:57:11.3 UTC, we find the preliminary
magnitudes of the afterglow of:
J = 14.12 +/- 0.03
H = 13.26 +/- 0.03
Ks = 12.65 +- 0.06
Imaging has continued since the trigger."
A false-color composite image of the field may be found at:
http://lyra.berkeley.edu/~jbloom/grb061126.ps.gz
This message may be cited.
GCN Circular 5857
Subject
GRB 061126: Faulkes Telescope North Optical Observations
Date
2006-11-26T09:57:27Z (19 years ago)
From
David Bersier at Liverpool John Moores U <dfb@astro.livjm.ac.uk>
R. Smith, A. Melandri, (Liverpool JMU), A. Gomboc (Ljubljana),
D. Bersier (Liverpool JMU) report on behalf of the RoboNet GRB
collaboration
The 2-m Faulkes North Telescope (Hawaii) automatically reacted to the
Swift burst GRB061126 (trigger=240766, Sbarufatti et al. GCN 5854).
Observations started about 4.3 min after the trigger time. We report
the detection of the optical counterpart at the position
RA(J2000) = 05:46:24.43
Dec(J2000) = +64:12:39.00
The automatic pipeline LT-TRAP identified a fading afterglow in BVRi'
filters, and we estimate an initial magnitude (10 second integration)
R = 15.97 +/- 0.05 (wrt USNOB) at t=4.30 min.
From the first 30 minutes of observations, a temporal decay index of
alpha ~ 1.0 has been measured.
Further observations and analysis are ongoing.
GCN Circular 5856
Subject
GRB 061126: Swift/UVOT Afterglow Detection
Date
2006-11-26T09:53:47Z (19 years ago)
From
Daniel E. Vanden Berk at PSU/Swift <danvb@astro.psu.edu>
D. E. Vanden Berk (PSU), B. Sbarufatti (INAF-IASFPA), and S. D. Barthelmy
(GSFC) report on behalf of the Swift team:
UVOT took a finding chart exposure of 100 seconds with the White (160-650
nm) filter starting 1605 seconds after the BAT trigger. Because of an
Earth limb constraint, the spacecraft did not slew promptly to the BAT
position. There is a candidate afterglow in the rapidly available
2.7'x2.7' sub-image at
RA(J2000) = 05:46:24.46 = 86.6019
DEC(J2000) = +64:12:38.5 = 64.2107
with a 1-sigma error radius of about 0.5 arc sec. This position is 83.0
arc sec. from the center of the BAT error circle, and 2.5 arc sec. from
the center of the XRT error circle. The estimated magnitude is 18.6 with
a 1-sigma error of about 0.5 mag. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.18.
GCN Circular 5855
Subject
GRB 061126: XRT position
Date
2006-11-26T09:49:51Z (19 years ago)
From
Boris Sbarufatti at INAF-IASF-Pa <sbarufatti@ifc.inaf.it>
B. Sbarufatti (INAF-IASFPA), S. D. Barthelmy (GSFC),
V. Mangano (INAF-IASFPA), K. L. Page (U Leicester),
D. M. Palmer (LANL), M. Stamatikos (NASA/ORAU) and
D. E. Vanden Berk (PSU) report on behalf of the Swift Team:
XRT slewed to the source after 23 minutes due to Earth constraint.
A source has been detected in downlinked TDRSS data (31 minutes after
the
trigger) at the position :
RA(hh mm ss.s) = 5h46m24.4s
Dec(dd mm ss.s) = +64:12:36.0
with a 4.2 arcsec uncertainty (90% containment).
GCN Circular 5854
Subject
GRB 061126: Swift detection of a burst
Date
2006-11-26T09:01:04Z (19 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
B. Sbarufatti (INAF-IASFPA), S. D. Barthelmy (GSFC),
V. Mangano (INAF-IASFPA), K. L. Page (U Leicester),
D. M. Palmer (LANL), M. Stamatikos (NASA/ORAU) and
D. E. Vanden Berk (PSU) report on behalf of the Swift Team:
At 08:47:56 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 061126 (trigger=240766). Swift did not slew immediately
to the burst location because of the Earth limb observing constraint.
The BAT on-board calculated location is RA,Dec 86.625, +64.190
{05h 46m 30s, +64d 11' 24"} (J2000) with an uncertainty of 3 arcmin
(radius, 90% containment, including systematic uncertainty). The BAT
light curve shows four somewhat overlapping peaks starting at ~T-5 sec
and ending at ~T+35 sec (duration ~40 sec). The peak count rate
was ~21000 counts/sec (15-350 keV), at ~6 sec after the trigger.
XRT and UVOT observations will begin when the GRB comes out of
Earth-limb constraint, at T+23 minutes.