GRB 061028
GCN Circular 5789
Subject
GRB061028: MAGIC telescope GeV observation
Date
2006-11-08T11:45:41Z (19 years ago)
From
Markus Garczarczyk at MPI/MAGIC <garcz@mppmu.mpg.de>
Gaug M. and Garczarczyk M., Bastieri D., Fagiolini M., Galante N.,
Longo F., Mizobuchi S., Piccioli A., Scapin V. and Stamerra A.
report for the MAGIC collaboration:
The MAGIC Imaging Atmospheric Cherenkov Telescope performed a follow-up
observation of the SWIFT-BAT burst GRB061028 (GCN circular 5762, Sakamoto
T. et al.). We received the GCN alert at T0+140s. The telescope slewed
immediately to the GRB sky coordinates and started data taking 29s after
the alert, at T0+169s. Due to the long time delay of the alert and the
burst duration of T90=106s, only the early afterglow phase could be
observed by MAGIC. Our observation window covered the weak tail emission
measured by BAT and the X-ray afterglow measured by XRT (Sakamoto T. et
al.). The observation continued for 100min.
No evidence for VHE gamma-ray emission above the analysis threshold of
110GeV was found. A preliminary analysis, for the hypothesis of steady
emission and assumption of a differential photon spectral index of -2.5,
yields the following 95% CL differential flux upper limits (inc. 30%
systematic error on the absolute flux level):
E(100-125 GeV) : 1.6 x 10^(-10) erg/cm^2/s
E(125-175 GeV) : 0.8 x 10^(-10) erg/cm^2/s
E(175-300 GeV) : 0.7 x 10^(-10) erg/cm^2/s
E(300-1000 GeV) : 0.3 x 10^(-10) erg/cm^2/s
The upper limits apply of the time window between T0+169s and T0+1969s
(the first 30min of the MAGIC data sample).
This message can be cited.
GCN Circular 5785
Subject
GRB 061028: Swift/XRT Astrometry Correction
Date
2006-11-02T16:30:42Z (19 years ago)
From
Judith Racusin at PSU <racusin@astro.psu.edu>
J. L. Racusin (PSU), D. N. Burrows (PSU), T. Mineo (INAF-IASFPA), T.
Sakamoto (NASA/ORAU), and N. Gehrels (NASA/GSFC) report on behalf of the
Swift XRT team:
We have re-analyzed the full XRT data set of GRB 061028. XRT observed the
field of GRB 061028 for a total exposure time of 49 ks between October 28
and October 29, 2006 in Photon Counting mode.
To further improve the accuracy of the previously reported position
(Cusumano et al., GCN 5767), we performed an astrometry correction using
46 ks of the total exposure time (when the satellite position was stable).
In this data set we find 18 serendipitous X-ray sources detected with the
XIMAGE detect algorithm with S/N > 3, 7 of which have near-by optical
counterparts in the USNO-B1 catalog. We match these sources to obtain a
best fit mean frame shift, carefully accounting for several instrumental
factors including exposure map correction, and additional hot pixel
removal.
We calculate the statistical position errors using the empirical fits as
described in Moretti et al. (2006, A&A, 448, L9), assuming that the
astrometric correction removes the 3.5" systematic error normally applied
to XRT positions to account for errors in the star tracker attitude
solution.
The result of this analysis leads to a mean frame shift from the
previously reported position (Cusumano et al., GCN 5767), of:
RA offset: +0.15s +/- 0.04s Dec offset: +1.3" +/- 0.7"
and a new XRT astrometry corrected position of:
RA(J2000): 06h 28m 54.66s
Dec(J2000): +46d 17' 57.0"
with an estimated uncertainty of 2.2 arcseconds (radius, 90% containment).
This position is 2.2 arcseconds from the refined XRT position given in
Cusumano et al. (GCN 5767), 0.7 arcseconds from the position measured by
Butler et al. (astro-ph/0611031), 1.5 arcseconds from the optical object
described in Cenko et al. (GCN 5770), and 4.0 arcseconds from the optical
object described in Bloom et al. (GCN 5768).
A figure comparing all of these positions is available at:
http://www.swift.psu.edu/images/grb061028_astrometry.gif
This Circular is an official product of the Swift XRT team.
GCN Circular 5779
Subject
GRB 061028: Optical R passband observations
Date
2006-11-02T07:06:44Z (19 years ago)
From
Alok Chandra Gupta at Nat. Astro. Obs./Yunnan Obs <alok@ynao.ac.cn>
A. C. Gupta & J. M. Bai
National Astronomical Observatories/Yunnan Observatory
CAS, P.O. Box 110, Kunming, Yunnan 650011, China
We observed the field of GRB 061028 detected by SWIFT
trigger no. 235715 (Sakamoto et al, GCN 5762) with CCD
detector at our 1.02 meter telescope of the Yunnan observatory,
Kunming, China.
We started our observation on Oct. 29, 2006 at UT 18:06:20.
We took 6 image frames of 300 seconds exposure time of each in
the optical R passband.
There is no detection of optical afterglow candidate in our
combined 6 images. The 5-sigma limiting magnitude of our observations
is R ~ 20.0 mag.
GCN Circular 5775
Subject
GRB 061028: VLA Observation
Date
2006-11-01T22:42:56Z (19 years ago)
From
Poonam Chandra at U Virginia/NRAO <pc8s@virginia.edu>
P. Chandra (UVA/NRAO) and D. A. Frail (NRAO) report on behalf of
the Caltech-NRAO-Carnegie GRB Collaboration:
"We observed the field centered on the BAT position of the Swift burst GRB
061028 (GCN#5762, 5767) using the VLA at a frequency of 8.46 GHz and
starting at 8.58 UT on 2006 Oct 31, about 3 days after the burst. There
is no detection of the afterglow at the GRB position (GCN#5767) with 2-sigma
upper limit of 80 microJy.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
GCN Circular 5772
Subject
GRB 061028: Futher P200 Observations
Date
2006-10-30T08:00:26Z (19 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. B. Cenko, E. O. Ofek, and M. Kasliwal (Caltech) report on behalf of a
larger collaboration:
We have re-imaged the field of GRB061028 (Sakamoto et al, GCN 5762) with
the Large Format Camera mounted on the 200" Palomar Hale telescope.
Observations consisted of 2 x 180 s images in r' and i' taken at a mean
epoch of approximately 29 Oct. 12:45 UT (~ 35.3 hr after the burst).
We find no evidence for variability in either afterglow candidate S1
(Bloom et al, GCN 5768) or S2 (Cenko et al, GCN 5770). Given the constant
flux level from ~ 5 hr (Mirabal et al, GCN 5771) to ~ 35 hr after the
burst, we consider both highly unikely to be related to the afterglow of
GRB061028.
GCN Circular 5771
Subject
GRB 061028: MDM Observations
Date
2006-10-29T22:15:52Z (19 years ago)
From
Nestor Mirabal at Columbia U <mirabal@astro.columbia.edu>
N. Mirabal (Columbia U.), R. J. Assef & K. Schlesinger (OSU) report on
behalf of the MDM Observatory GRB follow-up team:
"We observed the Swift error circle of GRB 061028 (Sakamoto et al., GCN
5762)
in r', i', and z' bands using the RETROCAM imager on the MDM 2.4m
telescope starting on October 28 06:47 UT, 5.35 hours after the trigger.
A summed 45-minute exposure in i' reveals no new object in the refined
XRT error circle (Cusumano et al., GCN 5767) down to I ~ 21.5 relative
to the USNO-B1.0 catalog. We clearly detect sources S1 (Bloom et al.,
GCN 5768) and S2 (Cenko et al., GCN 5770) at a preliminary magnitude of
I ~ 21.0 for both objects, consistent with the measurements reported by
Cenko et al (GCN 5770). Results of additional bands will be reported
subsequently.
This message may be cited."
GCN Circular 5770
Subject
GRB 061028: P200 Observations
Date
2006-10-28T23:53:54Z (19 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. B. Cenko, E. O. Ofek, and M. Kasliwal (Caltech) report on behalf of a
larger collaboration:
We have imaged the field of GRB061028 (Sakamoto et al, GCN 5762) with the
Large Format Camera mounted at the prime focus of the 200" Palomar Hale
telescope. Images consisted of 4 x 180 s in i' and 3 x 180 s in r' taken
at a mean epoch of approximately 28 October 12:30 UT (~ 11 hr after the
burst).
The afterglow candidate identified by Bloom et al. (S1, GCN 5768) is
clearly detected in our i'-band images and marginally detected in an r'
coaddition. We measure R ~ 22.4, I ~ 21.0 for this source, with large
uncertainties due to photometric calibration (relative to USNO-B R2 and I2
reference).
We also find another red source (S2) located several arcseconds to the
west of the XRT error circle (Cusumano et al., GCN 5767). The coordinates
(J2000.0) of this object are:
RA: 06:28:54.8
Dec: +46:17:56.8
We measure R ~ 22.6, I ~ 21.0 for this object, with similarly large
photometric uncertainties.
We find no sources inside the revised XRT error circle. The 5-sigma
limiting magnitudes of our observations are R >~ 22.0, I >~ 22.0. An
image of the field will be posted shortly at:
http://www.srl.caltech.edu/~cenko/public/grb/grb061028.jpg
Further observations are planned to search for variability in these two
objects.
GCN Circular 5769
Subject
GRB 061028: SARA upper limit
Date
2006-10-28T21:24:49Z (19 years ago)
From
Adria C. Updike at Clemson U <aupdike@clemson.edu>
A. C. Updike and D. H. Hartmann (Clemson University) report on behalf of
the Clemson GRB Follow-Up Team:
The .9m SARA telescope began imaging the field of GRB 061028 4 hours and
51 minutes after the Swift Trigger 235715 at 01:26:22 UT. Our initial
observations were comprised of 180-second exposures in the I band.
After stacking in sets of 5, we did not detect any new sources. Our
observations continued with 300-second exposures in the I band, 6 hours
and 6 minutes after the trigger. Based on a total of 25 minutes of
stacked I-band exposures we conclude that the XRT error circle (GCN
5762) does not contain a new or fading source to a limiting magnitude of
I ~ 20.1 � .4 mag (based on calibration of 10 field sources from USNO
B1.0 I2 band).
The Clemson University 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 5768
Subject
GRB 061028: z band imaging
Date
2006-10-28T18:51:37Z (19 years ago)
From
Josh Bloom at UC Berkeley <jbloom@astron.berkeley.edu>
GRB 061028: z-band imaging
J. S. Bloom (UC Berkeley), D. Charbonneau, M. J. Holman, E. E. Falco
(Harvard/CfA), H-. W. Chen (U Chicago) report on behalf of a larger
collaboration:
"We observed the field of GRB 061028 (Sakamoto et al. GCN 5762) using
the z-band filter of Keplercam mounted on the Mt. Hopkins 48-inch
telescope. In a stacked series of 5 minute exposures from 06:20 -
07:21 Oct 28, 2006 UTC (from about 4 - 5 hours after the GRB
trigger), we find no detected source consistent with the revised XRT
position (Cusumano et al. GCN 5767). We do note the presence of a
marginally detected faint red source (S1) to the north of the error
circle that is not in the DSS2 F or N plates at position 06:28:54.6,
46:18:01 (J2000). Photometric calibration is in progress but, for
reference, S1 is about 2.1 mag fainter in z-band than the object at
06:28:54.1, +46:18:15. Our 3 sigma limiting magnitude is roughly 0.2
mag fainter than S1."
An image of the field (XRT 90% confidence region circled) is
located at:
http://lyra.berkeley.edu/~jbloom/grb061028_zcompare_bloom.ps.gz
This message may be cited.
GCN Circular 5767
Subject
GRB061028: XRT refined analysis
Date
2006-10-28T14:25:10Z (19 years ago)
From
Teresa Mineo at INAF-IASFA <teresa.mineo@ifc.inaf.it>
G. Cusumano (IASF-Pa INAF), T. Mineo (IASF-Pa INAF), V. Mangano (IASF-Pa
INAF),
B. Sbarufatti (IASF-Pa INAF) and T. Sakamoto (GSFC/ORAU)
report on behalf of the Swift XRT team:
We have analyzed the first 4 orbits of Swift-XRT data obtained for GRB
061028 (trigger=235715, GCN 5762). The data consist of 100 s in Windowed
Timing (WT) mode, starting 205 seconds after the BAT trigger and 8 ks
in Photon Counting (PC) mode.
Using PC data we obtain a refined position of:
RA(J2000) = 06h 28m 54.53s
Dec(J2000)= +46d 17' 55.20"
with an estimated uncertainty radius of 3.9 arcsec (90% containment)
taking into account the new TELDEF files . This location is 0.4 arcsec
from the first XRT position (GCN 5762).
The light-curve shows a steep decay (alpha=3.9�0.4) up to the end of the
second orbit. Data relative to the next two orbits show a detection at 3
sigma level with a count rate of (3�1)E-3 corresponding to a flux of
1.5E-13 erg cm^-2 sec^-1, significantly higher than the model
extrapolation.
The spectrum from all the WT data can be modeled with a
power law of photon index Gamma = 1.4 � 0.1, with an absorbing
column of NH = (2.4�0.6)E21 cm^-2, significantly higher than the
Galactic value of 1.37E21 cm^-2. The 0.2-10 keV unabsorbed flux
during the WT is 5.7E-10 erg cm^-2 sec^-1. The spectrum from
the PC data is softer than the WT spectrum: it can be modeled with a
power-law of photon index Gamma = 2.4�0.4.
All errors are quoted at 90% confidence level.
This circular is an official product of the Swift-XRT team.
GCN Circular 5766
Subject
GRB 061028: Swift/UVOT Observations
Date
2006-10-28T14:07:19Z (19 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S.R. Oates (UCL-MSSL), T. Sakamoto (NASA/ORAU) report on behalf of the
Swift/UVOT team:
The Swift/UVOT began observing the field of GRB 061028 at
01:29:32 on 2006-10-28, 190s after the BAT trigger (Sakamoto et al.,
GCN 5762). No new source was detected within the XRT
error circle in coadded images in any filter down to the following
3-sigma magnitude upper limits:
Filter Start End Exposure 3-sigma UL
------------------------------------------------
V 190 6596 747 20.6
B 410 6131 274 20.3
U 386 5926 313 19.9
W1 362 5722 313 18.5
M2 338 5517 313 19.4
W2 438 6541 471 19.3
WHITE 208 6335 443 18.9
------------------------------------------------
These upper limits are not corrected for Galactic extinction
E(B-V) = 0.16.
GCN Circular 5765
Subject
GRB 061028, Swift-BAT refined analysis
Date
2006-10-28T13:26:20Z (19 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori@milkyway.gsfc.nasa.gov>
G. Sato (GSFC/ISAS), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
on behalf of the Swift-BAT team:
Using the data set from T-239 to T+963 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 061028 (trigger #235715)
(Sakamoto, et al., GCN Circ. 5762). The BAT ground-calculated position
is RA,Dec = 97.193, 46.290 deg {6h 28m 46.3s, 46d 17' 25.1"} (J2000)
+- 2.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 35%.
The mask-weighted lightcurve shows several weak pulses starting from T+55 sec,
and the highest peak at T+81 sec. The weak tail emission is ending around T+300 sec.
T90 (15-350 keV) is 106 +- 5 sec (estimated error including systematics).
The time-averaged spectrum from T+47 to T+166 is best fit by
a simple power-law model. The power law index of the time-averaged spectrum
is 1.73 +- 0.30. The fluence in the 15-150 keV band is
9.7 +- 1.7 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from
T+79.94 sec in the 15-150 keV band is 0.7 +- 0.2 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.
GCN Circular 5764
Subject
GRB 061028: TAROT Calern observatory late optical observations
Date
2006-10-28T03:00:50Z (19 years ago)
From
Alain Klotz at CESR-CNRS <Alain.Klotz@free.fr>
Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report:
We continued to monitor the XRT error box of
GRB 061028 defined Sakamoto et al. (GCNC 5762)
with TAROT. Early observations (Klotz et al.
GCNC 5763) did not shown any OT in this area.
Under excellent weather conditions, we can
now give the following upper limit derived
from a series of co-added 180s images images:
from t0+0.44 to t0+1.07 hour : R>20.1
where t0 is the BAT trigger date.
GCN Circular 5763
Subject
GRB 061028: TAROT Calern observatory optical observations
Date
2006-10-28T02:03:08Z (19 years ago)
From
Alain Klotz at CESR-CNRS <Alain.Klotz@free.fr>
Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report:
We imaged the field of GRB 061028 detected by SWIFT
(trigger 235715) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.
The observations started 145.4s after the GRB trigger
(6.7s after the notice). The elevation of the field increased from
from 67 degrees above horizon and weather conditions
were good.
The date of trigger : t0 = 2006-10-28T01:26:22.272
The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT with a limiting magnitude of:
t0+145.4s to t0+205.4s : R > 16.5
The second image is 30.0s exposure in tracking mode:
t0+212.1s to t0+242.1s : R > 17.5
We co-added a series of exposures:
t0+212.1s to t0+497.5s : R > 18.3
Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.
N.B. Galactic coordinates are lon=168.5115 lat=+15.6018
and the galactic extinction in R band is 0.4 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.
This message may be cited.
GCN Circular 5762
Subject
GRB 061028: Swift detection of a burst
Date
2006-10-28T01:52:38Z (19 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
T. Sakamoto (NASA/ORAU), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
M. M. Chester (PSU), H. A. Krimm (GSFC/USRA),
V. Mangano (INAF-IASFPA), C. B. Markwardt (GSFC/UMD),
F. E. Marshall (NASA/GSFC), T. Mineo (INAF-IASFPA),
D. M. Palmer (LANL) and M. Stamatikos (NASA/ORAU) report on behalf of
the Swift Team:
At 01:26:22 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 061028 (trigger=235715). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA,Dec 97.212, +46.270 {06h 28m 51s, +46d 16' 12"} (J2000)
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). This is a 128-sec image trigger and as is typical
the BAT lightcurve does not show any significant emission.
The XRT began observing the field at 01:29:40 UT, 198 seconds after the
BAT trigger. XRT found a bright, fading, uncatalogued X-ray source
located at RA(J2000) = 06h 28m 54.5s, Dec(J2000) = +46d 17' 55.4", with an
estimated uncertainty of 5.0 arcseconds (90% confidence radius).
This location is 110 arcseconds from the BAT on-board position, within
the BAT error circle. The initial flux in the 2.5s image was
1.5e-09 erg/cm2/s (0.2-10 keV).
UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 208 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 3-sigma
upper limit is 19.4 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 0.16.