GRB 060801
GCN Circular 5773
Subject
GRB 060801: Swift/XRT Astrometry Correction
Date
2006-10-30T16:30:13Z (19 years ago)
From
Judith Racusin at PSU <racusin@astro.psu.edu>
J. L. Racusin, D. N. Burrows (PSU), and N. Gehrels (NASA/GSFC) report on
behalf of the Swift XRT team:
We have re-analyzed the full XRT data set of the short hard GRB 060801.
XRT observed the field of GRB 060801 for a total of 75 ks between August 1
and August 5, 2006 in Photon Counting mode in order to obtain a more
accurate position of the short-lived X-ray afterglow.
In the full data set we find 23 serendipitous X-ray sources detected with
the XIMAGE detect algorithm with S/N > 3, 12 of which have near-by optical
counterparts in the SDSS. We match these sources to obtain a best fit
mean frame shift, carefully accounting for several instrumental factors
described below.
At the time of these observations there was a problem with the bias maps
that caused spurious hot pixels to remain in the cleaned event lists after
standard processing. To remove this contamination, we filtered out events
with energies < 0.4 keV. For more information on the bias map issue, see
http://www.swift.ac.uk/xrtdigest.shtml.
We also apply an exposure map correction to the images before input into
XRTCENTROID to account for any sources landing on or near the bad columns
in the XRT CCD. In the first orbit, the GRB did in fact lie on one of
these columns. We use XRTCENTROID to calculate the positions of the GRB
and the serendipitous sources.
Additional position error arises from the Swift star tracker solution
uncertainty. This error is small once the spacecraft has completely
settled after a slew, but is not achieved until ~100s after the XRT
observations begin. Therefore, we exclude the first 100s of each orbit,
reducing the total used exposure used time to 69 ks.
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 (Racusin et al., GCN 5382), of:
dRA: -3.60" dDec: -0.90" +/- 0.64"
and a new XRT refined position of:
RA(J2000): 14h 12m 01.31s
Dec(J2000): +16d 58' 54.0"
with an estimated uncertainty of 2.1 arcseconds (90% containment).
This position is 4.2 arcseconds from the refined XRT position given in
Racusin et al. (GCN 5382), 1.9 arcseconds from the boresight corrected XRT
position using the new TELDEF described by Burrows et al. (GCN 5750), and
0.5 arcseconds from the frame shifted position given in Butler et al. (GCN
5389) based upon only the first 25 ks of data. Potential host galaxies B
& D from Castro-Tirado et al. and Piranomonte et al. (GCNs 5384 & 5386)
both lie inside the new XRT refined error circle. A figure comparing all
of these positions is available at:
http://www.swift.psu.edu/images/grb060801_astrometry.gif
Galaxy B has a redshift of 1.131 as given by Cucchiara et al. (GCN 5460).
We encourage observations of galaxy D to obtain its redshift.
This Circular is an official product of the Swift XRT team.
GCN Circular 5470
Subject
GRB060801: host galaxy redshift
Date
2006-08-22T22:32:30Z (19 years ago)
From
Antonino Cucchiara at PSU <cucchiara@astro.psu.edu>
A. Cucchiara (PSU), D. B. Fox (PSU), E. Berger (OCIW) and P. A. Price
(IfA,UH) report:
Starting at August, 22nd at 06:05:49 UT, we obtained 2x900 sec spectra
of the
candidate host galaxy of GRB 060801 (extended source B in GCN5389) using
Gemini North observatory and GMOS spectrograph with 1 arcsec slit and
R400 grating.
We detect a bright emission line at 7942A, with no other apparent
features. Identifying this line as [OII] at 3727A yields a redshift of
z = 1.131 for this galaxy. At this redshift, the observed fluence of
8.1e-8 erg/cm2
(GCN 5381) corresponds to an isotropic-equivalent energy of 2.7e50 erg.
We thank the staff at Gemini for performing the observations.
[GCN OPS NOTE(15dec06): Per author's request, the Subject-line
was changed from "00801" to "060801".]
GCN Circular 5408
Subject
GRB 060801: Second Epoch WSRT Radio Observations
Date
2006-08-07T09:57:36Z (19 years ago)
From
Alexander van der Horst at U of Amsterdam <avdhorst@science.uva.nl>
A.J. van der Horst (University of Amsterdam) reports on behalf of a larger
collaboration:
"We reobserved the position of the GRB 060801 afterglow at 4.9 GHz with
the Westerbork Synthesis Radio Telescope on Aug 6 from 10.77 to 22.75 UT,
i.e. 4.94 - 5.44 days after the burst (GCN 5378).
We do not detect a radio source within the XRT error circle (GCN 5382) or
the refined XRT/SDSS error circle (GCN 5389). The rms noise in het map
within the XRT error circle is 27 microJy per beam. The formal flux
measurement for a point source at the center of the XRT error circle is 51
+/- 27 microJy."
GCN Circular 5392
Subject
GRB 060801: no variability of optical sources
Date
2006-08-03T15:13:42Z (19 years ago)
From
Daniele Malesani at SISSA-ISAS,Trieste,Italy <malesani@sissa.it>
S. Piranomonte (INAF-OARm), S. Covino (INAF-OABr), D. Malesani
(SISSA/ISAS), G. Tagliaferri (INAF/OABr), G. Chincarini (Univ.
Milano-Bicocca), and L. Stella (INAF-OARm) report on behalf of the
MISTICI collaboration:
We observed again the field of GRB 060801 (Racusin et al., GCN 5378,
5382; Sato et al., GCN5381) with the ESO VLT equipped with the FORS2
instrument. Standard star fields were observed in order to get a
reliable flux calibration. We find a significant mismatch (more than 1
mag) with respect to the USNO calibration. Adopting the naming
introduced by Castro-Tirado et al. (GCN 5384) and Piranomonte et al.
(GCN 5386), we find the following magnitudes for the four sources close
to the XRT position:
A: R = 21.95
B: R = 23.71 (extended)
C: R = 23.90
D: R = 24.62 (extended)
Between the night of Aug 1 (mean time Aug 2.026 UT) and Aug 2 (mean time
Aug 2.991 UT) we find no variability of any of the above sources up to
~0.1 mag.
We acknowledge the excellent support from the ESO staff, in particular
Oliver Hainaut.
This message can be cited.
GCN Circular 5390
Subject
GRB 060801: WSRT Radio Observations
Date
2006-08-03T01:29:48Z (19 years ago)
From
Alexander van der Horst at U of Amsterdam <avdhorst@science.uva.nl>
A.J. van der Horst (University of Amsterdam) reports on behalf of a larger
collaboration:
"We observed the position of the GRB 060801 afterglow at 4.9 GHz with the
Westerbork Synthesis Radio Telescope on Aug 2 from 11.03 to 23.01 UT, i.e.
0.95 - 1.45 days after the burst (GCN 5378).
We do not detect a radio source within the XRT error circle (GCN 5382) or
the refined XRT/SDSS error circle (GCN 5389), in particular at the
position of the optical sources mentioned in GCN 5384 and GCN 5386.
The rms noise in het map within the SWIFT/XRT error circle is 24 microJy
per beam. The formal flux measurement for a point source at the center of
the XRT error circle is 32 +/- 24 microJy.
We detect two sources close to the XRT error circle which are also present
in the FIRST survey at 1.4 GHz. These sources have fluxes of 854 +/- 37
microJy (RA(J2000)=14h12m00.39s, Dec(J2000)=16d59m05.3s) and 1031 +/- 37
microJy (RA(J2000)=14h12m01.18s, Dec(J2000)=16d59m06.7s) at 4.9 Ghz."
GCN Circular 5389
Subject
GRB 060801: XRT/SDSS Frame Offset and Refined XRT Position
Date
2006-08-02T17:27:20Z (19 years ago)
From
Nat Butler at MIT/CSR <nrbutler@space.mit.edu>
N. Butler (UC Berkeley) reports:
We detect 12 X-ray sources with signal-to-noise ratio >3 with wavdetect
in the 25.3 ksec exposure XRT image of the short GRB 060108 field (Racusin
et al. 2006; GCN 5378). Six position matches with optical sources in SDSS
DR5 (see, sdss.org) give the following sizable frame shift:
dRA -4.29", dDec -0.70"; +/-0.73" (90% conf.)
and the refined position:
RA, Dec: 14 12 01.30 +16 58 54.4; +/- 1.1" (J2000, 90% conf.)
Our refined position is marginally consistent with the refined position
of the XRT team (Racusin et al. 2006; GCN 5382). The position is fully
consistent with that of optical source B and marginally consistent with
that of optical source D (Castro-Tirado et al. 2006; GCN 5384; Piranomonte
et al. 2006; GCN 5386). It is inconsistent with the source A and C positions.
GCN Circular 5388
Subject
GRB060801: Radio Observations
Date
2006-08-02T17:21:35Z (19 years ago)
From
Alicia Soderberg at Caltech <ams@astro.caltech.edu>
A. M. Soderberg (Caltech), D. A. Frail (NRAO) and P. Chandra (UVA/NRAO)
report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration:
"We observed the field centered on the XRT position of the Swift burst
GRB 060801 (GCN#5378) using the VLA at a frequency of 8.46 GHz, beginning
at August 2.00 UT. We detect no sources within the XRT error circle
and place a 3-sigma limit of 105 uJy. 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 5386
Subject
GRB 060801: optical observations at FORS2/VLT
Date
2006-08-02T03:26:19Z (19 years ago)
From
Silvia Piranomonte at OAR <piranomonte@mporzio.astro.it>
S. Piranomonte (INAF, OAR), S. Covino (INAF, OABr), D. Malesani (SISSA/ISAS),
G.Tagliaferri (INAF, OABr), G. Chincarini (Univ Milano-Bicocca), L. Stella (INAF,
OARm), report on behalf of the MISTICI collaboration:
We observed the position of XRT error circle of GRB 060801 (Racusin, et al., GCN
Circ. 5378) with FORS2/VLT on August 2.0125 UT (about 12 hours post burst).
Eight exposures lasting 300s were acquired with the FORS2 instrument.
Preliminary analysis shows that the objects from Castro-Tirado et al. (GCN 5384)
are clearly evident (A: 14:12:01.65,+16:59:02.0 and B: 14:12:01.21, +16:58:55.7)
with R magnitudes about 20.8 and 22.6, respectively.
Object B seems to have a possible extended emission.
Inside the XRT errorbox we find two more ojects. One near the limit of the error
box (C: 14:12:01.88, 16:58:53.7 with R mag about 22.6) and one faint, possible
extended object (object D: 14:12:01.40,+16:58:54.7) with R magnitude about 23.6.
Objects B is distant 3-3.5 arcsec from object D.
Magnitudes were calibrated with the USNO catalogue and absolute uncertainty is
likely of the order of 0.5 magnitudes.
At the present stage, therefore, no object can be easily singled out as
the GRB afterglow, although source B and D could be the GRB host galaxy.
Further analysis are on-going
We thank the ESO staff for excellently performing these observations in
service mode.
This message may be cited"
"We observed the position of XRT error circle of GRB 060801 (Racusin, et al.,
GCN Circ. 5378) with FORS2/VLT on August 2.0125 UT (about 12 hours post burst).
Eight exposures lasting 300s were acquired with the FORS2 instrument.
Preliminary analysis shows that the objects from Castro-Tirado et al. (GCN 5384)
are clearly evident (A: 14:12:01.65,+16:59:02.0 and B: 14:12:01.21,+16:58:55.7)
with R magnitudes about 20.8 and 22.6, respectively.
Object B appear to have a possible extended emission.
Inside the XRT errorbox we find two ojects. One near the limit of the error box
(C: 14:12:01.88, 16:58:53.7 with R mag about 22.6) and one faint, possible
extended object (object D: 14:12:01.40,+16:58:54.7) with R magnitude about 23.6.
Objects B is distant 3.5 arcsec from object D.
Magnitudes were calibrated with the USNO catalogue and absolute
uncertainty is likely of the order of 0.5 magnitudes.
At the present stage, therefore, no object can be easily singled out as
the GRB afterglow, although source D could be the GRB host galaxy.
Further analysis are on-going.
We thank the ESO staff for excellently performing these observations in
service mode.
This message may be cited"
-------------------------------------------------
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GCN Circular 5385
Subject
GRB060801: Swift/UVOT Upper Limits
Date
2006-08-02T00:54:26Z (19 years ago)
From
Peter Brown at PSU <pbrown@astro.psu.edu>
P. J. Brown & J. L. Racusin (PSU)
report on behalf of the Swift/UVOT team:
The Swift UVOT began taking settled exposures
on the field of the short hard GRB060801
(BAT Trigger #222154), 67 s after the BAT trigger
(Racusin et al., GCN Circ. 5378). No new source,
relative to the DSS, is seen inside the refined XRT
error circle (Racusin et al., GCN Circ. 5382) or at
the positions of the optical sources reported by
Castro-Tirado et al. (GCN Circ. 5384).
The 3-sigma upper limits for the first finding
charts and the coadded images are listed below.
Finding charts:
Filter T_range(s) Exposure (s) 3-sigma UL
White 67-166 100 19.9
V 173-572 400 19.5
Coadded images:
Filter T_range(s) Exposure (s) 3-sigma UL
White 67-7181 461 20.8
V 173-6309 1023 20.1
B 651-7127 412 20.6
U 627-6922 432 20.3
UVW1 603-6718 432 20.3
UVM2 579-6513 245 20.2
UVW2 679-6104 236 20.4
T_range is calculated from the time of the burst. These
upper limits have not been corrected for the estimated
Galactic reddening of E_(B-V) = 0.018 mag (Schlegel et
al. 1998).
GCN Circular 5384
Subject
GRB 060801: optical observations at Hanle and Calar Alto
Date
2006-08-01T22:06:47Z (19 years ago)
Edited On
2024-11-18T09:44:31Z (a year ago)
From
Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct@iaa.es>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>
A. J. Castro-Tirado (IAA-CSIC Granada), G. C. Anupama,
S. Srividya, Ramya (IIAP-RES Bangalore), A. de Ugarte Postigo
(IAA-CSIC), S. Sánchez, L. Montoya (CAHA Almeria), A. Castillo,
J. C. Muñoz-Mateos (Univ. Complutense Madrid),
M. Jelínek and J. Gorosabel (IAA-CSIC),
report:
"Following the detection by SWIFT of the short GRB 060801
(Racusin et al. GCNC 5378, Sato et al. GCN 5381), we have
taken R-band frames at the 2.0m Hanle telescope in India
(+HFOSC) starting on Aug 1.75 UT. Additional BVR-band frames
have been taken with the auxiliary port camera at the 3.5m
telescope at the German-Spanish Calar Alto Observatory in
south Spain, starting on Aug 1.935 UT. Near the position of
the X-ray afterglow (Racusin et al. GCN 5382), we detect two
faint optical sources in the R-band images:
source A: 14 12 01.8 +16 59 00.5
source B: 14 12 01.3 +16 58 54.0
with 1" accuracy (for the time being).
source A is at the edge of the XRT error box and brighter than
source B and it seems to be constant in brightness over the time
interval of our observations. Source B is consistent with the
XRT error box and there is marginal evidence that source B has
declined in brightness, with R = 22.5 +/- 0.5 (preliminary) in the
3.5m CAHA images. Further analysis is in progress."
This message can be quoted.
[GCN OPS NOTE(08aug06): By author's request, the spelling of the
Sánchez and J. C. Muñoz-Mateos names were corrected.]
GCN Circular 5383
Subject
GRB060801: optical upper limit in R
Date
2006-08-01T21:31:40Z (19 years ago)
From
Gottfried Kanbach at MPE <gok@mpe.mpg.de>
S. Duscha, G. Kanbach, M. Muehlegger, A. Stefanescu, F. Schrey,
N. Prymak, H. Steinle (MPE Garching) of the OPTIMA-Burst team report from
the 1.3m Skinakas Observatory (University of Crete, Heraklion, Greece):
We observed the position of the XRT errorcircle of GRB 060801 (trigger
#222154, Racusin, et al., GCN Circ. 5378)
on 2006 Aug 01, 19:24 UT (mid-exposure; about 7 hours post burst):
in a 20 min R-filter exposure we do not detect a counterpart candidate
brighter than R=22.
GCN Circular 5382
Subject
GRB 060801: Swift XRT refined analysis
Date
2006-08-01T20:56:46Z (19 years ago)
From
Judith Racusin at PSU <racusin@astro.psu.edu>
J. L. Racusin, D. Grupe, D. Morris, and M. Stroh report on behalf of the
Swift XRT team:
We have analysed the first 2 orbits of XRT data from the short hard GRB
060801 (Racusin et al., GCN Circ. 5378), with a total exposure of 3.7 ks
in Photon Counting mode. The refined XRT position is:
RA(J2000) = 14h 12m 01.6s
Dec(J2000) = +16d 58m 54.8s
with an uncertainty of 3.7 arcsec (90% containment). This position is 1.8
arcsec away from the XRT position quoted in Racusin et al. (GCN Circ.
5378), and 71 arcsec away from the refined BAT position (Sato, et al., GCN
Circ. 5381).
The 0.3-10 keV X-ray light curve shows a plateau from 73s until ~115s
after the BAT trigger, followed by a decay with a power law index of -1.19
+/- 0.16 until a break at ~400s to a steeper decay with a power law index
of -5.84 +/- 3.3. The X-ray afterglow is not detected in the second
orbit.
A power-law fit to the 0.3-10 keV spectrum from the first orbit
gives a photon index of 1.67+/-0.20 and a column density of
(0.8+/-0.5)e21 cm**-2. We note the Galactic hydrogen column density
in the direction of the burst is 1.51e20cm**-2.
This circular is an official product of the Swift XRT Team.
GCN Circular 5381
Subject
GRB 060801: Refined analysis of the Swift-BAT short hard burst
Date
2006-08-01T20:04:07Z (19 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
G. Sato (GSFC/ISAS), L. Barbier (GSFC), S.D. Barthelmy (GSFC),
J. Cummings (GSFC/ORAU), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), M. Koss (GSFC/UMD),
C. Markwardt (GSFC/UMD), J. Norris (GSFC), 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-240 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 060801 (trigger #222154)
(Racusin, et al., GCN Circ. 5378). The BAT ground-calculated position is
RA,Dec = 212.987, 16.988 deg {14h 11m 56.9s, 16d 59' 17.4"} (J2000)
+- 1.8 arcmin, (radius, sys+stat, 90% containment). This burst
was in the fully-coded field-of-view.
The mask-weighted lightcurve shows two overlapping peaks. The first,
and brighter of the two, starts at T+0.0 sec and peaks at ~T+0.06 sec.
The second peaks at ~T+0.50 sec and ends at ~T+0.7 sec. At the ~2-sigma
level, there is a possible short peak at ~T+1.3 sec. T90 (15-350 keV)
is 0.5 +- 0.1 sec (estimated error including systematics).
There is no obvious emission, soft or otherwise, in the T+10 to T+200 sec
time range.
The time-averaged spectrum from T+0.0 to T+0.6 is best fit by a simple
power-law model. The power law index of the time-averaged spectrum
is 0.47 +- 0.24. The fluence in the 15-150 keV band is
8.1 +- 1.0 x 10^-8 erg/cm2. The 1-sec peak photon flux measured
from T-0.18 sec in the 15-150 keV band is 1.3 +- 0.2 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.
The lag for this burst is -0.008 +/- 0.008 sec, between the 25-50 keV
and 100-350 keV bands.
GCN Circular 5380
Subject
GRB 060801, optical observation
Date
2006-08-01T14:34:24Z (19 years ago)
From
Shouta Maeno at U.of Miyazaki <shouta@astro.miyazaki-u.ac.jp>
E.Sonoda, S.Maeno, M.Yamauchi
(University of Miyazaki)
We have observed the field covering the error circle of
GRB 060801 (GCN 5378) with the unfiltered CCD camera on
the 30-cm telescope at University of Miyazaki.
The observation was started 12:17:47 UT on Aug. 1.
We have compared our data of 30 sec exposures
with the USNO-A2.0 catalog, there is no new source
at the position reported by GCN 5378.
The upper limits are as follows:
--------------------------------------------------------------
Start(UT) End(UT) Num. of frames Limit (mag.)
--------------------------------------------------------------
12:17:47 12:18:17 1 ~14.5
12:21:23 12:33:37 12 ~17.1
12:37:12 12:53:03 14 ~17.0
---------------------------------------------------------------
GCN Circular 5379
Subject
GRB 060801: Kanazawa Optical Observation
Date
2006-08-01T13:32:44Z (19 years ago)
From
Daisuke Yonetoku at Kanazawa U <gcn@astro.s.kanazawa-u.ac.jp>
S.Okuno, D.Yonetoku, T.Murakami, H.Kodaira, S.Yoshinari, T.Kidamura,
S.Tanabe, S.Yokota, Y.Aoyama, R.Kozaka, Y.Kodama
report on behalf of the Kanazawa GRB team:
We have imaged the field of GRB 060801 (J. L. Racusin et al. GCN 5378)
in R band with 0.3m telescope at Kanazawa Japan.
The automated system took the first image at 300 s after the trigger
(under poor conditions). Compared with the USNO-A2.0 catalog, no new
source was detected brighter than the limiting magnitude of R>15.9 mag
in the XRT error circle. Further analysis is in progress.
GCN Circular 5378
Subject
GRB 060801: Swift detection of a short burst
Date
2006-08-01T12:36:52Z (19 years ago)
From
Judith Racusin at PSU <racusin@astro.psu.edu>
J. L. Racusin (PSU), L. M. Barbier (NASA/GSFC), P. J. Brown (PSU),
D. N. Burrows (PSU), N. Gehrels (NASA/GSFC),
C. Guidorzi (Univ Bicocca&INAF-OAB), J. A. Kennea (PSU),
V. Mangano (INAF-IASFPA), F. E. Marshall (NASA/GSFC),
K. M. McLean (LANL/UTD), D. M. Palmer (LANL),
M. Stamatikos (NASA/ORAU) and E. Troja (INAF-IASFPA) report on behalf
of the Swift Team:
At 12:16:15 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 060801 (trigger=222154). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA,Dec 213.025, +16.984 {14h 12m 06s, +16d 59' 03"} (J2000)
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a short burst
with a duration of about 0.5 sec. The peak count rate
was ~6000 counts/sec (15-350 keV), at ~0.5 sec after the trigger.
The XRT began taking data at 12:17:18 UT, 63 seconds after the BAT
trigger. The XRT on-board centroid algorithm did not find a source in
the image but ground processed data reveals an uncatalogued fading
point source at the following location:
RA(J2000): 14h 12m 01.5s, Dec(J2000): +16d 58m 55.1s with an estimated
error of 3.8 arcseconds radius (90% containment).
UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 67 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. The typical
3-sigma upper limit has been about 18.5 mag. Data for the list of
sources generated on-board are not available at this time. No
correction has been made for the expected extinction corresponding
to E(B-V) of 0.02.