GRB 050814
GCN Circular 3821
Subject
GRB050814: Radio Observation
Date
2005-08-17T17:52:41Z (21 years ago)
From
Dale A. Frail at NRAO <dfrail@nrao.edu>
P. B. Cameron (Caltech) and D. A. Frail (NRAO) report on behalf of a
larger collaboration:
"We have undertaken VLA observations at a frequency of 8.46 GHz toward
GRB 050814 (GCN 3803) on August 17.03 UT. No radio afterglow is
detected. At the position of the optical afterglow (GCN 3807) the
point-source limit is 73 +/- 36 microJy. 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 3818
Subject
GRB 050814: continued fading
Date
2005-08-16T17:39:27Z (21 years ago)
Edited On
2024-11-07T19:51:11Z (2 years ago)
From
Pall Jakobsson at Niels Bohr Inst <pallja@astro.ku.dk>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>
Páll Jakobsson, Johan P. U. Fynbo, Jens Hjorth, Brian L. Jensen,
José María Castro Cerón, Kristian Pedersen, Jesper Sollerman (DARK, NBI),
Kalle Torstensson, Karianne Holhjem (NOT, La Palma), Jan-Erik Solheim
(U. of Oslo, Norway), Sergio Sousa (CAUP and OAL, Portugal), and
Sarunas Mikolaitis (ITPA, Lithuania) report:
We have continued monitoring the field of GRB 050814.485 in the I band using
ALFOSC on the 2.56-meter Nordic Optical Telescope. Compared to our previous
epoch (Jensen et al. GCN#3809) the proposed afterglow appears to be fading.
By comparison with 5 standard stars in SA92 (Landolt, 1992, AJ, 104, 340)
we estimate the following magnitude for the afterglow:
Date (UT) Filter Exptime Seeing Mag
Aug 15.96 I 3x300s 0.8" 21.4
Using I = 20.5 from GCN#3809, the preliminary decay slope is alpha = 0.95.
[GCN OPS NOTE(16aug05): Per author's request, the institutional affiliation
was changed to Niels Bohr Inst; and the last two authors were added.]
GCN Circular 3809
Subject
GRB050814: Fading red source
Date
2005-08-15T08:36:17Z (21 years ago)
From
Brian Lindgren Jensen at U.of Copenhagen <brian_j@astro.ku.dk>
Brian L. Jensen, Johan P. U. Fynbo, Jens Hjorth, Jesper Sollerman,
Jos? Mar?a Castro Cer?n, Kristian Pedersen, P?ll Jakobsson,
Darach Watson (DARK, NBI), Anna S. Arnadottir (U. of Lund, Sweden),
Diana A. Fiuza (U. of Helsinki, Finland) and
Jan-Erik Solheim (U. of Oslo, Norway) report:
"Using ALFOSC on the Nordic Optical Telescope we have obtained VRI
imaging of the field of GRB 050814.485 (Retter et al., GCN#3799)
on August 15.1, 2005 UT (~13.5 h after the burst).
In the refined XRT error-circle (Morris et al., GCN#3805) we clearly
detect the source reported by Bradly Cenko (GCN#3807) in our I- and
R-band images, whereas the source is absent in the V-band.
Based on preliminary photometry, we obtain for the source :
Date (UT) Filter Exptime Seeing Mag
Aug 15.04 V 3x300s 1.1" >23.0
Aug 15.06 R 3x300s 1.0" 23.2
Aug 15.07 I 3x300s 0.9" 20.5
Compared to the preliminary I-band detection reported in GCN#3807, the
source appears to be fading.
The colours of the object, if it is the afterglow of GRB 050814.485,
indicate either a high redshift (4.5<z<6.5) or significant
dust-reddening.
In addition, we detect a fainter, bluer source on the edge of the XRT
error-circle (at (RA,Dec)(J2000.0) = 17:36:44.93, +46:20:22.33).
An image of the field is shown at:
http://www.astro.ku.dk/~brian_j/grb/grb050814.485/ "
[GCN OPS NOTE(15aug05): Per author's request Arnadottir and Fiuza
were added to the author list.]
GCN Circular 3807
Subject
GRB050814: P60 Optical Afterglow Candidate
Date
2005-08-15T06:47:06Z (21 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. Bradley Cenko (Caltech) reports on behalf of a larger collaboration:
We have imaged the field of GRB050814 (Swift 150314, Retter et al., GCN
3799) with the automated Palomar 60-inch telescope. Observations
consisted of 18 x 120 s images in both the Kron R and Gunn i filters,
and were taken at a mean epoch of 15 August 04:43 UT (~ 17.1 hours after
the burst).
In the revised XRT error circle (Morris et al, GCN 3805), we find a
faint source marginally detected (~2 sigma) in our i-band coadd. This
source is not present in any of the Second Generation Digital Sky Survey
plates, although it is likely below the detection threshold. The
coordinates (J2000) of the source are
RA: 17:36:45.39
Dec: +46:20:21.6
with an estimated uncertainty of ~0.2" in each direction.
By comparison with the USNO-B1 star located at 17:36:50.9, +42:20:45.0
(USNO 1363-0276928, I = 15.73), we estimate the magnitude of this source
is i ~ 21.4 +/- 0.3. Given its faintness, we cannot determine whether
the source is variable, and therefore cannot confirm whether it is the
afterglow of GRB050814.
We find no sources present in the XRT error circle in our R-band coadd
to a (3-sigma) limiting magnitude of R > 21.3.
Further observations and analysis are planned.
GCN Circular 3805
Subject
GRB 050814: XRT refined analysis
Date
2005-08-15T00:57:40Z (21 years ago)
From
David Morris at PSU/Swift-XRT <morris@astro.psu.edu>
D. C. Morris, D. N. Burrows, J. A. Kennea, J. L. Racusin (PSU), and N.
Gehrels (GSFC) report on behalf of the Swift XRT team:
We have analysed the first five orbits of data for GRB050814 (GCN 3799,
Retter et al., 2005). Using xrtcentoid, the refined position is:
RA(J2000) = 17h 36m 45.7s
Dec(J2000) = +46d 20' 20.5"
with an uncertainty of 8 arcsec. This is 5.4 arcsec from the original
XRT position (GCN 3800, Morris et al., 2005). The initially distributed
XRT position was based on the first orbit of PC data and may have been
effected by a hot column at the position of the source. The refined
position is calculated by analyzing several orbits of PC data, each
taken at slightly different positions on the detector, so that the hot
column in the first orbit of data is no longer a problem for the
centroiding algorithm.
The XRT began taking data at 11:41:15UT, 138 seconds after the BAT
trigger. Both the windowed timing and photon counting data from the
first orbit show a fading lightcurve consistent with a decay index of
~4. Photon counting data from subsequent orbits shows a flattening of
the lightcurve near T+1000s to a decay index of ~0.1.
The windowed timing spectrum (data from +165s to +383 after the BAT
trigger) is well fit (reduced chi-sq of 1.22 for 72 dof) by a power law
with neutral hydrogen somewhat larger than the galactic column density
of 2.57e20:
gamma=2.1 � 0.1
NH=6.94e20 � 2e18
The photon counting spectrum (from +383s through orbit 5) is well fit
(reduced chi-sq of 0.61 for 31 dof) by a power law also with excess
absorption:
gamma=1.8 � 0.2
NH=7.82e20 � 7e18
The count rate at 20000s after the trigger is ~0.15 cts/s which converts
to an unabsorbed flux of 4.76e-12 ergs cm^-2 s^-1.
It should be noted that the early versions of the SDC data contained
processing errors, likely due to earthlimb contamination, which may yet
be contributing to some peculiarities in the PC lightcurve.
GCN Circular 3804
Subject
GRB050814: SWIFT/UVOT observation
Date
2005-08-15T00:00:42Z (21 years ago)
From
Alexander Blustin at MSSL-UCL <ajb@mssl.ucl.ac.uk>
A. J. Blustin (UCL-MSSL), A. Retter (PSU), F. Marshall (GSFC),
M. Chester (PSU), N. Gehrels (GSFC) on behalf of the Swift/UVOT
team
Swift/UVOT began observing the field of GRB050814 at 11:41:44 UT,
167 s after the BAT trigger (Retter et al., GCN 3799). We detect no
new source with respect to the DSS image within the XRT error circle
(Morris et al., GCN 3800) in summed images from any filter
down to the following 3-sigma magnitude upper limits:
Filter T_range Exp (s) 3-sig UL (mag)
V 167-13371 1375 20.5
B 313-8353 1046 21.4
U 299-7587 1187 21.2
UVW1 285-6680 1194 20.3
UVM2 271-14137 1144 20.7
UVW2 328-12464 1277 20.8
Where T_range is the time range of the summed images in seconds
post-trigger.
These magnitudes are based on preliminary zero-points, measured in
orbit, and will require refinement with further calibration.
GCN Circular 3803
Subject
GRB050814: Refined analysis of the Swift-BAT burst
Date
2005-08-14T21:17:56Z (21 years ago)
From
Scott Barthelmy at NASA/GSFC <Scott@lheamail.gsfc.nasa.gov>
J. Tueller (GSFC), C. Markwardt (GSFC/UMD), L. Barbier (GSFC),
S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL),
N. Gehrels (GSFC), D. Hinshaw (GSFC-SPSYS), D. Hullinger (GSFC/UMD),
H. Krimm (GSFC/USRA), P. Meszaros (PSU), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/NRC)
on behalf of the Swift-BAT team:
Using the full data set from the recent telemetry downlink, we report
further analysis of Swift-BAT GRB 050814 (trigger #150314)
(Retter, et al., GCN 3799). The ground-analysis position is
RA,Dec 264.189,+46.354 (J2000) with an uncertainty of 3 arcmin
(radius, 90%, stat+sys). The light curve shows a gradual increase
in emission starting at T-15 sec with a peak at ~T+5 sec
and then a longer gradual decline out to ~T+120 sec.
T90 is 65 +40/-20 sec. Fitting a simple power law over
the interval from T-1 to T+67 sec, the photon index is
1.80 +/- 0.17 with a fluence of 2.17 +/- 0.36 X 10^-6 erg/cm^2
in the 15-350 keV band (90% c.l.). The peak flux in a 1-sec wide window
starting at T+4.2 seconds is 1.0 +/- 0.3 ph/cm^2/sec (15-350 keV).
GCN Circular 3800
Subject
GRB 050814: Swift XRT Afterglow Localization
Date
2005-08-14T18:16:05Z (21 years ago)
From
David Burrows at PSU/Swift <dxb15@psu.edu>
D. C. Morris, D. N. Burrows, J. A. Kennea, J. L. Racusin (PSU), and N.
Gehrels (GSFC) report on behalf of the Swift XRT team:
The Swift BAT instrument detected GRB 050814 at 11:38:57 UT (Retter et al.
2005, GCN 3799). The observatory executed an automated slew to the BAT
position and the XRT began taking data at 11:41:15 UT (138 seconds after
the BAT trigger). In spite of the presence of a bright source in the
field, the XRT did not succeed in calculating an on-board centroid,
probably because of a high background level. In the ground-processed data,
we find a bright, uncataloged, rapidly fading X-ray source located at:
RA(J2000) = 17:36:45,
Dec(J2000) = +46:20:19.
We identify this as the afterglow of the GRB. We estimate an uncertainty
of about 7 arcseconds radius (90% containment). This source is located 44
arcseconds from the BAT position in GCN 3799.
GCN Circular 3799
Subject
GRB 050814: Swift detection of a burst
Date
2005-08-14T12:35:37Z (21 years ago)
From
David Burrows at PSU/Swift <dxb15@psu.edu>
A. Retter (PSU), L. Barbier (GSFC), S. Barthelmy (GSFC), A. Blustin
(UCL-MSSL), D. Burrows (PSU), C. Markwardt (GSFC/UMD), F. Marshall (GSFC),
D. Morris (PSU), D. Palmer (LANL), J. Racusin (PSU), P. Roming (PSU), and
N. Gehrels (GSFC) report on behalf of the Swift team:
At 11:38:57 UT, Swift-BAT triggered and located GRB050814
(trigger=150314). The BAT on-board calculated location is
RA,Dec 264.204,+46.333, {+17h 36m 49s, +46d 19' 58"} (J2000),
with an uncertainty of 3 arcmin (radius, 90% containment,
stat+sys). There is a single peak with an approximate
duration of 25 sec FWHM. The peak rate is approx 800 ct/s in the
15-350 keV band. We note that no BAT Position Notice was
distributed through the GCN for this burst.
The S/C slewed immediately and the XRT began taking data at 11:41:15, 138 s
after the BAT trigger. The XRT on-board centroid algorithm did not
converge and no prompt position is available. However, the lightcurve
shows a bright, decaying source in the field of view, and the spectrum
looks like a GRB. We are waiting for down-linked data to determine a position.
The UVOT began observing at 11:41:43.9 UT, 167 s after the BAT trigger. In
a 100 s V-band image, no new source is detected with respect to the DSS
image down to a 5 sigma upper limit of 18.0 mag.