GRB 041223
GCN Circular 2913
Subject
GRB041223: decay of the afterglow
Date
2004-12-26T19:42:58Z (21 years ago)
From
Daniele Malesani at SISSA-ISAS,Trieste,Italy <malesani@sissa.it>
D. Malesani, S. Covino, P. D'Avanzo, G. Tagliaferri, G. Chincarini, L.A.
Antonelli, S. Campana, M. Della Valle, F. Fiore, L. Stella, and F.M.
Zerbi report on behalf of the MISTICI collaboration:
We observed again the field of the Swift GRB 041223 (Tueller et al., GCN
2898; Burrows et al., GCN 2901), using the ESO-VLT at Paranal. Optical
and NIR observations were performed under excellent conditions (seeing
0.4") during the night of 2004 Dec 24 (~1.5 days after the GRB). We
clearly detect the candidate afterglow reported by Berger et al. (GCN
2902), for which we measure J = 20.43 +- 0.05 on 2004 Dec 25.07. The
object is pointlike at the resolution of the VLT images, and clearly
faded since our previous observation (Malesani et al., GCN 2903),
confirming that this is indeed the afterglow of GRB 041223. The decay
index is alpha = 1.6 +- 0.1 (F = K*t^-alpha).
The photometric SED derived from our optical and NIR observations is
well represented by a hard powerlaw with a spectral index beta = 0.38 +-
0.05 (F = K * nu^-beta), after correcting for Galactic extinction (A_V =
0.394 mag). Such hard values are not common for afterglows at these
stages (even without any reddening correction, the spectrum is still
hard with beta = 0.65). We note that this value is very similar to the
X-ray spectral index ~6 hours after the GRB reported by Burrows et al.
(GCN 2901), namely alpha = 0.43 +- 0.09.
This message can be cited.
GCN Circular 2910
Subject
GRB 041223: XRT afterglow spectrum and light curve
Date
2004-12-25T02:02:16Z (21 years ago)
From
Daniele Malesani at SISSA-ISAS,Trieste,Italy <malesani@sissa.it>
G. Tagliaferri, A. Moretti, P. Romano, D. Malesani, G. Chincarini, S.
Campana, C. Pagani (OAB), D.N. Burrows, J.E. Hill, J. Racusin, J.
Kennea, D. Morris, J.A. Nousek (PSU), A. Wells, J. Osborne, A.
Beardmore, K. Page (U. Leicester), P. Giommi (ASI), M. Chester (PSU), L.
Angelini, S. Barthelmy, N. Gehrels, N. White (GSFC), K. Mason (MSSL), on
behalf of the Swift XRT team, report:
We have posted online the results of the analysis of the X-ray afterglow
of GRB 041223 (Tueller et al., GCN 2898; Burrows et al., GCN 2901).
Plots displaying the lightcurve and the spectrum can be seen at
http://www.merate.mi.astro.it/~taglia/GRB041223
At the same page, a finding chart for the afterglow is also shown,
reporting a refined X-ray position obtained after running the XRT
pipeline processing software. The coordinates are
R.A. = 06:40:47.4
Dec. = -37:04:22.3
This position is just 1.5" far from the optical/NIR afterglow (Berger et
al., GCN 2902; Malesani et al., GCN 2903).
This message can be cited.
GCN Circular 2909
Subject
GRB 041223 Fluence measured by Swift-BAT
Date
2004-12-25T01:41:53Z (21 years ago)
From
Craig Markwardt at NASA/GSFC/UMD <craigm@milkyway.gsfc.nasa.gov>
GRB041223 Fluence measured by Swift-BAT
C. Markwardt (GSFC/UMD), M. Suzuki (Saitama), L. Barbier, S. Barthelmy (GSFC),
J. Cummings (GSFC), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Hullinger (GSFC/UMD), H. Krimm (GSFC/USRA), K. McLean, D. Palmer (LANL),
A. Parsons (GSFC), G. Sato (ISAS), J. Tueller (GSFC),
on behalf of the Swift BAT team:
GRB 041223 (Tueller et al., GCN #2898) was a spectrally hard burst.
Fits to the total Swift-BAT burst spectrum are consistent with a power
law, with a photon index of 1.05-1.15.
The BAT team did not quote a total band fluence in GCN 2898, due to
uncertainty in the response at high energies. Now, with further
simulations and spectral analysis, we estimate that the 15-350 keV
fluence was ~5E-5 erg/cm^2. The peak flux was 3E-6 erg/cm^2/s (15-350
keV; 1 s sampling), which is dominated by the highest energy band.
GCN Circular 2907
Subject
GRB041223: optical and NIR observations with REM
Date
2004-12-24T16:37:59Z (21 years ago)
From
Daniele Malesani at SISSA-ISAS,Trieste,Italy <malesani@sissa.it>
S. Covino, F.M. Zerbi, E. Palazzi, G. Chincarini, G. Tagliaferri, E.
Molinari, V. Testa, G. Tosti, A. Monfardini, A. Di Paola, M. Rodon�,
L.A. Antonelli, P. Conconi, G. Cutispoto, P. D'Avanzo, L. Nicastro, on
behalf of the REM/ROSS team, report:
We imaged the field of GRB 041223 (Tueller et al., GCN 2898; Burrows et
al., GCN 2901) with the robotic 60-cm REM telescope located at La Silla,
Chile. Observations were carried both in the NIR and in the optical, on
2004 Dec 24 from 02:37 UT to 03:11 UT (i.e. ~12 hours after the burst).
REM was equipped with the REMIR near-IR camera (10x10 sq arcmin FoV, JHK
filters) and the ROSS optical spectrograph/imager (10x10 sq arcmin FoV,
VRI filters).
Observations were performed under good seeing conditions. The net
exposure times were: J: 500s; H: 500s; K: 500s; V: 150s; R: 150s; I: 150s.
The comparison with the 2MASS catalog did not reveal new infrared
sources with S/N>5 at the limit of the catalog. In particular no source
is present at the position of the X-ray afterglow detected by Swift-XRT
(Burrows et al. GCN 2901) and of the optical transient reported by
Berger et al. (GCN 2902) and Malesani et al. (GCN 2903).
Also the optical observations, partly affected by the bright Moon, did
not show any convincing candidate. The 3-sigma upper limit in the R band
is R ~ 18.
This message is citeable.
GCN Circular 2903
Subject
GRB 041223: J-band observations of the afterglow
Date
2004-12-24T11:52:52Z (21 years ago)
From
Daniele Malesani at SISSA-ISAS,Trieste,Italy <malesani@sissa.it>
D. Malesani, G. Tagliaferri, G. Chincarini, S. Campana, S. Covino, L.A.
Antonelli, M. Della Valle, F. Fiore, L. Stella, F.M. Zerbi, P. D'Avanzo,
A. Moretti, and P. Romano report on behalf of the MISTICI collaboration:
We observed the field of GRB041223 (Tueller et al., GCN 2898; Burrows et
al., GCN 2901) with the ESO-VLT-UT1 equipped with the ISAAC camera,
starting on 2004 Dec 24.256 (~16 hours after the GRB). The observing
conditions were good, with a seeing of 0.6". Twelve one-minute exposures
were acquired in the J band, with a mean UT 24.261.
The source reported by Berger et al. (GCN 2902) is clearly detected in
our images, with a magnitude J = 19.51+-0.05, based on comparison with 3
nearby bright nonsaturated stars from the 2MASS catalog.
We warmly thank the ESO staff at Paranal, in particular Olivier Marco
and Jonathan Smoker, for carefully performing the observations in
service mode.
This message can be cited.
GCN Circular 2902
Subject
GRB 041223: Detection of Optical Transient with LCO40
Date
2004-12-24T07:31:22Z (21 years ago)
From
Edo Berger at Carnegie Obs <eberger@ociw.edu>
E. Berger (Carnegie Observatories), W. Krzeminski and M. Hamuy (Las
Campanas Observatory) report:
"We imaged the 7-arcmin radius error circle of GRB 041223 (GCN 2898) with
the Swope 40-inch telescope at Las Campanas Observatory starting on
December 24.185 UT (14.4 hours after the burst) in r-band for a total of
20 minutes. We find a new bright source not present in the DSS which is
located at (J2000):
RA = 06:40:47.31
DEC= -37:04:22.5
This object is located 22.5 arcsec away from the nominal position of the
X-ray counterpart detected with the XRT (GCN 2901), or about 1.5 times the
15-arcsec uncertainty radius.
Further analysis and observations are in progress"
GCN Circular 2901
Subject
GRB041223: Swift XRT Detection of X-ray Afterglow Emission
Date
2004-12-24T05:41:36Z (21 years ago)
From
David Burrows at PSU/Swift <burrows@astro.psu.edu>
D. N. Burrows, J. E. Hill, J. Racusin, J. Kennea, D. Morris, J. A. Nousek
(PSU), G. Chincarini, G. Tagliaferri, A. Moretti, P. Romano, S. Campana, D.
Malesani, C. Pagani (OAB), A. Wells, J. Osborne, A. Beardmore, K. Page (U.
Leicester), P. Giommi (ASI), M. Chester (PSU), S. Barthelmy, N. Gehrels, N.
White (GSFC), K. Mason (MSSL), on behalf of the Swift XRT team.
The Swift X-Ray Telescope (XRT) was pointed at GRB041223 (GCN 2898, Tueller
et al.) on 2004/12/23 at 18:43:59 UT for 1490 s, at 20:16:24.4s for 1600 s,
and at 21:50:40 for 430 s. The spacecraft did not autonomously slew to the
burst since automated slewing is not yet enabled and the XRT is in the
midst of engineering measurements. The observation was performed as a
Target of Opportunity beginning about 4.5 hours after the burst.
We detect a fading X-ray source about 3.5 arcminutes from the BAT
position. The ground-calculated positions were checked through two
independent data processing and analysis techniques, which yielded
consistent sky positions within 22 arcseconds. Our best estimate of the
X-ray afterglow position is 06:40:49.2, -37:04:21.5 (J2000) for the first
observation. The position determined independently for the second
observation was within 4 arcseconds of these coordinates. The XRT
alignment is not yet fully calibrated, and we estimate a systematic
uncertainty of about 15 arcseconds in this position. Checks against
SIMBAD, DSS and X-ray catalogs from ROSAT, ASCA, XMM, and Chandra yielded
no known source at this position on the sky.
We have a total of about 580 counts from this object in the first two
observations. A simple power-law fit to the spectrum gives a photon index
of 1.43 +/- 0.09 and model fluxes of 1.7E-12 ( 0.5-2 keV) and 4.7E-12 (2-10
keV) ergs/cm**2/s. We caution that the instrument is not yet fully
calibrated and that these fluxes may have systematic uncertainties of
15%. The light curve based on all three observations is well fit with a
power-law index of 2.2 +/- 0.3.
GCN Circular 2899
Subject
GRB041223: ROTSE-III Optical Observations
Date
2004-12-23T20:08:44Z (21 years ago)
From
Eli Rykoff at Univ. of Michigan/ROTSE <erykoff@umich.edu>
E. Rykoff (U. Michigan) reports on behalf of the ROTSE collaboration:
ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia,
responded to Swift GRB041223 (GCN #2898). A manual response was
initiated at 18:27 UT, around 4.5 hours after the burst. We took 10 5-s
exposures followed by 200 20-s exposures. The first images were taken
during twilight, and all the images were taken with >90% moon
illumination. The unfiltered images were calibrated relative to USNO
A2.0. Individual images had limiting magnitudes around 16.8. Comparison
to DSS (second epoch) reveals no new sources within the 3-sigma error
circle to a limiting magnitude of 18.4 for a stack of the first 90 images.
GCN Circular 2898
Subject
GRB041223: Swift-BAT detection of a bright long burst
Date
2004-12-23T17:58:52Z (21 years ago)
From
Scott Barthelmy at NASA/GSFC <Scott@lheamail.gsfc.nasa.gov>
J. Tueller, L. Barbier, S. Barthelmy (GSFC), A. Beardmore (U.Leicester),
L. Cominsky (Sonoma State U), J. Cummings (GSFC), E. Fenimore (LANL),
N. Gehrels (GSFC), S.T. Holland (GSFC/USRA), D. Hullinger (GSFC/UMD),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean, D. Palmer (LANL),
A. Parsons (GSFC), G. Sato (ISAS), M. Suzuki (Saitama), G. Tagliaferri (OAB)
on behalf of the Swift BAT team:
At 14:06:18 UT, the Swift Burst Alert Telescope (BAT) triggered and
located on-board GRB041223. The spacecraft did not autonomously slew
to the burst since automated slewing was not yet enabled.
The BAT ground-calculated location is RA,Dec 100.183,-37.066 (J2000)
with an uncertainty of 7 arcmin (radius, 3-sigma, including systematic
uncertainty using a preliminary bore-sight alignment calibration).
This is 27 degrees off the BAT bore sight and was in the partially encoded
field of view.
The burst lightcurve is multi-peaked with structure within the peaks
with the main emission lasting ~60 sec. The peak flux was 7.5 events/cm^2/sec
(1-sec sampling; unsaturated; ~15 to 100 keV; ~28 Crab).
The total duration was ~130 sec. The fluence was ~2e-5erg/cm^2.
A reduced energy band is being quoted because of our response uncertainty
in the >100 keV band, and because of strong emission by this burst
in this band.