GRB 061218
GCN Circular 5980
Subject
GRB 061218: TAROT La Silla observatory early optical observations
Date
2006-12-25T01:46:47Z (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 solve technichal problems that prevent to
acces to the first trailed image of GRB 061218
obtained with TAROT located at the European Southern
Observatory, La Silla observatory, Chile.
The observations started 61s after the GRB trigger
(4s after the notice). The trailed image allows to
follow continuously variable sources during the 60s
integration time (see technichal description in
Klotz et al., 2006, A&A 451, L39). We analyzed
the GRB error box provided by Sato et al. GCN
Circ. 5940. No variable object is detected.
To summarize:
t0+ 61.0s to t0+121.0s : R > 15.8
t0+126.5s to t0+156.5s : R > 17.4 (CGNC 5943)
t0+162.3s to t0+192.3s : R > 17.4 (CGNC 5943)
t0+126.5s to t0+510.6s : R > 18.0 (CGNC 5943)
Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.
This message may be cited.
GCN Circular 5943
Subject
GRB 061218: TAROT La Silla observatory optical observations
Date
2006-12-19T22:54:35Z (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 061218 detected by SWIFT
(trigger 251863) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.
The observations started 126.5s after the GRB trigger
(69.6s after the notice). The elevation of the field increased from
from 30 degrees above horizon and weather conditions
were good.
The date of trigger : t0 = 2006-12-18T04:05:06.144
A technichal problem prevent to obtain a 60s image
at t0+58s. Moreover, images are slightly defocussed.
We examined the BAT position provided by
Sato et al. 2006 (GCN Circ. 5940).
The first image is 30.0s exposure in tracking mode:
We do not detect any OT with a limiting magnitude of:
t0+126.5s to t0+156.5s : R > 17.4
The second image is 30.0s exposure:
t0+162.3s to t0+192.3s : R > 17.4
We co-added a series of exposures:
t0+126.5s to t0+510.6s : R > 18.0
Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.
N.B. Galactic coordinates are lon=267.1250 lat=+15.3187
and the galactic extinction in R band is 0.3 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.
This message may be cited.
GCN Circular 5941
Subject
GRB 061218: TORTOREM optical upper limits
Date
2006-12-19T16:05:22Z (19 years ago)
From
Giuseppe Greco at U Bologna <giuseppe.greco2@studio.unibo.it>
S. Karpov, G. Beskin, S. Bondar, C. Bartolini, G. Greco, A. Guarnieri,
D. Nanni, A. Piccioni, F. Terra, E. Molinari, G. Chincarini, F.M. Zerbi,
S. Covino, V. Testa, G. Tosti, F. Vitali, L.A. Antonelli, P. Conconi, G.
Cutispoto, G. Malaspina, L. Nicastro, E. Palazzi, E. Meurs, P. Goldoni
report on behalf of the TORTOREM team:
The field of GRB 061218 (Zane et al. GCN 5936) has been observed by the
TORTORA (Telescopio Ottimizzato per la Ricerca di Transienti Ottici
RApidi) wide-field fast camera (12 cm diameter, 20x25 deg FOV) mounted
on REM robotic 60-cm telescope located at La Silla (Chile). The burst
was initially outside the camera field of view. The system was repointed
and the TORTORA began to acquire frames at 04:07:03 UT (118 sec after
trigger) with 7.5 Hz frame frequency (0.128 s exposure).
The summation of 100 frames with 12.8 s. effective exposure (middle time
04:07:16 UT) did not reveal any source down to the B = 11.3 mag (3-sigma).
We performed the Fourier analysis of 23 min data set (10000 successive
frames) to search for the periodic signal at the GRB position. The upper
limit for the amplitude of sinusoidal variability is B=16.4 (3-sigma)
over the 0.01 - 3.5 Hz range.
The message may be cited.
GCN Circular 5940
Subject
GRB 061218, Swift-BAT refined analysis
Date
2006-12-19T00:32:19Z (19 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <jayc@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),
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), S. Zane (UCL-MSSL)
on behalf of the Swift-BAT team:
Using the data set from T-120 to T+183 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 061218 (trigger
#251863) (Zane, et al., GCN Circ. 5936). The BAT ground-calculated
position is RA, Dec = 149.238, -35.221 deg which is
RA(J2000) = 09h 56m 57.0s
Dec(J2000) = -35d 13' 15.9"
with an uncertainty of 4 arcmin, (radius, sys+stat, 90% containment).
The burst was in the fully-coded field of view.
The mask-weighted lightcurve consists of a single very weak pulse
lasting about 7 sec. T90 (15-350 keV) is 4.1 +- 0.5 sec (estimated
error including systematics).
The time-averaged spectrum from T+0.0 to T+4.1 is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.76 +- 0.63. The fluence in the 15-150 keV band is 4.1 +- 1.5 x 10^-8 erg/cm2.
The 1-sec peak photon flux measured from T+0.00 sec in the 15-150 keV band
is 0.2 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
GCN Circular 5938
Subject
GRB 061218, SMARTS optical/IR observations
Date
2006-12-18T05:35:07Z (19 years ago)
From
Bethany Cobb at Yale U <cobb@astro.yale.edu>
B. E. Cobb (Yale), part of the larger SMARTS consortium, reports:
Using the ANDICAM instrument on the 1.3m telescope at CTIO, we
obtained optical/IR imaging of the error region of GRB 061218
(GCN 5936, Zane et al.), with a mid-exposure time of
2006-12-18 04:44:48 UT, which is ~0.7 hours post-burst.
Our optical images have a field of view of 6'x6' and,
therefore, cover the entire GRB error circle.
Our IR images have a smaller field of view, covering a region
totaling ~6 square arcminutes in the middle of the quoted error region.
Several dithered images were obtained in each filter,
with total summed exposure times of 180s in each of BRIYJK and
120s in each of H and V.
Preliminary visual comparison of the optical images to the DSS
and the IR images to 2MASS frames does not reveal any new sources
to the limit of the comparison frames.
GCN Circular 5937
Subject
GRB 061218: REM prompt observations
Date
2006-12-18T05:17:33Z (19 years ago)
From
Paolo D'Avanzo at INAF-OAB <paolo.davanzo@brera.inaf.it>
P. D'Avanzo, S. Covino, E. Molinari, G. Chincarini, F.M. Zerbi, V.
Testa, G. Tosti, F. Vitali, P. Conconi, L.A. Antonelli, G. Cutispoto,
G. Malaspina, L. Nicastro, E. Palazzi, E. Meurs, and P. Goldoni report
on behalf of the REM/ROSS team
We observed the field of the possible GRB 061218 (Zane et al. GCN 5936) with
the robotic 60-cm REM telescope located at La Silla (Chile). A set of
observations was performed automatically in the optical and near
infrared filters (V, R, I and J, H, K, z) starting on 2006 December 18
at 04:07:14 UT, 71 s after the BAT trigger and 129 s after the GRB time.
Preliminary analysis of the whole dataset does not show any new
variable source inside the BAT error box.
The 3-sigma limiting magnitudes are:
R~18.6
J~16.7
H~16.0
K~15.3
This message may be cited.