GRB 070220
GCN Circular 6223
Subject
GRB070220: optical observations
Date
2007-03-23T19:09:29Z (20 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Rumyantsev (CrAO), A. Pozanenko (IKI) on behalf of larger GRB follow up
collaboration report:
We observed error box of GRB070220 (Stamatikos et al., GCN 6114) with Shajn
2.6m telescope of CrAO in R-band on Feb. 8 between (UT)19:25 and 19:53. No
object is found in refined XRT error box (Beardmore et al., GCN 6118).
Limiting magnitude of a combined image is based on USANO A2.0:
Mid time (UT), Exposure, R_Lim (3sigma)
Feb. 8.819 22x60 23.9
The combined image can be found in
http://grb.rssi.ru/GRB070220/grb070220_R_ZTSh.gif
This message may be cited.
GCN Circular 6149
Subject
VLA observation of GRB 070220
Date
2007-02-26T17:50:18Z (20 years ago)
From
Poonam Chandra at U Virginia/NRAO <pc8s@virginia.edu>
Poonam Chandra (NRAO/UVA) and Dale A. Frail (NRAO) report on behalf of
the Caltech-NRAO-Carnegie GRB Collaboration:
"We used the Very Large Array to observe the field of view toward GRB
070220 (GCN 6114) at a frequency of 8.46 GHz on 2007 February 24 at
0.94 UT. The GRB is undetected and the peak radio brightness at the
SWIFT-XRT position (GCN 6118) is 15 uJy � 50 uJy.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
GCN Circular 6135
Subject
RHESSI Spectrum of GRB070220
Date
2007-02-23T18:32:12Z (20 years ago)
From
Eric Bellm at UCB/SSL <ebellm@ssl.berkeley.edu>
C. Wigger, E. Bellm, M. Bandstra, S. Boggs, W. Hajdas,
D. M. Smith, and K. Hurley on behalf of the RHESSI team report:
As observed by RHESSI, GRB070220 (M. Stamatikos et al., GCN 6114)
had a duration of ~30s starting at about T0=04:44:33 UT.
A fit to the time-integrated RHESSI spectrum of the main period of
emission from T0 - T0+18s between 30 keV and 3.0 MeV gives a
cutoff power law, with
alpha = -0.65 +0.40/-0.35
E0 = 235 +180/-90 keV
Epeak = 315 +115/-70 keV
(90% confidence levels).
The 20 keV-2 MeV fluence is (1.14 +0.16/-0.12) E-5 erg/cm^2.
GCN Circular 6129
Subject
GRB 070220: pseudo-z~2.15 from spectral parameters of the prompt
Date
2007-02-23T10:48:20Z (20 years ago)
From
Alexandre Pelangeon at LATT,OMP,Toulouse <alexandre.pelangeon@ast.obs-mip.fr>
A. Pelangeon & J-L. Atteia (LATT-OMP) report:
We have used the spectral parameters of GRB 070220
provided by Golenetskii et al. (GCNC 6124) to compute the spectral
pseudo-redshift** of this burst detected by SWIFT-BAT
(Stamatikos et al., GCNC 6114; Parsons et al., GCNC 6121).
We find a pseudo-redshift pz= 2.15 � 0.80
** cf. http://www.ast.obs-mip.fr/grb/pz
GCN Circular 6124
Subject
Konus-Wind and Konus-A observations of GRB 070220
Date
2007-02-21T14:46:52Z (20 years ago)
From
Valentin Pal'shin at Ioffe Inst <val@mail.ioffe.ru>
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and
T. Cline on behalf of the Konus-Wind team report:
The long GRB 070220 (Swift-BAT trigger #261299:
Stamatikos et al., GCN 6114; Parsons et al., GCN 6121)
triggered Konus-Wind at T0=17076.976 s UT (04:44:36.976).
Konus-A observed GRB 070220 in the waiting mode.
The Konus-Wind light curve shows a multipeaked pulse
with a long decaying tail clearly seen up to T-T0 ~130 sec
in both G1(18-70 keV) and G2(70-300 keV) bands.
So, the Swift XRT and UVOT were on target and begun
observations during the hard prompt emission
(Stamatikos et al., GCN 6114; Beardmore et al., GCN 6118;
M. De Pasquale and M. Stamatikos 6120).
As observed by Konus-Wind the burst had a
fluence of (2.98 +/- 1.15)x10^-5 erg/cm2,
and the 256-ms peak flux measured from T0+9.600 s
(2.47 +/- 0.50)x10^-6 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).
The time-integrated spectrum of the GRB
(from T0 to T0+123.136 s) is well fitted (in the 20 keV - 2 MeV range)
by GRBM (Band) model for which:
the low-energy photon index is alpha = -1.21 (-0.19, +0.29),
the high energy photon index beta = -2.02 (-0.44, +0.27),
the peak energy Ep = 299 (-130, +204) keV (chi2 = 52/60 dof).
Fitting by a power law with exponential cutoff model:
dN/dE ~ E^(-alpha) * exp(-(2-alpha)*E/Ep)
yields alpha = 1.33(-0.18, +0.15)
and Ep = 443(-150, +420) keV (chi2 = 55/61 dof).
The spectrum of the burst maximum
(accumulated from T0 s to T0+16.640 s)
is well fitted
(in the 20 keV - 2 MeV range)
by GRBM (Band) model for which:
the low-energy photon index is alpha = -1.04 (-0.15, 0.18),
the high energy photon index beta = -2.07 (-0.36, 0.18),
the peak energy Ep = 261 (-57, +81) keV (chi2 = 59/60 dof).
The fluence of this part is 1.62(-0.20, +0.19)x10^-5 erg/cm2.
All the quoted errors are at the 90% confidence level.
The Konus-Wind light curve of this GRB is available
at http://www.ioffe.rssi.ru/LEA/GRBs/GRB070220_T17076/
GCN Circular 6123
Subject
GRB 070220: MITSuME Okayama Optical Observation
Date
2007-02-21T09:43:09Z (20 years ago)
From
Michitoshi Yoshida at Okayama Astrophysical Obs <yoshida@oao.nao.ac.jp>
M. Yoshida, K. Yanagisawa, (OAO, NAOJ) and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:
We performed optical imaging observation of the field of GRB 070220
(GCN 6114, GCN 6118) with 50cm MITSuME telescope at Okayama Astrophysical
Observatory from UT 9:57 to UT 12:11 on Feb. 20 2007.
We coadded 105 Ic band frames with a 1 minute exposure time. We made
flux calibration using USNO B1.0 catalg. The three sigma limiting magnitude
of our observation was 20.2 in Ic band. We could not find optical afterglow
candidate in the error circle reported in GCN 6118.
----------------------------------------------------
band mid-UT exp.time upper limit
Ic Feb. 20 11:24 105 x 1 min. 20.2 mag
----------------------------------------------------
GCN Circular 6122
Subject
GRB 070220: ART-3 Optical and NIR limits
Date
2007-02-21T07:53:10Z (20 years ago)
From
Ken ichi Torii at Osaka U <torii@ess.sci.osaka-u.ac.jp>
K. Torii, S. Tanaka, and H. Tsunemi (Osaka U.) report:
The error region of GRB 070220 (Stamatikos et al. GCN 6114;
Beardmore et al. GCN 6118) was observed with the 14 inch
ART-3a and 0.35 m ART-3b, both located in Toyonaka, Osaka.
The imaging started at 2007 Feb. 20, 09:27:03 UT (4.7 hours
after the burst) in Ic band (ART-3a), and at 09:55:44 UT in
J band (ART-3b equipped with thermoelectrically cooled
InGaAs array). We do not detect neither optical nor near
infrared counterpart for the X-ray afterglow (GCN 6114,
6118), and derive the following 3 sigma upper limits
relative to USNO-B1.0 I2 and 2MASS J magnitudes.
-----------------------------------------
StartUT Filter Limit Exposure
=========================================
09:53:18 Ic 19.4 60s x 75
09:55:44 J 14.4 20s x 200
11:12:03 Ic 19.4 60s x 100
=========================================
GCN Circular 6121
Subject
GRB 070220 Swift-BAT Refined Analysis
Date
2007-02-20T22:38:05Z (20 years ago)
From
Michael Stamatikos at GSFC <michael@milkyway.gsfc.nasa.gov>
A. Parsons (GSFC), 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),
T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
on behalf of the Swift-BAT team:
Using the data set from T-240 to T+1000 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 070220
(trigger #261299) (Stamatikos, et al., GCN Circ. 6114). The BAT
ground-calculated position is RA, Dec = 34.800, 68.800 deg which is
RA(J2000) = 2h 19m 11.9s
Dec(J2000) = 68d 48' 1.6"
with an uncertainty of 1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 64%.
The mask-weighted lightcurve shows a multiple peaked structure.
T90 (15-350 keV) is 129 +- 6 sec (estimated error including systematics).
The time-averaged spectrum from T-17 to T+240 is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is 1.45
+- 0.04. The fluence in the 15-150 keV band is 1.06 +- 0.02 x 10^-5 erg/cm2.
The 1-sec peak photon flux measured from T+12 sec in the 15-150 keV band is
5.88 +- 0.29 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
GCN Circular 6120
Subject
Swift/UVOT refined analysis of GRB070220
Date
2007-02-20T20:00:11Z (20 years ago)
From
Massimiliano de Pasquale at MSSL-UCL <mdp@mssl.ucl.ac.uk>
M. De Pasquale (MSSL/UCL) and M. Stamatikos (NASA/ORAU) report on
behalf of the Swift UVOT team:
The Swift/UVOT observed the field of GRB 070220 starting 70 s
after the BAT trigger (Stamatikos et al. 2007, GCN Circ. 6114) with
the settling exposure.
We do not find any source, in any of the UVOT observations, inside
the refined XRT error circle (Beardmore et al., 2007 GCN Circ. 6118).
We have the following 3-sigma upper limits for a source inside the
XRT error circle in the first exposure with White filter and in the
co-added frames with all filters:
Filter T_start T_stop Exp(s) Mag (3-sigma UL)
-----------------------------------------------------------------
White 90 190 98 19.6
V 195 7101 1278 20.0
B 673 6487 276 20.2
U 649 7627 410 20.0
UVW1 625 7510 498 19.7
UVM2 601 7306 498 20.1
UVW2 701 6897 498 20.1
White 90 6691 638 20.6
-----------------------------------------------------------------
The values quoted above are not corrected for the expected Galactic
extinction corresponding to a reddening of E_{B-V} = 0.9 mag towards
the direction of the burst (Schlegel et al. 1998).
GCN Circular 6118
Subject
GRB 070220: Swift-XRT Refined Analysis
Date
2007-02-20T13:04:43Z (20 years ago)
From
Andy Beardmore at U Leicester <apb@star.le.ac.uk>
A.P. Beardmore (U. Leicester), M. Stamatikos (NASA/ORAU), P.A. Evans,
M.R. Goad, O. Godet, K.L. Page, (U. Leicester), M. Capalbi (ASDC),
J.P. Osborne, R.L.C. Starling (U. Leicester) report on behalf of the
Swift-XRT team:
We have analysed the first two orbits of Swift-XRT data available for
GRB 070220 (Stamatikos et al., GCN 6114), which were obtained prior to
the satellite entering the Malindi Gap. The data consist of 217s
exposure in Windowed Timing (WT) mode and 4090s in Photon Counting
(PC) mode.
Using the PC data, we find a refined XRT position, which has been
astrometrically corrected by matching the UVOT images with the
USNO-B1 catalogue, of:
RA(J2000) = 02h 19m 06.83s
DEC(J2000) = +68d 48' 16.1"
with an uncertainty of 2.0 arcseconds (90% confidence). This position
is 72.0 arcseconds and 3.0 arcseconds away from the original BAT and
XRT positions quoted in GCN 6114.
The 0.3-10.0 keV X-ray light curve out to T+7.6ks (where T is the BAT
trigger time) can be fit by a broken powerlaw, with an initial decay
slope of 1.76+/-0.06, a break time of 417+/-43s, and a post-break
slope of 0.99+/-0.04.
The WT spectrum from T+85s to T+294s can be modelled by an absorbed
powerlaw, with a photon index of 1.55+/-0.08 and a column density of
(4.9+/-0.5)e21 cm^-2 (compared with the Galactic value in this
direction of 3.8e21 cm^-2). The 0.3-10.0 keV observed flux over this
time interval is (1.21+/-0.05)e-9 ergs cm^-2 s^-1, which corresponds
to an unabsorbed flux of (1.65+/-0.10)e-9 ergs cm^-2 s^-1.
While the temporal decay parameters are uncertain based on such
limited data, assuming the source continues to fade at the same rate
we predict an X-ray count rate of 0.019 count/s at T+24 hours, which
corresponds to an observed (unabsorbed) 0.3-10.0 keV flux of 1.4e-12
(1.9e-12) ergs cm^2 s^-1.
This circular is an official product of the Swift-XRT team.
GCN Circular 6117
Subject
GRB 070220: Observation with the KANATA 1.5m telescope
Date
2007-02-20T11:00:27Z (20 years ago)
From
Akira Arai at Hiroshima U <arai-akira@hiroshima-u.ac.jp>
A. Arai, M. Uemura and T. Uehara (Hiroshima Univ.),
report on behalf of the KANATA GRB team:
We perfomed optical imaging of the field of GRB070220 (GCN 6114) at
9:59-10:20 UT 20 Feb. using TRISPEC attached to the KANATA
1.5-m telescope at Higashi-Hiroshima Observatory, Japan.
We obtained 10 Rc-band images with a 123-s exposure time.
The images were calibrated with neighbor stars
in the USNO A2.0 catalog (r mag ).
We cannot significantly detect the optical afterglow
at the position of the X-ray afterglow reported in GCN 6114 in our images.
The limit magnitude is estimated to be 21.2 (3-sigma).
UT Limit mag in Rc Exp. Time
Feb. 20.42381 21.2 123 * 10
-------------------------------------------
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$BJ*M}2J3X@l96(B $B9b%(%M%k%.!<1'Ch!&AGN3;R<B83(B
D1 $B?70f(B $B>4(B(Arai Akira)
-------------------------------------------
GCN Circular 6115
Subject
GRB 070220 : Faulkes Telescope North optical limit
Date
2007-02-20T06:15:07Z (20 years ago)
From
Andrea Melandri at Liverpool John Moores U <axm@astro.livjm.ac.uk>
A. Melandri (Liverpool JMU), A. Gomboc (Ljubljana), R. J. Smith,
C. G. Mundell, C. Guidorzi, D. Carter, I. A. Steele, C. J. Mottram,
D. F. Bersier, S. Kobayashi, M. F. Bode (Liverpool JMU), P. O'Brien,
E. Rol, N. Bannister (Leicester) report
The 2-m Faulkes Telescope North robotically followed up GRB070220
(Stamatikos et al., GCN 6114, trigger=261299) beginning ~2 minutes
after the GRB trigger time (UT:04:44:33).
No new object has been detected inside the XRT error circle (Stamatikos
et al., GCN 6114) down to a limiting magnitude of R~19.5 for a coadded
frame with a total exposure time of 420 sec, at a mean epoch of 28 min
after the burst (comparison with respect to the USNO B1 catalog).
Further observations are ongoing.
GCN Circular 6114
Subject
GRB 070220: Swift detection of a burst
Date
2007-02-20T05:05:13Z (20 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
M. Stamatikos (NASA/ORAU), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
N. Gehrels (NASA/GSFC), S. Immler (GSFC/USRA), J. A. Kennea (PSU),
F. E. Marshall (NASA/GSFC), C. Pagani (PSU),
K. L. Page (U Leicester), D. M. Palmer (LANL),
T. Sakamoto (NASA/ORAU), P. Schady (MSSL-UCL) and
D. E. Vanden Berk (PSU) report on behalf of the Swift Team:
At 04:44:33 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070220 (trigger=261299). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 34.819, +68.818 which is
RA(J2000) = +02h 19m 17s
Dec(J2000) = +68d 49' 06"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows multiple peaks
with a duration of about 60 sec. The peak count rate
was ~7000 counts/sec (15-350 keV), at ~15 sec after the trigger.
The XRT began observing the field at 04:45:51 UT, 79 seconds after the
BAT trigger. XRT found a bright, fading, uncatalogued X-ray source
located at RA, Dec 34.7765, +68.8052 which is
RA(J2000) = 02h 19m 06.3s
Dec(J2000) = 68d 48' 18.7"
with an uncertainty of 4.7 arcseconds (radius, 90% containment).
This location is 72 arcseconds from the BAT on-board position,
within the BAT error circle. The initial flux in the 2.5s image
was 4.5e-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 88 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 in a 100s white band exposure is 19.6 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 0.90.