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GRB 070224

GCN Circular 6137

Subject
GRB 070224: Swift detection of a burst
Date
2007-02-24T20:48:09Z (18 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
J. L. Racusin (PSU), L. M. Barbier (NASA/GSFC),
S. D. Barthelmy (GSFC), M. M. Chester (PSU),
G. Cusumano (INAF-IASFPA), D. Grupe (PSU), J. A. Kennea (PSU),
D. M. Palmer (LANL), R. L. C. Starling (U Leicester) and
L. Vetere (PSU) report on behalf of the Swift Team:

At 20:27:58 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070224 (trigger=261880).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 178.990, -13.340 which is 
   RA(J2000)  =  11h 55m 58s
   Dec(J2000) = -13d 20' 23"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single peak
with a duration of about 25 sec.  The peak count rate
was ~500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 20:30:21 UT, 143 seconds after the
BAT trigger. XRT found a bright, fading, uncatalogued X-ray source
located at RA, Dec 179.0257, -13.3294 which is
   RA(J2000)  =  11h 56m 06.2s
   Dec(J2000) = -13d 19' 46.0"
with an uncertainty of 4.2 arcseconds (radius, 90% containment). 
This location is 131 arcseconds from the BAT on-board position,
within the BAT error circle. The initial flux in the 2.5s image
was 3.1e-10 erg/cm2/s (0.2-10 keV). 

UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 153 seconds after the BAT trigger, and a
finding chart of nominal 400 seconds with the V filter starting 259
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 White at the XRT
position is 19.3 mag. The 8'x8' region for the list of sources
generated on-board covers 100% of the XRT error circle. No correction
has been made for the expected extinction corresponding to E(B-V) of
0.06.

GCN Circular 6138

Subject
GRB 070224: MASTER observations
Date
2007-02-24T21:03:48Z (18 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
V. Lipunov, V.Kornilov, D.Kuvshinov, N.Tyurina, A.Belinski, E.Gorbovskoy,
A.Krylov,N.Shatskiy ,G.Borisov, A.Sankovich, G.Antipov, V.Vladimirov
P.Gritsyk

Sternberg Astronomical Institute, Moscow Union 'Optic'
MASTER  robotic system (http://observ.pereplet.ru) responded to GRB070224.9 (GRB_TIME is 2007-02-24 20:27:58.21).
The first image was at 2007-02-24 20:30:04 UT, 51s after notice 
arrivel time and 00:02:05.79  after the GRB time
The unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B).
The robot not find OT-candidate in error box brighter then  16.2 (s/n=10).
The JPG-image will be  available at
http://observ.pereplet.ru/images/GRB070224.9/img/i12.jpg
The reduction is continuing.
This message can be cited.
Mailto: lipunov@sai.msu.ru

GCN Circular 6139

Subject
GRB 070224: MASTER-VWF-Kislovodsk observations
Date
2007-02-24T21:43:27Z (18 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
V. Lipunov, V.Kornilov, N.Shatskiy, E.Gorbovskoy, A.Belinski, D.Kuvshinov, 
N.Tyurina, P.Gritsyk
Sternberg Astronomical Institute, Moscow Union 'Optic'

A. Tlatov, I.Golubov
Kislovodsk Solar Station of the Pulkovo observatory

MASTER Very Wide Field Camera located at Kislovodsk Solar Station
(http://observ.pereplet.ru, D=70 mm, 420 square degrees, 11 Mpixel's CCD) has 
moved to the Swift-BAT trigger 261880 and it has taken a series of 5s 
exposures 
starting 2 s after notice arrivel time at  20:29:38.285 UT under good 
weather  condition and waxing moon.

We note that the GBR position (J. L. Racusin et al. GCN Circ No. 6137) was 
at 4 degrees outside of the our field of view.

We note that the VWF camera continuously takes frames during the night.


These unfiltered images are calibrated relative to USNO A2.0 (R).
There is no OT was found inside Swift error box.

T-Tgrb     Mean Time     Limit   Coadd?

29s        29.5s        11.0     no

29s        59 s         12.0     12




The message can be cited.

mailto: lipunov@sai.msu.ru

GCN Circular 6140

Subject
GRB 070224: MASTER-Net refind analysis
Date
2007-02-24T22:53:17Z (18 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
V. Lipunov, V.Kornilov, D.Kuvshinov,  A.Belinski, E.Gorbovskoy,
A.Krylov, N.Shatskiy, N.Tyurina,G.Borisov, A.Sankovich, V.Vladimirov, 
V.Vibornov, A.Kuznetsov
Sternberg Astronomical Institute, Moscow Union 'Optic'

A. Tlatov, I.Golubov
Kislovodsk Solar Station of the Pulkovo observatory

MASTER Very Wide Field Camera located at Kislovodsk Solar Station
(http://observ.pereplet.ru, D=70 mm, 420 square degrees, 11 Mpixel's CCD) 
has moved to the Swift-BAT trigger 261880 and it has taken a series of 5s
exposures starting 2 s after notice arrivel time at  20:29:38.285 UT under 
good weather  condition and waxing moon.

We note that the GBR position (J. L. Racusin et al. GCN Circ No. 6137) was
at 4 degrees outside of the our field of view.

We note that the VWF camera continuously takes frames during the night.
These unfiltered images are calibrated relative to USNO A2.0 (R).
The robot not find OT-candidate.

T-Tgrb     Mean Time     Limit   Coadd?   Exp

100s        100.5s        11.0     no      5s
100s        130 s         12.0     yes   12x5s
100s        222 s         13.3     yes   47x5s

MASTER  robotic system (D=355mm, http://observ.pereplet.ru, Moscow) 
responded to 
GRB070224  (GRB_TIME is 2007-02-24 20:27:58.21).
The first image was at 2007-02-24 20:30:04 UT, 51s after notice arrivel time 
and 00:02:05.79  after the GRB time at large zenit distance.
The unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B).
The robot not find OT-candidate.


T-Tgrb     Mean Time     Limit   Coadd?  Exp

125s        140s         16.2     no     30s
125s        924s         18.0    yes     31x30s


This message can be cited.
Mailto: lipunov@sai.msu.ru

GCN Circular 6141

Subject
GRB 070224, Swift-BAT refined analysis
Date
2007-02-25T00:34:25Z (18 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
J. Tueller (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),
A. Parsons (GSFC), J. L. Racusin (PSU), T. Sakamoto (GSFC/ORAU),
G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU)
on behalf of the Swift-BAT team:
 
Using the data set from T-239 to T+482 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 070224 (trigger #261880)
(Racusin, et al., GCN Circ. 6137).  The BAT ground-calculated position
is RA, Dec = 178.987, -13.356 deg which is 
   RA(J2000)  =  11h 55m 57.0s 
   Dec(J2000) = -13d 21' 20.1" 
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
 
The mask-weighted lightcurve shows two overlapping peaks starting at ~T-20 sec
and decaying back to background at ~T+50 sec.  T90 (15-350 keV) is 34 +- 1 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-13.8 to T+24.3 is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.42 +- 0.30.  The fluence in the 15-150 keV band is 3.1 +- 0.5 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-13.76 sec in the 15-150 keV band
is 0.3 +- 0.1 ph/cm2/sec.  All the quoted errors are at the 90%
confidence level.

GCN Circular 6142

Subject
GRB 070224: optical afterglow candidate
Date
2007-02-25T05:02:38Z (18 years ago)
From
Christina Thoene at Niels Bohr Institute,DARK Cosmo Ctr <cthoene@astro.ku.dk>
Christina C. Thoene (DARK), D. Alexander Kann (TLS Tautenburg) and Thomas
Augusteijn (NOT) report:

We observed the field of GRB 070224 (GCN 6137) with NOT and StanCAM in R
and I filters starting 4.35h after the burst.

In 3x300s stacked images, we detect a faint object in both R and I close
to the XRT error circle at

RA = 11:56:06.68
Dec = -13:19:47.6 (J2000)

with conservative errors of 1".
This is about 5 arcseconds from the refined XRT error circle center (GCN
6143).

We propose this object to be the optical afterglow of GRB 070224.
At the moment, we cannot confirm if the object is fading or not. Further
observations are planned.

GCN Circular 6143

Subject
GRB070224: Swift-XRT Refined Analysis
Date
2007-02-25T05:11:37Z (18 years ago)
From
Judith Racusin at PSU <racusin@astro.psu.edu>
J. Racusin, J. Kennea, D. Morris, C. Pagani, L. Vetere (PSU) report on 
behalf of the Swift-XRT team:

We have analysed the first 3 orbits of Swift-XRT data available for GRB 
070224 (Racusin et al., GCN 6137), consisting of 45 s of Windowed Timing 
(WT) mode data, and ~1.7 ks of Photon Counting (PC) mode data.  The 
refined XRT position from the PC data is RA,Dec= 179.02684, -13.3304 which 
is:

RA(J2000)  = 11h 56m 06.44s
Dec(J2000) = -13d 19' 49.5"

with an uncertainty of 3.8 arcsec (90% containment). This is 5.0 
arcseconds from the initial position reported in GCN 6137, and 134 
arcseconds from the BAT refined position (Tueller et al., GCN 6141).

The preliminary 0.3-10.0 keV lightcurve shows a steep fading behavior in 
the first orbit with a decay index of 3.1 +/- 0.2.  The data in the 
subsequent orbits provides only an upper limit.  It is not currently 
possible to determine if there has been a break to a flatter decay.

The WT spectrum is fit by an absorbed power-law with a photon index of 2.8 
+/- 0.6.  The absorption is at a level of 6.0e20 cm^-2, consistent with 
Galactic absorption along the line of sight (4.1e20 cm^-2).  The average 
0.3-10 keV unabsorbed flux of the WT spectrum is 2.1e-10 ergs cm^-2 s^-1.

This circular is an official product of the Swift-XRT team.

GCN Circular 6144

Subject
GRB 070224: SARA upper limit
Date
2007-02-25T07:49:49Z (18 years ago)
From
Adria C. Updike at Clemson U <aupdike@clemson.edu>
A. C. Updike, H. A. Eid, D. H. Hartmann (Clemson University), T. H.
Robertson, T. M. Jordan (Ball State University), and D. A. Kann (TLS)
report on behalf of the Clemson GRB Follow-Up Team:

The .9m SARA telescope began imaging the field of GRB 070224 approximately
9 hours after the Swift Trigger 261880 at 20:29:12 UT.  Our observations
were comprised of 180-second exposures in the R band.  After stacking 2
hours worth of exposures, we do not detect any new sources down to a
limiting magnitude of R ~ 21.4 +/- 0.4 mag (based on calibration to 10
field sources from USNO B1.0 R2 band).

The Clemson University GRB Response Site may be found at:
http://people.clemson.edu/~kgarime/burst/index.php

The SARA Homepage can be found at:
http://saraobservatory.org

This message may be cited.

GCN Circular 6145

Subject
GRB070224: Gemini Imaging Observations
Date
2007-02-25T07:55:51Z (18 years ago)
From
Hsiao-Wen Chen at U Chicago <hchen@oddjob.uchicago.edu>
H.-W. Chen (U Chicago), K. Glazebrook (Swinburne University), and J. S. 
Bloom (UC Berkeley) report on behalf of a larger collaboration:

"We obtained 2x900 sec dithered exposures of the field around GRB070224
(Racusin et al., GCN 6137), using GMOS and an i' filter on the Gemini
south telescope.  The observations started at Feb 25.102 UT, ~ 6 hours
after the initial Swift trigger.  We continued the observations with
2x900 sec dithered exposures in the z'-band, starting at Feb 25.125 UT.
Within the refined XRT position (Racusin et al., GCN 6143), we detect a
compact source at RA(J2000)=11:56:06.6 and Dec(J2000)=-13:19:48.9 (+/-
350 mas relative to USNO B1.0) that shows no apparent changes in the
brightness between two exposures of 15 min apart.  We note the presence
of extremely faint (~2 sigma) source at RA(J2000)=11:56:06.5 and
Dec(J2000)=-13:19:49.9 in the first i'-band exposure.  Further analysis is
underway."

GCN Circular 6146

Subject
GRB 070224: MDM Observations
Date
2007-02-25T08:03:48Z (18 years ago)
From
Nestor Mirabal at Columbia U <mirabal@astro.columbia.edu>
N. Mirabal, K. Stanonik, N. Zimmerman, S. Alayyoubi, & J. P. Halpern
(Columbia U.) report on behalf of the MDM Observatory GRB follow-up
team:

"We observed the field of GRB 070224 (Racusin et al., GCNs 6137, 6143)
in I-band with the MDM 1.3m telescope. The object reported by
Thoene et al. (GCN 6142) is present in our images, with
a preliminary magnitude I~22.1 +/- 0.2 on Feb. 25.287."

GCN Circular 6147

Subject
GRB 070224: WHT K-band imaging
Date
2007-02-25T11:08:53Z (18 years ago)
From
Nial Tanvir at IofA U.Cambridge <nrt@ast.cam.ac.uk>
E. Rol, N.R. Tanvir, R. Starling (U. Leicester) and P. Groot
(U. Nijmegen) report on behalf of a larger collaboration:

We observed the field of GRB 070224 with the WHT/LIRIS instrument
in poor seeing, beginning at Feb 24 23:06 UT.  Our 6 minute K-band
image reached a 3-sigma limit of K~19.2 (based on calibration via
four 2MASS stars in the field).

A later observation in better seeing, beginning at Feb 25 04:44 UT,
reached a limiting magnitude of K~19.7.

In both images within the XRT error circle (GCN 6143) we see a source
at the position of the candidate reported by Thoene et al. (GCN 6142),
with a magnitude that is consistent with K~19.2 in both cases,
although some fading can't be ruled out.

In the second image we also see (close to the limit) another source
with (2000) coordinates approximately:

 11 56 06.26   -13 19 50.0

GCN Circular 6148

Subject
GRB070224: Magellan Imaging Observations
Date
2007-02-26T02:43:41Z (18 years ago)
From
Hsiao-Wen Chen at U Chicago <hchen@oddjob.uchicago.edu>
H.-W. Chen (U Chicago), K. Glazebrook (Swinburne University), and J. S. 
Bloom (UC Berkeley) report on behalf of a larger collaboration:

"We continued imaging observations of the field around GRB 070224
(Racusin et al., GCN 6137), using MagIC on the Magellan Clay telescope.
The observations consisted of 5x300 sec dithered exposures in the i' band
and 6x600 sec dithered exposures in the z' band, starting at Feb 25.180 UT,
~ 8 hours after the initial Swift trigger.  The images were taken under
photometric conditions with a mean seeing of 0.5" in i' and 0.6" in z'.
Object photometry was calibrated using a Sloan Digital Sky Survey
photometric standard observed after the GRB field.  Combining the images
obtained using GMOS and MagIC, we measure photometry of the compact source
at RA(J2000)=11:56:06.6 and Dec(J2000)=-13:19:48.9 (Chen, Glazebrook, &
Bloom, GCN 6145; see also Thoene et al. GCN 6142, Mirabal et al. GCN
6146, Rol et al. GCN 6147) as the following:

   Filter         AB      UT(mid)         Camera

     i'    22.60 +/- 0.10  25.107          GMOS
     z'    22.40 +/- 0.20  25.135          GMOS
     i'    22.54 +/- 0.05  25.188         MagIC
     z'    22.56 +/- 0.05  25.221         MagIC

We therefore conclude that this is not a variable source.

The source at RA(J2000)=11:56:06.5 and Dec(J2000)=-13:19:49.9 that
appeared at low level in the first GMOS i'-band image (Chen,
Glazebrook, & Bloom GCN 6145) remains absent in the MagIC images."

GCN Circular 6151

Subject
GRB070224: Swift-XRT Astrometrically Corrected Position
Date
2007-02-26T19:22:30Z (18 years ago)
From
Judith Racusin at PSU <racusin@astro.psu.edu>
J. Racusin (PSU), M. Goad (U. Leicester), D.N. Burrows (PSU), O. Godet (U. 
Leicester), R. Starling (U. Leicester) report on behalf of the Swift XRT 
team:

Based on an accurate mapping between the XRT and UVOT detector coordinate 
systems, we have used the simultaneous UVOT V-band images to 
astrometrically correct (relative to stellar catalogues, e.g. USNO-B1) the 
XRT world coordinate system, and thereby refine the XRT position.  We 
obtain a new XRT position at RA,Dec=179.02792,-13.3304 which is:

RA(J2000):  11h 56m 06.7s
Dec(J2000): -13d 19' 49.6"

with an uncertainty of 2.6 arcseconds (90% containment).  This is 3.8 
arcseconds from the refined XRT position (Racusin et al., GCN 6143), and 
2.0 arcseconds from the optical candidate first identified by Thoene et 
al. (GCN 6142).

This circular is an official product of the Swift-XRT team.

GCN Circular 6152

Subject
GRB 070224: Swift/UVOT Upper Limits
Date
2007-02-26T20:25:11Z (18 years ago)
From
Stephen Holland at USRA/NASA/GSFC/SSC <sholland@milkyway.gsfc.nasa.gov>
S. T. Holland (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC),
M. M. Chester (PSU) and J. L. Racusin (PSU) report on the behalf of
the Swift/UVOT team:


       The Swift/UVOT observed the field of GRB 070224 starting 132 s
after the BAT trigger (Racusin et al. 2007, GCN Circ. 6137).  We do
not find any source, in any of the UVOT observations, inside the
astrometrically corrected XRT error circle (Racusin et al., 2007 GCN
Circ. 6151).

       The 3-sigma upper limits for detecting a source anywhere inside
the XRT error circle in the finding chart images, and the co-added
exposures are:


Filter     T_start   T_stop   Exp(s)  Mag (3-sigma upper limit)
-------------------------------------------------------------
White Finding  156      254      96       20.4
V Finding      259      659     393       20.1

    V           259     1367     806       20.5
    B           737      747      10       18.6
    U           713      733      19       18.7
  UVW1          689     5512     132       20.0
  UVM2          665      833      39       18.3
  UVW2          766      785      19       18.2
  White         154      962     206       20.9

    V        35,712  126,303    1553       20.9
    B          7159  128,636    1987       22.0
    U          6954   93,932    1952       21.7
  UVW1         6750  145,987    4321       22.2
  UVM2       12,574  143,883    4621       22.4
  UVW2       29,833  122,852    4358       22.6
-------------------------------------------------------------

The values quoted above are not corrected for the expected Galactic
extinction corresponding to a reddening of E_{B-V} = 0.06 mag towards
the direction of the burst (Schlegel et al. 1998).

GCN Circular 6154

Subject
GRB 070224: Optical afterglow confirmation
Date
2007-02-27T19:12:04Z (18 years ago)
From
Alexander Kann at TLS Tautenburg <kann@tls-tautenburg.de>
Christina C. Thoene (Dark/NBI), D. Alexander Kann (TLS Tautenburg), Thomas                                                    
Augusteijn (NOT) and Celine Reyle-Laffont (Observatoire de Besancon) 
report:

We observed the OT candidate (Thoene et al., GCN 6142) of GRB 070224 
(Racusin et al., GCN 6137) again on Feb. 27 (2.27 days after the burst) 
with NOT and StanCam in R.

The proposed candidate (Thoene et al., GCN 6142, see also Chen et al., GCN
6145, Mirabal et al., GCN 6146, Rol et al., GCN 6147 and Chen et al., GCN 
6148) is clearly fading between our three epochs.                               

We get the following magnitudes:

t after burst�� exptime�� R mag:
0.20 d����������� 900s��������22.1 +- 0.2 
0.39 d����������� 1800s������ 22.5 +- 0.2
2.27 d����������� 2400s������ 24.1 +- 0.3

based on two nearby USNO-B1.0 stars.

We therefore conclude that this object is the afterglow of GRB 070224.
It thus may have had an early plateau phase (Rol et al., GCN 6147, Chen et 
al., GCN 6148).

Improved astrometry gives a refined position of the afterglow at (J2000):

RA = 11:56:06.65  
Dec = -13:19:48.8  
 
with an error of 0.5 arcsec. 

This is 1.1 arcsec from the center of the revised XRT error circle 
(Racusin et al., GCN Report 36.1) and 0.8 arcsec from the center of Nat 
Butler's error circle (v2.5) 
(http://astro.berkeley.edu/~nat/swift/xrt_pos.html).

GCN Circular 6164

Subject
VLA observation of GRB 070224
Date
2007-03-01T16:40:05Z (18 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
070224 (GCN 6137) at a frequency of 8.46 GHz on 2007 February 28 at
9.99 UT.  The GRB is undetected and the peak radio flux at the SWIFT-XRT
position (GCN 6143) is -83 uJy � 47 uJy. 

The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."

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