- GCN/BACODINE POSITION NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Tue 02 Aug 05 10:20:36 UT
NOTICE_TYPE: Swift-BAT GRB Lightcurve
TRIGGER_NUM: 148646, Seg_Num: 0
GRB_RA: 219.287d {+14h 37m 09s} (J2000),
219.348d {+14h 37m 23s} (current),
218.739d {+14h 34m 57s} (1950)
GRB_DEC: +27.806d {+27d 48' 23"} (J2000),
+27.782d {+27d 46' 56"} (current),
+28.023d {+28d 01' 22"} (1950)
GRB_DATE: 13584 TJD; 214 DOY; 05/08/02
GRB_TIME: 36482.26 SOD {10:08:02.26} UT
TRIGGER_INDEX: 149
GRB_PHI: -6.38 [deg]
GRB_THETA: 51.88 [deg]
DELTA_TIME: 65504.00 [sec]
LC_URL: sw00148646000msb.lc
SUN_POSTN: 132.67d {+08h 50m 40s} +17.68d {+17d 40' 53"}
SUN_DIST: 79.02 [deg]
MOON_POSTN: 101.96d {+06h 47m 51s} +28.02d {+28d 01' 12"}
MOON_DIST: 98.06 [deg]
MOON_ILLUM: 7 [%]
GAL_COORDS: 40.74, 66.59 [deg] galactic lon,lat of the pointing direction
ECL_COORDS: 205.62, 40.60 [deg] ecliptic lon,lat of the pointing direction
COMMENTS: SWIFT-BAT GRB Lightcurve.
COMMENTS: This does not match any source in the ground catalog.
- red DSS finding chart
ps-file
- GCN/BACODINE POSITION NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Tue 02 Aug 05 10:20:38 UT
NOTICE_TYPE: Swift-XRT Nack-Position
TRIGGER_NUM: 148646, Seg_Num: 0
POINT_RA: 219.303d {+14h 37m 13s} (J2000)
POINT_DEC: +27.800d {+27d 47' 59"} (J2000)
GRB_DATE: 13584 TJD; 214 DOY; 05/08/02
GRB_TIME: 36770.78 SOD {10:12:50.78} UT
COUNTS: 157 Min_needed= 20
STD_DEV: 0.00 Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER: 4 Max_iter_allowed= 4
ERROR_CODE: 2
COMMENTS: SWIFT-XRT Nack Position.
COMMENTS: Algorithm did not converge; too many interations.
- GCN notice #3734
D. Band (GSFC-UMBC), C. Markwardt (GSFC-UMD), M. Perri
(ASDC), K. McGowan (MSSL), C. Gronwall (PSU), K. Page (U.
Leicester), J. Racusin (PSU), D. Burrows (PSU), N. Gehrels
(GSFC), J. Kennea (PSU), report on behalf of the Swift
Team:
At 10:08:02 UT, Swift-BAT triggered and located GRB050802
(trigger=148646). The spacecraft slewed immediately. The
BAT on-board calculated location is RA,Dec 219.287, +27.806
{+14h 37m 09s, +27d 48' 23"} (J2000), with an uncertainty
of 3 arcmin (radius, 90% containment, stat+sys). The BAT
light curve has a total duration of ~20 sec. The peak
count rate was ~2000 counts/sec (15-350 keV).
The XRT began observing at 10:12:51 UT, 289 seconds after
the BAT trigger. XRT was unable to centroid on any source,
however the downlinked lightcurve and raw spectrum show a
bright variable source is present in the XRT field of view.
There are no catalogued X-ray sources in the field,
suggesting that this bright source is the GRB afterglow.
Swift-UVOT began observations after the slew, however, the
UVOT dark burst image did not come down via TDRSS so no
information is available at this time. Detailed analysis
will be performed when data is available after the next
Malindi pass.
- GCN notice #3735
J.A. Kennea, D.N. Burrows (PSU) report on behalf of the Swift/XRT Team:
We have analysed the downlinked data on GRB 050802 (GCN 3734) and have
found a fading uncatalogued X-ray source at the following coordinates:
RA (J2000): 14:37:05.8,
Dec(J2000): 27:47:05.6,
with an error radius of 8 arcseconds (90% containment). This source is 87
arcseconds from the BAT position reported in GCN 3734. Further detailed
analysis of XRT data will be reported in a later GCN.
- GCN notice #3737
D. Palmer (LANL), L. Barbier (GSFC), S. Barthelmy (GSFC),
P. Boyd (GSFC-UMBC), J. Cummings (GSFC/NRC), E. Fenimore (LANL),
N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC),
G. Sato (ISAS), J. Tueller (GSFC), W. Voges (MPE),
on behalf of the Swift-BAT team:
At 10:08:02 UT Swift-BAT detected GRB 050802 (trigger=148646)
(GCN Circ 3734, Band, et al.). The refined BAT ground position
is (RA,Dec) = 219.287, +27.806 {14h37m08.9s, 27d48'21.6"} [deg; J2000]
+-3 arcmin, (95% containment). The partial coding was 27%.
The light curve has a 5 second rise time to the first and largest
of 3 symmetrical peaks in the interval T-5 to T+13 seconds. There
is a hint of a small peak at T+30 seconds. T90 (15-350 keV) is
(13 +- 2) seconds (estimated error including systematics).
The power law index of the time-averaged spectrum is 1.6 +- 0.1.
The fluence in the 15-350 keV band is (2.8 +- 0.3) x 10^-6 erg/cm2.
The 1-s peak photon flux measured from T0-0.4 second in the 15-350 keV
band is (3.3 +- 0.5) ph/cm2/s. All the quoted errors are at the 90%
confidence level.
There was no BAT Position GCN Notice on this burst, because none was
transmitted from the spacecraft. The cause is being investigated.
- GCN notice #3738
Y. Sato (Tokyo Univ.), N. Awajiya (Tokyo Gakugei Univ.),
D. Kinoshita, K-Y. Huang, W-H. Ip(NCU),
Y. Urata (RIKEN) on behalf of EAFON report:
" We have imaged the entire error region of GRB 050802 (Band et
al. #3734) using the imaging polarimeter PICO with Lulin One-meter
Telescope. After end of twilight, the observation was started at 12:42
(0.107 days after the burst). We have obtained 12 x 300 sec i'-band
images. These images show no optical counterpart brighter than
i'=17.2. These 3-sigma limiting magnitudes are derived from the
USNO-B1.0 catalog.
This message may be cited."
- GCN notice #3739
K. McGowan (MSSL), D. Band (GSFC-UMBC), P. Brown,
C. Gronwall (PSU), H. Huckle, B. Hancock (MSSL)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began observing the afterglow of
GRB 050802 at 2005-08-02T10:15:14, 286 s after the
BAT trigger (Band et al., GCN 3734). We detect the
afterglow in the V-band data at a position (J2000,
corrected to the DSS coordinates) of:
RA 14:37:5.69 (+/- 1 arcsec)
Dec +27:47:12.2 (+/- 1 arcsec)
The data are extracted using a 6 arcsec radius aperture
centered on the source position. If the significance of
the source detection was less than 2 sigma we determined a
3-sigma limiting magnitude.
Filter Exposure (s) T_mid (s) Magnitude Notes
V 100 336 17.07+/-0.09 detection
V 10 466 17.32+/-0.20 detection
V 10 550 17.10 3-sig limit
V 10 634 17.17 3-sig limit
V 10 718.5 16.77+/-0.20 detection
V 10 803 17.34 3-sig limit
V 10 887.5 17.04+/-0.20 detection
V 10 972 17.46 3-sig limit
V 100 1463 18.35+/-0.09 detection
V 100 2088 18.81+/-0.09 detection
where T_mid is the midpoint of the exposure post-trigger in seconds.
Analysis of the data from the other filters is ongoing.
The magnitudes are based on preliminary zero points, measured in
orbit, and will require refinement with further calibration.
- GCN notice #3740
M. Capalbi, M. Perri, P. Giommi (ASDC), J. Kennea, D.N. Burrows,
M.Chester (PSU), R. Fink (GSFC) report on behalf of the Swift XRT team:
We have analyzed the Swift XRT data from the first orbit observation of
GRB 050802 (Band et al., GCN 3734). The refined coordinates of the X-ray
afterglow are:
RA(J2000) = 14h 37m 06.1s
Dec(J2000) = +27d 47' 11"
This position is 80 arcseconds from the BAT refined position given in
GCN 3737 (Palmer et al.), 6.7 arcseconds from the early XRT position
reported in GCN 3735 (Kennea et al.) and 5.4 arcseconds from the UVOT
position (McGowan et al., GCN 3739). We estimate an uncertainty of 6
arcseconds radius in the derived position.
Data in Photon Counting (PC) mode starts at 10:15:57 UT, 475 seconds
from the BAT trigger. The 0.3-10 keV afterglow light curve shows a
fading which can be fitted with a power law of slope alpha=-0.7+/-0.1 up
to T+2875 s, when the first orbit ends.
A preliminary spectral fit in the 0.3-10.0 keV energy band to the first
orbit gives a spectral power law photon index of 1.9+/-0.1 with
nH=(6.6+/-2.5)E20 cm^-2. The Galactic nH along the line of sight is
1.8E20 cm^-2.
The unabsorbed 0.5-10.0 keV flux at 24 hours after the burst is
estimated to be 3.6E-12 erg cm^-2 s^-1.
- GCN notice #3742
Guy Pooley (Cavendish Laboratory, University of Cambridge) reports:
An observation of the field of GRB050802 (GCN 3734) was made with
the Ryle Telescope (Cambridge, UK) at 15 GHz from 18:54 to 22:53 UT
on 2005 Aug 02 (mid-observation 10h46m from the trigger), using
the Swift/UVOT position reported in GCN3739.
No source was detected - the formal flux density was -0.02 mJy
with an rms noise of 0.3 mJy.
This message can be cited.
- GCN notice #3744
E. Pavlenko, Yu. Efimov, A. Shlyapnikov, A. Baklanov(CrAO), A.Pozanenko
(IKI), M. Ibrahimov (MAO) on behalf of larger GRB follow up collaboration
report:
We observed the error box of GRB050802 (Band et al., GCN 3734) with 2.6m
Shain telescope (CrAO) on August 2 between (UT) 18:46 - 20:40. OT found by
McGowan et al. (GCN 3739) is clearly detected. Preliminary VRI photometry is
following:
Mean time Exposure Filter Magnitude
(UT) s
18:54 60 V 20.6
20:27 2x60 V 21.1
18:48 60 R 20.6
20:36 2x60 R 21.0
18:56 60 I 20.2
20:39 2x60 I 20.6
with a typical error of 0.1m.
Comparing decay index of fading light curve in V between magnitudes obtained
in UVOT observation (McGowan et al. GCN 3739) and our first observation in
18:54, and decay index obtained based on our observations we suggest that
the break of OT light curve occurs between (UT) 19:00 - 20:40. Detailed
analysis is underway.
Finding chart of the OT in V band can be found in
http://grb.rssi.ru/GRB050802
This message may be cited.
- GCN notice #3745
K. McGowan (UCL-MSSL), A. Morgan (PSU), K. Mason (PPARC),
T. Kennedy (UCL-MSSL) report on behalf of the Swift/UVOT team:
The Swift/UVOT began observing the afterglow of
GRB 050802 at 2005-08-02T10:15:14, 286 s after the
BAT trigger (Band et al., GCN 3734). In addition to our
reported detection from the initial V filter observations
(McGowan et al., GCN 3739), we now report that we detect
the afterglow in all six filters.
We extracted data using a 6 arcsec radius aperture
centered on the source position (McGowan et al., GCN 3739)
for the optical filters, a 12 arcsec radius for the W1 and
M2 filters, and 4 arcsec for the W2 filter. If the
significance of the source detection was less than 2 sigma
we determined a 3-sigma limiting magnitude.
The detection in UVW2 implies that the Lyman Limit must be blueward
of 2000 A, and we estimate that the burst is at redshift z < 1.2.
We obtain the following photometry of the afterglow candidate:
Filter Exposure (s) T_mid (s) Magnitude Notes
V 100 336 17.07+/-0.09 detection
V 900 12566 20.35+/-0.09 detection
B 10 437 17.66+/-0.20 detection
B 900 36405 21.10+/-0.08 detection
U 10 423 16.82+/-0.24 detection
U 899.79 35498 20.22+/-0.16 detection
W1 10 409 17.08+/-0.29 detection
W1 100 2296 19.22+/-0.23 detection
M2 278 1316 18.79+/-0.26 detection
M2 3753 28197 21.30+/-0.26 detection
W2 268 1240.5 20.73+/-0.27 detection
W2 3481 25890.5 >22.64 3-sig limit
where T_mid is the midpoint of the exposure post-trigger in seconds.
The magnitudes are based on preliminary zero points, measured in
orbit, and will require refinement with further calibration.
- GCN notice #3749
Johan P. U. Fynbo, Jesper Sollerman, Brian L. Jensen, Jens Hjorth,
Darach Watson, Jos=E9 Mar=EDa Castro Cer=F3n (DARK cosmology centre/Niels
Bohr Institute), Palle Moller (ESO), Thomas Augusteijn (Nordic Optical
Telescope), Javier Gorosabel (IAA-CSIC), Klaas Wiersema (Amsterdam)
report:
"Using ALFOSC on the Nordic Optical Telescope we have obtained
spectra of the afterglow of GRB 050802 (GCN 3734, 3739) on 2005,
August 2.9 UT. We detect several absorption features which we tentatively
identify as CIV and FeII lines, corresponding to a redshift of
z=3D1.71. This tentative redshift is at odds with the interpretation
of the UVOT results (GCN 3745). We encourage further observations."
- GCN notice #3756
FROM: Johan U. Fynbo at U.Copenhagen
Johan P. U. Fynbo, Brian L. Jensen, Jens Hjorth, Jesper Sollerman,
Darach Watson, Jos=E9 Mar=EDa Castro Cer=F3n (DARK Cosmology Centre/NBI),
Javier Gorosabel (IAA-CSIC), Magnus Galfalk (Stockholm), Amanda Kaas
(Nordic Optical Telescope) report:
"Using ALFOSC on the Nordic Optical Telescope we have obtained further
imaging of the field of GRB 050802.422 (Band et al. GCN 3734, McGowan et
al. GCN 3739) on 2005, August 3.9 UT. From Aug 2.9 UT to Aug 3.9 UT the
object has faded from about R=3D20.5 to R=3D22.5 (based on preliminary
photometry), indicating a fairly steep early decay.
In the image from Aug 3.9 there is contamination from an
extended source, presumably the host galaxy. This fairly bright host
galaxy makes it feasible to make an independent measurement of the
redshift of the burst and hence confirm or reject the tentative
measurement reported by Fynbo et al. GCN 3749.
An image can be seen here:
http://www.astro.ku.dk/~brian_j/grb/grb050802.422/"
- GCN notice #3765
V. Testa (INAF-OAR), A.Melandri , L.A. Antonelli, L. Stella (INAF-OAR),
S. Covino, D. Fugazza, G. Tagliaferri (INAF-OAB),
G. Chincarini (Univ. Milano-Bicocca), N. Masetti (INAF-IASF-Bologna),
G. Andreuzzi, M. Pedani (INAF-TNG),
on behalf of the CIBO collaboration report
We imaged the field of GRB050802 (GCN 3734, Band et al.) with the 3.5 m
Italian National Telescope (TNG) (Canary Islands). Observations were
carried out with the optical spectrograph Dolores on August 2.9 UT in 5
filters (U, B, V, R, I) and on August 3.9 UT in 2 filters (V, I).
In all images we detect an object at the position reported by McGowen
et al. (GCN 3739). Therefore, the detected object is identified as the
afterglow candidate reported in GCN 3739. Preliminary photometry shows
the object fading from V~21.1 to V~22.8 and from I~20.5 to I~21.9
between the two epochs.
We note also an extended fainter object near the afterglow in the V
frame obtained on August 3. This object is at the same position as can
be seen in the image linked in GCN 3756, that Fynbo et al. propose as
suspected host galaxy. Further refined analysis is ongoing.
This message may be cited.
- GCN notice #3855
A. Henden (AAVSO/USNO) reports on behalf of the USNO GRB Team:
We have acquired BVRcIc all-sky photometry for 23x23arcmin
fields centered on the coordinates of recent GRB localizations
with the USNOFS 1.0-m telescope on 1 or 2 photometric nights
but with bright moonlight and variable seeing. Stars brighter
than V=12.0 are saturated and should be used with care. We have
placed the photometric data on our anonymous ftp site:
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb050525.dat
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb050607.dat
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb050802.dat
The astrometry in these files is based on linear plate solutions
with respect to UCAC2 or USNO-A2.0. The external errors are usually
200mas or better. The estimated external photometric error is
about 0.03mag. Some fields are relatively crowded, and the
large apertures required to handle the variable seeing also
blended some measurements, so choose comparison stars wisely.
We have one additional night for GRB050525 that will be
added when reductions are complete.
As always, you should check the dates on the .dat file prior to
final publication to get the latest photometry. There is
a README file on the ftp directory to give you information
about the procedures used to calibrate these fields.
- 0706.0669from 5 Jun 2007
Oates: The Two-Component Afterglow of Swift GRB 050802
Abstract: This paper investigates GRB 050802, one of the best examples of a it Swift
gamma-ray burst afterglow that shows a break in the X-ray lightcurve, while the
optical counterpart decays as a single power-law. This burst has an optically
bright afterglow of 16.5 magnitude, detected throughout the 170-650nm spectral
range of the UVOT on-board Swift. Observations began with the XRT and UVOT
telescopes 286s after the initial trigger and continued for 1.2 x 10^6s. The
X-ray lightcurve consists of three power-law segments: a rise until 420s,
followed by a slow decay with alpha_2 = 0.63 +/- 0.03 until 5000s, after which,
the lightcurve decays faster with a slope of alpha_3 = 1.59 +/- 0.03. The
optical lightcurve decays as a single power-law with alpha_O = 0.82 +/- 0.03
throughout the observation. The X-ray data on their own are consistent with the
break at 5000s being due to the end of energy injection. Modelling the optical
to X-ray spectral energy distribution, we find that the optical afterglow can
not be produced by the same component as the X-ray emission at late times,
ruling out a single component afterglow. We therefore considered two-component
jet models and find that the X-ray and optical emission is best reproduced by a
model in which both components are energy injected for the duration of the
observed afterglow and the X-ray break at 5000s is due to a jet break in the
narrow component. This bright, well-observed burst is likely a guide for
interpreting the surprising finding of Swift that bursts seldom display
achromatic jet breaks.
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