- GCN/BACODINE POSITION NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Thu 05 May 05 23:31:20 UT
NOTICE_TYPE: Swift-BAT GRB Position
TRIGGER_NUM: 117504, Seg_Num: 0
GRB_RA: 141.782d {+09h 27m 08s} (J2000),
141.861d {+09h 27m 27s} (current),
141.040d {+09h 24m 10s} (1950)
GRB_DEC: +30.255d {+30d 15' 19"} (J2000),
+30.232d {+30d 13' 55"} (current),
+30.473d {+30d 28' 22"} (1950)
GRB_ERROR: 4.00 [arcmin radius, statistical only]
GRB_INTEN: 7633 [cnts] Peak=228 [cnts/sec]
TRIGGER_DUR: 2.048 [sec]
TRIGGER_INDEX: 486 E_range: 50-350 keV
BKG_INTEN: 74230 [cnts]
BKG_TIME: 84104.00 SOD {23:21:44.00} UT
BKG_DUR: 24 [sec]
GRB_DATE: 13495 TJD; 125 DOY; 05/05/05
GRB_TIME: 84141.09 SOD {23:22:21.09} UT
GRB_PHI: -157.17 [deg]
GRB_THETA: 49.32 [deg]
SOLN_STATUS: 0x3
RATE_SIGNIF: 15.45 [sigma]
IMAGE_SIGNIF: 10.00 [sigma]
MERIT_PARAMS: +1 +0 +0 +2 +3 +6 +0 +0 -1 +1
SUN_POSTN: 43.08d {+02h 52m 20s} +16.50d {+16d 29' 46"}
SUN_DIST: 89.05 [deg]
MOON_POSTN: 15.10d {+01h 00m 23s} +5.90d {+05d 53' 42"}
MOON_DIST: 117.56 [deg]
MOON_ILLUM: 6 [%]
GAL_COORDS: 196.28, 45.46 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 134.50, 14.46 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SWIFT-BAT GRB Coordinates.
COMMENTS: This is a rate trigger.
COMMENTS: A point_source was found.
COMMENTS: This does not match any source in the on-board catalog.
COMMENTS: This does not match any source in the ground catalog.
COMMENTS: This is a GRB.
- red DSS finding chart
ps-file
- GCN/SWIFT NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Thu 05 May 05 23:31:37 UT
NOTICE_TYPE: Swift-BAT GRB Lightcurve
TRIGGER_NUM: 117504, Seg_Num: 0
GRB_RA: 141.782d {+09h 27m 08s} (J2000),
141.861d {+09h 27m 27s} (current),
141.040d {+09h 24m 10s} (1950)
GRB_DEC: +30.255d {+30d 15' 19"} (J2000),
+30.232d {+30d 13' 55"} (current),
+30.473d {+30d 28' 22"} (1950)
GRB_DATE: 13495 TJD; 125 DOY; 05/05/05
GRB_TIME: 84141.09 SOD {23:22:21.09} UT
TRIGGER_INDEX: 486
GRB_PHI: -157.17 [deg]
GRB_THETA: 49.32 [deg]
DELTA_TIME: 19.00 [sec]
LC_URL: sw00117504000msb.lc
SUN_POSTN: 43.08d {+02h 52m 20s} +16.50d {+16d 29' 46"}
SUN_DIST: 89.05 [deg]
MOON_POSTN: 15.10d {+01h 00m 23s} +5.90d {+05d 53' 42"}
MOON_DIST: 117.56 [deg]
MOON_ILLUM: 6 [%]
GAL_COORDS: 196.28, 45.46 [deg] galactic lon,lat of the pointing direction
ECL_COORDS: 134.50, 14.46 [deg] ecliptic lon,lat of the pointing direction
COMMENTS: SWIFT-BAT GRB Lightcurve.
COMMENTS: This is a rate trigger.
COMMENTS: A point_source was not found.
COMMENTS: This does not match any source in the on-board catalog.
COMMENTS: This does not match any source in the ground catalog.
COMMENTS: This is not a GRB.
COMMENTS: Since the IMAGE_SIGNIF is less than 7 sigma, this is a questionable detection.
- GCN/SWIFT NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Fri 06 May 05 00:09:29 UT
NOTICE_TYPE: Swift-XRT Nack-Position
TRIGGER_NUM: 117504, Seg_Num: 0
POINT_RA: 141.757d {+09h 27m 02s} (J2000)
POINT_DEC: +30.245d {+30d 14' 43"} (J2000)
GRB_DATE: 13496 TJD; 126 DOY; 05/05/06
GRB_TIME: 563.20 SOD {00:09:23.20} UT
COUNTS: 1 Min_needed= 20
STD_DEV: 0.00 Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER: 0 Max_iter_allowed= 4
ERROR_CODE: 1
COMMENTS: SWIFT-XRT Nack Position.
COMMENTS: No source found in the image.
- GCN/BACODINE POSITION NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Fri 06 May 05 00:13:54 UT
NOTICE_TYPE: Swift-XRT Lightcurve
TRIGGER_NUM: 117504, Seg_Num: 0
POINT_RA: 141.755d {+09h 27m 01s} (J2000)
POINT_DEC: +30.244d {+30d 14' 37"} (J2000)
LC_START_DATE: 13496 TJD; 126 DOY; 05/05/06
LC_START_TIME: 565.90 SOD {00:09:25.90} UT
LC_STOP_DATE: 13496 TJD; 126 DOY; 05/05/06
LC_STOP_TIME: 812.24 SOD {00:13:32.24} UT
LC_LIVE_TIME: 242.70 [sec], 98.5%
DELTA_TIME: 86153.66 [sec]
N_BINS: 100
TERM_COND: 0
LC_URL: sw00117504000msx.lc
SUN_POSTN: 43.12d {+02h 52m 28s} +16.51d {+16d 30' 19"}
SUN_DIST: 89.00 [deg]
MOON_POSTN: 15.49d {+01h 01m 57s} +6.10d {+06d 06' 06"}
MOON_DIST: 117.11 [deg]
MOON_ILLUM: 6 [%]
GAL_COORDS: 196.29, 45.43 [deg] galactic lon,lat of the pointing direction
ECL_COORDS: 134.48, 14.44 [deg] ecliptic lon,lat of the pointing direction
COMMENTS: SWIFT-XRT Lightcurve.
- GCN notice #3360
C. Hurkett (UL), S. Barthelmy (GSFC), J. Cummings (GSFC/NRC),
N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
D. Palmer (LANL) for the Swift-team:
At 23:22:21 UT, the Swift Burst Alert Telescope (BAT) triggered and
located on-board GRB050505 (trigger #117504). The BAT on-board
calculated location is RA, Dec 141.782, +30.255 (J2000) with an
uncertainty of 4 arcmin (radius, 3-sigma, including estimated
systematic uncertainty, 90% containment). The BAT light curve
showed a multipeak structure with a duration of about 45 seconds.
The peak count rate measured by BAT was about 1500 counts/sec
in the 15 - 350 keV band, occurring at the trigger.
The Swift spacecraft did not make an immediate slew because of the
Earth observing constraint.
- GCN notice #3364
D. Hullinger (UMD), L. Barbier (GSFC), S. Barthelmy (GSFC),
L. Cominsky (Sonoma State), J. Cummings (GSFC/NRC),
E. Fenimore (LANL), R. Fink (GSFC), M. Galassi (LANL),
N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL),
A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS),
M. Suzuki (Saitama), M. Tashiro (Saitama U.), J. Tueller (GSFC),
on behalf of the Swift/BAT team:
At 23:22:21 UT, the Swift Burst Alert Telescope (BAT) triggered
and located GRB050505 (trigger=117504) (GCN Circ 3360, Hurkett
et al.). The refined BAT ground position is (RA,Dec) = 141.787,
+30.245, [deg; J2000] +- 3 arcmin, (95% containment). The burst
was 49 degrees off the Swift boresight, which is ~30% coded.
The BAT mask-weighted light curve shows a multi-peaked
structure with a total duration T90 (15-350 keV) 60 +- 2 seconds
(estimated error including systematics). The initial peak began
~15 seconds before the trigger and extended to 10 seconds after
the trigger. There were three further short peaks beginning at
T+20 seconds, T+31 seconds, and T+49 seconds.
The spectrum is well fit by a simple power law with photon index
of 1.5 +- 0.1. The fluence in the 15-350 keV band is
(4.1 +- 0.4) x 10^-6 erg/cm2. The 1-second peak photon flux in
the 15-350 band is (2.2 +- 0.3) ph/cm2/s recorded at 1 second
after the trigger. All the quoted errors are at the 90% confidence level.
We note that this burst appears to be well-suited for ground
follow-up observations, as it is located 90 degrees from the Sun,
120 degrees from the Moon, close to the ecliptic, and away from
the Galactic plane.
- GCN notice #3365
J. A. Kennea, D. N. Burrows (PSU), C. P. Hurkett, J. P. Osbourne (U.
Leicester) and N. Gehrels (NASA/GSFC) report on behalf of the Swift XRT
team:
The Swift BAT instrument detected a GRB at 23:22:21 UT on 5th May 2005
(GCN Circ 3360). The observatory executed an automated slew to the BAT
position and the XRT began taking data at 00:09:23 UT on 6th May 2005. The
XRT was in Auto state but was not able to centroid on the afterglow due to
low source brightness. From downlinked data we find a uncatalogued X-ray
source located at:
RA(J2000) = 9:27:03.2,
Dec(J2000) = +30:16:21.5
We estimate an uncertainty of about 6 arcseconds radius (90% containment).
This position is 124 arcseconds from the BAT position reported in GCN 3364.
- GCN notice #3366
S. Bradley Cenko, Chuck Steidel, Naveen Reddy, and Derek B. Fox report
on behalf of the Caltech-NRAO-Carnegie GRB Collaboration:
We have imaged the field of GRB050505 (GCN 3360) with the Keck Low
Resolution Imaging Spectrometer (LRIS) mounted on the 10-m Keck I
Telescope. Observations in imaging mode consisted of 2 x 300 s
simultaneous exposures in the g' and I filters. The mean epoch of our
observations is approximately 5:45 UT 6 May 2005 (~ 6.1 hours after the
burst).
In the XRT error circle reported in GCN 3365, we find one bright source,
with coordinates (J2000.0):
RA: 09:27:03.3
Dec: +30:16:23.7
We tentatively identify this source as the afterglow of GRB050505.
- GCN notice #3367
S. Rosen (MSSL), C. Hurkett (Leicester), W. Landsman (GSFC), P. Roming
(PSU), T. Poole (MSSL), N. Gehrels (GSFC), K. Mason (MSSL), J. Nousek
(PSU), on behalf of the Swift UVOT team
The Swift Ultra-Violet/Optical Telescope (UVOT) began observations of
GRB050505 on May 06, 2005 at 00:09:08 UT, ~48 minutes after the initial
Swift BAT trigger (Hullinger et al, GCN 3364) (the delay in observations
was due to the Earth-limb constraint, which prevented an immediate slew).
Initial data is limited to one 100s exposure in each of four filters.
We detect no source at the Swift XRT position (Kennea et al, GCN 3365) in
any filter. The limiting magnitudes (5-sigma in 6" radius apertures) in
each of the UVOT filters are as follows:
Filter Lim_Mag Duration (s) T_start (s)
V ~17.7 100 T + 2870
U ~18.4 100 T + 3180
UVW1 ~18.9 100 T + 3080
UVM2 ~19.7 100 T + 2970
The magnitudes are based on preliminary zero-points, measured in
orbit, and will require refinement with further calibration.
This message may be cited.
- GCN notice #3368
Edo Berger (Carnegie Observatories), S. Bradley Cenko, Chuck Steidel,
Naveen Reddy, and Derek B. Fox (Caltech) report on behalf of the
Caltech-NRAO-Carnegie GRB Collaboration:
"We obtained a 900-sec spectrum of the optical candidate (GCN 3366) of GRB
050505 (GCN 3360) with LRIS on the Keck I 10-m telescope on 2005, May 6.27
UT. We find very strong absorption over the range of 6200-6500 A,
corresponding to Ly alpha absorption around z = 4.1 to 4.3. In addition,
we find several metal absorption lines, including SiIV (1393,1402), at a
redshift of 4.27.
At this redshift, the second highest measured for any GRB, the isotropic
equivalent gamma-ray energy is 7.7e53 erg."
- GCN notice #3370
D. Hohman (Stone Edge Observatory), A. Henden (AAVSO) and A. Price (AAVSO)
report on behalf of the AAVSO International High Energy Network on
optical observations of GRB050505 (GCN #3360, Hurkett et al.):
No afterglow candidate is found in the field or at the location of
the afterglow reported by Cenko et al. (GCN 3366) to a limiting
unfiltered (R-like) magnitude of 18.5 using USNO-A2.0 reference
stars. Observation midpoint time was 02:19 UT on May 6, 2005
(2.9hrs after burst). Details of the observation are below along
with a link to the FITS image. The unfiltered observations have
significant Rc/Ic contribution and so are complementary to the
UVOT observations reported by Rosen, et al. (GCN 3367).
Name: Dennis Hohman
email: dennishohman@adelphia.net
Observer: Dennis Hohman
Site: Stone Edge Observatory
Location: Orchard park, NY
LatitudeLongitude: -78.75, 42.76
Elevation: 950 ft
Scope: C8
ScopeFocalRatio: 6.1
CCDVendor: ST7XME
CCDDetector: KAF401E
CCDSize: 382x255
CCDPixelScale: 3.0
CCDFOV: 12.9x19.4
Object: GRB050505
ObsDate: 05/06/05
ObsMidPointTime: 02:19
TimePerFrame: 240 sec
NumberOfFrames: 7
Filters: CR
Processing: Flatfield,Dark sub, avg
Seeing: 3.8
LimitingMag: 18.7
Sky: Clear, some high clouds
afterglowmag:
afterglowerr:
compstars:
Report: Entire error circle covered. No new object visible to
estimated mag 18.5
comments:
A FITS image has been uploaded to ftp://ftp.aavso.org/grb/DennisHohman_GRB050505_2453496.67896_.fits
The AAVSO thanks the Curry Foundation for their continued support of the
AAVSO International High Energy Network.
- GCN notice #3371
S. Rosen (MSSL), C. Hurkett (Leicester), S. Holland (GSFC), P. Roming
(PSU), A. Blustin (MSSL), N. Gehrels (GSFC), K. Mason (MSSL), J. Nousek
(PSU), on behalf of the Swift UVOT team
Further to the initial Swift UVOT results (Rosen et. al. 3367) we report
the results of co-added, deeper exposures of GRB 050505 with the Swift
Ultra-Violet/Optical Telescope (UVOT) on May 06, 2005.
We detect no source at the Keck determined location (Cenko et al, GCN
3366) in any of the UVOT filters with the following 5 sigma and 3 sigma
limits (in 6" radius apertures)
Filter Lim_Mag Lim_mag Total duration (s) T_range (s)
5sigma 3sigma
V 19.82 20.35 2527 2807 - 28543
B 20.50 21.04 1999 3236 - 26917
U 20.26 20.84 2890 3132 - 22757
UVW1 20.81 21.36 1999 3029 - 22040
UVM2 21.13 21.68 2422 2924 - 21132
UVW2 21.27 21.83 1997 3342 - 27826
T_range is since the BAT trigger time (Hullinger et al. 3364).
The magnitudes are based on preliminary zero-points, measured in
orbit, and will require refinement with further calibration.
We note that for the estimated redshift of 4.1 - 4.3 (GCN 3368), the Lyman
limit lies between the UVOT B and V filters - the lack of a UVOT
detection in V may be significant, depending on the brightness of the
source detected by Keck and the true redshift.
This message may be cited.
- GCN notice #3372
E. Rol (U. of Leicester), N. Tanvir (U. of Hertfordshire), A. Levan
(U. of Leicester), A. Adamson, L. Fuhrman (JAC), R. Priddey,
R. Chapman (U. of Hertfordshire) report:
We have observed the error circle of GRB050505 (GCN 3360) in K-band
with the WFCAM instrument on UKIRT. At the position of the optical
candidate (GCN 3366), we clearly detect a point-like source,
presumably the infrared counterpart.
Relative to 2MASS stars in the frame we measure a provisional
magnitude of K = 18.1 +/- 0.2 (error includes allowance for possible
systematics), 6.82 hours after the burst trigger (mid-exposure time).
- GCN notice #3373
M. Jelinek, A. J. Castro-Tirado, J. Gorosabel, A. de Ugarte Postigo,
S. Guziy (IAA-CSIC Granada), P. Kubanek, R. Hudec (Astronomical
Institute of the Academy of Sciences, Ondrejov), and S. Vitek
(Czech Technical University), report:
"The BOOTES-1 very wide field camera, located at Estacion de
Sondeos Atmosfericos (INTA-CEDEA) in Huelva (Spain), observed
the region of the sky containing the SWIFT/BAT error box for
GRB 050505 (Herkett et al. GCN 3366) as part of its routine
observing schedule. A 30 s exposure started at 23:22:00 UT
(21 s prior to the onset of the 90 s long burst), with the
following frame starting at 23:22:00 UT (i.e. covering the late
part of the event). A limiting (unfiltered, airmass 1.6)
magnitude of 9.2 is derived for any prompt optical flash
arising from this event."
This message can be quoted.
- GCN notice #3375
R. Chapman, N. Tanvir (U. of Hertfordshire), E. Rol, A.Levan (U. of
Leicester), R. Priddey (U. of Hertfordshire), I. Steele, R. Smith,
C. Mundell and M. Bode (Liverpool John Moores University) report on
behalf of the ROBONET collaboration:
The Swift/BAT error circle of GRB 050505 (GCN3360) was observed in
R-band starting May 6.30 UT with the 2m Faulkes Telescope North on
Haleakala. Several short exposures were combined and reveal a source
at the position of the candidate optical counterpart from GCN3366.
Preliminary photometry relative to USNO-B1 stars in the frame provides
a magnitude of R = 21.5 +/- 0.2 for this source.
Further observations are planned.
This message may be cited.
- GCN notice #3376
A. de Ugarte Postigo, M. Jelinek, J. Gorosabel (IAA-CSIC Granada),
A. de Ugarte Postigo, M. Jelinek, J. Gorosabel (IAA-CSIC Granada),
P. Kubanek, R. Hudec (ASU-CAS Ondrejov), T. J. Mateo Sanguino
(Univ. de Huelva), S. Castillo, S.Guziy and A. J. Castro-Tirado
(IAA-CSIC), report:
"Following the detection by SWIFT/BAT of GRB 050505
(Herkett et al., GCN 3360), the pair of 0.2m BOOTES-1B
telescopes at INTA-CSIC's Observatorio de Arenosillo
responded automatically at 23:32:30 UT (i.e. 70 s after
the alert which was received 9.5 min after the onset of
the event). A co-addition of the first V- and I-band
images taken do not reveal the optical afterglow at the
position given by Bradley Cenko et al., (GCN 3366).
On the other hand, the 0.6m telescope (+BOOTES-IR optical
camera) at IAA's Observatorio de Sierra Nevada
responded automatically at 23:31:57 UT (i.e. 37 s after
the alert received 9.5 min after the onset of the event).
Due to technical problems (the telescope is still in
commissioning phase), the first image was acquired at
00:09 UT (47 min after the GRB). A preliminary analysis
of our R-band observations (total exposure time = 1 hour)
imposes a limit of R > 19 to the afterglow optical emission
(Bradley Cenko et al., GCN 3366). Further analysis is
in progress."
This message may be cited.
- GCN notice #3377
S. Bradley Cenko, Chuck Steidel, Naveen Reddy, and Derek B. Fox report on
behalf of the Caltech-NRAO-Carnegie GRB Collaboration:
We have further analyzed the I band images of the afterglow of GRB 050505
reported in GCN 3366. Using the USNO-B1 star located at RA:
09:27:06.5667, Dec: +30:17:18.750 (I = 18.85) as a reference, we find the
following magnitude for the afterglow:
UT Time UT Date Time Since Burst (hr) Magnitude
------------------------------------------------------------------------
5:45:47 May 6 6.4 20.66 +/- 0.1
- GCN notice #3398
Autumn Homewood, Dieter H. Hartmann (Clemson), Matt Wood (FIT)
Report on behalf of the Follow-Up-Network (FUN) GRB collaboration:
We observed a 8x12 arcminute field centered on the optical afterglow (GCN
3366) of GRB 050505 discovered by Swift (GCN 3360) with the SARA 0.9 m
Telescope at KPNO. Observations were carried out under good seeing
conditions with the U55 CCD. We obtained 35 minutes of exposure in R.
Observations started at UT 05/05/06 03:03:37, and ended 03:43:43. We do
not detect the afterglow. Our R-band upper limit (1-sigma) is R(lim) =
19.7. The calibration was carried out using the USNO A2.0 catalog.
The SARA home page can be found at
http://www.astro.fit.edu/sara/sara.html
This message may be cited.
- GCN notice #3403
Klotz, A., Boer M. (OHP), and Atteia, J.L. (LAT) report:
We imaged the entire field of GRB 050505 (cf. Hurkett et al. GCNC 3360)
with the TAROT robotic telescope (D=25cm) located at the Calern observatory,
France. Observations started at 23:31:49 UT, 7 seconds after the GCN notice,
and 9.1 min after the GRB. The field had an elevation lower than 26 degrees
above horizon at the begining of the observations.
When we co-add series of 30s unfiltered images, we detect a source at the position
mentioned by S. Bradley Cenko et al. (GCNC 3366) until 23h47 UT.
As the redshift measured by Berger et al. (GCNC 3378) indicates a strong absorption
over the range of 6200-6500 A, we compared the flux of TAROT images (clear filter)
with the I band magnitudes of the USNO-B1 catalog. We find the following magnitudes:
2005-05-05T23:31:49 to 2005-05-05T23:39:25 I=18.2 +/- 0.2
2005-05-05T23:39:32 to 2005-05-05T23:47:08 I=18.4 +/- 0.2
2005-05-05T23:49:55 to 2005-05-05T23:59:39 I>18.8
The comparison with the I magnitude of 20.66 reported by Cenko et al. (GCN 3377)
6.4 hours after the GRB, indicate a slope of -0.7 for the temporal decay in I band.
Further information can be found at
http://www.cesr.fr/~klotz/grb050505/
- GCN notice #4184
A. Henden (AAVSO/USNO) reports on behalf of the USNO GRB Team:
We have acquired UBVRcIc 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.
We are using a new CCD, and so place an additional zeropoint
error of about 0.03mag that should be added in quadrature
to the errors reported in the files listed below.
Stars brighter than V=13.0 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/grb050505.dat
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb051021.dat
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb051022.dat
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb051028.dat
Since these bursts had identified optical afterglows, we may
improve the photometric calibration on subsequent observing runs.
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.
- astro-ph/0511498 from 16 Nov 2005
Berger: Spectroscopy of GRB 050505 at z=4.275: A logN(HI)=22.1 DLA Host Galaxy
We present the discovery of the optical afterglow of GRB 050505 and an
optical absorption spectrum obtained with the Keck I 10-m telescope. The
spectrum exhibits three redshifted absorption systems with the highest, at
z=4.2748, arising in the GRB host galaxy. The host absorption system is marked
by a damped Ly-alpha (DLA) feature with a neutral hydrogen column density of
logN(HI)=22.05+/-0.10, higher than that of any QSO-DLA detected to date, but
similar to several other recent measurements from GRB spectra. In addition, we
detect absorption lines from both low- and high-ionization species from which
we deduce a metallicity, Z~0.06 Z_solar, with a depletion pattern that is
roughly similar to that of the Galactic warm halo, warm disk, or disk+halo.
More importantly, we detect strong absorption from SiII* indicating a dense
environment, n_H>10^2 cm^-3, in the vicinity of the burst, with a size of about
4 pc. In addition, the CIV absorption system spans a velocity range of about
1000 km/s, which is not detected in any other absorption feature. We show that
the most likely interpretation for this wide velocity range is absorption in
the wind from the progenitor star. In this context, the lack of corresponding
SiIV absorption indicates that the progenitor had a mass of <25 M_solar and a
metallicity <0.1 Z_solar, and therefore required a binary companion to eject
its hydrogen envelope prior to the GRB explosion. Finally, by extending the
GRB-DLA sample to z~4.3 we show that these objects appear to follow a similar
metallicity-redshift relation as in QSO-DLAs, but with systematically higher
metallicities. It remains to be seen whether this trend is simply due to the
higher neutral hydrogen columns in GRB-DLAs, or if it is a manifestation of
different star formation properties in GRB-DLAs. [abridged]
- astro-ph/0602236 from 10 Feb 2006
Hurkett: GRB 050505: A high redshift burst discovered by Swift
We report the discovery and subsequent multi-wavelength afterglow behaviour
of the high redshift (z = 4.27) Gamma Ray Burst GRB 050505. This burst is the
third most distant burst, measured by spectroscopic redshift, discovered after
GRB 000131 (z = 4.50) and GRB 050904 (z = 6.29). GRB 050505 is a long GRB with
a multipeaked gamma-ray light curve, with a duration of T_90 = 63+/-2 s and an
inferred isotropic release in gamma-rays of ~4.44 x 10^53 ergs in the 1-10^4
keV rest frame energy range. The Swift X-Ray Telescope followed the afterglow
for 14 days, detecting two breaks in the light curve at 7.4(+/-1.5) ks and 58.0
(+9.9/-15.4) ks after the burst trigger. The power law decay slopes before,
between and after these breaks were 0.25 (+0.16/-0.17), 1.17 (+0.08/-0.09) and
1.97 (+0.27/-0.28) respectively. The light curve can also be fit with a
`smoothly broken' power law model with a break observed at ~ T+18.5 ks, with
decay slopes of ~0.4 and ~1.8 before and after the break respectively. The
X-ray afterglow shows no spectral variation over the course of the Swift
observations, being well fit with a single power law of photon index ~1.90.
This behaviour is expected for the cessation of continued energisation of the
ISM shock followed by a break caused by a jet, either uniform or structured.
Neither break is consistent with a cooling break. The spectral energy
distribution indeed shows the cooling frequency to be below the X-ray but above
optical frequencies. The optical -- X-ray spectrum also shows that there is
significant X-ray absorption in excess of that due to our Galaxy but very
little optical/UV extinction, with E(B-V) ~0.10 for a SMC-like extinction
curve.
Previous IAU Circulars 