- GCN/BACODINE POSITION NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Fri 11 Nov 05 06:00:02 UT
NOTICE_TYPE: Swift-BAT GRB Position
TRIGGER_NUM: 163438, Seg_Num: 0
GRB_RA: 348.157d {+23h 12m 38s} (J2000),
348.230d {+23h 12m 55s} (current),
347.536d {+23h 10m 09s} (1950)
GRB_DEC: +18.367d {+18d 22' 03"} (J2000),
+18.399d {+18d 23' 58"} (current),
+18.095d {+18d 05' 43"} (1950)
GRB_ERROR: 4.00 [arcmin radius, statistical only]
GRB_INTEN: 6814 [cnts] Image_Peak=525 [image_cnts]
TRIGGER_DUR: 1.024 [sec]
TRIGGER_INDEX: 146 E_range: 25-100 keV
BKG_INTEN: 33116 [cnts]
BKG_TIME: 21568.00 SOD {05:59:28.00} UT
BKG_DUR: 8 [sec]
GRB_DATE: 13685 TJD; 315 DOY; 05/11/11
GRB_TIME: 21581.47 SOD {05:59:41.47} UT
GRB_PHI: 136.06 [deg]
GRB_THETA: 27.16 [deg]
SOLN_STATUS: 0x3
RATE_SIGNIF: 37.09 [sigma]
IMAGE_SIGNIF: 15.07 [sigma]
MERIT_PARAMS: +1 +0 +0 +0 +2 +13 -1 +0 +57 +1
SUN_POSTN: 226.49d {+15h 05m 57s} -17.45d {-17d 27' 14"}
SUN_DIST: 124.81 [deg]
MOON_POSTN: 349.41d {+23h 17m 38s} -6.96d {-06d 57' 23"}
MOON_DIST: 25.38 [deg]
MOON_ILLUM: 74 [%]
GAL_COORDS: 92.44,-38.58 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 356.71, 21.51 [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 NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Fri 11 Nov 05 06:03:17 UT
NOTICE_TYPE: Swift-BAT GRB Lightcurve
TRIGGER_NUM: 163438, Seg_Num: 0
GRB_RA: 348.157d {+23h 12m 38s} (J2000),
348.230d {+23h 12m 55s} (current),
347.536d {+23h 10m 09s} (1950)
GRB_DEC: +18.367d {+18d 22' 03"} (J2000),
+18.399d {+18d 23' 58"} (current),
+18.095d {+18d 05' 43"} (1950)
GRB_DATE: 13685 TJD; 315 DOY; 05/11/11
GRB_TIME: 21581.47 SOD {05:59:41.47} UT
TRIGGER_INDEX: 146
GRB_PHI: 136.06 [deg]
GRB_THETA: 27.16 [deg]
DELTA_TIME: 65484.00 [sec]
TRIGGER_DUR: 1.024 [sec]
LC_URL: sw00163438000msb.lc
SUN_POSTN: 226.49d {+15h 05m 57s} -17.45d {-17d 27' 14"}
SUN_DIST: 124.81 [deg]
MOON_POSTN: 349.41d {+23h 17m 38s} -6.96d {-06d 57' 23"}
MOON_DIST: 25.38 [deg]
MOON_ILLUM: 74 [%]
GAL_COORDS: 92.44,-38.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS: 356.71, 21.51 [deg] ecliptic lon,lat of the pointing direction
COMMENTS: SWIFT-BAT GRB Lightcurve.
COMMENTS:
COMMENTS: The next comments were copied from the BAT_POS Notice:
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.
- GCN Circular #4247
W. Rujopakarn (U Mich), H. Swan (U Mich), E.S. Rykoff (U Mich), B. Schaefer
(Louisiana State), report on behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 051111A
(Swift trigger 163438). The first image was at 06:00:08.4 UT, 26.9 s after
the burst (6.4 s after the GCN notice time). The unfiltered images are
calibrated relative to USNO A2.0. We detect a new object, not visible in the
DSS (second epoch), with coordinates:
23:12:33.2 +18:22:29.1 (J2000)
start UT mag mlim(of image)
----------------------------------
06:00:08.4 13.0 15.6
Continuing observations are in progress.
- GCN Circular #4248
T. Sakamoto (GSFC), D. Burrows (PSU), S. Immler (GSFC/USRA),
N. Gehrels (GSFC), S. Hunsberger (PSU), F. Marshall (GSFC),
D. Palmer (LANL), V. La Parola (INAF-IASFPa)
on behalf of the Swift team:
At 05:59:41 UT, Swift-BAT triggered and located GRB051111
(trigger=163438).
The BAT on-board calculated location is RA,Dec=348.157,+18.367
{23h 12m 38s,+18d 22' 03"} (J2000), with an uncertainty of 3 arcmin
(radius, 90% containment, stat+sys). The BAT light curve showed a
broad single peak with a 10 second rise to a peak of 4000 counts/s
(15-350 keV) around T+0 with decaying emission at least to T+20.
The spacecraft did not automatically slew due to Moon constraint.
A ToO observation is being planned.
- GCN Circular #4250
C.G. Mundell (Liverpool JMU), E. Rol (Leicester), C. Guidorzi, A. Gomboc,
I. A. Steele, C.J. Mottram, A. Monfardini, R.J. Smith, D. Carter, M.F.
Bode (Liverpool JMU), P. O'Brien, N. Bannister (Leicester) report:
"The 2-m Faulkes North Telescope robotically followed up GRB051111
(Swift trigger 163438) at 06:04:44 UT. The automatic "detection mode"
procedure detected a fading candidate at:
23:12:33.17 +18:22:28.80 (J2000) - R = 14.86 mag (vs USNOB1)
Observations and analysis are ongoing.
This message may be cited"
- GCN Circular #4251
E.S. Rykoff (U Mich), W. Rujopakarn (U Mich), H. Swan (U Mich), B.
Schaefer (Louisiana State), S.A. Yost (U Mich), R. Quimby (U Texas),
report on behalf of the ROTSE collaboration:
A fast fading optical transient has been discovered inside the error
circle for GRB 051111A (Swift trigger 163438, Sakamoto et al, GCN 4248)
by the ROTSE-IIIb telescope, located at McDonald Observatory (see
Rujopakarn et al, GCN 4247). The initial response was during the BAT
emission, when the transient was at 13.0 mag (unfiltered, relative to
USNO A2.0). The transient faded as a simple power law with decay index ~
-0.9. At UT 06:41:57 (t+2500s), the transient was at 17.4 mag.
Continuing observations are in progress.
- GCN Circular #4252
P. Milne, G. Williams (U. of Arizona), H. S. Park (LLNL), S. Barthelmy
(GSFC), J. Crist-Lair (Clemson U) , report on behalf of the Super-LOTIS
collaboration.
The 0.6m automated Super-LOTIS telescope, located at Steward Observatory's
Kitt Peak site, responded to Swift trigger 163438, GRB051111A. The first
image began at 06:00:17.4 UT, 35.9 s after the burst. We clearly detect
the OT identified by W. Rujopakarn et al. (GCN 4247) and find that it has
faded considerably in images taken 15 minutes after the burst. The
approximate R band magnitude in the first 10 second exposure was
determined using the USNO B1 catalog.
UT Start Exp Time R mag delta R
06:00:17.4 10 s 13.2 0.1
Observations and analysis are continuing.
- GCN Circular #4253
K. Torii (Osaka U.) reports:
The error region of GRB 051111a (Sakamoto et al., GCN 4248) was
observed by the 0.3 m telescope in the New Mexico Skies
Observatory. Starting at 06:05:50 UT (382 s after the burst), 120 s
exposures in Ic band was repeated.
We confirm the presence of the bright afterglow (Rujopakarn et al.,
GCN 4247) and its fading. Between 06:07 UT and 06:36 UT, the
afterglow faded by about 1.7 mag in Ic band.
- GCN Circular #4254
W. Li, University of California, Berkeley, on behalf of the
KAIT GRB team, report:
The robotic 0.76-m Katzman Automatic Imaging Telescope (KAIT)
at Lick Observatory observed GRB051111 detected with Swift
(Trigger 163438; Sakamoto et al. GCN 4248). A series of
images was automatically obtained starting at 06:00:25 UT
(44s after the burst). The sequence includes a combination of
images taken with the V and I filters, as well as some that
are unfiltered. The OT identified by W. Rujopakarn et al. (GCN
4247) was detected with the following unfiltered magnitudes
(calibrated to USNO B1.0):
UT Start EXP time R mag delta R
06:00:25 15 s 13.40 0.05
06:01:46 20 s 14.32 0.05
Observations and analysis are continuing.
- GCN Circular #4255
G. Hill (Keck), J.X. Prochaska (UCO/Lick), D. Fox (Penn State),
B. Schaefer (Keck), M. Reed (Keck):
"We have observed GRB 051111 with HIRESr on the Keck telescope
for 1800s starting UT 07:03. We detect a series of strong MgII,
FeII and SiII absorption features at a redshift z=1.55. Because we
detect no additional features redward of the MgII doublet, we
adopt this as the redshift of GRB 051111."
A full analysis is underway.
- GCN Circular #4256
J. S. Bloom, on behalf of a larger collaboration, reports:
"As the poor transmission conditions (i.e. clouds) at Mt. Hopkins =20
improved, we managed to obtain a total imaging exposure of 188 =20
seconds on the field of GRB 051111a (GCN 4248) before hitting a =20
telescope limit. In simultaneous observations with PAIRITEL (*) we
measure magnitudes of the Rujopakarn transient (GCN 4247) of:
J = 16.55 +- 0.03, H = 15.85 +- 0.04 and Ks = 15.29 +- 0.06
from 2005-11-11 07:23:29 to 2005-11-11 07:28:26 UTC. A color
composite image may be found at:
http://astro.berkeley.edu/~jbloom/grb051111a.gif
This message may be cited."
(*) http://pairitel.org
- GCN Circular #4257
Kiran Garimella, Autumn Homewood, and Dieter Hartmann report on behalf of
the Clemson GRB Follow-Up Team:
We began observations in R-Band at UT 20051111 07:04:38, approximately 1
hour after the Swift Trigger (GCN 4248). We detect the OT reported by
ROTSE-III (GCN 4247). Preliminary analysis of the raw data yields R = 18.3
+/- 0.2 mag, based on stacked images with a total exposure time of 50
minutes. Images were calibrated using USNO B1.0 catalog. Analysis is
ongoing.
This message may be cited.
SARA Homepage: www.saraobservatory.org
Clemson GRB Follow-Up Homepage:
http://people.clemson.edu/~kgarime/burst
- GCN Circular #4258
GRB 051111A : Lulin BVRI multi band afterglow observation
F.Y. Huang, K.Y. Huang, W.H. Ip (NCU), Y. Urata(RIKEN),
Y. Qiu (BAO), Y.Q. Lou (THCA) on behalf of EAFON report:
" We started BVRI multi band imaging of the GRB 051111A afterglow using
Lulin 1-m telescope at 10:07 UT (4.1 h after the burst). We detected
the optical afterglow clearly in each band. Preliminary analysis of
the R-band image taken at 4.4 h after the burst with 300s exposure
yields R=19.2.
Further observation and analysis are in progress."
This message may be cited.
- GCN Circular #4260
H. Krimm (GSFC/USRA), M. Ajello (MPE), L. Barbier (GSFC),
S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL),
R. Fink (GSFC), N. Gehrels (GSFC), D. Hullinger (UMD),
C. Markwardt (GSFC/UMD),D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/NRC), G. Sato (ISAS), J. Tueller (GSFC),
on behalf of the Swift-BAT team:
Using the data set from T-300 to T+300 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 051111
(trigger #163438) (Sakamoto, et al., GCN 4248).
The BAT ground-calculated position is
(RA,Dec) = 348.134, +18.365 {23h 12m 32s, 18d 21' 54"} [deg; J2000]
+- 0.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 59%.
The light curve has a FRED-like structure with the duration of
the rising and the decay part of 10 sec and 40 sec, respectively.
The emission might be extended untill T+80 sec. Although there is
a bump around T+5s in the 100-350 keV band, this bump is not visible
below 100 keV. T90 (15-350 keV) is (47 +- 1) sec
(estimated error including systematics).
The power law index of the time-averaged spectrum is 1.32 +- 0.06.
The fluence in the 15-150 keV band is (3.9 +- 0.1) x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.56 sec in the 15-150 keV
band is (2.5 +- 0.2) ph/cm2/sec. All the quoted errors are at the 90%
confidence level.
- GCN Circular #4261
GRB051111: XRT preliminary analysis
V. La Parola (INAF-IASFPA), V. Mangano (INAF-IASFPA), T. Mineo
(INAF-IASFPA), G. Cusumano (INAF-IASFPA), D. N. Burrows (PSU), F.
Marshall (GSFC), A. Smale (NASA HQ), K. Page (U. Leicester) on behalf of
the Swift/XRT team:
We have analysed 4 ks of XRT observations of GRB051111
(Sakamoto et al., GCN 4248). A bright source is well detected.
The refined coordinates for this X-ray afterglow are:
RA(J2000): 23h 12m 33.362s
Dec(J2000): 18d 22' 29.535"
with an estimated uncertainty of 3.5 arcsec (90% containment) and
including the latest XRT boresight correction.
The position is 71 arcsec from the on-board BAT position reported by
Sakamoto et al. and 2.4 arcsec from the optical afterglow first
detected by ROTSE (Rujopakarn et al., GCN 4247).
The X-ray light-curve is steeply fading with a slope of -1.9+/-0.2.
The spectrum of the PC data can be modelled with an absorbed power-law
with photon index Gamma = 2.2+/-0.3 (90% containment).
There is a slight evidence for an absorbing column higher than the
Galactic value
(5.02e20 cm^-2) at a level of (9+/-5)e21 cm^-2 at the observed redshift
z=1.55 (Hill et al., GCN 4255).
The 0.2-10 keV unabsorbed flux at 5000 s is 1.8e-11 erg cm^-2 s^-1.
At 10000 s the afterglow had faded to flux level of 5.0e-12 erg cm^-2
s^-1.
The predicted flux at T+24h is 8.8e-14erg cm^-2 s^-1
- GCN Circular #4262
GRB 051111A : R-band temporal decay index based on Lulin observations
F.Y. Huang, K.Y. Huang, W.H. Ip (NCU), Y. Urata(RIKEN),
Y. Qiu (BAO), Y.Q. Lou (THCA) on behalf of EAFON report:
"We have observed the optical afterglow of GRB 051111 (GCN # 4247,
4248) using the Lulin 1m telescope with BVRI band filters between
10:07 UT and 14:54 UT on Nov 11 2005. Combine with our previous
preliminary result (GCN # 4258), the R-band light curve shows shallow
decay. When we fit all our R-band data with single power-law the
temporal index is determined as alpha~-0.6.
Further analysis is in progress."
This message may be cited.
- GCN Circular #4263
T.S. Poole (UCL-MSSL), T. Sakamoto (GSFC), A.J. Blustin (UCL-MSSL), B.
Hancock (UCL-MSSL) & T.Kennedy (UCL-MSSL) on behalf of the Swift/UVOT team
report:
The Swift-Ultra-Violet/Optical Telescope (UVOT) began observing the field
of GRB 051111 (BAT Trigger=163438; Sakamoto et al. GCN 4248) at 2005-11-11
7:47:20, 5560 seconds after the burst. We detect a source in the V, B, U
and UVW1 filters at position RA 23:12:33.17, DEC 18:22:28.80; this
position was also reported by Mundell et. al. (GCN 4250). The source is
not detected in the UVM2 or UVW2 filters.
The aperture used for optical observations was 6 arcsec, and 12 arcsec was
used for the ultraviolet observations. The limiting magnitudes are given
to a 3 sigma limit.
Filter T_range T_exp Mag
(sec) (sec)
V 16298-17198 900 19.33+/-0.35 - source detection
B 11237-12136 900 20.38+/-0.35 - source detection
U 10329-11229 900 20.09+/-0.46 - source detection
UVW1 6467-7153 686 20.25+/-0.85 - source detection
UVM2 5560-11832 1800 20.92 - upper limit
UVW2 12145-12938 793 20.64 - upper limit
Where T_range is time post-trigger, and T_exp is the exposure time of the
observation. Magnitude errors include statistical and systematic errors.
These results were obtained from intital UVOT exposures, and the
observations of GRB051111 are continuing.
This message may be cited.
- GCN Circular #4267
Ian A. Smith (Rice U) and Heather F. Swan (U Mich) report on
behalf of the MARGE collaboration:
The Rice University CCD Camera (RUCCD) on the AEOS telescope,
located at the Maui Space Surveillance System on Haleakala,
observed the fading counterpart to GRB 051111 (Swift trigger
163438). VRI images were taken between 2005-11-11 06:31 UT
(32 minutes after the trigger) and 07:08 UT. A preliminary
analysis gives R=17.7 at 07:05 UT in a 30 second exposure.
- GCN Circular #4270
Dale A. Frail (NRAO) reports on behalf of a larger collaboration:
"We observed the field of the bright GRB 051111 (GCN 4248) with the
Very Large Array at 8.5 GHz around November 13.15 UT. At the position
of the optical transient (GCN 4247; GCN 4250) there is a weak radio
source with a flux density 98 +/- 28 uJy. We identify this as the radio
afterglow of GRB 051111.
Further observations are planned.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
- GCN Circular #4271
J.X. Prochaska (UCO/Lick) on behalf of GRAASP reports:
"We have further analyzed the Keck/HIRES spectrum of GRB 051111.
A total integration of 5400s was acquired covering 4200-8400Ang
with a SNR~20 per 1.3km/s pixel at 5500Ang. The main component
is ~30km/s wide, contains 90% of the gas and is centered at
z=1.54948 +/- 0.00001. The full line-profile, however, spans
~250km/s.
The gas in the GRB host is remarkable for several reasons:
(1) The SiII 1808 and ZnII 2026, 2062 transitions are saturated
implying log N(Zn) > 13.5 and log N(Si) > 15.9. We believe these are
the largest Zn and Si column densities recorded outside the Local Group;
(2) The observed Zn/Fe ratio is [Zn/Fe] > 1.2 indicating significant
differential depletion; (3) We detect the fine-structure SiII* 1816
transition and observe that the weak MgI 2026 transition is saturated.
(4) Perhaps more stunning, we detect nearly every FeII excited
transition
in the Morton catalog redward of 2300Ang. This includes several
transitions from the 977K excited level. These suggest both a large
volume density and a warm gas.
We place a lower limit to N(HI) assuming a solar metallicity for
the gas: log N(HI) > 20.8. The high metal column density and
significant differential depletion imply a rest-frame V-band
extinction A(V) > 0.5mag. Adopting the Milky Way extinction curve,
this implies an observed R-band extinction A(R_obs) > 1.4mag.
The extinction is several times larger if one adopts the SMC or
Calzetti curves.
We also identify a very strong intervening MgII system at z=1.18975.
These data were kindly obtained by the Keck observing staff during
engineering and will be publically released. For now, the raw data
are archived at www.graasp.org."
This GCN may be cited.
- GCN Circular #4298
D. Nanni, (INAF/Osservatorio di Roma), F. Terra (Second
University of Rome "Tor Vergata" , C. Bartolini, G. Greco,
A. Guarnieri, A. Piccioni (Bologna University), R. Poggiani (Pisa
University), A. De Blasi (INAF/Osservatorio di Bologna) and
G. Pizzichini (INAF/IASF, Bologna) report:
We observed the error box of GRB051111 (Swift trigger 163438)
with the 152 cm Loiano Telescope and the BFOSC camera system
in poor sky conditions.
We obtained the following images, all of them in the Rc filter,
and detected the optical candidate first reported by Rujopakarn et
al., GCN 4247 with the following magnitudes:
Start time (UT) Exposure Mag
(min)
051111 18:26:55 20 20.0 +- 0.2
051111 19:31:51 20 20.5 +- 0.3
051111 22:05:51 20 20.9 +- 0.5
051111 22:27:31 20 20.9 +- 0.5
051111 22:50:56 20 21.5 +- 0.8
051111 23:12:35 20 20.9 +- 0.5
The coadded images and the observation log will be posted in our
public directory from where they can be retrieved by sftp using
hostname: ermione.bo.astro.it, username: publicGRB,
- GCN Circular #4299
K.Yamaoka, S.Sugita (Aoyama Gakuin U.), M.Ohno,
T.Takahashi, Y.Fukazawa (Hiroshima U.),
Y.Terada (RIKEN), K.Abe, Y.Endo, S. Hong, K.Onda,
M.Tashiro (Saitama U.), K.Nakazawa, G.Sato,
T.Takahashi (ISAS/JAXA), R.Miyawaki,
M.Kokubun, K.Makishima (Univ. of Tokyo) and the HXD-II team:
The bright burst, GRB 051111(Krimm et al., GCN4260), triggered
the Suzaku Wideband All-sky Monitor (WAM) which covers
an energy band of 50 keV - 5 MeV at 05:59:39 (UT).
The observed prompt emission exhibits a FRED-like lightcurve
with a duration (T90) of 31 seconds.
The fluence in 100 - 700 keV was (8.4 +/- 0.8)X10^-6 erg/cm2.
The 1-s peak flux was 1.0 +/- 0.1 photons/cm2/s
in the same energy range.
Preliminary result shows that the time-averaged spectrum
is well fitted by a single power law with a photon index
of 1.5 +/- 0.3.
All the quoted errors are at statistical 90% confidence level.
The WAM onboard calibration is still under way, and
systematic errors, such as the flux calibration uncertainties of
about 20%, are not included in the errors.
The WAM light curve of this event is available at
http://www.astro.isas.ac.jp/suzaku/research/HXD-WAM/WAM-GRB/grb/grb_table.html
Further detailed analyses are in progress.
- GCN Circular #4302
In GCN 4298 on GRB051111: Rc optical observations, by D. Nanni et al.,
after the hostname: ermione.bo.astro.it and username: publicGRB
for our public directory, the password: GRB_bo and directory: GRB051111
were omitted.
- GCN Circular #4307
D. Sharapov, M. Ibrahimov (MAO), A.Pozanenko (IKI),V.Rumyantsev (CrAO) on
behalf of larger GRB follow up collaboration report:
We observed the error box of GRB051111 (Sakamoto et al., GCN 4248) with
1.5m telescope of Maidanak Astronomical Observatory. Set of BR images were
taken between Oct.11 (UT) 18.11 - 18.40. Optical source (Rujopakarn et al.,
GCN 4247) is detected in a stacked R-image. Preliminary photometry against
of USNO A2.0 is following:
Mid time, Exposure, Filter, Mag.
(UT) (s)
Nov.11 18:19:35 900 R 19.78 +- 0.14
Nov.11 18:34:51 600 B >19.0 (3 sigma UL)
The message may be cited.
- astro-ph/0512280 from 12 Dec 2005
Berger: Fine-Structure FeII and SiII Absorption in the Spectrum of GRB 051111:
We present an analysis of fine-structure transitions of FeII and SiII
detected in a high-resolution optical spectrum of the afterglow of GRB 051111
(z=1.54948). The fine-structure absorption features arising from FeII* to
FeII****, as well as SiII*, are confined to a narrow velocity structure
extending over +/-30 km/s, which we interpret as the burst local environment,
most likely a star forming region. We investigate two scenarios for the
excitation of the fine-structure levels by collisions with electrons and
radiative pumping by an infra-red or ultra-violet radiation field produced by
intense star formation in the GRB environment, or by the GRB afterglow itself.
We find that the conditions required for collisional excitation of FeII
fine-structure states cannot be easily reconciled with the relatively weak
SiII* absorption. Radiative pumping by either IR or UV emission requires >10^3
massive hot OB stars within a compact star-forming region a few pc in size, and
in the case of IR pumping a large dust content. On the other hand, it is
possible that the GRB itself provides the source of IR and/or UV radiation, in
which case we estimate that the excitation takes place at a distance of ~10-20
pc from the burst. Detailed radiative transfer calculations are required in
order to verify that excitation of the low-ionization fine-structure states is
possible given the intense UV flux from the burst. Still, it is clear that GRB
absorption spectroscopy can provide direct information on the mode and
conditions of star formation at high redshift.
- astro-ph/0512340 from 14 Dec 2005
Penprase: Spectroscopy of GRB 051111 at z=1.54948: Kinematics and Elemental
We present a high-resolution, high signal-to-noise optical spectrum of the
afterglow of GRB 051111 obtained with the HIRES spectrograph on the Keck I 10-m
telescope. The spectrum exhibits three redshifted absorption systems with the
highest, at z=1.54948, arising in the GRB host galaxy. While the Ly-alpha
feature is outside the range of our spectrum, the high column density of
weakly-depleted Zn suggests that the host is a damped Lyman-alpha system with
N(HI)>10^21(Z/Z_sun)^-1. The bulk of the gas (>80%) is confined to a narrow
velocity range of |v|<30 km/s exhibiting strong dust depletion of refractory
elements such as Fe and Cr. The depletion pattern is similar to that observed
in warm disk clouds of the Milky Way. We also detect absorption from all
ground-level fine-structure states of FeII, the first such example in a QSO-DLA
or GRB-absorption spectrum, which indicate conditions that are consistent with
the "warm disk" depletion pattern. The absorption profiles of FeII and MgII
extend over several hundred km/s, with a depletion pattern that more closely
resembles that of QSO-DLAs, suggesting that the sight line to GRB 051111 probes
the halo of the host galaxy in addition to the dense disk. Thus, detailed
diagnostics of the interstellar medium of GRB host galaxies continue to provide
insight into regions which are generally missed in quasar surveys.
- astro-ph/0606763 from 30 Jun 2006
Butler: When Do Internal Shocks End and External Shocks Begin? Early-Time Broadband Modelling of GRB 051111
Even with the renaissance in gamma-ray burst (GRB) research fostered by the
Swift satellite, few bursts have both contemporaneous observations at long
wavelengths and exquisite observations at later times across the
electromagnetic spectrum. We present here contemporaneous imaging with the KAIT
robotic optical telescope, dense optical sampling with Lulin, and supplemented
with infrared data from PAIRITEL and radio to gamma-ray data from the
literature. For the first time, we can test the constancy of microphysical
parameters in the internal-external shock paradigm and carefully trace the flow
of energy from the GRB to the surrounding medium. KAIT data taken <~ 1 minute
after the start of GRB 051111 and coinciding with the fading gamma-ray tail of
the prompt emission indicate a smooth re-injection of energy into the shock. No
color change is apparent in observations beginning ~1.5 minutes after the GRB
and lasting for the first hour after the burst, at which point the external
shock afterglow emission clearly dominates. There are prominent and apparently
achromatic flux modulations about the best-fit model curves at late (t~ 10^4 s)
times, which may be due to energy injection or possibly to variations in the
external density. Using IR data taken with PAIRITEL and UV data from Swift, we
find that the host-galaxy extinction is well fit by a curve similar to that of
the Small Magellanic Cloud. Low visual extinction, A_V~ 0.2 mag, combined with
high column densities determined from the X-ray and optical spectroscopy (N_H>
10^21 cm^-2), indicate a low dust-to-metals ratio and a possible over-abundance
of the light metals. An apparent small ratio of total to selective extinction
(R_V~ 2) and time constancy of both optical and X-ray spectra argue against
dust destruction by the GRB itself.
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