- GCN/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Sat 21 Jan 06 22:24:58 UT
NOTICE_TYPE: HETE S/C_Alert
TRIGGER_NUM: 4010, Seq_Num: 1
GRB_DATE: 13756 TJD; 21 DOY; 06/01/21
GRB_TIME: 80694.50 SOD {22:24:54.50} UT
TRIGGER_SOURCE: Trigger on the 6-80 keV band.
GAMMA_RATE: 420 [cnts/s] on a 1.300 [sec] timescale
SC_LONG: 38 [deg East]
SUN_POSTN: 304.00d {+20h 15m 59s} -19.77d {-19d 46' 11"}
MOON_POSTN: 201.35d {+13h 25m 24s} -10.66d {-10d 39' 44"}
MOON_ILLUM: 57 [%]
COMMENTS: No s/c ACS pointing info available yet.
COMMENTS: Probable GRB.
- GCN/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Sat 21 Jan 06 22:25:08 UT
NOTICE_TYPE: HETE S/C_Update
TRIGGER_NUM: 4010, Seq_Num: 2
GRB_DATE: 13756 TJD; 21 DOY; 06/01/21
GRB_TIME: 80694.50 SOD {22:24:54.50} UT
TRIGGER_SOURCE: Trigger on the 6-80 keV band.
GAMMA_RATE: 420 [cnts/s] on a 1.300 [sec] timescale
SC_-Z_RA: 122 [deg]
SC_-Z_DEC: 24 [deg]
SC_LONG: 38 [deg East]
WXM_CNTR_RA: 137.575d {+09h 10m 18s} (J2000),
137.676d {+09h 10m 42s} (current),
136.739d {+09h 06m 57s} (1950)
WXM_CNTR_DEC: +45.764d {+45d 45' 52"} (J2000),
+45.740d {+45d 44' 23"} (current),
+45.969d {+45d 58' 07"} (1950)
WXM_MAX_SIZE: 28.00 [arcmin] diameter
WXM_LOC_SN: 6 sig/noise (pt src in image)
WXM_IMAGE_SN: X= 4.5 Y= 4.5 [sig/noise]
WXM_LC_SN: X= 4.0 Y= 5.2 [sig/noise]
SUN_POSTN: 304.00d {+20h 15m 59s} -19.77d {-19d 46' 11"}
SUN_DIST: 151.69 [deg] Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN: 201.35d {+13h 25m 25s} -10.66d {-10d 39' 46"}
MOON_DIST: 80.12 [deg]
MOON_ILLUM: 57 [%]
GAL_COORDS: 174.41,42.87 [deg] galactic lon,lat of the burst
ECL_COORDS: 125.69,28.04 [deg] ecliptic lon,lat of the burst
COMMENTS: Probable GRB.
COMMENTS: WXM error box is circular; not rectangular.
- GCN/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Sat 21 Jan 06 22:25:13 UT
NOTICE_TYPE: HETE S/C_Update
TRIGGER_NUM: 4010, Seq_Num: 3
GRB_DATE: 13756 TJD; 21 DOY; 06/01/21
GRB_TIME: 80694.50 SOD {22:24:54.50} UT
TRIGGER_SOURCE: Trigger on the 6-80 keV band.
GAMMA_RATE: 420 [cnts/s] on a 1.300 [sec] timescale
SC_-Z_RA: 122 [deg]
SC_-Z_DEC: 24 [deg]
SC_LONG: 38 [deg East]
WXM_CNTR_RA: 137.017d {+09h 08m 04s} (J2000),
137.119d {+09h 08m 29s} (current),
136.169d {+09h 04m 41s} (1950)
WXM_CNTR_DEC: +47.191d {+47d 11' 26"} (J2000),
+47.166d {+47d 09' 57"} (current),
+47.393d {+47d 23' 34"} (1950)
WXM_MAX_SIZE: 28.00 [arcmin] diameter
WXM_LOC_SN: 5 sig/noise (pt src in image)
WXM_IMAGE_SN: X= 3.5 Y= 4.7 [sig/noise]
WXM_LC_SN: X= 6.7 Y= 5.7 [sig/noise]
SUN_POSTN: 304.00d {+20h 15m 59s} -19.77d {-19d 46' 11"}
SUN_DIST: 150.59 [deg] Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN: 201.35d {+13h 25m 25s} -10.66d {-10d 39' 47"}
MOON_DIST: 81.10 [deg]
MOON_ILLUM: 57 [%]
GAL_COORDS: 172.51,42.38 [deg] galactic lon,lat of the burst
ECL_COORDS: 124.74,29.26 [deg] ecliptic lon,lat of the burst
COMMENTS: Probable GRB.
COMMENTS: WXM error box is circular; not rectangular.
- GCN/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Sat 21 Jan 06 22:25:34 UT
NOTICE_TYPE: HETE S/C_Update
TRIGGER_NUM: 4010, Seq_Num: 4
GRB_DATE: 13756 TJD; 21 DOY; 06/01/21
GRB_TIME: 80694.50 SOD {22:24:54.50} UT
TRIGGER_SOURCE: Trigger on the 6-80 keV band.
GAMMA_RATE: 420 [cnts/s] on a 1.300 [sec] timescale
SC_-Z_RA: 122 [deg]
SC_-Z_DEC: 24 [deg]
SC_LONG: 38 [deg East]
WXM_CNTR_RA: 137.342d {+09h 09m 22s} (J2000),
137.443d {+09h 09m 46s} (current),
136.506d {+09h 06m 01s} (1950)
WXM_CNTR_DEC: +45.767d {+45d 45' 59"} (J2000),
+45.742d {+45d 44' 30"} (current),
+45.970d {+45d 58' 12"} (1950)
WXM_MAX_SIZE: 28.00 [arcmin] diameter
WXM_LOC_SN: 12 sig/noise (pt src in image)
WXM_IMAGE_SN: X= 8.5 Y= 8.7 [sig/noise]
WXM_LC_SN: X= 13.0 Y= 11.5 [sig/noise]
SUN_POSTN: 304.00d {+20h 15m 59s} -19.77d {-19d 46' 11"}
SUN_DIST: 151.76 [deg] Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN: 201.36d {+13h 25m 25s} -10.66d {-10d 39' 52"}
MOON_DIST: 80.27 [deg]
MOON_ILLUM: 57 [%]
GAL_COORDS: 174.42,42.70 [deg] galactic lon,lat of the burst
ECL_COORDS: 125.52,27.99 [deg] ecliptic lon,lat of the burst
COMMENTS: Probable GRB.
COMMENTS: WXM error box is circular; not rectangular.
- GCN/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Sat 21 Jan 06 22:28:24 UT
NOTICE_TYPE: HETE S/C_Last
TRIGGER_NUM: 4010, Seq_Num: 5
GRB_DATE: 13756 TJD; 21 DOY; 06/01/21
GRB_TIME: 80694.50 SOD {22:24:54.50} UT
TRIGGER_SOURCE: Trigger on the 6-80 keV band.
GAMMA_RATE: 420 [cnts/s] on a 1.300 [sec] timescale
SC_-Z_RA: 122 [deg]
SC_-Z_DEC: 24 [deg]
SC_LONG: 38 [deg East]
WXM_CNTR_RA: 137.342d {+09h 09m 22s} (J2000),
137.443d {+09h 09m 46s} (current),
136.506d {+09h 06m 01s} (1950)
WXM_CNTR_DEC: +45.767d {+45d 45' 59"} (J2000),
+45.742d {+45d 44' 30"} (current),
+45.970d {+45d 58' 12"} (1950)
WXM_MAX_SIZE: 28.00 [arcmin] diameter
WXM_LOC_SN: 12 sig/noise (pt src in image)
WXM_IMAGE_SN: X= 8.5 Y= 8.7 [sig/noise]
WXM_LC_SN: X= 13.0 Y= 11.5 [sig/noise]
SUN_POSTN: 304.00d {+20h 15m 60s} -19.77d {-19d 46' 09"}
SUN_DIST: 151.76 [deg] Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN: 201.38d {+13h 25m 31s} -10.68d {-10d 40' 31"}
MOON_DIST: 80.29 [deg]
MOON_ILLUM: 57 [%]
GAL_COORDS: 174.42,42.70 [deg] galactic lon,lat of the burst
ECL_COORDS: 125.52,27.99 [deg] ecliptic lon,lat of the burst
COMMENTS: Probable GRB.
COMMENTS: WXM error box is circular; not rectangular.
- red DSS finding chart
ps-file
- GCN NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Sat 21 Jan 06 23:12:35 UT
NOTICE_TYPE: HETE Ground Analysis
TRIGGER_NUM: 4010, Seq_Num: 6
GRB_DATE: 13756 TJD; 21 DOY; 06/01/21
GRB_TIME: 80694.49 SOD {22:24:54.49} UT
TRIGGER_SOURCE: Trigger on the 6-80 keV band.
GAMMA_RATE: 420 [cnts/s] on a 1.300 [sec] timescale
SC_-Z_RA: 122 [deg]
SC_-Z_DEC: 24 [deg]
SC_LONG: 38 [deg East]
WXM_CNTR_RA: 137.516d {+09h 10m 04s} (J2000),
137.617d {+09h 10m 28s} (current),
136.681d {+09h 06m 43s} (1950)
WXM_CNTR_DEC: +45.690d {+45d 41' 24"} (J2000),
+45.665d {+45d 39' 54"} (current),
+45.894d {+45d 53' 38"} (1950)
WXM_MAX_SIZE: 16.00 [arcmin] diameter
WXM_LOC_SN: 25 sig/noise (pt src in image)
WXM_IMAGE_SN: X= 10.2 Y= 9.6 [sig/noise]
WXM_LC_SN: X= 19.2 Y= 16.5 [sig/noise]
SUN_POSTN: 304.03d {+20h 16m 07s} -19.76d {-19d 45' 44"}
SUN_DIST: 151.78 [deg] Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN: 201.72d {+13h 26m 53s} -10.84d {-10d 50' 38"}
MOON_DIST: 80.49 [deg]
MOON_ILLUM: 57 [%]
GAL_COORDS: 174.51,42.83 [deg] galactic lon,lat of the burst
ECL_COORDS: 125.68,27.96 [deg] ecliptic lon,lat of the burst
COMMENTS: Definite GRB.
COMMENTS: WXM error box is circular; not rectangular.
COMMENTS: Burst_Validity flag is true.
COMMENTS: WXM data refined since S/C_Last Notice.
- GCN NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Sat 21 Jan 06 23:53:06 UT
NOTICE_TYPE: HETE Ground Analysis
TRIGGER_NUM: 4010, Seq_Num: 7
GRB_DATE: 13756 TJD; 21 DOY; 06/01/21
GRB_TIME: 80694.49 SOD {22:24:54.49} UT
TRIGGER_SOURCE: Trigger on the 6-80 keV band.
GAMMA_RATE: 420 [cnts/s] on a 1.300 [sec] timescale
SC_-Z_RA: 122 [deg]
SC_-Z_DEC: 24 [deg]
SC_LONG: 38 [deg East]
WXM_CNTR_RA: 137.516d {+09h 10m 04s} (J2000),
137.617d {+09h 10m 28s} (current),
136.681d {+09h 06m 43s} (1950)
WXM_CNTR_DEC: +45.690d {+45d 41' 24"} (J2000),
+45.665d {+45d 39' 54"} (current),
+45.894d {+45d 53' 38"} (1950)
WXM_MAX_SIZE: 16.00 [arcmin] diameter
WXM_LOC_SN: 25 sig/noise (pt src in image)
WXM_IMAGE_SN: X= 10.2 Y= 9.6 [sig/noise]
WXM_LC_SN: X= 19.2 Y= 16.5 [sig/noise]
SXC_CNTR_RA: 137.489d {+09h 09m 57s} (J2000),
137.590d {+09h 10m 22s} (current),
136.654d {+09h 06m 37s} (1950)
SXC_CNTR_DEC: +45.675d {+45d 40' 30"} (J2000),
+45.650d {+45d 39' 00"} (current),
+45.879d {+45d 52' 44"} (1950)
SXC_MAX_SIZE: 2.67 [arcmin] diameter
SXC_LOC_SN: 3 sig/noise (pt src in image)
SUN_POSTN: 304.06d {+20h 16m 14s} -19.76d {-19d 45' 21"}
SUN_DIST: 151.81 [deg] Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN: 202.03d {+13h 28m 08s} -11.00d {-10d 59' 54"}
MOON_DIST: 80.82 [deg]
MOON_ILLUM: 56 [%]
GAL_COORDS: 174.54,42.81 [deg] galactic lon,lat of the burst
ECL_COORDS: 125.66,27.94 [deg] ecliptic lon,lat of the burst
COMMENTS: Definite GRB.
COMMENTS: WXM error box is circular; not rectangular.
COMMENTS: SXC error box is circular; not rectangular.
COMMENTS: Burst_Validity flag is true.
COMMENTS: WXM data refined since S/C_Last Notice.
COMMENTS: SXC data refined since S/C_Last Notice.
- GCN Circular #4550
GRB 060121: A bright short/hard GRB localized by HETE-2 WXM
M. Arimoto, G. Ricker, J-L. Atteia, N. Kawai, D. Lamb, and S. Woosley,
on behalf of the HETE Science Team;
T. Donaghy, E. Fenimore, M. Galassi, C. Graziani, N. Ishikawa,
A. Kobayashi, J. Kotoku, M. Maetou, M. Matsuoka, Y. Nakagawa,
T. Sakamoto, R. Sato, T. Shimokawabe, Y. Shirasaki, S. Sugita,
M. Suzuki, T. Tamagawa, K. Tanaka, and A. Yoshida, on behalf of the
HETE WXM Team;
N. Butler, G. Crew, J. Doty, G. Prigozhin, R. Vanderspek,
J. Villasenor, J. G. Jernigan, A. Levine, G. Azzibrouck, J. Braga,
R. Manchanda, G. Pizzichini, and S. Gunasekera, on behalf of the HETE
Operations and HETE Optical-SXC Teams;
M. Boer, J-F Olive, J-P Dezalay, and K. Hurley, on behalf of the HETE
FREGATE Team;
report:
At 22:24:54.5 UTC (80694.5 SOD) on 21 January 2006 the HETE FREGATE,
WXM, and SXC instruments detected event H4010, a bright short/hard GRB.
The WXM flight location was distributed in a GCN Notice at 22:25:08
UTC, 13 seconds after the start of the burst. Ground analysis of the
WXM data yields a best-fit location
R.A. = +09h 10m 04s ; Dec. = +45d 41' 24" (J2000),
with a 90% confidence error radius of 8 arcminutes.
The T90 duration of the burst is approximately 2 s in the FREGATE
80-400 keV energy band.
Further analyses are in progress. Further information about this burst
will be available at the following URL:
http://space.mit.edu/HETE/Bursts/GRB060121
- GCN Circular #4551
GRB 060121: A bright short/hard GRB localized by HETE-2 SXC
G. Prigozhin, G. Ricker, J-L. Atteia, N. Kawai, D. Lamb,
and S. Woosley, on behalf of the HETE Science Team;
M. Arimoto, T. Donaghy, E. Fenimore, M. Galassi, C. Graziani,
N. Ishikawa, A. Kobayashi, J. Kotoku, M. Maetou, M. Matsuoka,
Y. Nakagawa, T. Sakamoto, R. Sato, T. Shimokawabe, Y. Shirasaki,
S. Sugita, M. Suzuki, T. Tamagawa, K. Tanaka, and A. Yoshida, on behalf
of the HETE WXM Team;
N. Butler, G. Crew, J. Doty, R. Vanderspek, J. Villasenor,
J. G. Jernigan, A. Levine, G. Azzibrouck, J. Braga, R. Manchanda,
G. Pizzichini, and S. Gunasekera, on behalf of the HETE Operations and
HETE Optical-SXC Teams;
M. Boer, J-F Olive, J-P Dezalay, and K. Hurley, on behalf of the HETE
FREGATE Team;
report:
At 22:24:54.5 UTC (80694.5 SOD) on 21 January 2006 the HETE FREGATE,
WXM, and SXC instruments detected event H4010, a bright short GRB.
Ground analysis of the SXC data yields a best-fit location
R.A. = +09h 09m 57s ; Dec. = +45d 40' 30" (J2000),
with a 90% confidence error radius of 80 arcseconds.
Further analyses are in progress. Further information about this burst
will be available at the following URL:
http://space.mit.edu/HETE/Bursts/GRB060121
- GCN Circular #4552
GRB 060121 (=H4010): Results of preliminary spectral analysis
M. Boer, G. Ricker, J-L. Atteia, N. Kawai, D. Lamb, and S. Woosley, on
behalf of the HETE Science Team;
M. Arimoto, T. Donaghy, E. Fenimore, M. Galassi, C. Graziani,
N. Ishikawa, A. Kobayashi, J. Kotoku, M. Maetou, M. Matsuoka,
Y. Nakagawa, T. Sakamoto, R. Sato, T. Shimokawabe, Y. Shirasaki,
S. Sugita, M. Suzuki, T. Tamagawa, K. Tanaka, and A. Yoshida, on behalf
of the HETE WXM Team;
N. Butler, G. Crew, J. Doty, G. Prigozhin, R. Vanderspek,
J. Villasenor, J. G. Jernigan, A. Levine, G. Azzibrouck, J. Braga,
R. Manchanda, G. Pizzichini, and S. Gunasekera, on behalf of the HETE
Operations and HETE Optical-SXC Teams;
J-F Olive, J-P Dezalay, and K. Hurley, on behalf of the HETE FREGATE
Team;
report:
A preliminary analysis of the WXM and FREGATE spectral data for GRB
060121 (=H4010) shows that the data is adequately fit by a power-law
times exponential model with best-fit parameters
alpha = -0.46 +/- 0.07
E_peak = 120 +/- 7 keV.
Thus the spectrum of the burst is very hard, as expected for a
short/hard GRB.
The preliminary spectral analysis gives fluences for the burst of 0.66
x 10-6 erg cm-2 in the 2-30 keV energy band, 4.3 x 10-6 erg cm-2 in the
30-400 keV energy band, and 4.9 x 10-6 erg cm-2 in the 2-400 keV energy
band. The burst is thus quite bright, given that its T90 duration is
about 2 seconds.
Further information about this burst will be available at the following
URL:
http://space.mit.edu/HETE/Bursts/GRB060121
- GCN Circular #4553
E. O. Ofek (Caltech) report:
The position of the short-hard burst GRB060121 (Arimoto et al. GCN 4550;
Prigozhin et al. GCN 4551) is located 10.3 arcmin from the center of
the galaxy cluster ZwCl 0906.7+4603.
Note, that the probability to find a galaxy cluster
in the NED archive, within 10 arcmin from a random position
on the celestial sphere (with Galactic latitude |b|>25 deg),
is about 5%.
A graph of this probability as function of angular distance is
available from:
http://astro.caltech.edu/~eran/GRB/060121/ProbDistCluster.jpg
- GCN Circular #4554
Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona), David
W. Hogg (NYU), Michael R. Blanton (NYU), David J. Schlegel (LBNL),
J. Brinkmann (APO), Donald P. Schneider (PSU), and Daniel E. Vanden
Berk (PSU) report:
The Sloan Digital Sky Survey (SDSS) imaged the field of burst
GRB060121 prior to the burst. As these data should be useful
as a pre-burst comparison and for calibrating photometry, we are
supplying the images and photometry measurements for this GRB field
to the community.
Data from the SDSS, including 5 FITS images, 3 JPGS, and
3 files of photometry and astrometry, are being placed at
http://mizar.as.arizona.edu/~grb/public/GRB060121
We supply FITS images in each of the 5 SDSS bands of a 8'x8' region
centered on the GRB position (ra=137.488 (09:09:57.0), dec=45.6750
(45:40:30.0); GCN 4550), as well as 3 gri color-composite JPGs (with
different stretches). The units in the FITS images are nanomaggies
per pixel. A pixel is 0.396 arcsec on a side. A nanomaggie is
a flux-density unit equal to 10^-9 of a magnitude 0 source or,
to the extent that SDSS is an AB system, 3.631e-6 Jy. The FITS
images have WCS astrometric information.
In the file GRB060121_sdss.calstar.dat, we report photometry
and astrometry of 422 bright stars (r<20.5) within 15' of the
burst location. The magnitudes presented in this file are asinh
magnitudes as are standard in the SDSS (Lupton 1999, AJ, 118,
1406). Beware that some of these stars are not well-detected in
the u-band; use the errors and object flags to monitor data quality.
In the files GRB060121_sdss.objects_flux.dat and
GRB060121_sdss.objects_magnitudes.dat, we report photometry of
621 objects detected within 6' of the GRB position. We have
removed saturated objects and objects with model magnitudes
fainter than 23.0 in the r-band. The fluxes listed in
GRB060121_sdss.objects_flux.dat are in nanomaggies while the
magnitudes listed in GRB060121_sdss.objects_magnitudes.dat are
asinh magnitudes.
All quantities reported are standard SDSS photometry, meaning that
they are very close to AB zeropoints and magnitudes are quoted
in asinh magnitudes. Photometric zeropoints are known to about
2% rms. None of the photometry is corrected for dust extinction.
The Schlegel, Finkbeiner, and Davis (1998) predictions for this
region are A_U=0.079 mag, A_g=0.058 mag, A_r = 0.042 mag, A_i=0.032
mag, and A_z=0.023 mag.
The file GRB060121_sdss.spectro.dat contains a list of the 4 objects
with SDSS spectroscopy within 6 arcminutes of the GRB position.
In addition to the redshift and 1-sigma error for each object,
this file also lists the object spectroscopic classification.
SDSS astrometry is generally better than 0.1 arcsecond per
coordinate. Users requiring high precision astrometry should take
note that the SDSS astrometric system can differ from other systems
such as those used in other notices; we have not checked the offsets
in this region.
More detailed information pertaining to our SDSS GRB releases
can be found in our initial data release paper (Cool et al. 2006,
astro-ph/0601218). See the SDSS DR4 documentation for more details:
http://www.sdss.org/dr4.
These data have been reduced using a slightly different pipeline
than that used for SDSS public data releases. We cannot guarantee
that the values here will exactly match those in the data release
in which these data are included. In particular, we expect the
photometric calibrations to differ by of order 0.01 mag.
This note may be cited, but please also cite the SDSS data
release paper, Adelman-McCarthy et al. (2006, ApJS, in press,
astro-ph/0507711), when using the data or referring to the technical
documentation.
- GCN Circular #4555
Johan P. U. Fynbo, Jens Hjorth (DARK Cosmology Centre),
Andrew Levan, Nial Tanvir (University of Hertfordshire),
Kari Nilsson (University of Turku) report:
"Using ALFOSC on the Nordic Optical Telescope we have obtained
BRI imaging of the field of the short/hard GRB060121 (GCN #4551)
around Jan 22.05. A visual examination reveals a westward moving
source in the error circle, but no other new sources are
detected in comparison with the SDSS images of the field
(GCN #4554). No known asteroid is expected in the field according
to the JPL Small Body Search and the Harvard Planet Checker.
Further observations are planned."
- GCN Circular #4556
L.A. Antonelli (INAF/OAR), D. Malesani (SISSA), S. Covino (INAF/OABr),
G. Andreuzzi, and G. Tessicini (INAF/TNG), report:
"We observed the field of GRB 060121 (Arimoto et al., GCN 4550;
Prigozhin et al., GCN 4551; Boer et al., GCN 4552) with the Italian
3.6m TNG telescope, located at the Canary Islands.
Preliminary analysis of a set of R-band exposures (totalling 30 minutes
on-source) reveals no new sources brighter than the SDSS limit reported
by Cool et al in GCN 4554.
This message can be cited."
- GCN Circular #4557
J. S. Bloom, K. Alatalo (UC Berkeley) report on behalf of a larger
collaboration:
"We observed the field of GRB 060121 (Arimoto et al., GCN 4550;
Prigozhin et al. GCN 4551) with the 1.3 meter Peters Automated
Infrared Imaging Telescope (PAIRITEL) on Mt. Hopkins, Arizona,
beginning at 2006-01-22 04:43:15 UT. In a stack of the first 345
seconds of integration, we find no new objects in the HETE-SXC error
circle in JHKs bands brighter than the 2MASS detection levels. All
significantly detected sources fainter than 2MASS have optically pre-
imaged counterparts from SDSS (Cool et al. GCN 4554). Our approximate
10 sigma detection levels are J=18.7, H=17.6, Ks=16.6 mag,
respectively."
This message may be cited.
- GCN Circular #4558
G. G. Williams, E. Olszewski, and P. A. Milne (Steward Observatory)
report:
We observed the HETE-SXC error region of the short/hard GRB 060121
(Arimoto et al., GCN 4550, Prigozhin et al., GCN 4551, Boer et al., GCN
4552) with the 90prime imager on the Steward Observatory 90-inch Bok
telescope at Kitt Peak. We obtained two sets of summed images in Rc, each
with a total exposure time of 1800 seconds, beginning at 04:02:45 UT (5.6
hours after the GRB) and at 05:40:29 UT. Visual comparison of these
images reveals no significantly variable sources to approximately 1.0
magnitudes deeper than the SDSS r' image (Cool et al., GCN 4554).
This message may be cited.
- GCN Circular #4559
Jim Webb (UGA), A.L. Homewood, K.V. Garimella, and D.H. Hartmann
(Clemson), on behalf of the Clemson GRB Follow-Up Team, report:
We observed the Hete-SXC error box of GRB060121 (Arimoto et al., GCN 4550,
Prigozhin et al., GCN 4551, Boer et al., GCN 4552) with the SARA 0.9-m at
Kitt Peak. We co-added 24 R-Band exposures of 300 seconds each, for a
total integrated exposure time of 7200 seconds (2 hours), beginning at
UT060122 03:12:50 and ending at 05:29:53. We detect no new sources down to
a limiting magnitude of R=19.77 +/- 0.23 mag compared to the USNOA2.0
catalogue. We would like to thank Dr. Webb for the ToO interrupt
observations.
The Clemson Unversity GRB Response SIte may be found at:
http://people.clemson.edu/~kgarime/burst/index.php
The SARA Homepage may be found at: http://www.saraobservatory.org
This message may be cited.
- GCN Circular #4560
V. Mangano, V. La Parola, T. Mineo (INAF-IASFPA), G. Tagliaferri, P.
Romano (INAF-OAB), P. O'Brien (UL), D.N. Burrows (PSU) on behalf of the
Swift XRT team:
We have analyzed the first 5 ks of XRT data of the Swift ToO observationb
of the HETE burst GRB 060116 (M. Arimoto at al. 2006, GCN 4550). The XRT
observation started on 2006-01-22 at 01:21:37 UT, 2hr 56min 42.5s after
the HETE trigger.
We find a single bright fading source at
RA(J2000) = 09h 09m 52.13s
Dec(J2000) = +45d 39m 44.9s
with an uncertainty of 3.7 arcsec (90% containment). This position includes
the latest XRT boresight correction. This position is 69 acrsecond from the
refined HETE posizion (G. Prigozhin et al. 2006, GCN 4551), well within
the HETE error box.
- GCN Circular #4561
D. Malesani (SISSA/ISAS), L.A. Antonelli (INAF/OAR), S. Covino
(INAF/OABr), E. Palazzi (INAF/IASF Bo), G. Andreuzzi (INAF/TNG), and G.
Tessicini (INAF/TNG), report on behalf of a larger Italian collaboration:
We observed the field of GRB 060121 (Arimoto et al., GCN 4550;
Prigozhin et al., GCN 4551; Boer et al., GCN 4552) at two epochs with
the Italian TNG telescope located in the Canary Islands. Photometry was
performed in the R-band starting on Jan 22.021 UT (Antonelli et al., GCN
4556) and Jan 22.193 UT (2.1 and 6.2 h after the GRB, respectively). The
second run provided images of lower quality, due to bad observing
conditions.
Inside the XRT error circle (Mangano et al., GCN 4560), we see a faint
source which is detected in our first dataset but is not detected in the
second epoch (which is, however, shallower).
The coordinates are (J2000):
alpha = 09:09:51.93
delta = +45:39:45.4
We estimate an error of about 0.5" (mainly due the low S/N of the object).
Even if at the moment we do not makeany claim of variability, we suggest
this object may be the optical counterpart of GRB 060121.
This message can be cited.
- GCN Circular #4562
A.J. Levan, N.R. Tanvir (U. Hertfordshire), J. Fynbo, J. Hjorth (DARK
Cosmology Centre), A. Fruchter (STScI), T. Grav (IfA, Hawaii), K. Nilsson
(U. Turku), J. Rhoads (ASU) report for a larger collaboration:
Inspection of our images of GRB 060121 obtained at the NOT (GCN 4555) on
Jan 22.05UT reveal a faint source coincident with the suggested X-ray (GCN
4560) and optical (GCN 4561) counterparts. Further R-band imaging was
obtained with the WIYN telescope starting at Jan 22.48UT, the object is
still visible, however has clearly faded between the two observations,
confirming that it is the afterglow of GRB 060121.
Further observations are planned.
- GCN Circular #4563
M. Nysewander, J. Kirschbrown, D. Reichart, P. Holvorcem, M. Schwartz
report on behalf of the UNC GRB Team:
We began imaging the error circle of GRB 060121 (Arimoto et al., GCN 4550)
at 03:58:17 UT, 5.6 hours after the burst, with the Tenagra II 32-inch
Telescope in the I filter. The images are calibrated to 5 transformed
I-band magnitudes derived from the photometry of the SDSS (Cool et al., GCN
4554).
In a stack of 12 x 300s exposures, we do not see the optical afterglow
(Malesani et al., GCN 4561; Levan et al., GCN 4562) down to a 3-sigma
limiting magnitude of I = 20.9 at a mean time of 6.1 hours after the burst.
- GCN Circular #4564
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and
T. Cline on behalf of the Konus-Wind team report:
The GRB 060121 (=H4010; Arimoto et al., GCN 4550;
Prigozhin et al., GCN 4551)
triggered Konus-Wind at T0=80700.890 s UT (22:25:00.890).
The Konus-Wind light curve shows a single pulse with
a duration of ~2 sec.
As observed by Konus-Wind the burst had
a fluence of 4.71(-3.71,+0.44)x10^-6 erg/cm2 and
peak flux measured from T0+0.448 sec on 64 msec time scale
1.64(-1.32,+0.18)x10^-5 erg/cm2/sec
(both in the 20 keV - 1 MeV energy range).
The time-integrated spectrum of the GRB is well fitted (in the 20 keV -
1 MeV range) by GRBM (Band) model for which:
the low-energy photon index is alpha = -0.51(-0.60,+0.55),
the high energy photon index beta = -2.39(-1.41,+0.27),
the break energy E0 = 70(-52, +90) keV (chi2 = 59/59 dof).
The fitting by a power law with exponential cutoff model:
dN/dE ~ E^(-alpha) * exp(-E*(2-alpha)/Ep)
in the same energy range gives
alpha = 0.82(-0.21,+0.38)
and Ep = 134(-17, +32) keV (chi2 = 63/60 dof).
All the quoted errors are at the 90% confidence level.
- GCN Circular #4565
V. Mangano, V. La Parola, T. Mineo (INAF-IASFPA), P. O'Brien (UL),
P. Romano (INAF-OAB), D.N. Burrows (PSU), M. Chester (PSU),
L. Angelini (GSFC) on behalf of the Swift XRT team:
The Swift XRT instrument began observing the HETE-discovered GRB 050121
(Arimoto et al., GCN 4550; Prigozhin et al., GCN 4551) at 01:21:37 UT
on 22 January 2006 (Mangano et al., GCN 4560) 10.6 ks after the burst.
Further analysis of the first 5 ks of XRT data of GRB 060121
spanning three orbits (Mangano et al., GCN 4560)
revealed that the source is fading with a power law decay index
of -1.08 + / - 0.24.
The average spectrum is well fitted by an absorbed power law
model with a photon index of 2.07 + / - 0.25 (90% confidence level).
The best fit absorption column of (7.8 + / - 4.5)e20 cm^-2 is
slightly in excess of the Galactic absorption column of 1.7e20 cm^-2.
The average unabsorbed 0.2-10 keV flux in the time range
10.6 - 22 ks after the trigger is at the level of
4.6e-12 ergs cm^-2 s^-1.
The predicted flux at 24 hours after the trigger is at the
level of 6.8e-13 ergs cm^-2 s^-1 (corresponding to a count rate
of about 1.1e-2 counts/s).
New observations are beein performed.
According to NED, the nearest two galaxies with known redshifts
are SDSS J091016.39+453819.9 and SDSS J091023.53+454159.8 with a
redshift of 0.154357 and 0.154272, respectively.
They are 4.5 and 6 arcmin from the Swift GRB position
(Mangano et al., GCN 4560).
- GCN Circular #4566
A. Monfardini, A. Melandri, C. Guidorzi, C.G. Mundell, A. Gomboc,
I.A. Steele (Liverpool JMU) on behalf of the Liverpool GRB group report:
"On Jan 21.968 UT and Jan 22.035 UT the Liverpool Telescope imaged the
field of GRB060121 (HETE alert 4010, Arimoto et al., GCN 4550;
Prigozhin et al. GCN 4551), beginning at 0.83 and 2.44 hours after the
GRB, respectively. Images were taken with r', i' and z' filters.
The SXC error circle (Prigozhin et al. GCN 4551) was partially covered
(about 50%) during the first hour of observations. In the second hour
it was entirely inside the Liverpool Telescope 4.6 arcmin field of
view, as was the Swift-XRT error circle provided by Mangano et
al. (GCN 4560).
The optical counterpart suggested by Malesani et al. (GCN 4561) and
Levan et al. (GCN 4562) is not detected in our images. Manual
inspection reveals no afterglow candidate down to a magnitude limit of
r'> 22.5, i'> 22.2 and z'> 21.6 at approximately 2.7 hours after the
burst. The limits are determined by comparison with SDSS pre-burst
photometry.
This message can be cited"
- GCN Circular #4567
A. A. Breeveld (UCL-MSSL), L. Angelini (GSFC), D. Hinshaw (GSFC-SPSYS),
M. Carter (UCL-MSSL), N. Gehrels (GSFC) on behalf of the Swift/UVOT
team
The Swift UVOT instrument began observing the HETE-discovered GRB
050121 (Arimoto et al., GCN 4550; Prigozhin et al., GCN 4551) as a
target of opportunity at 01:21:28 UT on 22 January 2006 10.6 ks after
the burst. No new source is found at the XRT position (Mangano et al.,
GCN 4565) in coadded images from the first ToO observation, with any of
the filters used down to the following 5-sigma magnitude upper limits.
No exposures were taken in UVW1 or UVM2. These values are not corrected
for Galactic extinction.
Filter T_range(s) Exp(s) 5sigUL(mag)
B 10593-16768 1099 20.6
V 11917-12639 712 19.4
U 21650-22022 368 19.7
UVW2 11003-18423 1625 21.2
White 10798-17682 1099 20.7
- GCN Circular #4582
Klotz, A. (CESR-OMP), Damerdji Y. (OHP), Vachier F. (OHP) report:
We imaged the field of GRB 060121 detected by HETE
(Arimoto et al. GCNC 4550) with the 120cm at the
Observatoire de Haute-Provence - France.
First image was acquired 1.65h after the GCN trigger.
We do not detected an OT source.
According to the limiting magnitude: R>20.0
Magnitude was estimated with the nearby USNO-A2 stars
This message may be cited.
- GCN Circular #4604
GRB 060121: Probable Detection of NIR Afterglow
F. Hearty (Colorado), M. Bayliss (Chicago), D. Q. Lamb (Chicago), G.
Gyuk (Chicago), M. Hammergren (Adler Planetarium), A. Puckett
(Chicago), B. Ketzeback (APO), J. Barentine (APO), J. Dembicky (APO),
R. McMillan (APO), and D. G. York (Chicago) report:
We observed the afterglow (Malesani et al. GCN 4561, Levan et al. GCN
4562) of GRB 060121, a bright short/hard burst localized by HETE-2
(Arimoto et al. GCN 4550, Prigozhin et al. GCN 4551, Boer et al. GCN
4552), on the night of January 22nd, using NIC-FPS on the ARC 3.5-meter
telescope at Apache Point Observatory. The observation began at 7.25
UT on 23 January (32.83 hours after the burst) and ended at 8.63 UT on
23 January (34.21 hours after the burst). The observation consisted of
a series of 180 20-second exposures in Ks. We have constructed from
them a stacked image of the GRB field, corresponding to a 60-minute
exposure.
We detect an object at the 5-sigma confidence level within 1" of the
location of the optical afterglow and well within the revised XRT
error circle (Mangano et al. GCN 4560). The PSF of the object is
consistent with that of a point source. We therefore identify the
object as the probable NIR afterglow of GRB 060121. We measure Ks ~ 20
mag, calibrated relative to four 2MASS stars in the field.
Extended emission is visible about 1" SE and NE of the probable NIR
afterglow, but is detected at less than the 2-sigma confidence level.
Therefore the emission might be due to nearby galaxies (possibly
including the host of GRB060121) or merely to a background fluctuation.
Further observations are in progress.
NIC-FPS is currently in its commissioning phase.
- GCN Circular #4611
GRB 060121: Confirmation of NIR Afterglow
F. Hearty (Colorado), M. Bayliss (Chicago), D. Q. Lamb (Chicago), G.
Gyuk (Chicago), M. Hammergren (Adler Planetarium), A. Puckett
(Chicago), B. Ketzeback (APO), J. Barentine (APO), J. Dembicky (APO),
R. McMillan (APO), and D. G. York (Chicago) report:
We have obtained a second-epoch observation of the afterglow (Malesani
et al. GCN 4561, Levan et al. GCN 4562) of GRB 060121, a bright
short/hard burst localized by HETE-2 (Arimoto et al. GCN 4550,
Prigozhin et al. GCN 4551, Boer et al. GCN 4552), using NIC-FPS on the
ARC 3.5-meter telescope at Apache Point Observatory. The second-epoch
observation began at 5.50 UT on 27 January (5.30 days after the burst)
and ended at 6.92 UT on 27 January (5.35 days after the burst). The
observation consisted of a series of 195 20-second exposures in Ks.
Using these exposures, we have constructed a stacked image of the GRB
field, corresponding to a 65-minute exposure.
In this image, we no longer detect the Ks-band source that we reported
in GCN 4604. Therefore, the source has clearly faded between the two
observations, confirming that it is the NIR afterglow of GRB 060121
The extended emission features that were visible in the first epoch
image about 1" SE and about 1" NE of the NIR afterglow are detected in
the second epoch image, but at lower significance than in the first
epoch image because of somewhat poorer seeing. We are therefore
unable to establish with confidence the reality of either emission
feature.
NIC-FPS is currently in its commissioning phase.
- GCN Circular #4627
Richard J. Cool (University of Arizona) reports:
Based upon feedback from users of our online releases of SDSS photometry
and astrometry of GRB fields, we have discovered an error in several past
releases. In preparing the releases, we inadvertently neglected to remove
duplicate listings of several objects from the online catalogs. Several
of the secondary observations of the objects included are of lower
photometric quality than the primary observation and thus photometric
zeropoints derived with them may shift slightly. We removed all duplicate
observations from the online catalogs for past
bursts located at
http://mizar.as.arizona.edu/grb/public/.
We apologize for any inconvenience.
- GCN Circular #4628
S. B. Cenko, E. Ofek (Caltech), D. B. Fox (Penn State), and E. Berger
(Carnegie) report on behalf of a larger collaboration:
We have imaged the region of the short-hard GRB060121 (GCNs 4550, 4551)
with the GMOS instrument on the Gemini North Telescope. Images consisted
of 3 x 360 s exposures taken in r' and 5 x 210 s exposures taken in i' at
a mean epoch of approximately Feb. 1.55. The 3-sigma limiting magnitude
of these images, estimated with respect to the SDSS field calibration (GCN
4554), is approximately r' > 25.6, i' > 25.4.
We find no evidence for any source within 0.5" of the transient reported
by Malesani et al. (GCN 4561) to the limits stated above. However, within
the XRT error circle (GCN 4560), approximately 1" to the east of the OT
position, we find evidence for a marginal source. The coordinates of
this source (J2000.0) are:
RA: 09:09:52.019
Dec: +45:39:45.45
We estimate photometry for this object as r' ~ 26.4, i' ~ 26.0, although
the errors on these measurements are very large due to 1) the faintness of
the object, and 2) an unexpectedly large scatter in the
photometric zeropoint. We note that this position likely coincides with
the possible identification of a host galaxy in the NIR by Hearty et al.
(GCN 4604).
- GCN Circular #4711
K. Onda, K. Abe, M. Tashiro (Saitama-U), T. Tamagawa, Y. Urata
(RIKEN), H. Azuma, M. Kuwahara (RIKEN/TUS), F. Usui (ISAS/JAXA)
on behalf of the WIDGET collaboration report:
"A very wide field camera, WIDGET, located at Akeno, Japan, observed
the HETE-2 error region of GRB 060121 (Arimoto et al., GCN 4550). We
continuously monitored the the region with repeat of unfiltered 5 sec
exposure from 8 hours before the burst through the beginning of
twilight (3.5 hours before the burst). Those images did not show any
optical emission at the afterglow position reported by Malesani et
al. (GCN 4561). The 1-sigma limiting magnitude of each frame derived
by the Tycho 2 catalog is around V=10.7 magnitude."
This message may be cited.
- GCN Circular #4756
V. Rumyantsev (CrAO), D. Sharapov (MAO, and NOT La Palma), M. Ibrahimov
(MAO), and A. Pozanenko (IKI), on behalf of larger GRB follow up
collaboration report:
We observed error box of GRB060121 (Arimoto et al., GCN 4550) with 1.5m
telescope of Maidanak Astronomical Observatory in R-band on Jan. 23 between
(UT) 17:49 and 18:26. Within XRT error circle (Mangano et al., GCN 4560)
we do not detect OT (Malesani et al., GCN 4560) and optical source
mentioned by Cenko et al., (GCN 4628). Coordinates of the closest to the XRT
error circle faint optical source, which is ~7" from the center of the XRT
error circle are:
RA(J2000) = 09 09 52.18
DEC(J2000) = +45 39 37.4
with uncertainties in both coordinates of 0.3 arcsec. Brightness estimation
of the faint source is following:
Obs. time, Exp., R (mag), Mag.(UL), Seeing
(UT) (s)
Jan. 23 17:49-18:26 1800 22.6(+/-0.3) 22.9 1.6"
The photometry and astrometry reduction is based on USNO A2.0.
The stacked image can de found in
http://grb.rssi.ru/GRB060121/
- GCN Circular #4841
A.J. Levan, N.R. Tanvir (University of Hertfordshire), A. Fruchter
(STScI), J. Fynbo, J. Hjorth (Dark Cosmology Centre), E. Rol
(University of Leicester), D. Bersier (Liverpool JMU), J. Gorosabel,
A.J. Castro-Tirado (IAA-CSIC Granada) report for a larger collaboration:
We observed the location of the HETE-2 short hard burst GRB 060121
(Prigozhin et al. GCN 4551; Malesani et al. GCN 4561) with HST on 27
February 2006 using both ACS and NICMOS. Approximately 4500 s of
observations in each of F606W and F160W were obtained. Performing
astrometry between these images and those obtained at the WIYN (Levan et
al. GCN 4562) reveals no evidence for an afterglow to R>28, although the
position of the burst lies close to a faint red galaxy with F160W =24.0,
F606W =26.8. The morphology of the galaxy is long and thin, possibly an
edge on disk. If this object is the host galaxy of GRB 060121 then it is
relatively red compared to the hosts of long bursts, and there are also
several other galaxies with very red colours within 30" of the burst
position. Short bursts have been observed in a greater variety of
host galaxies, but in this case, the faintness of the galaxy in both the
optical and IR favour a higher redshift than has been measured for most
short bursts to date (which is also consistent with the red colour of the
afterglow).
We thank Matt Mountain for using Director's Discretionary Time to observe
GRB 060121.
Further analysis is ongoing.
- astro-ph/0603282 from 11 Mar 2006
Levan: The faint afterglow and host galaxy of the short-hard GRB 060121
We present optical and X-ray observations of the afterglow and host galaxy of
the short-hard GRB 060121. The faint R-band afterglow is seen to decline as
t^(-0.66) while the X-ray falls as t^-1.18, indicating the presence of the
cooling break between the two frequencies. However, the R-band afterglow is
very faint compared to the predicted extrapolation of the X-ray afterglow to
the optical regime (specifically, beta_OX ~ 0.2), while the K-band is
consistent with this extrapolation (beta_KX ~ 0.6), demonstrating suppression
of the optical flux. Late time {\it HST} observations place stringent limits on
the afterglow R-band flux implying a break in the R-band lightcurve. They also
show that the burst occurred at the edge of a faint red galaxy which most
likely lies at a significantly higher redshift than the previous optically
identified short-duration bursts. Several neighboring galaxies also have very
red colors that are similarly suggestive of higher redshift. We consider
possible explanations for the faintness and color of the burst. Our preferred
model is that the burst occurred at moderately high redshift and was
significantly obscured; however, it is also possible that the burst lies at z >
4.5 in which case the faintness of the R-band afterglow could be attributed to
the Lyman-break. We discuss the implications that either scenario would have
for the nature of the progenitors of short bursts.
- astro-ph/0605516 from 19 May 2006
Postigo: GRB 060121: Implications of a Short/Intermediate Duration Gamma-Ray Burst at High Redshift
Since the discovery of the first short-hard gamma-ray burst afterglows in
2005, the handful of observed events have been found to be embedded in nearby
(z < 1), bright underlying galaxies. We present multiwavelength observations of
the short-duration burst GRB 060121, which is the first observed to clearly
outshine its host galaxy (by a factor >10^2). A photometric redshift for this
event places the progenitor at a most probable redshift of z = 4.6, with a less
probable scenario of z = 1.7. In either case, GRB 060121 could be the
farthermost short-duration GRB detected to date and implies an
isotropic-equivalent energy release in gamma-rays comparable to that seen in
long-duration bursts. We discuss the implications of the released energy on the
nature of the progenitor. These results suggest that GRB 060121 may belong to a
family of energetic short-duration events, lying at z > 1 and whose optical
afterglows would outshine their host galaxies, unlike the first short-duration
GRBs observed in 2005. The possibility of GRB 060121 being an intermediate
duration burst is also discussed.
- astro-ph/0605570 from
22 May 2006
Donaghy: HETE-2 Localizations and Observations of Four Short Gamma-Ray
Bursts: GRBs 010326B, 040802, 051211 and 060121
Here we report the localizations and properties of four short-duration GRBs
localized by the High Energy Transient Explorer 2 satellite (HETE-2): GRBs
010326B, 040802, 051211 and 060121, all of which were detected by the French
Gamma Telescope (Fregate) and localized with the Wide-field X-ray Monitor (WXM)
and/or Soft X-ray Camera (SXC) instruments. We discuss eight possible criteria
for determining whether these GRBs are "short population bursts" (SPBs) or
"long population bursts" (LPBs). These criteria are (1) duration, (2) pulse
widths, (3) spectral hardness, (4) spectral lag, (5) energy Egamma radiated in
gamma rays (or equivalently, the kinetic energy E_KE of the GRB jet), (6)
existence of a long, soft bump following the burst, (7) location of the burst
in the host galaxy, and (8) type of host galaxy. In particular, we have
developed a likelihood method for determining the probability that a burst is
an SPB or a LPB on the basis of its T90 duration alone. A striking feature of
the resulting probability distribution is that the T90 duration at which a
burst has an equal probability of being a SPB or a LPB is T90 = 5 s, not T90 =
2 s, as is often used. All four short-duration bursts discussed in detail in
this paper have T90 durations in the Fregate 30-400 keV energy band of 1.90,
2.31, 4.25, and 1.97 sec, respectively, yielding probabilities P(S|T90) = 0.97,
0.91, 0.60, and 0.95 that these bursts are SPBs on the basis of their T90
durations alone. All four bursts also have spectral lags consistent with zero.
These results provide strong evidence that all four GRBs are SPBs.
- GCN Circular #6498
A. Pelangeon & J-L. Atteia (LATT-OMP) report:
We have used the spectral parameters of GRB 060121 detected by=20
HETE-2/FREGATE
and localized by the WXM (Arimoto et al., GCNC 4550) and by the SXC
(Prighozin et al., GCNC 4551) to compute the spectral pseudo-redshift(**)
of this burst.
We find a pseudo-redshift pz =3D 1.92 =B1 0.35
This value is in agreement with the lowest of the two values derived
by de Ugarte-Postigo et al. for the photometric redshift
of the host-galaxy: z =3D 1.7 =B1 0.4, and z =3D 4.6 =B1 0.5 (ApJ, 2006, =
648, L83)
This pseudo-redshift relies on the assumption that GRB 060121 follows
the Amati relation. Hence we caution that if GRB 060121 is a short burst,
as suggested by Donaghy et al. (astro-ph/0605570), this pseudo-redshift
is not reliable.
(**) cf. http://www.ast.obs-mip.fr/grb/pz
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