- GCN/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Wed 26 Feb 03 05:35:58 UT
NOTICE_TYPE: HETE Ground Analysis
TRIGGER_NUM: 10893, Seq_Num: 1
GRB_DATE: 12696 TJD; 57 DOY; 03/02/26
GRB_TIME: 13591.99 SOD {03:46:31.99} UT
TRIGGER_SOURCE: Trigger on the 25-400 keV band.
SC_-Z_RA: 159 [deg]
SC_-Z_DEC: 10 [deg]
SC_LONG: 296 [deg East]
WXM_CNTR_RA: 173.400d {+11h 33m 36s} (J2000),
173.441d {+11h 33m 46s} (current),
172.743d {+11h 30m 58s} (1950)
WXM_CNTR_DEC: +25.833d {+25d 49' 58"} (J2000),
+25.815d {+25d 48' 56"} (current),
+26.109d {+26d 06' 33"} (1950)
WXM_MAX_SIZE: 30.00 [arcmin] diameter
WXM_LOC_SN: 15 sig/noise (pt src in image)
WXM_IMAGE_SN: X= 5.3 Y= 5.0 [sig/noise]
WXM_LC_SN: X= 13.7 Y= 6.9 [sig/noise]
SUN_POSTN: 338.84d {+22h 35m 22s} -8.89d {-08d 53' 35"}
SUN_DIST: 158.12 [deg]
MOON_POSTN: 278.97d {+18h 35m 53s} -26.03d {-26d 01' 51"}
MOON_DIST: 114.06 [deg]
MOON_ILLUM: 24 [%]
GAL_COORDS: 212.77,72.55 [deg] galactic lon,lat of the burst
ECL_COORDS: 163.30,21.02 [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/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Wed 26 Feb 03 05:47:21 UT
NOTICE_TYPE: HETE Ground Analysis
TRIGGER_NUM: 10893, Seq_Num: 2
GRB_DATE: 12696 TJD; 57 DOY; 03/02/26
GRB_TIME: 13591.99 SOD {03:46:31.99} UT
TRIGGER_SOURCE: Trigger on the 25-400 keV band.
SC_-Z_RA: 159 [deg]
SC_-Z_DEC: 10 [deg]
SC_LONG: 296 [deg East]
SXC_CNTR_RA: 173.255d {+11h 33m 01s} (J2000),
173.296d {+11h 33m 11s} (current),
172.598d {+11h 30m 23s} (1950)
SXC_CNTR_DEC: +25.899d {+25d 53' 56"} (J2000),
+25.882d {+25d 52' 54"} (current),
+26.175d {+26d 10' 31"} (1950)
SXC_MAX_SIZE: 4.00 [arcmin] diameter
SXC_LOC_SN: 5 sig/noise (pt src in image)
SUN_POSTN: 338.84d {+22h 35m 22s} -8.89d {-08d 53' 35"}
SUN_DIST: 158.16 [deg]
MOON_POSTN: 278.97d {+18h 35m 53s} -26.03d {-26d 01' 51"}
MOON_DIST: 114.21 [deg]
MOON_ILLUM: 24 [%]
GAL_COORDS: 212.49,72.43 [deg] galactic lon,lat of the burst
ECL_COORDS: 163.14,21.02 [deg] ecliptic lon,lat of the burst
COMMENTS: Definite GRB.
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.
- red DSS finding chart
ps-file
- Galactic Coordinates and Extinction
LII , BII 212.772408 72.551619
Weighted average nH (cm**-2) 1.72E+20
- GCN notice #1879
D.W. Fox (Caltech), H.W. Chen (MIT), and P.A. Price (RSAA/MSSSO)
report:
"We have observed the error circle of GRB030226 (HETE Trigger #10893)
with the Dupont 100" telescope + WFCCD at Las Campanas Observatory for
2x4.5 min in I-band. We identify a bright, new, stationary object by
reference to the digitized sky survey f- (~R-band) and n-emulsion
(~I-band) images. The approximate coordinates of the source are:
RA 11:33:05.07, Dec +25:53:53.4 (J2000)
with an accuracy of perhaps 2" in each coordinate. Photometering our
image against the R-band magnitudes of three GSC stars, we find the
source to have an approximate R- (I?) magnitude of 20 at the epoch of
these images, 06:24 UT.
Further observations of this region and analysis of these data are in
progress."
- GCN notice #1880
P.A. Price (RSAA, ANU), D.W. Fox (Caltech) & H.W. Chen (MIT) report:
The optical afterglow candidate reported in GCN #1879 has faded by
approximately 0.3 mag in an image taken 9 minutes later, and has no
discernible proper motion.
The afterglow coordinates are:
RA: 11:33:04.9 Dec: 25:53:55.6 (J2000)
with error in each coordinate of approximately 0.5 arcsec.
A finding chart is available from
http://www.mso.anu.edu.au/~pap/grb030226finder.ps
Offsets from the indicated sources to the afterglow are in:
http://www.mso.anu.edu.au/~pap/grb030225finder.txt
This message may be cited.
- GCN notice #1881
K. von Braun (DTM), P. Garnavich (Notre Dame), K. Stanek (CfA)
We have imaged the error circle of the HETE burst GRB 030226
with the 40-inch Swope telescope at Las Campanas beginning
Feb. 26.30 (UT). The R-band images confirm the presence
of a new source (GCN 1879). We derive a position of
RA=11:33:04.92 DEC=+25:53:55.62 (2000) based on stars from
the USNO A-2.0 catalog. Assuming the USNO star with end figures
of 03.214 51:30.73 has an R mag of 15.0, we estimate the
brightness of the transient at R=18.0.
This message may be cited.
- GCN notice #1882
M. Ando, K. Ohta, C. Watanabe (Kyoto Univ.), K. Aoki, Y. Ohyama,
K. S. Kawabata, S. Harasawa, D. Scarla (Subaru NAOJ), and
N. Kawai (Tokyo Tech) report:
We have obtained optical images and optical spectra of the afterglow
of GRB030226 (=H10893) with FOCAS attached to Subaru 8.2m on Mauna Kea.
R-, I-, and z'-band images taken at Feb 26.29 (UT) reveal the presence
of the optical afterglow with an R magnitude of ~17.8 mag. We derived
a position of RA=11:33:04.9, Dec=+25:53:55 (J2000) with an accuracy of
1" using the USNO A-2.0 catalog.
We have also taken optical spectra covering wavelength regions of
3700-6000 A and 5800-10000 A at Feb 26.31 (UT) with an exposure time
of 20 min. each. The spectral resolutions are about R=1000. The
optical spectra show intergalactic absorption lines clearly; roughly
derived the highest redshift absorbers are MgII 2800 and CVI 1550 at
z=2.1, indicating that a redshift of GRB 030226 is 2.1 or larger.
This message may be cited.
- GCN notice #1883
D.W. Fox (Caltech), P.A. Price (RSAA/ANU), and H.W. Chen (MIT) report:
"Observations from the Dupont telescope at Las Campanas reveal
continued fading of this afterglow (GCNs 1879, 1880, 1881, 1882). In
four I-band images taken over the period from 0.1 to 0.2 days after
the burst (Epoch: 26 Feb 03:46:32 UT), the afterglow decay may be fit
with a power-law of index alpha~-0.85, as referenced against a large
number of stars in the field."
- GCN notice #1884
M. Ando, K. Ohta, C. Watanabe (Kyoto Univ.),
K. Aoki, Y. Ohyama, K. S. Kawabata, S. Harasawa, D. Scarla (Subaru NAOJ),
and N. Kawai (Tokyo Tech) report:
We obtained R, I, and z' images of the afterglow of GRB030226(=H10893)
at Feb 26.65 (UT) with FOCAS attached to Subaru 8.2m telescope. The
R-band magnitude of the OT is derived to be 19.0+-0.2 using four stars
close to the OT in the USNO-A2.0 catalog.
With further analyses of the optical spectra reported in GCN 1882,
we find the highest redshift for the absorbers to be z=1.99.
This message may be cited.
- GCN notice #1885
P. Garnavich (Notre Dame), K. von Braun (DTM), K. Stanek (CfA)
We have calibrated the R-band images of the GRB 030226 field
(Fox et al. GCN 1879; von Braun et al. GCN 1881) taken
with the 1-m Swope telescope on Feb. 26 (UT). The Landolt
standard field PG1323-086 (Landolt 1992, AJ, 104, 340) was
observed at the end of the photometric night. We estimate the
following magnitudes for stars near the optical afterglow:
Star A 11:33:03.214 +25:51:30.73 (2000) R=15.39 +/-0.05
Star B 11:32:59.808 +25:52:38.73 (2000) R=17.06 +/-0.05
where most of the error is due to the uncertain airmass correction.
Star A was noted in GCN 1881 as having a USNO magnitude of 15.0.
Using this calibration we find the following brightness for
the afterglow from the Swope data:
Feb. 26.305 (3.5 hours after the burst) R=18.44 +/-0.05
The images show only a 0.02 mag variation in the
brightness of the afterglow over a 20 minutes span.
A finder chart for the afterglow and calibrated stars
can be found at:
http://www.nd.edu/~pgarnavi/grb030226.jpg
This message may be cited.
- GCN notice #1886
J. Greiner (MPE Garching),
E. Guenther, S. Klose (both TLS Tautenburg),
R. Schwarz (Uni. Goettingen), on behalf of the GRACE collaboration
report:
The afterglow of the HETE burst (H10893) GRB 030226 (Fox et al., GCN 1879;
Price et al., GCN 1880) was observed with the VLT Yepun and the FORS2
spectrograph, equipped with the 300V grism on Feb. 26, beginning at 08:52 UT.
The total exposure time was 15 min. In the calibrated spectrum, covering
the 360-900 nm region, we clearly identify two distinct absorption-line
systems of Fe II (160.8), Al II (167.1) and CIV (154.8) at redshifts
z=1.962+/-0.001 and 1.986+/-0.001, improving earlier findings
(Ando et al., GCN 1884). We conclude that the redshift of the burster
is z=1.986+/-0.001 or larger.
We are grateful for the assistence of the staff at Paranal.
- GCN notice #1887
A. J. Castro-Tirado (IAA-CSIC and LAEFF-INTA),
A. de Ugarte Postigo (IAA-CSIC), T. J. Mateo
Sanguino, M. T. Fern=E1ndez Palomo (CEDEA-INTA),
M. J=E9linek, P. Kub=E1nek, R. Hudec (ASU), S. Vitek,
P. P=E1ta (CVUT) and J. =C1. Bern=E1 (Univ. de Alicante)
on behalf of the BOOTES team,
=20
report:
=20
"We have obtained several unfiltred exposures (180-s each)
under thin thirrus covering the GRB 030226 error box. The
images covered the period 03:45:16 - 03:56:26 UT 26 Feb 2003
(i.e. between 1.5-minutes before the trigger and 9.9-minutes
after the trigger) with the wide-field camera of BOOTES-1.
=20
After a visual inspection of the HETE-2 error box in all
frames, we do not find evidence of optical emission at the
position of the bright optical counterpart (GCNC 1879, 1881,
1882), in particular simultaneously to the burst itself, for
which we have an image covering the time interval 03:45:16 -
03:48:16 UT. Therefore we derive an upper limit of R =3D 11.5
for the reverse shock emission (if any) arising from this GRB,
in contrast to the 9-th magnitude prompt flash emission
recorded for GRB 990123 (Akerloff et al. 1999, Nat 398, 400)".
=20
=20
=20
This message can be cited.
- GCN notice #1888
M. Suzuki, Y. Shirasaki, C. Graziani, M. Matsuoka, T. Tamagawa, K.
Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner,
and T. Donaghy, Y. Nakagawa, D. Takahashi, R. Satoh, and Y. Urata, on
behalf of the HETE WXM Team;
G. Ricker, J-L Atteia, N. Kawai, D. Lamb, and S. Woosley on behalf of
the HETE Science Team;
J. Doty, J. Villasenor, R. Vanderspek, G. Crew, G. Monnelly, N.
Butler, T. Cline, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G.
Prigozhin, G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini,
on behalf of the HETE Operations and HETE Optical-SXC Teams;
M. Boer, J-F Olive, J-P Dezalay, C. Barraud and K. Hurley on behalf
of the HETE FREGATE Team;
write:
At 03:46:31.99 UTC (13591.99 s UT) on 26 Feb 2003, the HETE FREGATE,
WXM, and SXC instruments detected event U10893, a long GRB. No prompt
notification was issued, because the on-board Trigger Monitor was
configured to reject triggers near the SAA. The event was detected by
event detection software in the ground processing pipeline.
Ground analysis of the WXM data produced a localization which was
reported in a GCN Notice at 05:35:58 UT, 109 minutes after the burst.
The WXM localization SNR was 15. The WXM location can be expressed as
a 90% confidence circle that is 15 arcminutes in radius and is
centered at
WXM: RA = +11h 33m 36s, Dec = +25d 49' 58" (J2000).
Further ground analysis of the WXM data produced a refined localization
that can be expressed as a 90% confidence circle that is 6.8 arcminutes
in radius and is centered at
WXM: RA = +11h 33m 07.9s, Dec = +25d 51' 14.4" (J2000).
Ground analysis of the SXC data for the burst produced a more accurate
location, which was reported in a GCN Notice at 05:47:21 UT, 121
minutes after the burst. The SXC localization SNR was 5. The SXC
location can be expressed as a 90% confidence circle that is 2
arcminutes in radius and is centered at
SXC: RA = +11h 33m 01s, Dec = +25d 53' 56" (J2000).
The SXC localization may be improved.
The burst duration in the 30-400 keV band was > 100 s. The fluence of
the burst was 5.7 x 10-6 ergs cm-2 in the 30-400 keV energy band. The
peak flux was ~1.2 x 10-7 ergs cm-2 s-1 (i.e., ~ 5 x Crab flux) in 1.2
sec in the same energy band.
A light curve and skymap for GRB030226 is provided at the following URL:
http://space.mit.edu/HETE/Bursts/U10893
- GCN notice #1889
P.A. Price (RSAA,ANU), D.W. Fox and S.G. Djorgovski (Caltech), M. West
(UH Hilo), and P. Cote and A. Jordan (Rutgers) report on behalf of the
Caltech-NRAO-CARA GRB collaboration:
"We have observed the afterglow of GRB 030226 (Suzuki et al. GCN 1888;
see also GCNs 1879,1880) with the Echellette Spectrograph and Imager
on the Keck II 10-m telescope, in a single 2700-s integration
beginning at 08:00 UT on Feb 26, which provides a high-resolution
(R~5,000) spectrum with high S/N. In a preliminary analysis of the
data, we identify three absorption systems at z=1.984, z=1.961, and
z=1.043. The two higher-redshift systems have been reported
independently by Greiner et al. (GCN 1886), expanding on the initial
reports of Ando et al. (GCN 1884).
For the higher-redshift systems we detect Mg II 2795,2803; Al II 1671;
Al III 1863; Si II 1527; Si IV 1394 and 1403; C IV 1548,1551; and
various Mn II and Fe II lines. For the z=1.043 system, we detect Mg
II 2795,2803, and possibly some Fe II lines.
The two higher-redshift systems exhibit very strong equivalent widths,
whereas the equivalent widths for the z=1.043 system are much weaker,
consistent with the population of field galaxy QSO absorbers.
Moreover, each of the higher-redshift systems, separated by 2300 km/s
in the rest frame, consists of multiple components with further
velocity substructure at the <100 km/s level.
Our results are reminiscent of the findings of several groups with
respect to GRB021004 (Castander et al. GCN 1599, Salamanca et al. GCN
1611, Mirabal et al. GCN 1618, Savaglio et al. GCN 1633, Castro-Tirado
et al. GCN 1635, Moeller et al. astro-ph/0210654, Schaefer et
al. astro-ph/0211189, Wang et al. astro-ph/0301266).
Further analysis of these data and follow-up observations are
ongoing."
This message may be cited.
- GCN notice #1890
P.A. Price and B.E. Warren (RSAA, ANU) report:
We have observed the afterglow of GRB 030226 (GCN ##1879,1880) with the
ANU 2.3m telescope at Siding Spring Observatory. We detect the afterglow
in a single 300 sec exposure with the Imager at Feb 26.67 UT. Using the
same reference star as von Braun et al. (GCN #1881), we measure that the
afterglow was R ~ 19.2 mag at the epoch of our observation. The derived
temporal decay index is alpha ~ 0.88, in agreement with the earlier index
reported by Fox et al. (GCN #1883).
This message may be cited.
- GCN notice #1892
A. Guarnieri, (Bologna University), L. Cortese (Milano Bicocca University),
C.Bartolini, A.Piccioni, R.Gualandi, S. Bernabei (Bologna University and
Bologna Astronomical Observatory), and G. Pizzichini (IASF-CNR, Sezione di
Bologna) report:
On 2003, February 27, 01h19m57s UT we started an observation of the afterglow
of GRB030226 (Fox,Chen and Price, GCN 1879) with the 152 cm telescope in Loiano,
(R band, 900 sec exposure). Using the calibration stars A and B of Garnavich,
von Braun and Stanek (GCN 1885), we preliminary estimate the brightness of the
OT at R = 20.4. Further observations in B, V, R, I bands are in progress.
This message may be cited.
- GCN notice #1893
J. E. Rhoads, J.M. Castro Cer=F3n, J. Gorosabel, A. Fruchter,=20
and C. Kouveliotou report:
Using the redshift lower limit (z > 2; Ando et al, GCNC 1884)
and the GRB fluence (5.7e-6 erg/cm2, 30 keV < E < 400 keV;=20
Suzuki et al, GCNC 1888), we can predict the time of the break
in GRB 030226 light curve, assuming the standard burst energy
of Frail et al (2001) (or more precisely, exploiting their empirically
demonstrated correlation between break time and apparent isotropic
gamma ray energy).
Based on the relations in Frail et al, we obtain
t_jet =3D 10.6 days
for a redshift z=3D2.0 (and t_jet < 10.6 days for z > 2.0).
Prior to that time the current slow decay may continue;
thereafter a much steeper decay, t^-2 or faster, may
occur (Rhoads 1999).
The primary uncertainty in the predicted break time arises from
the observed scatter in the E_isotropic - t_jet correlation. The
quoted one-sigma scatter in gamma ray energy in Frail et al (2001)
is a factor of 2. We infer a corresponding scatter of a factor
of 2.5 in t_jet, placing a one-sigma lower limit t_jet > 4 days.
Together with the current decay slope (0.88; Price & Warren, GCNC 1890)
and the t=3D3.5 hour flux (R=3D18.44; Garnavich et al, GCNC 1885)
this suggests that the optical afterglow of GRB 030226 will be rather
bright during the interval 1 day < t < t_jet, relative to most afterglows
at the same observed age. Representative fluxes using this naive
extrapolation are
GRB age (days): 0.75 1.0 1.5 2.0 3.0 4.0 5.0 7.5 10.0
Projected R magnitude: 20.0 20.3 20.7 20.9 21.3 21.6 21.8 22.2 22.5
We stop our projections at the nominal 10 day jet break time, and
further caution even a modest steepening of the decay index early on
would substantially reduce the fluxes at a few days.
- GCN notice #1894
J. Greiner (MPE Garching),
C. Ries, H. Barwig (Uni. Munich),
J. Fynbo (Uni Aarhus),
S. Klose (TLS Tautenburg),
on behalf of the GRACE collaboration
report:
We observed the afterglow of the HETE burst (H10893; Suzuki et al., GCN 1888)
GRB 030226 (Fox et al., GCN 1879; Price et al., GCN 1880) in the R band
with the EMMI and SUSI instruments at the NTT (La Silla, ESO) and the MONICA
imager at the Wendelstein 0.8 m telescope (Germany). We calibrated against
the USNO-B R2 magnitudes of 5 surrounding stars which provides basically
the same calibration as that given for stars A and B by Garnavich et al.
(GCN 1885; R=15.39 +/-0.05 and R=17.06 +/-0.05, respectively). A preliminary
reduction gives the following magnitudes:
Start time exposure OT star A star B
NTT/EMMI Feb 26 08:27 3x300 s 18.80+-0.07 15.40+-0.05 17.05+-0.05
Wendelstein Feb 26 19:04 2x600 s 19.87+-0.10 15.47+-0.08 17.05+-0.10
Wendelstein Feb 27 03:12 600 s 20.60+-0.13 15.42+-0.08 17.04+-0.10
Wendelstein Feb 27 03:23 600 s 20.74+-0.13 15.43+-0.08 17.05+-0.10
NTT/SUSI Feb 27 05:25 3x180 s 21.00+-0.20 15.47+-0.10 ---
We confirm the decay slope of -0.88 as communicated by Price & Warren
(GCN 1890) until about 0.8 days after the GRB. Thereafter, the brightness
seems to drop significantly faster. A light curve plot will be available
at http://www.mpe.mpg.de/~jcg/grb030226.html. Further monitoring is strongly
encouraged.
We are grateful for the assistence of the staff at La Silla and Wendelstein.
- GCN notice #1897
R. Chornock and A. V. Filippenko (UC Berkeley) report:
We obtained a pair of spectra (2 x 1000 s) of the optical afterglow (GCN
1879) of GRB 030226 (GCN 1888) using the Low Resolution Imaging
Spectrometer (resolution ~ 6 angstroms, spectral range 3150-10000
angstroms) on Keck I. We see the three previously noted absorption
systems, at redshifts 1.044, 1.962, and 1.986 (GCNs 1882, 1884, 1886, and
1889). The higher redshift absorbers have many lines of common
interstellar species. In addition, we note a broad absorption system with
multiple components from 3600 and 3640 angstroms. We identify these as
the Lyman-alpha absorptions of the two high-redshift systems. Blueward of
this complex, the continuum has many absorption lines, which we identify
as the onset of the Lyman-alpha forest. Therefore, we conclude that the
highest redshift absorption system is at the redshift of the GRB.
- GCN notice #1898
A. Zeh, S. Klose (both TLS Tautenburg),
J. Greiner (MPE Garching),
J. Fynbo (University of Aarhus),
P. Jakobsson (University of Copenhagen),
on behalf of the GRACE collaboration
report:
Based on a compilation of all R-band data published so far on the
afterglow of GRB 030226 (von Braun et al., GCN 1881; Ando et al., GCN
1882; Garnavich, von Braun & Stanek, GCN 1885; Price & Warren, GCN
1890; Guarnieri et al., GCN 1892; Greiner et al., GCN 1894) we have
fitted a preliminary light curve. Following Garnavich et al. (GCN
1885), we corrected the data published in GCNs 1881 and 1882 by 0.39
mag. For these data and for those reported in GCNs 1890 and 1892 we
estimated a conservative photometric error of 0.3 mag. Finally, we
included in the fit another data point based on observations with the
ESO NTT telescope last night.
Numerical fits were obtained with the formula of Beuermann et al. (1999;
A&A 352, L26). The result is:
early-time slope: alpha_1 = 0.62 +/- 0.19
late-time slope: alpha_2 = 1.95 +/- 0.26
break time: t = 0.51 +/- 0.12 days,
assuming no contribution from an underlying host galaxy. So, we
confirm the earlier finding of Greiner et al. (GCN 1894) of a break in
the optical light curve less than 1 day after the burst. We note
that, if confirmed, these afterglow parameters are similar to those
found for GRB 010222 (e.g., Masetti et al. 2001, A&A 374, 382).
We publish the results of this fit in order to help observers to plan
their further observing strategy. The fitted light curve is posted at
http://www.mpe.mpg.de/~jcg/grb030226.html. Note that the data are not
corrected for Galactic extinction.
- GCN notice #1902
K. von Braun (DTM), P. Garnavich (Notre Dame), K. Stanek (CfA)
We have imaged the optical afterglow of GRB 030226
(Fox et al. GCN 1879; von Braun et al. GCN 1881) with the
1-m Swope telescope at Las Campanas on Feb. 27.17 (UT),
or 1.01 days after the burst. Using the calibration of
Garnavich, von Braun & Stanek (GCN 1885), we find a
brightness of R=20.65 +/- 0.10 for the afterglow. This
is agrees within the errors with the observations by
Greiner et al. (GCN 1894) and is consistent with an
early break.
This message may be cited.
- GCN notice #1905
W. M. Wood-Vasey, Lawrence Berkeley National Laboratory, using images
obtained by R. Bambery, S. Pravdo, M. Hicks, and K. Lawrence
(Near-Earth Asteroid Tracking project, Jet Propulsion Laboratory),
reports upper limits for previous observations at the location of the
object identified by Price et al. (GCN 1880) as the optical
counterpart to GRB 20030226 from unfiltered observations with the
Oschin 48" telescope at Palomar Observatory.
A co-addition of images from 2003 February 21.53, 21.54, and 21.55
shows no source visible at this location to a limiting unfiltered
magnitude of 21.3 (calibrated to USNO R-band stars on the image frame)
at a S/N of 3.
A co-addition of 9 images from 2002 March 31, 2003 January 19,
and 2003 February 21 shows no source visible at this location
to a limiting unfiltered magnitude of 21.6 (calibrated to USNO
R-band stars on the image frame) at a S/N of 3.
The full co-added of all 9 images is available at
http://supernova.lbl.gov/~wwoodvas/GRB/#GRB20030226
All dates UT.
This message may be cited.
- GCN notice #1908
V.Rumyantsev (CrAO), V.Biryukov(SAI) and A.Pozanenko (IKI) report:
We have obtained 9 unfiltered exposures (180-s each) of the GRB 030226
error box (HETE #10893). The images were taken with the AT-64 telescope of
Crimean Astrophysical observatory and cover the period UT 17:58 - UT 19:26
Feb 26, 2003. We used CCD SBIG ST-8 with maximum of sensitivity in the red
spectral band.
In a co-added image the OT is visible at the position of reported by D. Fox
et al. (GCN 1880). The brightness was estimated in respect to the stars A
and B (GCN 1885) as R~19.5 +/- 0.2.
Start time exposure OT
Feb 26 17:58 9x180 s 19.5+-0.2
Detailed calibration is underway.
The image is available at
http://grb.rssi.ru/GRB030226
This message can be cited.
- GCN notice #1909
S. Covino, G. Ghisellini, D. Malesani, G. Tagliaferri, F. Zerbi (INAF Brera,
Italy); A. Cimatti, M. Della Valle, S. Di Serego (INAF Arcetri, Italy); F.
Fiore, G.L. Israel, L. Stella (INAF Roma, Italy); E. Costa, P. Soffitta (IASF
Roma, Italy), S. Mereghetti (IASF Milano, Italy), N. Kawai (Tokyo Tech,
Japan); D. Lazzati (IoA, Cambridge, UK); S. Ortolani (Univ. of Padova,
Italy); L. Pasquini (ESO, Germany); G. Ricker (MIT, USA); E. Le Floch, P.
Goldoni, F. Mirabel (CEA, France), E. Mason, P.M. Vreeswijk (ESO Paranal), P.
Price (RSAA, Australia), report:
We observed the optical counterpart to GRB 030226 (Suzuki et al. GCN1888; Fox
et al. GCN 1879) on February 27.261 (26.5 hours after the GRB trigger). The
observations were performed with the ESO VLT-UT1 (Antu) telescope equipped
with FORS1 and a Bessel R filter in the imaging polarimetry mode.
The transient source is clearly detected in the acquisition frames with
magnitudes:
R = 20.64 +/- 0.02 at 27.212 UT and
R = 20.79 +/- 0.02 at 27.261 UT.
Magnitude are calibrated following Garnavich et al. (GCN 1885).
Preliminary results for the analysis of the polarimetric frames in the R band
yielded a very strict upper limit:
P < 1.1% (95% confidence level) at 27.261 UT
The observation was performed about 14 hours after the break identified in the
afterglow lightcurve (Greiner et al. GCN 1894, Zeh et al. GCN 1898).
See also
http://www.sissa.it/~malesani/GRB/030226 .
This message is citeable.
- GCN notice #1911
S. R. Kulkarni, D. W. Fox, E. Berger and A. M. Soderberg,
California Institute of Technology, Pasadena, CA 91125, USA
report
"We have continued observations of the optical afterglow (Fox, Chen and
Price GCN 1879) of GRB 030226 (Suzuki et al. GCN 1888) with the
Echellette Spectrograph Imager (ESI) mounted at the Cassegrain focus
of of the Keck-II telescope. Over the last 24 hours (from epoch day 2.3
to day 3.3) the R band flux has faded by 1.6 +/- 0.1 magnitudes. If
interpreted as a power law decay the power law index, alpha, is about 4
(flux, f(t) proportional to t^-alpha).
Such a steep decline is unprecedented. Even a density discontinuity
does not produce such a steep decrease (see Panaitescu & Kumar ApJ 541,
L51, 2000). Substructure (in the ejecta or circumburst medium) or
copious radiative losses can potentially account for the steep
decline.
Separately, we note that GRB 030226 with it's early steepening (``jet
break time'' of 0.5 day; see Greiner et al. GCN 1894 and Zeh et al. GCN
1898) joins GRB 980519 and GRB 980326. These latter GRBs are notable
for being under-energetic when compared to the known GRB sample and may
form an interestind sub-class of cosmlogical GRBs (see Bloom, Frail and
Kulkarni, astro-ph/0302210).
The diversity both in energetics and circumburst density demonstrate
that bursts are those which deviate from the sample are likely to be
very interesting. Extrapolations of based on mean values of
the current sample of GRBs can thus be misleading and
lead observers astray."
- GCN notice #1916
A. Henden (USRA/USNO) reports on behalf of the USNO GRB team:
We have acquired BVRcIc all-sky photometry for
a 20x20 arcmin field centered at the coordinates
for the optical transient (Fox et al., GCN 1879)
associated with the HETE burst GRB030226 (Suzuki et al., GCN 1888)
with the USNOFS 1.0-m telescope on one photometric night. Stars
brighter than V=13.5 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/grb030226.dat.
The astrometry in this file is based on linear plate solutions
with respect to UCAC2. The external errors are less than 100mas.
The estimated external photometric error is 0.03mag.
In particular, the two comparison stars listed by Garnavich,
et al. (GCN 1885) can be found in this file with Rc magnitudes:
ID Garnavich Henden
Star A 15.39 15.45
Star B 17.06 17.05
In agreement within the quoted errors.
This calibration will be extended with additional nights to
ensure against a systematic zeropoint error, but current
weather forecasts indicate that this may be a week or two.
We will not be performing U-band calibration unless requested.
As always, you should check the dates on the .dat file prior
to final publication to get the latest photometry.
- GCN notice #1921
M. C. Nysewander, J. Moran, D. Reichart (U. North Carolina), A. Henden
(USRA/USNO), and M. Schwartz (Tenagra Observatories) report on the behalf
of a larger collaboration:
We observed the the optical afterglow (Fox et al., GCN 1879) of GRB 030226
(Suzuki et al., GCN 1888) with the 32-inch Tenagra II telescope at a mean
time of 27.357 UT. In a stacked series of 14 x 300 second images we find
the source magnitude to be Ic = 20.52 +- 0.10 based on 5 stars from the
calibration of Henden (GCN 1916).
Recalibrating the 27.261 UT Rc magnitude of Covino et al. (GCN 1909) and
transforming it to the time of our observation using the post-break
temporal index of Zeh et al. (GCN 1898) we find the spectral slope at this
time to be -0.99 +- 0.42.
Pre- and post-break temporal indexes of -0.62 +- 0.19 and -1.95 +- 0.26
(Zeh et al., GCN 1898) and a spectral index of -0.99 +- 0.42 suggest, at
least prior to two days (see Kulkarni et al., GCN 1911), that the afterglow
is probably expanding into a constant density medium of non-negligible
extinction and that the cooling break is blueward of the observations.
However, ISM and WIND models with negligible extinction and the cooling
break redward of the observations are also possible (e.g., Sari, Piran &
Narayan 1998; Chevalier & Li 2000).
Chevalier, R. A., and Li, Z. 2000, ApJ, 536, 195
Sari, R., Piran, T., and Narayan, R. 1998, ApJ, 497, L17
- GCN notice #1923
S. Klose, B. Stecklum, A. Zeh (all TLS Tautenburg),
J. Greiner (MPE Garching),
A. A. Henden (USRA/USNO, Flagstaff),
on behalf of the GRACE collaboration
report:
We have continued our efforts of a multi-color imaging of the optical/
near-infrared afterglow of GRB 030226 with the ESO VLT telescopes at
Paranal.
Observations performed 4 days after the burst clearly show a source
at the position of the optical transient (OT; Price et al., GCN
1880). This source is detected in all photometric bands. Based on an
aperture photometry, a comparison of the pre-break
optical/near-infrared colors of the optical transient with its
post-break colors reveals no apparent differences. Although this
result is still preliminary and small differences might still
be detectable based on a more accurate PSF photometry, we conclude:
To a good approximation, the break in the light curve was
achromatic and at the time of the VLT observations the OT's light
was still dominated by the afterglow.
A first inspection of the data obtained 4 days after the burst seemed
to confirm a further steepening of the light curve in all bands some
days after the burst (Kulkarni et al., GCN 1911). However, our data do
not rule out the possibility that the reported steepening was a
temporary fluctuation between t ~2 and 3...4 days after the burst. In
particular, very recent VLT/FORS data show that the overall brightness
evolution of the OT still follows the predicted light curve (Zeh et
al., GCN 1898) with alpha_2 ~2 (assuming that we do not begin to see
the host galaxy).
We are grateful for the assistence of the staff at Paranal.
- GCN notice #1924
Kristian Pedersen (U. of Copenhagen), Johan Fynbo (U. of Aarhus),
Jens Hjorth (U. of Copenhagen), Darach Watson (U. of Copenhagen)
report on behalf of the GRACE collaboration:
"Chandra X-ray Observatory observed the field of the GRB 030226
(Suzuki et al., GCN 1888) with the ACIS-S3 detector for a total of
11.9 hours, starting Feb 27, 16:49 UT, 37.1 hours after the GRB trigger.
Based on a preliminary analysis we identify a previously unknown, fading
X-ray source at the position
RA (J2000.0) = 11 33 04.93, Dec (J2000.0) = +25 53 55.3
consistent with the position of the optical transient (Price et al.,
GCN 1880). The positional accuracy is better than one arcsec. Hence
we identify the source as the X-ray afterglow of GRB 030226.
The 0.3-10 keV count rate averaged over the observation is 9.7e-03 counts/s,
and the average 2-10 keV flux is 3.2e-14 erg/cm^2/s. The spectrum is well
fitted by an absorbed power law with spectral index 1.0 +/-0.2, absorption
fixed at the Galactic value (1.6e20 cm^2), and an absorbing column density
of 1e22 +/- 0.5e22 cm^-2 at a redshift of 1.98. A power law with Galactic
absorption only is not an acceptable fit to the soft part of the Chandra
spectrum. No other obvious spectral features are detected.
We thank Harvey Tananbaum for rapidly approving Director's Discretionary
Time for this observation, and the staff at the Chandra Science Center
for smoothly implementing and processing the observation."
- GCN notice #1925
T. Fatkhullin, V. Komarova, V. Sokolov, A. Cherepashchuk,
k. Postnov report for the larger GOSH collaboration:
The field of the GRB 030226 optical transient (Fox et al., GCN #1879)
was observed with CCD-photometer at the 1-m (Zeiss-1000) and
SCORPIO at the 6-m telescopes of SAO RAS during three nights.
Data from the 6-m telescope were obtained during time of the
scheduled program "Search for optical emission of nearby pulsars"
(P.I. V.G. Kurt). The weather conditions were slightly variable with
cirruses and seeing of 2.5-3.0 arcsec in the first night, 2.5 arcsec
seeing in the second one and 1.4 arcsec seeing in the third one. The B,
V, Rc filters were used. Photometric calibration was performed using
secondary standard stars of Henden et al., GCN #1916. The results of
our photometry are presented below:
Telescope | Mean Date, UT | Tot. exp. | Filter | Mag.
--------------------------------------------------------------
Zeiss-1000 | 27.96 Feb. | 2400s | V | 22.07 +/- 0.19
Zeiss-1000 | 27.92 Feb. | 2000s | Rc | 21.75 +/- 0.18
6-m | 28.99 Feb. | 1200s | B | 24.64 +/- 0.21
6-m | 01.00 Mar. | 1350s | V | 23.66 +/- 0.16
6-m | 28.99 Feb. | 720s | Rc | 22.96 +/- 0.12
6-m | 01.94 Mar. | 1200s | V | 23.89 +/- 0.12
6-m | 01.92 Mar. | 1200s | Rc | 23.39 +/- 0.09
In the images obtained at the last night we clearly detect an
extended object (R=22.9) 2.5 arsec South-East from optical
transient (OT) position. Thus, the results of our aperture photometry
of the OT may be affected by this object. We are planning to recalibrate
the data provided additional realiable secondary standards are available.
We thank V.G. Kurt for sharing observational time and O. Spiridonova
for kind assistance in the Zeiss-1000 observations.
This message is citeable.
- GCN notice #1928
M. Sako and D.W. Fox (Caltech) report on behalf of a larger
collaboration:
"We find that the detection of excess soft X-ray absorption reported
by Pedersen et al. (GCN 1924) in the Chandra spectrum of GRB030226 is
not required by the data. A power law of photon index 2.0 +/- 0.1
with Galactic absorption of 1.6 x 10^20 cm^-2 provides a statistically
acceptable fit with chi-squared = 12.6 for 14 degrees of freedom. The
90%-confidence upper limit on the amount of absorption by neutral
material at a redshift of 1.98 is N_H = 4.8 x 10^21 cm^-2 using the
best current low-energy calibration. We note that our derived limit
depends sensitively on the calibration below E = 0.4 keV where the
response is known to be strongly time-dependent (see
http://asc.harvard.edu/cal/Acis/Cal_prods/qeDeg/index.html). The
power-law decay of the flux between 0.3 and 8 keV is found to be
alpha_X = -3.6 +/- 1.0 over the course of the observation (epoch day
1.56 to day 2.02). This provides a statistically acceptable fit to
the data (chi-squared of 7.3 for the 18 degrees of freedom of a 20-bin
light curve)."
- GCN notice #1929
V.Rumyantsev (CrAO), L.Sergeeva(CrAO) and A.Pozanenko (IKI) report:
We have obtained 8 exposures (180-s each) of the GRB 030226
error box (HETE #10893). The images were taken with the AZT-8 telescope
(0.7m) of Crimean Astrophysical Observatory in R filter and cover the period
(UT) Feb, 26 23:55 - Feb, 27 02:25.
In a co-added image the OT is clearly visible at the position reported by D.
Fox et al. (GCN 1880). The brightness was estimated in respect to the stars
A and B of GCN 1885 (P. Garnavich et al), using photometry by A. Henden (GCN
1916):
Start time (UT) exposure OT
Feb 26 23:55 8x180 s 20.37+/-0.16 (R-band)
The image is available at
http://grb.rssi.ru/GRB030226/
This message can be cited.
- GCN notice #1933
E. Maiorano (Univ. Bologna & IASF/CNR, Bologna), N. Masetti, E. Palazzi
(IASF/CNR, Bologna), H. Navasardyan (INAF - Astron. Obs. of Asiago),
E. Pian (INAF - Astron. Obs. of Trieste), L.A. Antonelli (INAF - Astron.
Obs. of Rome) and D. Malesani (SISSA, Trieste), on behalf of a larger
Italian collaboration, report:
"We have obtained BVRI images of the OT (Fox et al., GCN 1879) of
GRB030226 (Suzuki et al., GCN 1888) with the 1.82-m "Copernico" telescope
(plus AFOSC) of the Astronomical Observatory of Asiago (Italy).
Observations started on February 26.947 UT, i.e. 0.79 days after the GRB.
The seeing ranged between 2.0 and 2.4 arcsec.
The OT is well detected in all bands; we measure for it the following BVRI
magnitudes with respect to stars A and B (Garvanich et al., GCN 1885) and
using the photometry by Henden (GCN 1916):
mid-exposure exptime filter mag err
time (UT) (s)
-------------------------------------------------------
Feb. 26.961 2x1200 B 21.03 0.04
Feb. 26.987 2x900 V 20.76 0.02
Feb. 27.030 2x600 R 20.47 0.03
Feb. 27.078 2x600 I 20.24 0.06
This message is citeable."
[GCN OPS NOTE (06mar03): This Circular was delayed 6.3 hours due to
an address change by the submitter.]
- GCN notice #1935
E. Semkov (Institute of Astronomy, Sofia, Bulgaria) report:
The afterglow of the HETE burst (H10893) GRB 030226 (Fox et al., GCN 1879;
Price et al., GCN 1880) was observed with the 2m RCC telescope of the
National Observatory Rozhen (Bulgaria) on 26 and 27 February, R band, 3
x 300 sec coo-added exposures.
We used A and B stars from Garnavich et al. (GCN 1885) as a references.
We estimate the brightness of the optical afterglow in R band as follows.
26 (UT 22.2) R=20.27 +/-0.1
27 (UT 01.2) R=20.4 +/-0.15
27 (UT 21.3) R=21.3 +/-0.3
This message may be cited.
[GCN OPS NOTE (08Mar03): This Circular was received 15:44 UT 06 Mar 03.
It was delayed due to an invalid address.
This has been happening more frequently lately. I remind people
that if you change your email address, you need to communicate it to me
so that the Circular list can be updated.]
- GCN notice #1940
subject: GRB030226, addendum to GCN 1892
Testo:
A. Guarnieri, (Bologna University), L. Cortese (Milano Bicocca University),
C.Bartolini, A.Piccioni, R.Gualandi, S. Bernabei (Bologna University and
Bologna Astronomical Observatory), G. Pizzichini and P. Ferrero (IASF-CNR,
Sezione di Bologna) report:
With reference to GCN n. 1892, the complete list of our observations from
the 152 cm telescope in Loiano is given below:
mid exp filter exposure time
date (UT) (Johnson) (seconds)
26.871 R 1800
26.894 I 1800
26.916 V 1800
26.939 R 1800
26.968 R 1800
26.994 B 2400
27.021 V 1800
27.044 R 1800
27.061 R 900
27.069 R 300
27.088 B 2700
27.116 V 1800
27.134 I 1200
27.153 R 1200
27.166 I 900
Our images can be retrieved in format jpeg by sftp using
hostname: ermione.bo.astro.it
username: publicGRB
password: GRB_bo
This message may be cited.
- astro-ph/0608327 from 16 Aug 2006
Shin: High-Resolution Spectroscopy of GRB030226: Features of a
Massive Star Progenitor or Intervening Absorption Systems?
We present a high-resolution Keck/ESI spectrum of GRB, which exhibits four
absorption systems at z=1.04329, 1.95260, 1.96337, and 1.98691. The two highest
redshift systems, separated by about 2400 km/s, have been previously suspected
as kinematic features arising in the circumstellar wind around the progenitor
star. However, the high column densities of low-ionization species (including
possibly neutral hydrogen) in the blue-shifted system, are inconsistent with
the expected highly ionized state of the circumstellar wind from the massive
progenitor star, even prior to the GRB explosion. This conclusion is also
supported by the lack of detectable absorption from fine-structure transitions
of SiII and FeII. Instead we conclude that the two redshift systems are similar
to multiple DLAs found in QSO sight lines with a similar velocity separation
and chemical abundance of [Cr/Fe] and [Zn/Fe]. The absorption system at
z=1.96337 is likely an intervening low-mass galaxy, possibly related to the GRB
host as part of a forming large-scale structure.
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