GRB 050408
GCN Circular 3188
Subject
GRB050408: MASTER optical observations
Date
2005-04-08T18:01:34Z (20 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
V. Lipunov, A.Krylov, V.Kornilov, G.Borisov, D.Kuvshinov,
A.Belinski, M.Kuznetsov, S.Potanin, G.Antipov,
E.Gorbovskoy, N.Tyurina
Sternberg Astronomical Institute, Moscow
After HETE alert 3711 MASTER robotic telescope
(http://observ.pereplet.ru)
had imaging the corresponding area of the sky under the bad weather
conditions at 17h21m53.75 UT (1h 09m after GRB Time, OUR SUNSET ).
There are no new object up to 14.7 on unfiltered image of the error box
(30s exposition, 6 square degrees field).
The JPG-images are available at
http://observ.pereplet.ru/images/GRB050408/1.jpg
This is preliminary result.
Observations are continuing.
This message may be cited.
This work is supported by Moscow Union "Optic" and partly supported by
RFFI 04-02-16411.
Mailto: lipunov@sai.msu.ru
GCN Circular 3189
Subject
GRB 050408 (=H3711): A Long X-Ray-Rich GRB Detected by HETE
Date
2005-04-08T18:23:42Z (20 years ago)
From
Don Lamb at U.Chicago <lamb@oddjob.uchicago.edu>
GRB 050408 (=H3711): A Long X-Ray-Rich GRB Detected by HETE
T. Sakamoto, 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,
J. Kotoku, M. Maetou, M. Matsuoka, Y. Nakagawa, R. Sato, Y. Shirasaki,
M. Suzuki, T. Tamagawa, K. Tanaka, Y. Yamamoto, 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, and G. Pizzichini, 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:
The HETE FREGATE, WXM, and SXC instruments detected GRB 050408 (=H3711)
at 16:22:50.93 UT (58970.93 SOD) on 8 April 2005. WXM and SXC flight
localizations were reported in a GCN Notice issued at 16:23:02, which
was 11 sec after the burst trigger and while the burst was still in
progress.
The final WXM and SXC flight localizations were reported in a GCN
Notice issued at 16:23:13 UT. The final WXM flight localization can be
expressed as a circle of 14 arcminutes radius (90% confidence) that is
centered at
WXM-Flight: RA = 12h 01m 55s, DEC = +10d 51' 38" (J2000).
The final SXC flight localization can be expressed as a circle of 150
arcseconds radius that is centered at
SXC-Flight: RA = +12h 02m 15s, DEC = +10d 51' 03" (J2000).
Ground analysis produced an updated SXC localization that was reported
in a GCN Notice issued at 17:36:02. This ground SXC localization can
be expressed as a circle of 80 arcseconds radius that is centered at
SXC-Ground: RA = +12h 02m 15s, DEC = +10d 52' 01" (J2000).
The burst has a duration T_90 of ~34 seconds in 7-40 keV and 7-80 keV,
and T_90 of ~15 seconds in 30-400 keV. Preliminary spectral analyses
show the 2-30 keV fluence of GRB 050408 to be ~1.4 x 10-6 ergs cm-2 and
the 30-400 keV fluence to be ~1.9 x 10-6 ergs cm-2. Therefore
GRB 050408 is an "X-ray-rich" GRB.
A light curve, skymap, and spectral information for GRB 050408 are
provided at the following URL:
http://space.mit.edu/HETE/Bursts/GRB050408
This message may be cited.
GCN Circular 3190
Subject
GRB 050408: ROTSE-III Optical Limits
Date
2005-04-08T18:53:32Z (20 years ago)
From
Don Smith at U michigan <dasmith@rotse2.physics.lsa.umich.edu>
GRB 050408: ROTSE-III Optical Limits
D.A. Smith, S.A. Yost, & E.S. Rykoff (U of Michigan) report on behalf of the
ROTSE collaboration:
ROTSE-IIIa, located at Siding Spring Observatory, Australia, responded to GRB
050408 (HETE trigger 3711). An automated response produced images beginning at
16:23:09.4 UT, 18.5 s after the trigger time and 6.6 s after the alert was
distributed. The first few images were therefore recorded while the burst was
still active at high energies (Sakamoto et al., GCN Circ. #3189). The
telescope took 10 5-sec, 10 20-sec, and a series of 60-sec eposures. These
unfiltered images are calibrated relative to USNO A2.0 (R). The ROTSE-III
images show strong and increasing degredation from clouds. After the 20th
image (~7.7 min after the trigger time), clouds became opaque enough to render
many images useless.
Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma
SXC error circle. Individual images have limiting magnitudes ranging from
14.7-16.9. In particular, we set a limit of magnitude 14.7 in the first 5 s
exposure. Coadding the first ten images yields a limiting magnitude of 15.1,
and coadding the 20-s images (165.5-522.5 s after the trigger time) yields a
limiting magnitude of 17.8.
GCN Circular 3191
Subject
GRB 050408: Swift XRT Position
Date
2005-04-08T19:24:18Z (20 years ago)
From
Jamie A. Kennea at PSU/Swift-XRT <kennea@astro.psu.edu>
A. A. Wells, A. F. Abbey, J. P. Osborne, A. P. Beardmore, (U. Leicester),
J. A. Kennea, M. Chester, D. N. Burrows, J. A. Nousek (PSU), M. Capalbi,
F. Tamburelli (ASDC), P. Romano, C. Pagani, G. Chincarini (INAF-OAB), G.
Cusumano, V. La Parola, (INAF-IASF/Palermo), D. Lamb (U. Chicago), G.
Ricker (MIT) and N. Gehrels (GSFC), report on behalf of the Swift XRT
team:
The Swift XRT observed the field of the HETE burst GRB050408 (Sakamoto
etal. 2005, GCN 3189) at 17:05:18 UT. We find a bright fading uncataloged
X-ray source located at:
RA(J2000) = 12:02:17.4,
Dec(J2000) = +10:51:03
We estimate an uncertainty of about 6 arcseconds. This source is located
78 arcseconds from the HETE SXC-Ground position in GCN 3189.
GCN Circular 3192
Subject
GRB 050408 optical candidate
Date
2005-04-08T20:24:33Z (20 years ago)
From
Alberto Castro-Tirado at LAEFF-INTA <ajct@laeff.esa.es>
A. de Ugarte Postigo (IAA-CSIC Granada), V. Komarova,
T. Fathkullin, T. Sokolova, V. Sokolov, V. Vlasyuk,
Yu. Balega (SAO RAS, Russia), S. Guziy (Univ. of Nikolaev),
M. Jelinek, J. Gorosabel and A.J. Castro-Tirado
(IAA-CSIC Granada),
report:
Following the detection by HETE-2 of the long X-ray gamma-
ray burst GRB 050408 (Sakamoto et al., GCN 3189), we have
taken R-band images at the 1m and 6m telescope at the Special
Astrophysical observatory starting at 20.25 UT (i.e. 3.9 hr
after the event). Within the X-ray error box provided by
SWIFT/XRT (Wells et al. GCN 3191), we identify three
point-like sources. The brightest one (R = 20.5) is at
preliminary coordinates RA(2000) = 12 02 17.32, Dec(2000) =
+10 51 10 (error 1"), which we identify at the potential
GRB 050408 optical afterglow. The object does not appear in
the corresponding DSS-2 plate. Further observations are in
progress.
We thanks the SAO RAS director Yu. Balega for his support
for the SAO RAS GRB ToO programme.
GCN Circular 3194
Subject
GRB 050408, optical observations
Date
2005-04-08T20:56:55Z (20 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
S. Klose, U. Laux, and B. Stecklum, Thuringer Landessternwarte Tautenburg,
J. Greiner, MPE Garching,
report:
Tautenburg started observing the field of GRB 050408 (Sakamoto et al.
2005, GCN 3189) at 19:01 UT on Apr 08. Observations were performed in
V, R, and I, even though the weather conditions were not good.
A first inspection of the R-band images obtained between 19:29 and 19:40
UT does not show a source in the Swift/XRT error circle, implying R>20
about 3 hrs after the burst.
GCN Circular 3195
Subject
GRB 050408: opitcal observation
Date
2005-04-08T21:18:10Z (20 years ago)
From
Nobuyuki Kawai at Tokyo Tech <nkawai@hp.phys.titech.ac.jp>
D. Kuroda (JAXA/ISAS), K. Yanagisawa (OAO), and N. Kawai (Tokyo Tech)
report on behalf of MITSUME collaboration:
"We observed the field covering the entire error circle of GRB050408
(GCN 3189, Sakamoto et al.) with the 50 cm Mitsume Telescope at Okayama,
Japan in V, R, and I bands from 17:49 to 18:32 (UT), and obtained 37
frames of 60 sec exposure.
Comparison of the co-added image to the DSS revealed no new objects
down to a limiting magnitude of R=17.8 as estimated using USNO A2.0
catalog."
GCN Circular 3196
Subject
GRB 050408: Optical afterglow confirmed
Date
2005-04-08T22:50:57Z (20 years ago)
From
Kuiyun Huang at IANCU <d919003@astro.ncu.edu.tw>
GRB 050408: Optical afterglow confirmed
K.Y. Huang, W.H. Ip, D. Kinoshita (NCU), Y. Urata, T. Tamagawa
(RIKEN), Y. Qiu (BAO) and Y.Q. Lou (THCA) on behalf of the East-Asia
GRB Follow-up Observation Network (EAFON)report:
" We have started the observation for the field of GRB 050408 at 17:10
UT on Apr 08 (55 min after the burst). Using Lulin-One meter Telescope
(LOT), we have performed 'VR broad band' filter imaging
observation. These images show a source in the Swift/XRT error
circle. The coordinate is consistent with that of A. de Ugarte Postigo
et al. (GCN 3193). Based on our preliminary 'VR-band' photometry, the
source shows variability which decay index is about -0.6 between
17:17(UT) and 18:33(UT). This source is therefore likely to be the
optical afterglow of GRB 050408. Further analysis is in progress.
This message may be cited."
GCN Circular 3197
Subject
GRB 050408: steepening of the optical decay
Date
2005-04-09T01:29:19Z (20 years ago)
From
Alberto Castro-Tirado at LAEFF-INTA <ajct@laeff.esa.es>
M. Jelinek (IAA-CSIC Granada), T. Fathkullin, V. Komarova,
T. Sokolova, V. Sokolov, V. Vlasyuk, Yu. Balega (SAO RAS,
Russia), S. Guziy (Univ. of Nikolaev), A. de Ugarte Postigo,
J. Gorosabel and A.J. Castro-Tirado (IAA-CSIC Granada),
report:
Further monitoring of the optical source reported by de
Ugarte Postigo et al. (GCNC 3192), confirms a steepening
of the optical decline, when comparing to the Huang et al.
results (GCNC 3196). From the first frame obtained at the 6m
SAO RAS telescope on Apr 8, 18:49 UT (this value supersedes
the one given on GCN 3192) to the last one (at 21:38 UT),
the object has declined significantly, implying a decay
index alpha of -1.6 . An ID-chart is posted at:
http://sirrah.cz/mates/grb050408.jpg .
GCN Circular 3198
Subject
GRB 050408: First Optical observations with TFOSC at the RTT150
Date
2005-04-09T02:08:11Z (20 years ago)
From
Irek Khamitov at TUG <irekk@tug.tug.tubitak.gov.tr>
Z. Aslan,I. Khamitov,T. Ozisik, K. Uluc(TUG), U. Kiziloglu (METU),I.
Bikmaev, R. Gumerov, N. Sakhibullin (KSU/AST), A. Alpar (SabUni), R.
Burenin, M. Pavlinsky, R. Sunyaev (IKI),
report:
We have observed the error box of GRB 050408(GCN 3189 and GCN 3191)
with TFOSC (the imaging and spectroscopic camera of the TUBITAK National
Observatory, Turkey) attached to the Russian-Turkish 1.5-m telescope
(Bakyrlytepe, Turkey). We made series of 30s and 60s exposures in Rc,
starting at 18:46 UT. We have found the OT candidate indicated in GCN 3193
getting fainter with a spectral index of -0.63. We have determined its
postion and magnitudes using USNO-B1. The position and the preliminary R
photometry are as follows:
RA: 12:02:17.31 Dec: +10:51:9.4 (+/- 0.1 arcsec)(2000)
T-T0(hours) Rc
3.7 20.94 +/- 0.1
4.4 21.05
5.4 21.17
6.7 21.31
8.3 21.50
The reductions are in progress.
This message may be cited.
GCN Circular 3199
Subject
GRB 050408: Magellan astrometry and photometry
Date
2005-04-09T02:27:11Z (20 years ago)
From
Josh Bloom at Harvard/CFA <jbloom@cfa.harvard.edu>
H.- W. Chen (MIT), Paul J. Green (CfA), J. S. Bloom (UCB), & J. X.
Prochaska (UCSC) report on behalf of the GRAASP collaboration:
"We began imaging the position of GRB050408 at 00:12, April 9 (UT), using
IMACS on the Magellan/Baade telescope in the R and I bands. The afterglow
candidate reported by de Ugarte Postigo et al. (GCN #3193) is detected in
both bandpasses. Based on a comparison with objects found in the 2MASS
catalog, we measured the coordinates of the afterglow as RA(J2000)=
12:02:17.328 and Dec(J2000)=+10:51:09.47 with an error of 250 mas in each
coordinate. We also measure the afterglow brightness to be R = 21.7 +/-
0.1 mag and I = 21.4 +/- 0.1 mag with R-I=0.3, 7h50m after the initial
trigger."
This message may be cited.
GCN Circular 3200
Subject
GRB 050408: Mercator Optical Observations
Date
2005-04-09T05:17:53Z (20 years ago)
From
Peter Curran at U of Amsterdam <pcurran@science.uva.nl>
K. Wiersema, P. Curran (University of Amsterdam),
K. Lefever, H. van Winckel, C. Waelkens (Katholieke Universiteit Leuven),
O. van Braam, Y. Grange, R. de Rooij, A. de Vries, L. Waters, (University
of Amsterdam),
report:
"We have taken R- and I-band images of the optical afterglow
reported by de Ugarte Postigo et al. (GCN 3193) of the
HETE-2 GRB 050408 (Sakamoto et al., GCN 3189) at the
1.2m Mercator Telescope at La Palma.
The R-band observation started at 20:56 UT and consisted of
3 x 5m, 1 x 3m and 1 x 8m exposure time, making the
total exposure time 26 minutes, with midpoint 4.82h after burst.
The I-band observation started at 21:30 UT and consisted of
2 x 5 minutes exposure time, with midpoint 5.22h after burst.
We calibrate our photometry using the USNO-B catalogue values.
We find an R-band magnitude of 21.25 +/- 0.2 and a
I-band magnitude of 20.4 +/- 0.3.
We thank the staff of the Mercator Telescope for the
excellent assistance."
GCN Circular 3201
Subject
GRB 050408: Emission and absorption redshift
Date
2005-04-09T07:17:46Z (20 years ago)
From
Edo Berger at Carnegie Obs <eberger@ociw.edu>
Edo Berger, Mike Gladders, and Gus Oemler (Carnegie Observatories) report:
"On 2005, April 9.22 UT we obtained a spectrum of the optical afterglow
(GCN 3193) of GRB 050408 (GCN 3189) with LDSS-3 on the Magellan/Clay
telescope. We find a broad emission line which we interpret as [OII]3727
at a redshift of z=1.236 and an absorption doublet which we interpret as
MgII 2796/2803 at the same redshift.
Given a fluence of about 3.3e-6 erg/cm^2 the isotropic-equivalent
gamma-ray energy is 1.3e52 erg."
GCN Circular 3202
Subject
GRB 050408 Optical Observations
Date
2005-04-09T07:47:47Z (20 years ago)
From
Kuntal Mishra at ARIES,Nainital,India <kuntal@upso.ernet.in>
Kuntal Misra, S. B. Pandey (ARIES Naini Tal) and Atish P. Kamble
(Raman Research Institute, Bangalore) on behalf of larger Indian
GRB collaboration
We acquired V, R, I frames of GRB 050408 error box localized by HETE-II
(GCN 3189) and SWIFT (GCN 3191) around 2 hours after the burst in thin
cloudy conditions. The afterglow candidate by Postigo et al. (GCN 3192)
is seen in our frames. The magnitude of our frame taken around 2.4 hours
after the burst (exp-time 300secx2) is R_c = 20.4 +/- 0.2, calibrated with
respect to USNO B1.0 stars 1008-0199794 (R ~ 16.62) and
1008-0199752 (R ~ 15.89).
Our derived magnitude in combination with the R band magnitudes by
Aslan et al. (GCN 3198) follow the power law decay index of 0.70 +/- 0.06,
consistent to those by Huang et al. (GCN 3196) and Aslan et al. (GCN
3198).
This message can be cited.
GCN Circular 3203
Subject
GRB 050408,optical observation
Date
2005-04-09T08:04:43Z (20 years ago)
From
Shouta Maeno at U.of Miyazaki <shouta@astro.miyazaki-u.ac.jp>
S.Maeno,E.Sonoda,Y.Tokunaga,M.Yamauchi
(University of Miyazaki)
"We have observed the field covering the error circle of
GRB 050408 (GCN 3189;HETE Trigger time is 16:22:50.93 UT)
with the unfiltered CCD camera on the 30-cm telescope
at University of Miyazaki.
The observation was started 16:52:23 UT on Apr.8.
After co-adding a set of 20 images (16:52:23 UT - 17:29:14 UT)
of 30 sec exposures, we have compared with the USNO-A2.0 catalog.
Preliminary analysis shows there is no new source brighter than
17.6 mag. at the reported position by A. de Ugarte Postigo et al.
(GCN3192). "
GCN Circular 3204
Subject
GRB 050408: Moderate-resolution Gemini Spectroscopy
Date
2005-04-09T09:41:01Z (20 years ago)
From
Josh Bloom at Harvard/CFA <jbloom@cfa.harvard.edu>
Jason X. Prochaska (UCO/Lick Obs.), J. S. Bloom (UCB), H.-W. Chen (MIT),
R. J. Foley (UCB) & K. Roth (Gemini Obs.) report on behalf of the GRAASP
collaboration:
"We acquired a Gemini/GMOS optical spectrum (R~3000) of the afterglow GRB
050408 (GCN #3189) on UT April 9.42. We identify MgI absorption at a
heliocentric redshift of z=1.2357 +/- 0.0002, consistent with the
previously reported value (GCN #3201). In addition we confirm the
presence of a resolved emission doublet consistent with redshifted
[OII]3727. We also report tentative detections of the TiII 3230, 3384
transitions suggesting the gas associated with the host galaxy is
relatively dust poor and/or high in metal content."
We thank the Gemini observing staff for assistance.
GCN Circular 3205
Subject
GRB050408: REM NIR and Optical observation
Date
2005-04-09T10:36:40Z (20 years ago)
From
Andrea Melandri at Rome Astro Obs <melandri@mporzio.astro.it>
A. Melandri, L. A. Antonelli, S. Covino, V. Testa, A. Monfardini,
E. Palazzi, G. Chincarini, F. M. Zerbi, G. Tosti, E. Molinari,
L. Nicastro, F. Vitali, on behalf of the REM/ROSS team, report:
"On Apr 9, 2005 the REM telescope observed the field of GRB050408
(Sakamoto et al. GCN 3189) from La Silla Observatory (Chile).
The field was imaged with both REM instruments REM-IR and ROSS in
V, R, I, J, H and Ks filters starting at 00:31 UT (approximately 8.2
hours after the burst) for a total integration time of 200 seconds
for each filter.
No sources are detected within SWIFT XRT error circle (Wells et al. GCN
3191) and at the position of the Optical Transient (Ugarte et al., GCN
3192; Huang et al., GCN 3196) down to a limiting magnitude of 18.5,
18.3, 17.9, 16.8, 17.4, 18.4 (5-sigma upper limit)
This message can be cited."
GCN Circular 3206
Subject
GRB 050408, optical observations
Date
2005-04-09T11:57:15Z (20 years ago)
From
Vasilij Rumjantsev at CrAO <rum@crao.crimea.ua>
V.Rumyantsev (CrAO), V.Biryukov (SAI, MSU), and A.Pozanenko (IKI) on behalf
of larger GRB follow up collaboration report:
We have obtained 20 unfiltered images of the GRB050408 (HETE 3711) error box
(Sakamoto et al., GCN 3189). The images were taken with the AT-64 telescope
of Crimean Astrophysical observatory and cover the period UT 18:19:33 -
18:45:57 of April 08, 2005. No source was detected within SWIFT XRT error
box (Wells et al. GCN 3191) and at the position of the optical transient
(Ugarte et al., GCN 3192). Best limiting magnitude of the combined image
(S/N=3) calibrated against R USNO-A2.0 is following
Mid Time(UT) telescope exposure limiting mag.
April 08 18:33 AT-64 20x60 s 19.9
This message can be cited.
GCN Circular 3207
Subject
GRB 050408: Optical limit at 20 min after the burst
Date
2005-04-09T12:27:01Z (20 years ago)
From
Yuji Urata at RIKEN <urata@crab.riken.go.jp>
T. Mizuno, Y. Arai, H. Yamagishi (Tokyo Gakugei Univ.),
T. Soyano (Kiso observatory), Y. Urata, T. Tamagawa(RIKEN),
K.Y. Huang(NCU) on behalf of EAFON report,
" We have imaged the entire error region of GRB 050408 (GCN3189) with
1.05m Schmidt telescope at Kiso observatory, Japan in R band.
Utilizing HETE-2 GCN alert, the observation was started at 16:42 UT
(20 min after the burst) and lasted to 1 hour. There is no optical
emission from the optical afterglow (GCN 3192, GCN 3196) down to a
limiting magnitude of R=19.1 as estimated using USNO B1.0 catalog.
This message may be cited."
GCN Circular 3208
Subject
GRB 050408, SMARTS optical/IR afterglow observations
Date
2005-04-09T16:21:14Z (20 years ago)
From
Bethany Cobb at Yale U <cobb@astro.yale.edu>
B. E. Cobb and C. D. Bailyn (Yale), part of the larger SMARTS
consortium, report:
Using the ANDICAM instrument on the 1.3m telescope at CTIO, we
obtained optical/IR imaging of the error region of GRB 050408
(GCN 3189, Sakamoto et al.) beginning ~10.9 hours post-burst
(2005-04-09 03:14 UT). Total summed exposure times amounted to
36 minutes in I and 30 minutes in J.
The optical afterglow reported by de Ugarte Postigo et al. (GCN 3193)
is detected in both our I and J-band images, though the source appears
only slightly above the background in J. Preliminary comparison
with Landolt standard stars yields an I magnitude of 21.3+/-0.1.
Comparison with IR standard stars LCO-LHS2397a and PERSSON-P9144 yields a
J magnitude of 21.0+/-0.8.
GCN Circular 3209
Subject
GRB 050408: Swift XRT analysis
Date
2005-04-09T17:07:34Z (20 years ago)
From
David Burrows at PSU/Swift <dxb15@psu.edu>
G. Chincharini, P. Romano, S. Campana, C. Pagani, G. Tagliaferri
(INAF-OAB), M. Capalbi, P. Giommi (ASDC), J. Kennea, D. N. Burrows (PSU),
A. Wells, O. Godet (U. Leicester), G. Cusumano, V. Mangano (IASF/Palermo),
L. Cominsky (Sonoma State U.), K. Hurley (UCB), and N. Gehrels (GSFC),
report on behalf of the Swift XRT team:
We have analyzed the Swift XRT data from GRB 050408 (Sakamoto et al. 2005,
GCN 3189; Wells et al. 2005, GCN 3191) using 8 orbits with a total exposure
time of 6417 s in Photon Counting (PC) mode. The refined coordinates of the
X-ray afterglow are:
RA(J2000) = 12:02:17.5
Dec(J2000) = +10:51:06.5
We estimate an uncertainty of 5 arcseconds radius (90% containment). This
position is 3.9 arcsec from the optical candidates (De Ugarte-Postigo et
al., GCN 3192; Chen et al., GCN 3199).
The [0.2-10] keV light curve in PC mode starts 2555 seconds after the
HETE-II trigger (T0). The count rate is decaying following a power law
with a slope of about 0.8 over a time interval of 40 ks. With the current
data we do not see evidence of a break in the XRT light curve.
A preliminary spectral fit to the PC data gives a power law photon index of
2.2 +/- 0.2 in the [0.5-10] keV band, with a column density of
(2.5+/-0.6)E21 cm^-2 (the Galactic value is 1.8E20 cm^-2). The average
unabsorbed 0.5-10 keV flux is about 6.2E-12 erg
cm^-2 s^-1 (in the time range 2.5-43.5 ks from trigger).
GCN Circular 3210
Subject
GRB050408: Radio Observations
Date
2005-04-09T17:38:35Z (20 years ago)
From
Alicia Soderberg at Caltech <ams@astro.caltech.edu>
A. M. Soderberg (Caltech) reports on behalf of the
Caltech-NRAO-Carnegie GRB collaboration:
"Using the Very Large Array at 8.5 GHz, we observed the
field of GRB050408 (GCN 3189) on 2005 Apr 9.26 UT.
We do not detect a radio source coincident with the
X-ray or optical afterglow positions (GCNs 3191 and 3192).
We place a 2-sigma limit of 74 uJy at the optical position.
Further observations are planned."
GCN Circular 3211
Subject
GRB 050408: Mercator Optical Observations
Date
2005-04-09T23:43:33Z (20 years ago)
From
Klaas Wiersema at GRACE/U of Amsterdam <kwrsema@science.uva.nl>
P. Curran, K. Wiersema (University of Amsterdam), K. Lefever, H. van
Winckel, C. Waelkens (Katholieke Universiteit Leuven), O. van Braam, Y.
Grange, R. de Rooij, A. de Vries, L. Waters, (University of Amsterdam),
G.Bourban, G.Burki, F.Carrier (Geneva Observatory), E. Rol (University of
Leicester)
report:
"On 09 April we continued our observations (GCN 3200) of the
optical afterglow reported by de Ugarte Postigo et al. (GCN 3193) of the
HETE-2 GRB 050408 (Sakamoto et al., GCN 3189) at the 1.2m Mercator
Telescope at La Palma.
The R-band observation started at 05:15 UT and consisted of 2 x 8 minute
exposures, with midpoint 13.02h after burst.
We calibrated our photometry using the USNO-B catalogue.
We find a marginal R-band detection of 22.3 +/- 0.3.
We thank the staff of the Mercator Telescope for the excellent
assistance."
GCN Circular 3212
Subject
GRB 050408: Properties of the Host Galaxy
Date
2005-04-10T00:57:26Z (20 years ago)
From
Don Lamb at U.Chicago <lamb@oddjob.uchicago.edu>
GRB 050408: Properties of the Host Galaxy
D. Q. Lamb, D. G. York, and D. E. Reichart report:
The field of GRB 050408 (Sakamoto, et al., GCN Circular 3189) has been
observed by the Sloan Digital Sky Survey and the data is publicly
available as part of Data Release 3. Examination of the SDSS image
of the field of GRB 050408 reveals a galaxy at
RA = (180.57109 deg), Dec = (+10.85051 degree),
coincident with the optical afterglow of GRB 050408. The magnitudes
of the galaxy are u = 23.49, g = 23.30, r = 22.37, i = 21.95, and z =
21.39, with errors of +/- 0.01 mag, with the exception of the z band
where the uncertainty is somewhat larger.
These results suggest that light from the host galaxy may contribute
significantly to the optical magnitudes reported for the optical
afterglow of GRB 050408 as early as ~10 hours after the burst. This
implies that continued Swift XRT observations of the X-ray afterglow
of GRB 050408 (e.g., Wells et al., GCN Circular 3191; Chincharini et
al. 3209) may be the only way of determining the light curve, and
therefore the jet break time, for the afterglow of this burst.
This message may be cited.
GCN Circular 3213
Subject
GRB 050408: SOAR UBVRc Observations
Date
2005-04-10T01:13:30Z (20 years ago)
From
Daniel E. Reichart at U.North Carolina <reichart@physics.unc.edu>
M. Nysewander, S. Heathcote (CTIO), D. Reichart, M. Bayliss report on
behalf of the UNC team of the FUN GRB Collaboration:
We observed the afterglow of GRB 050408 (Sakamoto et al., GCN 3189; Wells
et al., GCN 3191; de Ugarte Postigo et al., GCN 3192) with the 4.1-meter
diameter SOAR Telescope at CTIO, using the SOAR Optical Imager.
Beginning 9.3 hours after the burst, we observed for 10 x 200 sec in Rc, 9
x 200 sec in each of V and B, and 9 x 300 sec in U. The afterglow is well
detected in Rc, V, and B.
Between 9.3 and 10.7 hours after the burst, the Rc light curve faded with a
temporal index of -2.23 +/- 0.60. However, between 10.7 and 13.4 hours
after the burst, the temporal index is only -0.54 +/- 0.36. This suggests
that the afterglow was fading rapidly but is now contaminated by a host
galaxy. This confirms the host galaxy identified by Lamb et al. (GCN 3212)
in the SDSS DR3.
We are very grateful to the SOAR staff for supporting these observations
during SOAR's commissioning period.
GCN Circular 3214
Subject
GRB 050408: WIDGET simultaneous optical observations
Date
2005-04-10T10:38:01Z (20 years ago)
From
Toru Tamagawa at RIKEN <tamagawa@riken.jp>
T. Tamagawa, Y. Urata (RIKEN), F. Usui (ISAS/JAXA), K. Onda, K. Abe,
M. Tashiro (Saitama-U) on bealf of the WIDGET collaboration
report:
"The very widefield camera, WIDGET, located at Akeno, Japan, observed
the region of HETE-2 error box for GRB 050408 (GCN 3189, Sakamoto et
al.). We continuously monitored the HETE-2 field-of-view with repeat
of unfiltered 5 sec exposures from 5 hours before the burst time to 4
hours after it. We have not found any optical emission at the
afterglow position reported by Postigo et al. (GCN 3192) during our
observation period. Coadding the ten images around the burst time
yields the 1-sigma limiting magnitude of R~11 listed below, which was
calibrated relative to USNO B1.0 catalogue.
t-t0 (sec)
start end limit mag.
-------------------------------------
-293.93 -198.93 10.9
-193.93 -98.93 10.9
-93.93 1.07 10.9
6.07 101.07 11.0
106.07 201.07 10.9
-------------------------------------
Further analysis is in progress. This message may be cited.
http://cosmic.riken.jp/grb/widget/"
GCN Circular 3215
Subject
GRB 050408: Subaru Observations
Date
2005-04-10T11:26:35Z (20 years ago)
From
Nobuyuki Kawai at Tokyo Tech <nkawai@hp.phys.titech.ac.jp>
G. Kosugi, T. Yamada, H. Furusawa, Y. Matsuda,
R. Yamauchi, Y. Nakamura, N. Kawai, and A. Yoshida
report on behalf of the Subaru GRB team:
"We have observed the position of GRB 050408 afterglow reported by
de Ugarte Postigo et al. (GCN #3192) in z'-band with SuprimeCam on the
Subaru 8.2m telescope atop Mauna Kea on Apr. 09 and 10, approximately
13.3 and 37.3 hours after the burst event, respectively. The seeing
condition was around 0.6 arcsec for the both nights. We measured the
afterglow brightness to be z'(Vega) = 21.2 +/- 0.2 and 22.0 +/- 0.2,
and the temporal index to be -0.7.
Although these magnitudes are inconsistent with the magnitude of the
host galaxy candidate proposed by Lamb et al. (z = 21.39 mag; GCN #3212),
the position of the proposed host coincides with a field galaxy
(z'(AB)= 21.34 mag in our measurement) located 8 arcsec South-West to
the afterglow."
This message may be cited.
[GCN_OPS(11apr05): Per author's request the "040508" in the Subject-line
was changed to "050408".]
GCN Circular 3216
Subject
GRB 050408: Inconsistency of host galaxy identification
Date
2005-04-10T12:45:35Z (20 years ago)
From
Alessandro Monfardini at JMU/Liverpool Robotic Tele <am@astro.livjm.ac.uk>
A. Monfardini, I. Steele, C.G. Mundell C. Guidorzi, A. Gomboc, M. Bode
(Liverpool), N. Tanvir (Hertfordshire), P. O'Brien and E. Rol
(Leicester) report:
"Since 4.3 hours after the burst, we are monitoring the field of the
GRB050408 (HETE GCN 3189) with the 2m telescopes of the ROBONET network.
We clearly detect the fading afterglow at the position suggested by
A. de Ugarte Postigo et al. (GCN3192) and then refined in subsequent
GCNs. We also detect the SDSS galaxy quoted by Lamb et al. (GCN3212) about
8arcsec from the afterglow position and conclude that this is VERY
unlikely the GRB050408 host galaxy.
This message can be cited."
GCN Circular 3217
Subject
GRB 050408: Retraction of Proposed Host Galaxy
Date
2005-04-10T13:38:51Z (20 years ago)
From
Don Lamb at U.Chicago <lamb@oddjob.uchicago.edu>
GRB 050408: Retraction of Proposed Host Galaxy
D. Q. Lamb, D. G. York, and D. E. Reichart report:
We agree that the galaxy we proposed as the host galaxy of GRB 040508
lies ~ 8 arcsec South-West of the burst afterglow (Kosugi et al., GCN
Circular 3215; Monfardini, GCN Circular 3216) and therefore cannot be
the host galaxy of the burst.
This message may be cited.
GCN Circular 3222
Subject
GRB 050408: Swift XRT measurement of possible jet break
Date
2005-04-10T20:00:03Z (20 years ago)
From
David Burrows at PSU/Swift <dxb15@psu.edu>
O. Godet, K. L. Page, M. R. Goad, J. P. Osborne (U. Leicester), M. Capalbi,
P. Giommi (ASDC), D. Grupe, D. N. Burrows (PSU), S. Campana, G. Chincarini
(INAF-OAB), V. La Parola, T. Mineo (INAF-IASF/Palermo), S. Barthelmy, L.
Angelini, N. Gehrels (GSFC), and P. Meszaros (PSU) report on behalf of the
Swift XRT team:
The Swift XRT instrument observed GRB 050408 as a Target of Opportunity for
20 ks (exposure time) on 8/9 April 2005, beginning 40 minutes after the
HETE trigger and lasting for 60 ks of real time . Analysis of the data
shows evidence for a possible jet break at about 24 ks post-burst, with the
following parameters:
initial slope: -0.71 +0.10/-0.12
Break time : 24 +25/-12 ks
later slope -1.43 +0.72/-0.40
Both single power-law and broken power-law fits to the lightcurve are
statistically acceptable at this point. Further observations planned for
April 11 will give more information to help distinguish between the two and
determine the jet break time.
GCN Circular 3227
Subject
GRB 050408: Early Optical/Ultraviolet Observations with Swift/UVOT
Date
2005-04-10T22:54:37Z (20 years ago)
From
Stephen Holland at USRA/NASA/GSFC/SSC <sholland@milkyway.gsfc.nasa.gov>
S. T. Holland (GSFC-USRA), M. Capalbi (ASDC), A. Morgan, S. Kobayashi,
(PSU), A. Breeveld (MSSL), P. Boyd (GSFC-UMBC), N. Gehrels (GSFC), D.
Hinshaw (GSFC-SPSYS), K. Mason (MSSL), J. Nousek (PSU), and A. Wells
(Leicester) on behalf of the Swift UVOT team report:
The Swift Ultra-Violet/Optical Telescope (UVOT) observed the field of
GRB 050408 (Sakamoto et al., GCN 3189) starting at 17:07:08 UT on 8 April
2005. There is a faint source at the location of the optical afterglow
(de Ugarte Postigo et al., GCN 3192) visible in the coadded U-band image.
This source has U = 21.30 (-0.32,+0.45) mag and the total coadded exposure
time is 2927 s. This source is at the 3-sigma detection limit of the
coadded image and is only marginally consistent with being a point source.
There is no detection in the other filters. The 3-sigma limiting
magnitudes in a 3.5 arcsecond radius circular aperture , and the coadded
exposure times, are: V = 21.3 (3866 s), B = 22.2 (2910 s), UVW1 = 17.8
(3223 s), UVM2 = 17.6 (1989 s), and UVW2 = 17.82 (3402 s). The magnitudes
reported in this Circular are based upon preliminary flight calibrations.
The first Swift/UVOT image of the field was a 100 s V-band exposure
centred 45.117 minutes after the BAT trigger. No source is detected in
this image down to a 3-sigma limiting magnitude of V = 19.9.
GCN Circular 3228
Subject
GRB 050408: PROMPT VRcIc Observations
Date
2005-04-10T23:35:56Z (20 years ago)
From
Matt Bayliss at UNC,Chapel Hill <mbayliss@physics.unc.edu>
M. Bayliss, M. Nysewander, J. Haislip, J. A. Crain, A. Foster, J.
Kirschbrown, C. MacLeod, and D. Reichart report on behalf of the UNC
team of the FUN GRB Collaboration:
We have observed the position of the GRB 050408 afterglow reported by de
Ugarte Postigo et al. (GCN #3192) with three telescopes of the PROMPT
robotic array, one in each of VRcIc.
In one epoch of V-band observations, 122 x 60s exposures centered on
April 9, 02:06:44 UT (t + 9.7 hours), we have a 3 sigma detection of the
afterglow at V ~ 21.4. In a second epoch of 137 x 60s eposures centered
at 05:37:31 UT (t + 13.2 hours) we do not detect the afterglow down to a
limiting magnitude of V = 21.7 (2 sigma).
V filter calibrations were made relative to 6 Nomad stars.
PROMPT is still being built and commissioned.
GCN Circular 3232
Subject
GRB 050408: Optical limit
Date
2005-04-11T06:39:05Z (20 years ago)
From
Ken ichi Torii at RIKEN <torii@crab.riken.go.jp>
K. Torii (Osaka U.) reports
"The error region of GRB 050408 (Sakamoto, et al. GCN 3189) was
observed by the ART 14-inch telescope. BVRcIc imaging started at 2005
April 8, 16:23:48 UT (57-s after trigger) and 60-s exposure in each
filter was repeated.
The optical afterglow (de Ugarte Postigo, et al. GCN 3192) is not
detected in our frames and the following 3-sigma upper limits are
derived relative to USNO-A2.0 (R).
MeanEpoch(UT) Magnitude Exposure
16:24:18 >16.2Rc 60s
16:28:50 >16.2Rc 60s
16:33:22 >17.0Rc 60sx5
"
GCN Circular 3234
Subject
GRB050408: Radio Observations
Date
2005-04-11T17:10:52Z (20 years ago)
From
Alicia Soderberg at Caltech <ams@astro.caltech.edu>
A. M. Soderberg (Caltech) reports on behalf of the
Caltech-NRAO-Carnegie GRB collaboration:
"Using the Very Large Array at 8.5 GHz, we observed again
the field of GRB050408 (GCN 3189) on 2005 Apr 11.21 UT.
We still do not detect a radio source coincident with the
X-ray or optical afterglow positions (GCNs 3191 and 3192).
Coaddition with our previous observation (GCN 3210) yields a
flux of 74 +- 29 uJy at the optical position."
GCN Circular 3246
Subject
GRB 050408: SDSS Field Calibration
Date
2005-04-12T13:37:03Z (20 years ago)
From
Melissa Nysewander at UNC,Chapel Hill <mnysewan@physics.unc.edu>
M. Nysewander, D. Reichart, D. Lamb, and D. York report:
Using ugriz magnitudes from the SDSS DR3 and the transformation
equations of Smith (2002; AJ, 123, 2121), we have calculated the
UBVRcIc magnitudes of 50 sources in the field of GRB 050408:
http://www.physics.unc.edu/~mnysewan/grb050408_fc.txt
Systematic errors are typically 0.02 mag in the gri bands and 0.05
mag in the u and z bands. Statistical errors begin to dominate in u
and z at roughly 21 mag and in gri at roughly 21.5-22 mag. All of
these sources have been classified as stars by the SDSS frames
pipeline; however, some of the fainter sources may be galaxies,
regardless of this.
Users can find the statistical and systematic error on the magnitude of
any SDSS object in the field at
http://cas.sdss.org/astro/en/tools/explore/obj.asp?ra=180.571087&dec=10.850506
by clicking on the "Field" button under "PhotoObj" in the column at the
far left, and make their own decision about whether an object is a
galaxy or a star at
http://cas.sdss.org/astro/en/tools/chart/navi.asp?ra=180.571087&dec=10.850506
GCN Circular 3254
Subject
GRB 050408: refined XRT analysis, no jet break seen yet
Date
2005-04-12T19:26:43Z (20 years ago)
From
David Burrows at PSU/Swift <dxb15@psu.edu>
M. Capalbi (ASDC), P. Romano (INAF-OAB), V. Mangano (INAF-IASF/Palermo), O.
Godet (U. Leicester), L. Angelini (GSFC) and D. N. Burrows (PSU) report on
behalf of the
Swift XRT team:
On 10 April 2004 we reported detection of a possible jet break in Swift XRT
data on GRB 050408, with additional observations scheduled to verify the
break in the light curve (Godet et al. 2005, GCN 3222). We now have
analyzed new data extending to about 300,000 s after the burst, and can
state that the reported possible jet break is not confirmed by the later
observations. No jet break is seen in the XRT data up to 300,000 s after
the burst.
Additional observations are planned over the next several days to continue
to search for a jet break in this afterglow.
GCN Circular 3258
Subject
GRB 050408: Kuiper 1.5m observations
Date
2005-04-13T19:37:03Z (20 years ago)
From
Peter A. Milne at super-LOTIS <pmilne@as.arizona.edu>
P.A.Milne, G.G.Williams (Steward Obs), H.-S.Park (LLNL),
on behalf of the Super-LOTIS GRB team report:
We have observed the field of GRB 050408 over two nights
with the 1.5m Kuiper telescope on Mt. Bigelow, AZ., USA.
We have performed BVRI broad-band imaging and have detected
a source at a position consistent with that reported by
A. de Ugarte Postigo et al. (GCN 3193).
UT Mag Exp(sec)
9.16 R=21.888 +/- 0.150 11x120
9.18 I=21.305 +/- 0.203 9x120
9.20 V=22.069 +/- 0.171 11x120
9.26 R=21.963 +/- 0.129 8x300
9.29 I=20.691 +/- 0.132 8x300
9.32 V=22.618 +/- 0.191 7x300
9.35 B=22.369 +/- 0.166 6x300
10.26 I=22.288 +/- 0.390 4x300
10.29 V=23.480 +/- 0.612 4x300
The field was calibrated from Landolt fields observed during
the first night. Two field stars were compared against the
field calibration compiled by Nysewander et al. (GCN 3246).
We were brighter in all cases, by 0.20/0.02/0.16/0.14 magnitudes
for B/V/R/I respectively.
Further observations are planned to obtain images suitable for
use in image subtraction.
GCN Circular 3261
Subject
GRB050408: optical observation
Date
2005-04-13T20:25:10Z (20 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
B. Kahharov, M. Ibrahimov, D. Sharapov (MAO), A.Pozanenko (IKI),
V.Rumyantsev (CrAO), G.Beskin (SAO) report:
We observed the afterglow (Ugarte et al., GCN 3192) of the HETE GRB050408
(Sakamoto et al., GCN 3189) with 1.5m telescope of the Maidanak
Astronomical Observatory (MAO), Uzbekistan under modarate weather conditions
(seeing ~1.8 arcsec) on April 9 between 19:29:30 - 20:09:00 (UT). The
optical source is clearly visible in the position of OT (Ugarte et al., GCN
3192; Huang et al., GCN 3196). A preliminary R-photometry against of
USNO-B1.0 Catalog is the following:
Mean time Exposure Mag.
(UT) (s)
Apr. 9.828 7x300 22.55 +/- 0.35
This message can be cited.
GCN Circular 3262
Subject
GRB 050408: RTT150 optical observations
Date
2005-04-14T07:29:26Z (20 years ago)
From
Irek Khamitov at TUG <irekk@tug.tug.tubitak.gov.tr>
I. Bikmaev, N. Sakhibullin (KSU/AST), Z. Aslan, I. Khamitov (TUG),
U. Kiziloglu (METU), A. Alpar (SabUni), R. Burenin, M. Pavlinsky,
R. Sunyaev (IKI), report:
We have observed OT of GRB 050408 (A. de Ugarte Postigo et al., GCN
3192) with Rc-filter and ANDOR CCD at the Russian-Turkish 1.5-m telescope
(RTT150, Bakyrlytepe, Turkey). We have made a set of 30 exposures with
5 min duration each during UT 18:30 - 20:10 , April 13. The weather was
clear with average seeing of 1.8 arcsec.
We have marginaly detected the OT at the limit of co-added frame with
Rc = 23.7 +/-0.2 mag.
We have re-reduced our previous observations (Aslan et al, GCN 3198)
by using Landolt standard stars.
RTT150 photometry of OT is given below:
t-t0 (hours) Rc err exposure
midtime (sec)
3.72 21.01 0.07 900 (30*30s)
4.37 21.10 0.05 1080 (18*60s)
4.89 21.25 0.05 960 (16*60s)
5.39 21.27 0.05 960 (16*60s)
5.79 21.44 0.06 960 (16*60s)
6.55 21.37 0.06 720 (12*60s)
6.85 21.50 0.06 720 (12*60s)
8.24 21.64 0.07 1200 (20*60s)
8.75 21.60 0.07 1200 (20*60s)
123.78 23.7 0.2 9000 (30*300s)
The power law decay index between 3.7h and 8.7h calculated on the
basis of the RTT150 data in Rc-band is -0.68+/-0.06 and the newly
obtained value of Rc = 23.7 shows that the lightcurve is still fit by a
single power law of -0.7 (GCN 3215, GCN 3222, GCN 3254).
RTT150 optical light curve of OT GRB050408 is shown at
http://www.tug.tubitak.gov.tr/~irekk/grb/grb050408/lc.jpg
This message may be cited.
GCN Circular 3508
Subject
GRB 050408: jet break in the XRT light curve
Date
2005-06-01T18:38:09Z (20 years ago)
From
David Burrows at PSU/Swift <dxb15@psu.edu>
S. Covino (OAB), M. Capalbi, M. Perri (ASDC), V. Mangano (INAF-IASF/Palermo),
and D. N. Burrows (PSU) report on behalf of the Swift XRT team:
We have analyzed the Swift XRT data from 12 observations of GRB 050408
(Sakamoto et al., GCN 3189) performed over a period of 38 days.
The [0.3-10] keV light curve shows a break at (1.2 � 0.5 )E5 seconds after
the trigger. We interpret this as a jet break, implying a jet opening angle
of 8.2 degrees, given an isotropic-equivalent gamma-ray
energy of 1.3E52 erg (Berger et al., GCN 3201).
GCN Circular 3561
Subject
GRB 050408: ARC 3.5-meter NIR Observations
Date
2005-07-02T15:17:43Z (20 years ago)
From
Don Lamb at U.Chicago <lamb@oddjob.uchicago.edu>
GRB 050408: ARC 3.5-meter NIR Observations
J. Flasher (Colorado), F. Hearty (Colorado), G. Stringfellow (Colorado),
J. Walawender (Colorado), D. Q. Lamb (Chicago), T. Lisker (Washington),
V. Debattista (Washington), J. Dembicky (APO), J. Barentine (APO),
R. McMillan (APO), B. Ketzeback (APO), and D. G. York (Chicago) report
on behalf of the ARC GRB team of the FUN GRB collaboration:
We observed the afterglow (Wells et al., GCN Circular No. 3191; Postigo
et al., GCN Circular No. 3192) of GRB 050408, a burst localized by
HETE-2 (Sakamoto et al., GCN Circular No. 3189), on the night of April
8th, using NIC-FPS on the ARC 3.5-meter telescope at Apache Point
Observatory. The observation began at 04.47 UT (12.29 hours after the
burst) and ended at 07.06 UT (14.68 hours after the burst). The
observation consisted of a series of 120-, 120-, 20-, and 20-second
exposures in Z, J, H, and Ks, respectively. We have constructed
stacked images of the GRB field, corresponding to 20-minute exposures
in each filter. We detect the afterglow in all four filters, and
measure Z = 21.8 � 0.12, calibrated relative to the SDSS stars in the
field.
NIC-FPS is currently in its commissioning phase.
This message may be cited.