GRB 050730
GCN Circular 3704
Subject
GRB050730: Swift-BAT detection of a weak burst
Date
2005-07-30T21:00:41Z (20 years ago)
From
Scott Barthelmy at NASA/GSFC <Scott@lheamail.gsfc.nasa.gov>
S.T. Holland (GSFC/USRA), S. Barthelmy (GSFC), D.N. Burrows (PSU),
C. Gronwall (PSU), J. Kennea (PSU), N. Gehrels (GSFC), D. Palmer (LANL),
A. Parsons (GSFC), P. Schady (MSSL),
on behalf of the Swift team:
At 19:58:23 UT, Swift-BAT triggered and located GRB050730 (trigger=148225).
The spacecraft slewed immediately. The BAT on-board calculated location
is RA,Dec 212.065d,-3.762d {14h 08m 16s,-03d 45' 41"} (J2000), with an
uncertainty of 3 arcmin (radius, 90% containment, stat+sys). The BAT
light curve shows a broad weak bump with a total duration of 30-40 sec.
The peak count rate was ~500 counts/sec (15-350 keV).
The XRT began observing at 20:00:33 UT, 130 seconds after the BAT trigger.
XRT was unable to centroid on any source, however the downlinked lightcurve
shows a bright variable source is present in the XRT field of view.
There are no catalogued X-ray sources in the field, suggesting that this
bright source is the GRB afterglow.
The Swift Ultra-Violet/Optical Telescope (UVOT) observations began at
20:00:22 UT, 119 seconds after the BAT trigger. The first data taken
in the V band after the spacecraft settled was a 100 sec exposure.
A comparison against the DSS catalogue reveals a possible new source inside
the BAT error circle at 14h 08m 17.09s,-3d 46' 18.9" +- 1 arcsec (radius,
sys+stat, 90% c.l., J2000). The V band magnitude was 17.62 +- 0.22.
It is noted that the position of this GRB lies in the direction
of the Galaxy Cluster ZwCl 1406-0334 (z=0.088). The s/c is currently
in the gap of downlink passes, so further analysis will not be forthcoming
for at least 5 hours.
GCN Circular 3705
Subject
GRB 050730, optical candidate
Date
2005-07-30T21:15:44Z (20 years ago)
Edited On
2024-11-18T09:46:38Z (7 months ago)
From
Alberto Castro-Tirado at LAEFF-INTA <ajct@laeff.esa.es>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>
A. Sota, A.J. Castro-Tirado, S. Guziy, M. Jelínek,
A. de Ugarte Postigo and J. Gorosabel (IAA-CSIC),
A. Bodganov (Nikolaev St. Univ.) and M.D. Pérez-
Ramírez (Univ. de Jaén):
report:
"We have imaged a 7' x 7' region centred on the SWIFT/
BAT error box for GRB 050730 (trigger 148225) with the
1.5-m OSN telescope (+ Albireo) at the Observatorio de
Sierra Nevada starting on July 30 (20:26 UT, i.e. 0.45
hours after the GRB) under good meteorological conditions.
Within the SWIFT/BAT error box, a single R-band image
(300 s exposure time) shows a bright point source close
to the center of the error not present in the DSS-2.
Coordinates yield: RA(2000) = 14 08 17.14, Dec(2000)
= -03 46 17.8 (+/- 0.35"). We measure R = 17.0 using the
USNO-A2.0. This is very likely optical afterglow to GRB
050730."
This message can be quoted.
GCN Circular 3706
Subject
GRB050730: Liverpool Telescope optical observations
Date
2005-07-30T21:53:17Z (20 years ago)
From
Andreja Gomboc at LT,ARI,Liverpool JMU <ag@astro.livjm.ac.uk>
A. Gomboc, C. Guidorzi, I.A. Steele, A. Monfardini, C.G. Mundell,
C.J. Mottram, R.J. Smith, D. Carter, M.F. Bode (Liverpool JMU) report:
The 2-m Liverpool Telescope followed up the Swift GRB050730 (Holland et
al, GCN 3704) and started observing its position at UT 20:37:21.
The GRB pipeline automatically detected an OT candidate at the position
RA 14:08:17.13, dec -03:46:17.7 (J2000) in agreement with the candidate
from UVOT (Holland et al., GCN 3704) and Sota et al. (GCN 3705).
The magnitude of the source is r'~17.3 (USNO-B1 calibrated) at ~50 min
after the burst.
This message can be cited.
>
>
>
>
GCN Circular 3707
Subject
GRB 050730 : Planned XMM-Newton observation
Date
2005-07-31T00:51:59Z (20 years ago)
From
Norbert Schartel at XMM-Newton/ESA <too@xmm.vilspa.esa.es>
XMM-Newton will observe GRB 050730 at location
(RA=14h 08m 17.1s, DEC=-03d 46' 18", J2000),
starting at 03:00:08 UT, on July 31, 2005,
for an exposure of 35000 seconds.
GCN Circular 3708
Subject
GRB 050730, SMARTS optical/IR afterglow observations
Date
2005-07-31T01:07:04Z (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 050730
(GCN 3704, Holland et al.) with a mid-exposure time of
2005-07-30 23:05 UT, which is ~3.1 hours post-burst.
Total summed exposure times amounted to 15 minutes in I and V and
12 minutes in J and K.
The candidate afterglow (Holland et al, GCN 3704,
Sota et al. GCN 3705, Gomboc et al. GCN 3706) is
well detected in our images.
Assuming the nearby USNO-B1.0 star 0862-0270654
has a magnitude of I = 17.6 (USNO-B1.0 I2 magnitude)
and J = 16.4 (2MASS magnitude), then the magnitude
of the afterglow candidate is I ~ 17.2 and J ~ 16.3
in the total combine frames.
The afterglow candidate also shows strong evidence of decay
between successive frame. Preliminary analysis suggests
that the afterglow may have decayed in I by
~ 0.5 magnitudes between the first and last frame taken
over a 40 minute period. Given this evidence of decay,
this source is very likely the optical afterglow
of GRB 050730.
GCN Circular 3709
Subject
GRB 050730: Redshift Measurement based on Magellan/MIKE Observations
Date
2005-07-31T01:42:59Z (20 years ago)
From
Hsiao-Wen Chen at MIT/CSR <hchen@space.mit.edu>
Hsiao-Wen Chen (MIT), Ian Thompson (Carnegie Observatory), Jason X.
Prochaska (UCO/Lick Observatory), Josh Bloom (UCB) report on behalf of the
GRAASP collaboration:
"We observed the afterglow of GRB050730 reported by Holland et al. (GCN 3704)
and Sota et al. (GCN 3705) using the MIKE echelle spectrograph on Magellan II.
The observations started at UT 00:00:04 on July 31, 2005, ~ 4 hours after
the inital Swift/BAT trigger (GCN 3704). We obtained a high signal-to-noise
(S/N ~ 20 at 8000 Ang) spectrum with a resolution element of ~10 km/s. We
measure the afterglow at redshift z=3.967 based on a broad absorption trough
at 6040 Ang, which we identify as the Lya absorption line originated in the
host of the GRB. We also detect a suite of strong absorption lines, which we
confirm as OI1302, SiII 1304, and CII 1334 at this redshift.
Further analysis is underway.
This message may be cited."
GCN Circular 3710
Subject
GRB050730: confirmation of redshift
Date
2005-07-31T02:25:13Z (20 years ago)
From
Evert Rol at U.Leicester <er45@star.le.ac.uk>
E. Rol (U. of Leicester), R. Starling, K, Wiersema (U. of Amsterdam),
P. Vreeswijk (ESO), Andrew Levan (U. of Leicester), Neil O'Mahony
(ING), C. Tadhunter, Javier Rodriguez (Sheffield University), Rosa
M. Gonzlez Delgado (IAA CSIC) report for a larger collaboration:
We have observed the optical afterglow (GCN 3705) of GRB 050730 (GCN
3704) using the ISIS spectrograph on the William Herschel Telescope at
the Observatorio del Roque de los Muchachos on La Palma.
The mid-point of our observations is at 0.143 days after burst. We
obtained 1260+1800 seconds exposures in both the 300B and 300R grisms
with a 2.5 arcsec slit. Though data were taken under high airmass, a
high signal to noise spectrum was obtained.
We find strong damped Ly alpha and Ly beta systems, as well as a
multitude of metallic lines in the spectrum, from which we determine a
redshift of 3.97, confirming the redshift reported in GCN 3709.
We thank the staff of the WHT for outstanding support for these
observations.
GCN Circular 3711
Subject
GRB050730, afterglow observations
Date
2005-07-31T03:01:08Z (20 years ago)
From
Arne A. Henden at AAVSO <arne@aavso.org>
C. Jacques and E. Pimentel, CEAMIG-REA Observatory
(Brazil) report on behalf of the AAVSO International
High Energy Network:
We observed the afterglow candiate proposed (Holland et al.,
GCN 3704; Sota et al., GCN 3705, Gomboc et al., GCN 3706)
for the Swift GRB 050730 (Holland et al., GCN 3704).
It is detectable in our 6x60 second summed unfiltered
CCD image using a 30cm SCT and ST7XME camera with an
R-band equivalent magnitude of 18.4 using USNO-A2 calibration.
The mid-exposure time was 2005-07-30 at 23:38 UT.
Astrometry using 32 UCAC2 reference stars, with residuals
of 0.08" in RA and 0.07" in Dec, is
14:08:17.13 -03:46:16.7 J2000
A FITS image will be available later on our web site.
The AAVSO thanks the Curry Foundataion for their continued
support of the AVSO International High Energy Network.
GCN Circular 3712
Subject
GRB 050730: PROMPT VRcIc Observations
Date
2005-07-31T04:10:36Z (20 years ago)
From
Josh Haislip at U.North Carolina <haislip@physics.unc.edu>
J. Haislip, J. Kirschbrown, D. Reichart, M. Bayliss, A. Crain, M.
Nysewander report on behalf of the UNC team of the FUN GRB Collaboration:
Under the control of Skynet, PROMPT automatically observed the localization
of GRB 050730 (Holland et al., GCN 3704) beginning 3.1 hours after the
burst in repeating blocks of VRcIc.
We detect the afterglow (Holland et al., GCN 3704; Cobb et al., GCN 3708).
At 3.3 hours after the burst, we measure Rc = 17.82 +/- 0.05, based on 3
USNO-B1.0 stars.
PROMPT is still being built and commissioned.
GCN Circular 3713
Subject
GRB 050730 XMM-Newton observation
Date
2005-07-31T05:01:25Z (20 years ago)
From
Norbert Schartel at XMM-Newton/ESA <too@xmm.vilspa.esa.es>
M. Ehle and B. Juarez report:
Quick-Look-Analysis of the XMM-Newton observation of the GRB 050730
field based on an exposure in the EPIC pn camera that started at 04:09 UT,
shows the presence of a source within the SWIFT/XRT error circle
(Holland et al., GCN 3704).
The estimated EPIC pn count rate for the first 2.8 ksec was 1.6 counts/sec.
GCN Circular 3714
Subject
GRB 050730: Swift XRT afterglow observations
Date
2005-07-31T05:31:24Z (20 years ago)
From
David Burrows at PSU/Swift <dxb15@psu.edu>
D. Grupe, J. A. Kennea, and D. N. Burrows (PSU) report on behalf of the
Swift-XRT
team:
We have analyzed the Swift XRT data from the first three orbits of
observations of GRB 050730 (Holland et al., GCN 3704). The satellite slewed
to this burst immediately and the XRT began collecting data at T+130 s, but
was unable to determine an on-board position for the afterglow. In
ground-processed data we find a bright, fading, uncataloged X-ray source
that we identify as the afterglow of this burst. The XRT ground-calculated
coordinates are:
RA(J2000) = 14h 08m 17.7s
Dec(J2000) = -03 46 09.7.
This position is 42 arcseconds from the BAT position given in GCN 3704, and
13.4 arcseconds from the UVOT position given in GCN 3704. However, we note
that there is accumulating evidence of a time-dependent systematic shift in
XRT positions derived from ground-processed data compared with the optical
counterparts. This effect is being investigated but is not yet
understood. Extrapolation of earlier positional errors suggests that the
correct position could have a systematic error of at least 7 arcseconds in
addition to the standard error circle of about 6 arcseconds radius.
A preliminary spectral fit (simple absorbed power-law) to the WT data
yields a photon index of 1.6+/-0.2. The derived NH is (4.4+/-0.6)E20 cm^-2,
which is roughly consistent with the Galactic value (3.1E20 cm^-2; Dickey &
Lockman 1990).
The light curve is complex, with at least 3 X-ray flares in the first orbit
of data (T+130 to T+ 1000 s), making it difficult to estimate a decay
slope. A rough approximation of the average decay slope over the first 3
orbits of data is about -0.8.
Further observations are in progress.
GCN Circular 3715
Subject
GRB050730: Refined BAT analysis of the Swift-BAT burst
Date
2005-07-31T05:50:18Z (20 years ago)
From
Craig Markwardt at NASA/GSFC/UMD <craigm@milkyway.gsfc.nasa.gov>
C. B. Markwardt (GSFC/UMD), L. Barbier (GSFC), S. Barthelmy (GSFC),
J. Cannizzo (GSFC-UMBC), J. Cummings (GSFC/NRC), E. Fenimore (LANL),
N. Gehrels (GSFC), D. Hullinger (GSFC/UMD), H. Krimm (GSFC/USRA),
D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC),
M. Tashiro (Saitama U.), J. Tueller (GSFC)
on behalf of the Swift-BAT team:
Using the full BAT data set from the recent telemetry downlink, we report
further analysis of Swift-BAT GRB 050730 (trigger #148225)
(Holland, et al., GCN 3704). The ground-analysis position is
RA,Dec 212.063,-3.740 (J2000) with an uncertainty of 3 arcmin
(radius, 90%, stat+sys). The light curve shows a gradual increase
in emission starting at T-60 sec with a peak at T+10 sec
and then a gradual decline out to T+120 sec. T90 is 155 +- 20 sec.
Fitting a simple power law over the full interval from T-60 to T+120 seconds,
the photon index is 1.5 +/- 0.1 with a fluence of 4.4 +/- 0.4 X 10^-6 erg/cm^2
in the 15-350 keV band (90% c.l.). The peak flux in a 1-sec wide window
starting at T+4.8 seconds is 0.74 +/- 0.17 ph/cm^2/sec (15-350 keV).
GCN Circular 3716
Subject
GRB 050730, spectra and optical photometry
Date
2005-07-31T06:44:05Z (20 years ago)
From
Peter Garnavich at U of Notre Dame <pgarnavi@nd.edu>
M. Holman (CfA), P. Garnavich (Notre Dame), K.Z. Stanek (Ohio State)
Spectra of the afterglow of GRB 050730 (Holland et al. GCN 3704)
were obtained with the Magellan Observatory Baade Telescope and
IMACS imaging spectrograph beginning 2005 July 30 23:57 (UT).
The spectra cover 360 to 950 nm with a dispersion of 0.74 A/pix.
We find a clear Ly-alpha absorption system with the GRB flux
reaching zero between 598 nm and 609 nm. This confirms the
redshift of 3.97 found for the burst by Chen et al.
(GCN 3709) and Rol et al. (GCN 3710).
An image of the GRB field was obtained July 30 23:10 (UT) with
IMACS and the afterglow flux calibrated with Landolt standard
SA110-360. We estimate the afterglow brightness at R=17.50+/-0.05
mag. A star to the west of the afterglow at
14:08:14.62 -03:46:29 (2000) has a brightness of R=17.18+/-0.05 mag.
A plot of the spectrum and the image of the afterglow obtained with
IMACS are available at http://www.nd.edu/~pgarnavi/grb050730 .
GCN Circular 3717
Subject
Swift/UVOT photometry of GRB050730
Date
2005-07-31T20:48:41Z (20 years ago)
From
Alexander Blustin at MSSL-UCL <ajb@mssl.ucl.ac.uk>
A. J. Blustin (UCL-MSSL), S. T. Holland (GSFC/USRA), A. Cucchiara (PSU),
N. White (GSFC), D. Hinshaw (GSFC-SPSYS) on behalf of the Swift/UVOT
team report:
Swift/UVOT began observing GRB050730 at 2005-07-30T20:00:22, 119 s after
the BAT trigger (Holland et al. GCN 3704). A bright source was detected
in the genie image at 14h 08m 17.09s,-3d 46' 18.9" (Holland et al.
GCN 3704). Further analysis of data returned via the Malindi ground
station shows that this source is fading; we report the following V band
lightcurve, including detections significant at greater than 2.8 sigma:
Tmid (s) Exp (s) Magnitude
170 99.77 17.842 +/- 0.152
300 9.78 17.473 +/- 0.380
384 9.78 17.477 +/- 0.383
468 9.78 16.737 +/- 0.238
553 9.76 16.568 +/- 0.216
637 9.76 17.119 +/- 0.302
722 9.78 16.706 +/- 0.231
3978 99.77 18.274 +/- 0.259
11948 837.11 19.200 +/- 0.150
23520 835.72 20.211 +/- 0.371
35088 843.21 20.286 3-sigma upper limit
Where Tmid is the time after trigger of the mid-point of the
exposure.
Additionally the source was detected at greater than 2.8 sigma
significance in the B-band in 3 images:
Tmid (s) Exp (s) Magnitude
271 9.76 18.874 3-sigma upper limit
355 9.77 18.303 +/- 0.321
440 9.77 18.662 3-sigma upper limit
524 9.76 18.492 +/- 0.364
608 9.76 18.766 3-sigma upper limit
693 9.77 18.076 3-sigma upper limit
777 9.76 18.734 3-sigma upper limit
10164 899.77 20.447 +/- 0.208
21737 899.73 21.087 3-sigma upper limit
33309 901.43 21.126 3-sigma upper limit
There was no detection in U or in any of the UV filter exposures.
The upper limits for the summed images in these bands are:
Filter T range (s) Exp (s) 3-sigma magnitude upper limit
U 252-29724 2490.71 21.747
UVW1 238-28880 3665.12 21.98
UVM2 224-27972 3620.41 22.30
UVW2 281-34660 2765.25 22.40
where T range is the time range post-trigger over which the images
were taken.
The magnitudes are based on preliminary zero points, measured in
orbit, and will require refinement with further calibration. All
magnitudes are uncorrected for Galactic reddening.
GCN Circular 3718
Subject
GRB 050730: RTT150 optical observations
Date
2005-07-31T23:27:15Z (20 years ago)
From
Rodion Burenin at IKI, Moscow <rodion@hea.iki.rssi.ru>
R. Burenin, A. Tkachenko, M. Pavlinsky, R. Sunyaev (IKI),
I. Khamitov, Z. Aslan (TUG), U. Kiziloglu (METU), A. Alpar (SabUni),
I. Bikmaev, N. Sakhibullin (KSU/AST)
report:
We observed optical afterglow of GRB 050730 (Holland et al., GCN #3704)
with Russian-Turkish 1.5-m telescope (RTT150, Bakyrlytepe, TUBITAK
National Observatory, Turkey). Observations were made under partially
clouded sky. We obtained a set of 180s images in BVRI filters. Object
was clealy detected in I and R and marginally in V. Using reference star
from Holman et al. (GCN #3716) we estimate R=21.24+-0.17 at 19:01 UT,
July 31.
This message may be cited.
GCN Circular 3720
Subject
GRB 050730: early TAROT optical observations
Date
2005-08-01T08:18:52Z (20 years ago)
From
Michel Boer at Obs Haute Prov. <Michel.Boer@oamp.fr>
Klotz, A. (CESR-OMP), Boer M. (OHP), and Atteia, J.L. (LAT-OMP) report:
We imaged the entire field of GRB 050730 detected by SWIFT (Holland et al. GCNC
3704) with the TAROT robotic telescope (D=25cm) located at the Calern
observatory, France. Observations started 7.5 seconds after the GCN notice (and
66.3 s after the GRB). The field had an elevation of
29 degrees above horizon at the begining of the observations and then decreased.
The first three images taken between 2005-07-30T19:59:29.53 (GRB +
66.3s) and 2005-07-30T20:00:27.38 (GRB + 124.2s) were co-added. The afterglow is
perhaps detected very marginally. The magnitude is estimated to be
R=15.5 +/- 0.4 comparing with the USNO-B1 nearby stars. This magnitude should be
rather considered as an upper limit.
A second set of three images taken between 2005-07-30T20:00:33.60 (GRB +
130s) and 2005-07-30T20:01:46.25 (GRB + 203s) we co added.
The afterglow is not detected, suggesting R>15.9 comparing with the
USNO-B1 nearby stars.
Co addition of the six first images (GRB + 66.3s to 203s) shows the afterglow
measured to be R=16.24 +/- 0.41.
Later images were taken with longer exposure times and were co added to measure
the afterglow magnitude with a reasonable accuracy:
t=GRB + 26.79 min R=17.00 +/- 0.41
t=GRB + 37.61 min R=17.30 +/- 0.44
t=GRB + 48.61 min R=17.34 +/- 0.37
t=GRB + 61.20 min R=17.92 +/- 0.42
t=GRB + 78.47 min R=17.54 +/- 0.39
t=GRB + 97.40 min R=18.74 +/- 0.53
This later series gives a decay index of 0.89 +/- 0.38.
An extrapolation towards the early measurement shows that a break or a
re-brightening should occured considering our R=16.24 measurement at t=GRB +
2.31 min.
Further informations (light curve and images) on:
http://www.cesr.fr/~klotz/grb050730
This message can be cited.
--
Michel Boer
Observatoire de Haute Provence
F - 04870 Saint Michel l'Observatoire
04 92 70 64 59 - Michel.Boer@oamp.fr
GCN Circular 3722
Subject
GRB 050730: XRT refined analysis
Date
2005-08-01T17:37:06Z (20 years ago)
From
Matteo Perri at ISAC/ASDC <perri@asdc.asi.it>
M. Perri, M. Capalbi, P. Giommi (ASDC), D. Grupe, D.N. Burrows (PSU), L.
Angelini (GSFC-JHU), J. Greiner (MPE) report on behalf of the Swift XRT
team:
We have analysed the first 13 orbits of Swift XRT data for GRB 050730
(Holland et al., GCN 3704). Using Photon Counting (PC) mode
observations, the refined position of the X-ray afterglow is:
RA(J2000) = 14h 08m 17.5s
Dec(J2000) = -03d 46' 19"
with an uncertainty of 6 arcsec. This is 6 arcsec from the UVOT position
(Holland et al., GCN 3704) and 10 arcsec from the original XRT position
(Grupe et al., GCN 3714).
XRT observations began in Windowed Timing (WT) mode 133 seconds after
the BAT trigger. The early light curve shows three X-ray flares at about
T+230 s, T+430 s and T+680 s. The temporal decay for the first orbit has
not been determined due to the flaring nature of the emission. An X-ray
flare is also observed in the second orbit in PC mode at about T+4500 s.
Starting from 15 ks after the trigger, the afterglow light curve shows a
decline with a power-law decay index alpha=-2.3+/-0.1.
The X-ray spectrum in the time interval 15-35 ks after the trigger is
well described by an absorbed power-law with photon index
Gamma=1.8+/-0.1 and NH=(1.0+/-0.4)E21 cm^-2.
The unabsorbed flux in the 0.3-10 keV energy band at T+24 hours is
7.3e-13 ergs cm^-2 s^-1.
GCN Circular 3727
Subject
GRB 050730, corrected photometry and break?
Date
2005-08-01T20:39:19Z (20 years ago)
From
Peter Garnavich at U of Notre Dame <pgarnavi@nd.edu>
M. Holman (CfA), P. Garnavich (Notre Dame), K.Z. Stanek (Ohio State)
The photometry of the GRB 050730 afterglow and comparison
star reported on GCN 3716 requires correction. The CCD gain
between the standard star and GRB observations differed by 20%.
The IMACS photometry of the afterglow taken on July 30 23:57 (UT)
should be R=17.73 +/-0.05 mag and the comparison star at
14:08:14.62 -03:46:29 (2000) has R=17.41 +/-0.05 mag.
The photometry of Burenin et al. (GCN 3718) based on our old
calibration should be made 0.23 mag fainter. Even
without these corrections, the R-band observations
imply a power-law decay index of -1.7 between 4 hours and
23 hours after the burst. This is much steeper than the V-band
index suggested by Swift UVOT photometry (Blustin et al. GCN 3717).
The Swift V-band data between 12 minutes and 6.5 hours after
the burst is consistent with a power-law decay index of -0.9.
If the spectral index has not changed significantly,
then the combined Swift and ground data suggests a steepening
in the power-law decay occurred between 6 hours and 23 hours
post-burst.
GCN Circular 3732
Subject
GRB 050730: Preliminary Analysis of MIKE Spectrum
Date
2005-08-02T06:00:34Z (20 years ago)
From
Jason Prochaska at UCO/Lick Obs <xavier@ucolick.org>
J. X. Prochaska (UCO/Lick), H.-W. Chen (MIT), J. S. Bloom (UCB),
J. O'Meara (MIT), S. M. Burles (MIT), I. Thompson (OCIW)
report on behalf of the GRAASP collaboration:
"We have performed preliminary analysis of our MIKE spectrum of
the afterglow of GRB 050730. A profile fit to the Lya and Lyb
absorption lines of the sightline through the host galaxy gives
N(HI) = 22.15 +/- 0.05. The simple and narrow metal-line profiles
give a redshift z=3.96855 +/- 0.00005. We estimate a neutral gas
metallicity of S/H ~ 1/100 solar which is lower than the
mean metallicity of damped Lya system at this redshift. More
strikingly,
we identify fine-structure lines of SiII*, OI*, OI**, and FeII*, the
majority of which are saturated. Also, we identify absorption
features near 6150A which we interpret as the NV absorption doublet.
Finally, we identify an intervening damped Lya system at
z=3.5650 +/- 0.0001 with log N(HI)= 20.30 +/- 0.15 and low metallicity
as well as a z=1.773 MgII absorber.
A full analysis is underway.
Figures can be found at this following site:
http://www.graasp.org/Data/index.html
GCN Circular 3741
Subject
GRB 050730: OHP optical observations
Date
2005-08-03T08:42:35Z (20 years ago)
From
Jean-Luc Atteia at Lab d Astrophys.,OMP,Toulouse <atteia@ast.obs-mip.fr>
Damerdji, Y. (OHP), Klotz, A. (CESR-OMP),
Boer M. (OHP), Atteia J.L. (LATT-OMP) report:
We imaged the field of GRB 050730
detected by SWIFT (Holland et al. GCNC 3704)
with the 0.8m (F/15) telescope
located at the Observatoire de Haute Provence
Observatory (OHP), France.
Camera is an Andor 47-40 equiped by a R band filter.
We measured the magnitudes of the afterglow
described in Holland et al. (GCNC 3704):
Tmid (julian day) Exp (s) R-Mag
2453582.35721 300 17.14 � 0.10
2453582.36875 300 17.43 � 0.09
2453582.37226 300 17.38 � 0.09
2453582.37577 300 17.31 � 0.06
2453582.37928 300 17.39 � 0.09
2453582.38279 300 17.37 � 0.11
2453582.38630 300 17.45 � 0.13
Magnituded were computed as differential with
the three nearby USNO-B1 stars:
0862-0270612 R=14.96
0862-0270590 R=15.22
0861-0264205 R=15.35
These OHP data seems to show a flattening of the decay
(or a rebrightening) starting after the second exposure.
This message can be cited.
GCN Circular 3746
Subject
GRB050730: FORS1 and UVES/VLT low- and high-resolution spectroscopy
Date
2005-08-03T16:33:49Z (20 years ago)
From
Stefano Covino at Brera Astronomical Observatory <covino@merate.mi.astro.it>
V. D'Elia, A. Melandri, F. Fiore, L. Stella, L. Sbordone (INAF-OAR), G.
Tagliaferri, S. Covino, D. Fugazza, D. Malesani (INAF/OABr), G.
Chincarini (Univ. Milano-Bicocca), M. Della Valle (INAF/Arcetri), L.
Pellizza (CEA, Saclay), R. Scarpa (ESO-Chile) on behalf of the MISTICI
collaboration, report:
Starting on July 31, 2005 00:01:02 UT (about 4 hours after the GRB
trigger) we have obtained low- and high-resolution spectra (FORS1, Grism
300V, R~800; UVES, R~40,000, 7.5 km/s in the observer frame) of the
optical afterglow of GRB050730 (Holland et al., GCN 3704). The
observations consisted of 2 exposures for a total of 1800 second with
FORS1 and 2 exposures for a total of 6000 seconds with UVES covering the
full spectral range 3500-9800 Angstrom.
At the time of the observations the afterglow magnitude was R~17.7 and
the decay of the afterglow, as measured from the FORS1 flux-calibrated
spectra, is consistent with a temporal decay index of about -1. For the
UVES spectra, the resulting continuum signal to noise per resolution
element spans from 10 to 20 in the 6000-9000 Angstrom range.
A preliminary analysis of the data confirms a very rich spectrum and all
features reported by the GRAASP collaboration (GCN 3709 and 3732). We
also detect strong, saturated, SiIV1393,1402, CIV1548,1550, CII1334,
CII*1335, Al1670, AlII1854 absorption lines at z=3.968. The main
absorption systems span a velocity range of up to 100 km/s.
A full analysis is underway.
We thank the ESO staff for the excellent support in performing these
observations in service mode.
This message can be quoted.
GCN Circular 3761
Subject
GRB050730: Radio Detection
Date
2005-08-04T17:42:00Z (20 years ago)
From
Patrick B. Cameron at Caltech <pbc@astro.caltech.edu>
P. B. Cameron (Caltech) reports on behalf of the Caltech-NRAO-Carnegie
collaboration:
"We observed the field of GRB050730 (GCN 3704) with the Very Large Array
at 8.5 GHz beginning August 2.03 UT. We detect a radio source consistent
with the optical source (GCN 3705) with position
RA(J2000): 14:08:17.11 +/- 0.01
DEC(J2000): -03:46:17.2 +/- 0.2
and flux density 145 +/- 28 uJy. Further observations are planned.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
GCN Circular 3775
Subject
GRB050730, optical observations
Date
2005-08-06T11:16:35Z (20 years ago)
From
T.P. Prabhu at Indian Astro. Obs. <tpp@crest.ernet.in>
B.C.Bhatt and D.K. Sahu communicate on behalf of a larger GRB
collaboration group:
GRB050730 was observed with the 2-m Himalayan Chandra Telescope of Indian
Astronomical Observatory, Hanle, on 2005 July 31, 16:10 UT (300s+900s).
The magnitude of the OT with repect to USNO B1.0 0862-0270612,
0862-0270590, and 0862-0264205 (GCN 3741) was R=21.39+/-0.08.
This message may be cited.
GCN Circular 3778
Subject
GRB 050730, optical observation
Date
2005-08-06T19:15:13Z (20 years ago)
From
Peter Garnavich at U of Notre Dame <pgarnavi@nd.edu>
S. Kannappan (U. Texas), P. Garnavich (Notre Dame),
K.Z. Stanek (Ohio State), D. Christlein (Yale), and
D. Zaritsky (U. Arizona)
We imaged the position of the GRB 050730 afterglow (Holland et al.
GCN 3704) with the Magellan Observatory Baade Telescope and IMACS
imaging spectrograph on 2005 Aug. 3 23:40 (UT) which is 99.7 hours
after the burst. Three, 300 sec exposures were obtained in the
R band and combined into a deep image. The afterglow (+possible host
galaxy) is detected and the brightness is estimated to be
R=23.4+/-0.1 mag based on the calibration by Holman et al. (GCN 3727).
The power-law decay index between the IMACS R-band observation obtained
3 hours after the burst and 100 hours is -1.5 which confirms the light
curve break suggested by Holman et al. (GCN 3727). We note that the
strong Lyman absorption (GCN 3709,3710,3716) falls at the peak of the
standard R-band transmission making comparison between magnitude
estimates made with different detector/filter combinations difficult.
GCN Circular 3781
Subject
GRB 050730: WSRT Radio Observations
Date
2005-08-08T12:24:03Z (20 years ago)
From
Alexander van der Horst at U of Amsterdam <avdhorst@science.uva.nl>
A.J. van der Horst (University of Amsterdam) and E. Rol (University of
Leicester) report on behalf of a larger collaboration:
"We observed the position of the GRB 050730 afterglow at 4.9 GHz with the
Westerbork Synthesis Radio Telescope at Aug 5 11.10 UT to 22.40 UT, i.e.
4.63 - 5.10 days after the burst (GCN 3704), and at Aug 7 10.96 to 16.00
UT, i.e. 6.63 - 6.84 days after the burst.
At the position of the radio source (GCN 3761), we measure a formal flux
of 61 +/- 30 microJy on Aug 5 and 72 +/- 43 microJy on Aug 7. However, the
North-South smearing at this declination is such that it is hard to assess
the reality of this 2-sigma detection. A combined map of these two
observations gives a formal flux measurement of 54 +/- 26 microJy."
This message may be cited.
GCN Circular 3810
Subject
GRB 050730: Third Epoch WSRT Radio Observations
Date
2005-08-15T12:10:52Z (20 years ago)
From
Alexander van der Horst at U of Amsterdam <avdhorst@science.uva.nl>
A.J. van der Horst (University of Amsterdam) and E. Rol (University of
Leicester) report on behalf of a larger collaboration:
"We reobserved the position of the GRB 050730 afterglow at 4.9 GHz with
the Westerbork Synthesis Radio Telescope at Aug 13 10.57 UT to 21.88 UT,
i.e. 12.61 - 13.08 days after the burst (GCN 3704).
We do not detect a radio source at the position of the source in GCN 3761.
At the position of the source we measure a formal flux of 22 +/- 38
microJy."