GRB 060729
GCN Circular 5365
Subject
GRB 060729: Swift detection of a burst with an UVOT optical counterpart
Date
2006-07-29T19:53:56Z (19 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
D. Grupe (PSU), L. M. Barbier (NASA/GSFC), S. D. Barthelmy (GSFC),
D. N. Burrows (PSU), M. M. Chester (PSU),
C. Guidorzi (Univ Bicocca&INAF-OAB), J. A. Kennea (PSU),
C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), J. L. Racusin (PSU)
and M. Stamatikos (NASA/ORAU) report on behalf of the Swift Team:
At 19:12:29 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 060729 (trigger=221755). Swift slewed immediately to the burst.
The BAT on-board calculated location is RA,Dec 95.338, -62.345
{06h 21m 21s, -62d 20' 41"} (J2000) with an uncertainty of 3 arcmin
(radius, 90% containment, including systematic uncertainty).
The BAT light curve shows a small peak at T_zero of ~5 sec duration
and a possible much larger peak starting at ~T+70 until ~T+120.
The peak count rate was ~2000 counts/sec (15-350 keV),
at ~T+90 sec after the trigger.
The XRT began observing the field at 19:14:33 UT, 124 seconds after the
BAT trigger. XRT found a bright, fading, uncatalogued X-ray source
located at RA(J2000) = 06h 21m 31.3s, Dec(J2000) = -62d 22' 13.4", with an
estimated uncertainty of 4.7 arcseconds (90% confidence radius).
This location is 116 arcseconds from the BAT on-board position, within
the BAT error circle. The initial flux in the 0.1s image was
7.7e-08 erg/cm2/s (0.2-10 keV).
UVOT began observing in the White filter at 19:14:43.95 UT, 134.7 sec
after the BAT trigger. An uncataloged source is detected at RA, DEC =
95.3827, -62.3702, 3.2 arcsecs from ground-determined XRT position,
which brightens from 19.2 to 17.8 in the second White image. The
magnitudes have not been corrected for galactic absorption in this
direction, E(B-V) = 0.054.
We are currently in the Malindi gap so we will not have the full data set
for this burst for another 7 hours.
GCN Circular 5366
Subject
GRB 060729: ROTSE-III Detection of Optical Counterpart
Date
2006-07-29T20:49:33Z (19 years ago)
From
Robert Quimby at U of Texas/ROTSE <quimby@astro.as.utexas.edu>
R. Quimby (U Texas), H. Swan (U Mich), W. Rujopakarn (U Mich), and
D.A. Smith (Guilford), report on behalf of the ROTSE collaboration:
ROTSE-IIIa, located at the Siding Spring Observatory, Australia,
responded to Swift trigger 221755 (GRB 060729; Grupe et al. GCN
5365). The first image was taken at 19:13:33.5 UT, 64.3 s after the
burst (8.5 s after the GCN notice time). We detect a source coincident
with the UVOT position (GCN 5365). In a 5-second image beginning at
19:14:02.1 and coincident with the second, larger peak in the BAT
light curve, the object is approximately 15.5 magnitude (unfiltered;
calibrated against the USNO A2.0), while a co-addition of our first 10
5-second images shows the object at approximately 16.6 magnitude.
Images taken over the next 30 minutes do not show significant
evolution, and have a mean magnitude of 16.5.
GCN Circular 5367
Subject
GRB 060729: Swift/UVOT Observations
Date
2006-07-29T23:33:34Z (19 years ago)
From
Stefan Immler at NASA/GSFC <immler@milkyway.gsfc.nasa.gov>
S. Immler (NASA/USRA/GSFC) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began observing the field of GRB 060729 at
19:14:45 UT on 2006-07-29, 135 s after the BAT trigger (Grupe et al.,
GCN 5365). An optical counterpart was detected in the White
(160-650 nm) and V filters at a position of RA, Dec = 06:21:31.85,
-62:22:12.7 (J2000), located within the XRT error circle.
A White filter image taken 12 min later showed that the source
brightened by about 1 magnitude, while the source stayed constant
in images obtained in the V filter within the same period.
The photometry results are given for the UVOT filters below:
Filter T_start(s) Exposure(s) Mag
White 135 100 17.75
White 860 100 16.65
V 241 396 17.30
V 966 400 17.35
Statistical and systematic errors are 0.1 mag each.
The values quoted above are not corrected for the expected
Galactic extinction of E_{B-V}=0.054 (Schlegel et al. 1998).
More UVOT data are expected after the next Malindi contact
(2006-07-30 01:27 UT).
GCN Circular 5368
Subject
GRB 060729 : Planned XMM-Newton observation
Date
2006-07-30T00:11:09Z (19 years ago)
From
Norbert Schartel at XMM-Newton/ESA <too@xmm.vilspa.esa.es>
XMM-Newton will observe GRB 060729 at location
(RA=06h 21m 30.7s, DEC=-62d 22' 15.6", J2000),
starting at 07:41 UT, on July 30, 2006,
for an exposure of 62600 seconds.
GCN Circular 5369
Subject
GRB 060729: Swift-XRT refined analysis
Date
2006-07-30T05:21:51Z (19 years ago)
From
Dirk Grupe at PSU/Swift-XRT <grupe@astro.psu.edu>
GRB 060729: Swift-XRT refined analysis
D. Grupe (PSU) reports on behalf of the Swift/XRT team
We have analyzed the first 5 orbits with a total observing time of 10.9 ks
of Swift XRT data (2.3 ks in Windowed Timing and 8.6 in photon counting
mode)
of GRB 060729 (Grupe et al., GCN 5365). The Photon Counting mode image
provides a refined XRT position:
RA(J2000) = 06h 21m 31.29s,
Dec(J2000) = -62d 22' 13.4"
with an error of 3.5" (90% confidence). This position is 3.2"
away from the preliminary XRT position reported in GCN 5365.
The X-ray light curve displays the end of a giant flare (at the
beginning of the
XRT observation this flare had a count rate of 1000 counts/s) followed by a
second flare at 174s after the burst. The afterglow shows a long
late-time flare
between 1 ks to 10 ks after the burst. We do not see a break in the
light curve
yet that allows us to give a reliable prediction of the flux for the
next 24h.
Right now the count rate is at a level of 0.3 counts s**-1 or a flux of
about
1.5e-11 ergs s**-1 cm**-2.
Spectral fits to the Windowed Timing mode data during the flare phase
suggest a significant absorption column density in excess of the
Galactic value
(4.82e20 cm**-2). The later photon counting mode data after the flares
can be fitted by a single power law model with a photon index Gamma =
2.14+0.15-0.14 and an absorption column density NH=1.0+/-0.3 e21 cm**-2.
We also want to point out that this burst is also an optically bright burst
(Immler 2006, GCN 5267). Even
though it is only 2h away from the sun in RA, it is circumpolar for most
southern observatories. We would like to encourage all southern observers to
obtain a spectrum of this burst in order to determine its redshift.
This circular is an official product of the Swift XRT Team.
GCN Circular 5370
Subject
GRB 060729: Refined analysis of the Swift-BAT burst
Date
2006-07-30T05:37:16Z (19 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
A. Parsons (GSFC), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/ORAU), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Grupe (PSU), D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA),
M. Koss (GSFC/UMD), C. Markwardt (GSFC/UMD), D. Palmer (LANL),
T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC)
on behalf of the Swift-BAT team:
Using the data set from T-240 to T+742 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 060729 (trigger #221755)
(Grupe, et al., GCN Circ. 5365). The BAT ground-calculated position
is RA,Dec = 95.288, -62.221 deg {6h 21m 9.1s, -62d 13' 16.3"} (J2000)
+- 4.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 18%.
The mask-weighted lightcurve 4 main peaks. The first starts at T-2 sec and
ends at T+10 with a peak at T+2 sec. The second, somewhat smaller peak goes
from T+20 to T+26 sec. Then come two overlapping peaks that start at T+70 sec
and end at roughly T+135 sec with peaks at T+80 and T+93 sec.
There is no significant indication of any emission at the time of the flare
listed in Grupe et al., GCN Circ 5369 (T+174 sec). T90 (15-350 keV) is
116 +- 10 sec (estimated error including systematics).
The time-averaged spectrum from T+1 to T+132 is best fit by
a simple power-law model. The power law index of the time-averaged
spectrum is 1.86 +- 0.14. The fluence in the 15-150 keV band is
2.7 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured
from T+91.97 sec in the 15-150 keV band is 1.4 +- 0.2 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.
GCN Circular 5371
Subject
GRB 060729: Swift/UVOT Detections
Date
2006-07-30T06:29:16Z (19 years ago)
From
Stefan Immler at NASA/GSFC <immler@milkyway.gsfc.nasa.gov>
S. Immler (NASA/USRA/GSFC) reports on behalf of the Swift/UVOT team:
Analysis of the merged Swift/UVOT data of GRB 060729 (GCN 5365, 5366,
5367, 5369) obtained on 2006-07-29 shows that the optical afterglow
was detected in the White, V, B, U, UVW1, UVM2, and UVW2 filters.
The detection in all of the UVOT bands suggests that the redshift is
less than
approx. 1.1. The photometry results are given for the 7 UVOT filters below:
Filter T_start(s) Exposure(s) Mag
White 135 726 17.2
V 115 1,846 17.4
B 711 461 18.3
U 686 491 17.3
UVW1 663 491 17.4
UVM2 640 306 17.7
UVW2 730 1,088 18.0
Statistical and systematic errors are 0.1 mag each.
The values quoted above are not corrected for the expected
Galactic extinction of E_{B-V}=0.054 (Schlegel et al. 1998).
GCN Circular 5373
Subject
GRB 060729 redshift
Date
2006-07-30T17:06:56Z (19 years ago)
From
Christina Thoene at Niels Bohr Institute,DARK Cosmo Ctr <cthoene@astro.ku.dk>
Christina C. Thoene (DARK Cosmology Centre), Andrew Levan, Pall Jakobsson
(Univ. of Hertfordshire), Evert Rol (Univ. of Leicester), Javier Gorosabel
(IAA-CSIC Granada) Johan P.U. Fynbo, Brian L. Jensen, Jens Hjorth (DARK)
and Paul Vreeswijk (ESO) report:
Starting at 08:41 UT, we obtained 3x30min spectra of the OT of GRB 060729
(GCN 5365) using FORS2 at the VLT and grism 300V. Spectra were also taken
at the Gemini south observatory and GMOS beginning at 09:37UT (3x400s
using the B600 grating). At the time of the GMOS observations, the
afterglow had a magnitude of i~18 using instrumental zeropoints.
The absorption lines identified as Mg II + I, Ca H&K and Fe II give a
redshift of z=0.54 for the GRB. We don't detect any [O II] 3728 in
emission, indicating that the host is relatively faint.
The faintness of the host and the relatively low redshift makes this a
suitable target for follow-up supernova search.
We thank the staff at VLT and Gemini for performing the observations,
especially Arjan Bik and Marcel Bergmann.
GCN Circular 5377
Subject
GRB060729: ROTSE-III Observations of the Slow Optical Decay
Date
2006-08-01T03:57:17Z (19 years ago)
From
Robert Quimby at U of Texas/ROTSE <quimby@astro.as.utexas.edu>
R. Quimby (U Texas) and E. S. Rykoff (U Mich), report on behalf of the
ROTSE collaboration:
ROTSE-IIIa, located at the Siding Spring Observatory, Australia, responded
to Swift trigger 221755 (GRB 060729; Grupe et al., GCN 5365) with an
automatic sequence of 10 5-second, 10 20-second, and 34 60-second
integrations before twilight set in (Quimby et al., GCN 5366). Another 30
60-second images were taken on July 30, and 60 further 60-second frames
were recorded on July 31.
No optical source was detected in our first image, but seconds later we
clearly detect a 15.7 magnitude transient object at the location of the
UVOT source (GCN 5365; Immler, GCN 5367). The object faded over the next
100 seconds, and then brightened to about 16.5 magnitude around 400
seconds after the BAT trigger. After this, the optical transient slowly
began to fade, approximately following a t^-0.23 power-law at least until
the July 30 observations. On July 31, the optical transient was about 19.4
magnitude, significantly fainter than an extrapolation of the simple
power-law would predict. The 2.9 magnitude drop from t~400-seconds marks
one of the slowest 2 day average decline rates ever recorded by ROTSE-III.
We set the following representative detections and limits:
tstart tend exp mag emag
-----------------------------------------------
64.26 69.26 5 >16.60
92.86 97.86 5 15.67 0.10
187.06 219.96 15 >17.28
448.57 604.68 120 16.56 0.05
2269.84 2830.05 480 16.93 0.05
72997.24 75133.01 1800 18.00 0.18
171304.69 175581.44 3600 19.39 0.18
(times are seconds after the BAT trigger; magnitudes are unfiltered and
calibrated against the USNO-B1.0 R2)
GCN Circular 5432
Subject
GRB 060729: An update on the Swift XRT and UVOT observations
Date
2006-08-09T19:48:25Z (19 years ago)
From
Dirk Grupe at PSU/Swift-XRT <grupe@astro.psu.edu>
D. Grupe (PSU) reports on behalf of the Swift team
We report on an update of the Swift XRT and UVOT observations of
GRB 050729 (Grupe et al., GCN 5365). The afterglow still
appears to be bright in both narrow-field instruments,
XRT and UVOT.
In the XRT,
after the initial steep decay during a giant flare the light
curve of the after glow became flat at about 1000s
after the burst with a decay slope
0.34+/-0.04. The light curve shows a second break
at about 40 ks after the burst and is decaying now with a
power law decay slope 1.21+/-0.08.
Currently (2006 August 09) the XRT count rate is
at a level of 0.01 counts s-1
(which converts to about 4e-13 ergs s-1 cm-2).
In the UVOT the afterglow is not detected any more in V and
barely detectable in B and U. However, it is still clearly
detectable in the three UV filters and
by the end of 2006 August 08 (UT) we measure the following
magnitudes (not corrected for reddening):
V > 20.4 (3.0 sigma upper limit)
B = 22.1+/-0.7 (2.6 sigma)
U = 22.3+/-1.1 (1.1 sigma)
UVW1 = 21.36+/-0.36 (3.6 sigma)
UVM2 = 21.53+/-0.27 (4.0 sigma)
UVW2 = 22.15+/-0.33 (3.4 sigma)
The afterglow is decaying and from the flux light curves we
measured power law decay slopes of 1.0 in V, 0.8 in B,
1.2 in U, 1.3 in UVW1, 1.3 in UVM2, and 1.4 in UVW2.
We continue observing the afterglow with Swift and encourage all
ground-based observers with access to southern hemisphere
telescopes to follow this afterglow at optical wavelengths in
order to monitor the possible appearance of a supernova.
This circular is an official product of the Swift Team.
GCN Circular 5465
Subject
GRB 060729, SMARTS optical/IR observations
Date
2006-08-18T15:15:20Z (19 years ago)
From
Bethany Cobb at Yale U <cobb@astro.yale.edu>
B. E. Cobb and C. D. Bailyn, 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 060729
(Grupe et al. GCN 5365) with the following mid-exposure times:
obs1 2006-08-03 10:07 UT - 4.6 days post-burst
obs2 2006-08-12 10:11 UT - 13.6 days post-burst
obs3 2006-08-14 09:26 UT - 15.6 days post-burst
obs4 2006-08-16 09:27 UT - 17.6 days post-burst
For each observation, total summed exposure times amounted to
36 minutes in I and 30 minutes in J.
The afterglow of GRB 060729 is clearly visible in the I-band in
our first observation (obs1), despite 4.6 days having past since the
GRB occurred. The preliminary afterglow magnitude is I = 20.0 +/- 0.1.
The I-band photometry is calibrated to a number of secondary stars in the
field of GRB 060729. The magnitude of these secondary stars was
derived using Landolt standard star observations obtained
during the night of obs4, which was a photometric night at CTIO.
The afterglow is only marginally detected in the corresponding
J-band image, which has an approximate limiting magnitude of J > 19
(calibrated based on several 2MASS stars in the field).
No source appears at the position of the afterglow in the individual
observations taken 13.6 to 17.6 days post-burst (obs2 - obs4).
When these three images are combined, however, a faint source is
detected in the I-band, with magnitude I = 21.9 +/- 0.2
(no source is detected in the combined J-band image to a limiting
magnitude of J > 19.5). A decay of ~2 magnitudes between day ~5
and day ~16 is consistent with an afterglow decay rate
of alpha ~ -1.5, but steeper than the late-time optical
decay noted by Grupe (GCN 5432). If the host galaxy contributes
significantly, the afterglow decay must be steeper still.
GCN Circular 5469
Subject
GRB060729: analysis of XMM-Newton observation
Date
2006-08-21T17:48:27Z (19 years ago)
From
Sergio Campana at INAF-OAB <sergio.campana@brera.inaf.it>
Sergio Campana (OAB) & Andrea De Luca (IASF Mi)
on behalf of a larger collaboration report:
We have analyzed the data from the XMM-Newton observation of
GRB060729, discovered by Swift on 2006, Jul 29, 19:12:29 UT
(Grupe et al., GCN5365).
The XMM-Newton observation started on 2006, July 30 07:59 UT
and lasted for ~61 ks. A high particle background level affects
only mildly the whole observation and only the highest flares
have been cut out, in consideration also of the source strength.
The background subtracted pn light curve (0.3-10 keV) shows a
clear decay from about 5 c/s at the beginning of the observation
down to 2 c/s. The light curve can be fit with a power law decay
with index delta=1.04+/-0.02 but with a large chi2=1.8 (58 dof).
This is due to a large bump in the middle of the exposure. Adding
a Gaussian we obtain a better chi2=0.7 (55 dof). The central time
is 69+/-1 ks (90% confidence) from the burst start and the
(Gaussian) width over the time is about 7+/-2%. We note also that
the time of the XMM-Newton observation is close to the break time
observed by Swift XRT in the GRB060729 light curve (Grupe, GCN5432).
Fitting a broken power law to we obtain a first decay index
delta1=0.85+/-0.05, which is inconsistent with the early slope of
0.34 reported by Grupe.
We extracted time-averaged spectra from the EPIC pn camera (since
in the initial part of the MOS observation the GRB spectrum should
be mildly piled-up) and the two RGS spectrometers (first and second
order) and we generated ad-hoc response files.
A simultaneous fit with an absorbed power law model with Galactic
and intrinsic (at a redshift of z=0.54, Thoene et al. GCN5373)
yields a reduced chi2 of 1.05 (1824 dof, without any systematic
error). The resulting NH=(3.9+/-0.9)x1020 cm-2 (consistent with
the Galactic value of NH=4.8x1020 cm-2, Dickey & Lockman 1990)
and a relatively low NH_host=(9.2+/-0.4)x1020 cm-2. The best
fitting power law photon index is Gamma=2.09+/-0.01.
The RGS spectrometers do now show any clear evidence of absorption
or emission lines in the 0.3-2 keV energy range.
The observed flux is of 9.5x10-12 erg cm-2 s-1 in 0.3-10 keV;
the corresponding unabsorbed flux is of 1.2x10-11 erg cm-2 s-1.
This message may be cited.
GCN Circular 5652
Subject
GRB 060729: An update on the late-time Swift observations
Date
2006-09-29T12:56:18Z (19 years ago)
From
Dirk Grupe at PSU/Swift-XRT <grupe@astro.psu.edu>
D. Grupe (PSU) and Caryl Gronwall (PSU) report on behalf of the Swift team
We report on an update of the Swift XRT and UVOT observations
of GRB 060729 (Grupe et al., GCN 5365). The afterglow is still
detectable in X-rays at a level of 1e-3 counts/s in the Swift
XRT (5e-14 ergs/s/cm2). The late-time decay slope is 1.29+/-0.03.
Assuming this decay slope continues, we expect the afterglow to
be still detectable in the XRT until the end of December 2006.
We plan to follow the afterglow as long as possible.
Currently we are at day 61 after the burst, which is the
longest period Swift has ever followed and detected an
afterglow in X-rays.
In the UVOT the afterglow was still visible in all 6 filters
until 9 days after the burst. In UV W1 the afterglow was
detectable until 2006-August-29 (31 days after the burst).
we still obtain a 3.9 sigma detection at a level of 22.8+/-0.3
mag. We calculated the following late-time flux decay slopes in
the 6 UVOT filters:
V: 1.11+/-0.14
B: 0.98+/-0.07
U: 1.40+/-0.08
UVW1: 1.29+/-0.03
UVM2: 1.45+/-0.07
UVW2: 1.38+/-0.04
These values are slightly different than what has been reported
earlier by Grupe (2006, GCN Circ. 5432). However, our new
light curves contain more data than what was available earlier.
Assuming the power law decay continues without a break in the
optical, our extrapolation of the light curves show that the
afterglow will be visible at the beginning of October with
V=24.0 mag, B=23.4 mag, U=24.0 mag. At this level a detection
of the afterglow is still feasible for a large southern telescope.
We, therefore, encourage everybody again who has access to one
of the large southern telescopes to follow this afterglow in V,
B, and U in order to search for a break in the light curves.
This circular is an official product of the Swift XRT Team.