GRB 070611
GCN Circular 6601
Subject
GRB 070611: VLT observations
Date
2007-07-06T09:59:43Z (19 years ago)
From
Pall Jakobsson at U Hertfordshire <P.Jakobsson@herts.ac.uk>
Pall Jakobsson (U. Hertfordshire), Daniele Malesani,
Dong Xu, Johan P.U. Fynbo, Jens Hjorth and Christina
C. Thoene (DARK, NBI) report:
Using FORS1 on the Very Large Telescope during
non-photometric conditions, we obtained a total of
4200 s R-band imaging of the GRB 070611 field
(Stroh et al., GCN 6494) on June 15.375 (4.26 days
after the burst). On the edge of the refined XRT circle
(Butler 2007, AJ, 133, 1027; DSS catalog; version 3.6),
we clearly detect a source that is consistent with the
UVOT position (Landsman et al., GCN 6504).
Compared to the acquisition image obtained on June 11.040
(7.58 hr post-burst; Thoene et al., GCN 6499), the source
has faded by dm = 5.3 +/- 0.3 mag. If the optical afterglow
displays a similar fading behaviour as the X-ray afterglow
with a possible jet-break around 1 day (Stroh et al.,
GCN Report 63.3), we would expect dm = 3.5 +/- 1.4 mag.
Thus, the VLT observations are marginally consistent with a
break occurring in the optical band as well.
We note that the source is somewhat extended at the latter
epoch, implying that the host might contribute to the flux
and hence the observed dm could be larger. An image of the
field (on June 15.375) is shown at:
http://star-www.herts.ac.uk/~palli/grb070611/grb070611.jpg
GCN Circular 6528
Subject
GRB 070611: Watcher Observations
Date
2007-06-13T17:57:50Z (19 years ago)
From
Gary Melady at UCD <gmelady@bermuda.ucd.ie>
Gary Melady, John French, (University College Dublin), Petr Kubanek,
Martin Jelinek (IAA CSIC Granada, Spain)
on behalf of the Watcher collaboration report:
The Watcher 40cm robotic telescope, located at Boyden Observatory, South
Africa, began imaging the field of GRB 070611 (Stroh et al., GCN
6494) at 01:58:33 UT, 1m 17s after the Swift trigger (40s after receipt of
the GCN notice).
We combined our initial series of 10s exposures to create a 440s unfiltered
image with an exposure mid-time of 2:05:21 (501s after the burst). This shows
no new source in the XRT error box (Stroh et al., GCN 6496) down to an R-band
limiting magnitude of approx. 19.2 (in comparison to USNO-B1). Later images show
a faint, uncatalogued source within the XRT error box coincident with the ROTSE
detection (Rykoff et al., GCN 6497).
These observations are summarised below:
mean time UT t-t0(s) exp(s) Rmag
--------------------------------------------------------
02:18:56 1316 900 19.08 +/- 0.24
02:32:48 2148 210 18.53 +/- 0.24
02:37:11 2411 180 19.12 +/- 0.30
02:42:46 2746 240 18.99 +/- 0.26
02:48:54 3144 330 19.19 +/- 0.24
The source is not detected in subsequent observations down to an R-band limiting
magnitude of approx 19.2.
The field was no longer observed after 02:54 due to the system's
incorrect handling of the retracted XRT position.
This message may be cited.
GCN Circular 6504
Subject
GRB 070611: Swift/UVOT Observations
Date
2007-06-11T20:39:22Z (19 years ago)
From
Wayne Landsman at GSFC/SSAI <landsman@milkyway.gsfc.nasa.gov>
W. Landsman (NASA/GSFC), F.E. Marshall (NASA/GSFC) and M.C. Stroh (PSU)
report on behalf of the Swift/UVOT team.
UVOT took a finding chart exposure of 98 seconds of the field of GRB
070611 (Stroh et al., GCN 6494) with the White (160-650 nm) filter
starting 3295 seconds after the BAT trigger. The UVOT finding chart
was delayed due to an Earth limb constraint.
We detect the afterglow candidate reported by Rykoff et al. (GCN 6497),
and measure a position of
RA(J2000) = 00 07 58.01
Dec(J2000) = -29 45 20.0
with an estimated 90% uncertainty of 0.5".
Because of a configuration problem, most subsequent UVOT images do not
include the afterglow position, but there is a 3.5 sigma detection in a
subsequent image taken with the UVW1 (2600 A) filter. Magnitudes
and 3 sigma upper limits are reported below.
Filter T_start(sec) Exposure(sec) Mag
White 3295 98 19.12 � 0.11
UVW1 4632 197 19.51 � 0.31
UVW1 10046 886 >20.72 (3 sigma)
UVM2 4427 197 >19.64 (3 sigma)
UVW2 4019 197 >19.97 (3 sigma)
The lack of detections in the UVM2 (2260 A) and UVW2 (1930 A) filters
are consistent with the redshift of z=2.04 reported by Thoene et al.
(GCN 6499).
No correction has been made for the expected reddening of E(B-V) = 0.012
[GCN OPS NOTE(11jun07): Per author's request, the Subject-line was corrected;
"070610" was changed to "070611".]
GCN Circular 6503
Subject
GRB 070611: Swift-XRT refined analysis
Date
2007-06-11T18:10:42Z (19 years ago)
From
Michael Stroh at PSU/Swift <stroh@astroh.org>
M.C. Stroh, C. Pagani & J. Racusin report on behalf of the Swift XRT team:
We have analysed the first four orbits of XRT data of GRB 070611 (Stroh et
al., GCN Circ. 6494) with total exposure time of 8.9 ks in Photon Counting
mode. The calculated XRT position is RA(J2000) = 1.9927, Dec (J2000) =
-29.7557, corresponding to:
RA(J2000) = 00h 07m 58.3s
Dec(J2000) = -29d 45' 20.4"
with an uncertainty of 4.0 arcsec (radius, 90% containment). This is 6.1
arcsec from the initial XRT position, and 3.4 arcsec from the ROTSE-III
optical candidate reported by Rykoff, et al. (GCN Circ. 6497).
The XRT light curve follows a power-law decay with index 0.83 +/- 0.27
continuing through T+30 ks.
The PC spectrum can be fit with an absorbed power law with photon index of
1.9 +/- 0.5 and column density of (5 +/- 5) E20 cm-2, consistent with the
Galactic absorption column density (1.34E20 cm-2; Dickey & Lockman, 1990).
The absorbed (unabsorbed) 0.3-10.0 keV average flux in the T+3 ks - T+30
ks time interval is 6.056E-13 (6.825E-13) ergs cm-2 s-1.
Assuming that the source continues its decay at the present rate, we
predict an XRT count rate of 4.9E-3 counts/s at T+24 h, which corresponds
to an absorbed (unabsorbed) flux of 2.144E-14 (2.417E-14) ergs cm-2 s-1.
This circular is an official product of the Swift XRT team.
GCN Circular 6502
Subject
GRB 070611, Swift-BAT refined analysis
Date
2007-06-11T16:20:31Z (19 years ago)
From
Ann M. Parsons at NASA/GSFC/Swift <parsons@milkyway.gsfc.nasa.gov>
L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC),
E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU),
M.C. Stroh (PSU), J. Tueller (GSFC), T. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 070611 (trigger #282003)
(Stroh et al., GCN Circ. 6494). The BAT ground-calculated position is
RA, Dec = 2.003, -29.758 deg which is
RA(J2000) = 0h 8m 0.8s
Dec(J2000) = -29d 45' 28"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 50%.
The BAT light curve shows a single, symmetric peak. T90 (15-350 keV)
is 12.0 +- 1 sec (estimated error including systematics). There is a
possible second episode of emission ( at ~4.5 sigma) starting at T+70
and lasting for ~15 sec.
The time-averaged spectrum from T-6.3 to T+7.3 sec is best fit by a
simple power-law model. The power law index of the time-averaged
spectrum is 1.66 +- 0.22. The fluence in the 15-150 keV band is
3.9 +- 0.6 x 10^-07 erg/cm2. The 1-sec peak photon flux measured
from T+2.76 sec in the 15-150 keV band is 0.8 +- 0.2 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.
GCN Circular 6499
Subject
GRB 070611: VLT redshift
Date
2007-06-11T13:34:01Z (19 years ago)
From
Christina Thoene at Niels Bohr Institute,DARK Cosmo Ctr <cthoene@astro.ku.dk>
Christina C. Thoene (DARK), Pall Jakobsson (Univ. of Hertfordshire), Johan
P. U. Fynbo, Daniele Malesani, Jens Hjorth (DARK) and Paul M. Vreeswijk
(ESO) report:
We observed the OT (Rykoff et al., GCN 6497) of GRB 070611 (Stroh et al.,
GCN 6494) with FORS2/VLT using grism 300V through thin clouds. 2x30 min
spectra were acquired starting on June 11, UT 09:37.
In the spectra, we detect Lyman alpha, SiII, OI, CII, CIV and AlII from
which we infer a redshift of z=2.04 for that burst. In addition, we detect Mg II
and Fe II from an intervening system at z=1.29.
We thank the Paranal staff for excellent support, in particular Arjan Bik
and Mario van den Ancker.
GCN Circular 6497
Subject
GRB 070611: ROTSE-III Detection of Late Rising Optical Counterpart
Date
2007-06-11T04:26:49Z (19 years ago)
From
Eli Rykoff at U of Michigan/ROTSE <erykoff@umich.edu>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
E. S. Rykoff, F. Yuan, S. A. Yost (U. Mich), report on behalf of the
ROTSE collaboration:
ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia,
responded to GRB 070611 (Swift trigger 282003; Stroh et al.,
GCN 6494), producing images beginning 7.6 s after the GCN notice time,
as reported in GCN 6495 (Schaefer, et al.). These unfiltered images are
calibrated relative to USNO-B1.0 (R).
Further analysis reveals a faint, late-rising counterpart at a position
consistent with the XRT position reported in GCN 6496 (Stroh, et al.).
At a midpoint of 2157 s after the burst (in a 600 s stacked image), the
counterpart was at a peak magnitude of 18.4+/-0.1 at a position:
00:07:58.0 -29:45:19.4 (J2000) [uncertainty < 1"]
The counterpart then faded below 19th magnitude by 6000 s post-burst.
A jpeg image is available at
http://www.rotse.net/images/gsb282003_3c041-050_key.jpg
Note that the object marked 156 is the candidate in question.
GCN Circular 6496
Subject
GRB 070611; Swift-XRT position
Date
2007-06-11T04:06:42Z (19 years ago)
From
Michael Stroh at PSU/Swift <stroh@astroh.org>
GRB 070611; Swift-XRT position
M.C. Stroh, J. A. Kennea & C. Pagani (PSU) report on behalf of the
Swift-XRT team:
We have analyzed the first 1.8 ks of prompt downlinked data for GRB 070611
(trigger=282003, GCN Circ. 6494). Because of an Earth limb constraint, the
spacecraft did not slew promptly to the BAT position and the XRT
observations started 3.3 ks since the BAT Trigger.
In the BAT error circle we find an uncatalogued source at position
RA, Dec 1.9912, -29.7568 which is
RA(J2000) = 00 07 57.9
Dec(J2000) = -29 45 24.3
with an uncertainty of 5.1 arcsec (radius, 90% containment).
The XRT position is 15arcsec from the BAT on board position (GCN Circ.
6494), within the BAT error circle. We are waiting for additional
downlinked data to assess the fading behavior of the proposed X-ray
afterglow.
This circular is an official product of the Swift-XRT team.
GCN Circular 6495
Subject
GRB 070611: ROTSE-III Optical Limits
Date
2007-06-11T02:31:23Z (19 years ago)
From
Brad Schaefer at LSU <schaefer@grb.phys.lsu.edu>
Bradley E. Schaefer (Louisiana State), S.A. Yost (U Mich), E.S. Rykoff (U
Mich), and F. Yuan (U Mich) report on behalf of the ROTSE collaboration:
ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia,
responded to GRB 070611 (Swift trigger 282003; M. C. Stroh et al. 2007,
GCN 6494), producing images beginning 7.6 s after the GCN notice time. An
automated response took the first image at 01:57:58.6 UT, 44.7 s after the
burst, under excellent conditions. We took 10 5-sec, 10 20-sec and 20
60-sec exposures, with further exposures now ongoing. These unfiltered
images are calibrated relative to USNO A2.0 (R).
Comparison to the DSS (second epoch) reveals no new sources within the
3-sigma Swift/BAT error circle; the field is not crowded. Individual
images have limiting magnitudes ranging from 15.7-17.2; we set the
following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
01:57:58.6 01:58:03.6 5 15.8 44.7 N
01:57:58.6 01:59:16.6 78 17.0 44.7 Y
02:04:20.5 02:15:45.2 684 18.3 426.6 Y
GCN Circular 6494
Subject
GRB 070611: Swift detection of a burst
Date
2007-06-11T02:08:47Z (19 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
M. C. Stroh (PSU), S. D. Barthelmy (GSFC), J. R. Cummings (NASA/UMBC),
N. Gehrels (NASA/GSFC), D. Grupe (PSU),
S. T. Holland (CRESST/GSFC/USRA), J. A. Kennea (PSU),
W. B. Landsman (NASA/GSFC), C. B. Markwardt (GSFC/UMD),
F. E. Marshall (NASA/GSFC), C. Pagani (PSU), D. M. Palmer (LANL),
A. M. Parsons (GSFC), M. Stamatikos (NASA/ORAU) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:
At 01:57:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070611 (trigger=282003).
The BAT on-board calculated location is
RA, Dec 1.987, -29.755 which is
RA(J2000) = 00h 07m 57s
Dec(J2000) = -29d 45' 18"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a single peak
with a duration of about 10 sec. The peak count rate
was ~800 counts/sec (15-350 keV), at ~2 sec after the trigger.
Because of an Earth limb constraint, the spacecraft did not slew promptly
to the BAT position, and so there are no immediate XRT or UVOT data
products to analyze. XRT and UVOT will begin observing this target
at 02:50 UT.