GRB 070518
GCN Circular 6415
Subject
GRB 070518: Swift detection of a burst with optical afterglow
Date
2007-05-18T14:50:19Z (18 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
C. Guidorzi (Univ Bicocca&INAF-OAB), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
S. Campana (INAF-OAB), M. M. Chester (PSU),
G. Cusumano (INAF-IASFPA), P. A. Evans (U Leicester),
N. Gehrels (NASA/GSFC), C. Gronwall (PSU),
S. T. Holland (CRESST/GSFC/USRA), J. A. Kennea (PSU),
H. A. Krimm (GSFC/USRA), F. E. Marshall (NASA/GSFC),
A. Moretti (INAF-OAB), P. T. O'Brien (U Leicester),
D. M. Palmer (LANL), J. L. Racusin (PSU),
P. Romano (Univ. Bicocca & INAF-OAB), T. Sakamoto (NASA/ORAU),
G. Sato (GSFC/ISAS), B. Sbarufatti (INAF-IASFPA),
M. Stamatikos (NASA/ORAU), R. L. C. Starling (U Leicester),
E. Troja (INAF-IASFPA), D. E. Vanden Berk (PSU) and
S. D. Vergani (DIAS-DCU) report on behalf of the Swift Team:
At 14:26:21 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070518 (trigger=279592). Swift slewed immediately to the
burst. The BAT on-board calculated location is RA, Dec 254.223, +55.297 which
is
RA(J2000) = 16h 56m 54s
Dec(J2000) = +55d 17'47"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a single
(FRED-like) peak with a duration of about 7 sec. The peak count rate
was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 14:27:31 UT, 70 seconds after the
BAT trigger. XRT found a variable, uncatalogued X-ray source
located at RA, Dec 254.1979, +55.2974 which is
RA(J2000) = 16h 56m 47.5s
Dec(J2000) = 55d 17' 42.5"
with an uncertainty of 4.7 arcseconds (radius, 90% containment).
This location is 52 arcseconds from the BAT on-board position,
within the BAT error circle. The initial flux in the 2.5s image
was 5.8e-10 erg/cm2/s (0.2-10 keV).
UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 82 seconds after the BAT trigger. We
see a fading afterglow located at RA, Dec 254.1986, 55.2951 which is
RA(J2000) = 16h 56m 47.7s
Dec(J2000) = 55d 17' 42.3"
with an uncertainty of 1 arcsecond (radius, 90% containment)
with an estimated magnitude of 18. No correction
has been made for the expected extinction corresponding to E(B-V) of
0.02.
GCN Circular 6416
Subject
GRB 070518: OT confirmed form Xinglong TNT observation
Date
2007-05-18T16:06:03Z (18 years ago)
From
L.P. Xin at NAOC <xlp@bao.ac.cn>
L.P. Xin, M.Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng,
Y. Urata, and W.K. Zheng on behalf of EAFON report:
We have imaged the field of GRB 070518 (C. Guidorzi et al., GCN 6415)
with the TNT 0.8m and EST 1m telescope at Xinglong Observatory started
from 14:34:53 UT, 512s after the burst. Observation were performed with
White, R, V and I filter, we estimate the OT has faded to ~ R=19.84 derieved
form USNO A-2.0, 32.73 minutes after the burst
Observation is still undergoing, deep observation are encouraged.
This message may be cited.
GCN Circular 6417
Subject
GRB 070518, Swift-BAT refined analysis
Date
2007-05-18T21:36:24Z (18 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
H. Krimm (GSFC/USRA), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
C. Guidorzi (Univ Bicocca&INAF-OAB), C. Markwardt (GSFC/UMD),
D. Palmer (LANL), A. Parsons (GSFC), 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-119 to T+183 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 070518 (trigger #279592)
(Guidorzi, et al., GCN Circ. 6415). The BAT ground-calculated position is
RA, Dec = 254.221, 55.285 deg which is
RA(J2000) = 16h 56m 52.9s
Dec(J2000) = 55d 17' 5.6"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 84%.
The mask-weighted lightcurves shows a single peak starting a ~T-5 sec
and ending at ~T+10 sec. T90 (15-350 keV) is 5.5 +- 0.2 sec
(estimated error including systematics).
The time-averaged spectrum from T-1.8 to T+4.5 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.11 +- 0.25. The fluence in the 15-150 keV band is 1.6 +- 0.2 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.12 sec in the 15-150 keV band
is 0.7 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
GCN Circular 6418
Subject
GRB070518: OSN observation
Date
2007-05-19T01:04:27Z (18 years ago)
From
Martin Jelinek at Inst.Astrophys.Andalucia,Granada <mates@iaa.es>
Martin Jelinek, Alberto J. Castro-Tirado, Victor Casanova,
Javier Gorosabel, Antonio de Ugarte Postigo, Stanislav Vitek,
Ronan Cunniffe and Petr Kubanek (IAA CSIC Granada, Spain)
report
We observed the optical afterglow of GRB070518 (Guidorzi et
al, GCN6415) with a 1.5m telescope at Observatorio Sierra
Nevada using R and I-band filters. The afterglow is found to
have R~22.2, relatively to the nearby USNO-A2.0 (R_usno=18.7)
on a 60-minute combined image with exposure mean time 23:04UT
(i.e. 8.6h after the GRB).
This message may be cited
GCN Circular 6419
Subject
GRB070518: UVOT refined analysis
Date
2007-05-19T03:18:58Z (18 years ago)
From
Antonino Cucchiara at PSU <cucchiara@astro.psu.edu>
Cucchiara A. (PSU), Marshall F. E. (NASA/GSFC) and Guidorzi C.
(Univ. Bicocca&INAF-OAB) reports on behalf of the Swift/UVOT team:
The Swift/UVOT observed the field of GRB070518 starting
82 sec after the trigger (Guidorzi et al., GCN Circ. 6415).
The afterglow was clearly detected in all the 7 filters.
This suggest a redshift lower than 0.7.
The estimated magnitude for the V and White filters are:
Filter T_start(sec) Exposure(sec) Mag
White 82 93 18.16 +/- 0.06
White 873 94 19.14 +/- 0.09
White 5517 191 20.08 +/- 0.14
White 6951 191 21.33 +/- 0.20
V 187 391 19.31 +/- 0.13
V 978 391 20.08 +/- 0.24
V 5927 363 21.05 +/- 0.48
Assuming a single power-low, the decay index is ~1.17 in V band.
The extrapolated V mag at T+10h is 22.59.
The values quoted above are not corrected for the expected Galactic
extinction of E_{B-V} = 0.017 mag (Schlegel et al. 1998).
GCN Circular 6421
Subject
GRB 070518: Swift-XRT refined analysis
Date
2007-05-19T07:50:58Z (18 years ago)
From
Cristiano Guidorzi at INAF-OAB <cristiano.guidorzi@brera.inaf.it>
C. Guidorzi, P. Romano (Univ Bicocca&INAF-OAB), A. Moretti (INAF-OAB),
S.D. Vergani (DIAS-DCU) report on behalf of the Swift team:
We have analysed the first two orbits of GRB 070518 (Guidorzi
et al., GCN Circ. 6415) with total observing times of 186 s in
Windowed Timing mode and 4.2 ks in Photon Counting mode in the Swift XRT.
The Photon Counting mode image provides a refined XRT
position at RA,DEC(J200) = 254.19800, +55.29444 which is
RA(J2000) = 16h 56m 47.52s
Dec(J2000) = +55d 17' 40.0"
with an uncertainty of 3.9 arcsec (radius, 90% containment).
This is 2.5 arcsec from the initial X-ray position,
2.8 arcsec from the UVOT position (GCN Circ. 6415)
and 57 arcsec from the BAT refined position (Krimm et al., GCN Circ. 6417).
The XRT light curve exhibits an initial flaring behaviour up to
~T+200 s, after which a steep decay (4.7 � 0.4) follows after the
last flare, with a break at T+460 (+/- 40) s to a shallower
decay (1.11 � 0.13) up to T+11ks.
We extracted two spectra from the WT data during the flaring
activity, due to a strong spectral evolution.
The first spectrum, from 77 s to 158 s, can be fit with an
absorbed power law with a photon index of 2.3+/-0.1 and
column density of (9.6+/-1.6)E20 cm^-2 significantly in excess
of the Galactic value (2.2E20 cm^-2; Dickey & Lockman, 1990).
The second spectrum, from 165 to 253 s, has a photon index
of 2.9+/-0.1 and same column density as that of the first spectrum.
The absorbed (unabsorbed) 0.3-10.0keV flux for the first spectrum
is 5.1E-10 (7.2E-10) ergs cm^-2 s^-1.
Assuming the source continues to decay at the same rate, we predict
an XRT count rate of 6.3E-4 counts/s at T+24 hours, which corresponds
to an observed (unabsorbed) flux of 2.0E-14 (2.8E-14) ergs cm^-2 s^-1.
This circular is an official product of the Swift XRT team.
GCN Circular 6422
Subject
VLA observation of GRB 070518
Date
2007-05-19T14:12:01Z (18 years ago)
From
Poonam Chandra at U Virginia/NRAO <pc8s@virginia.edu>
Poonam Chandra (NRAO/UVA) and Dale A. Frail (NRAO) report on
behalf of the Caltech-NRAO-Carnegie GRB Collaboration:
"We used the Very Large Array to observe the field of view toward
GRB 070518 (GCN 6415) at a frequency of 8.46 GHz on 2007 May 19th
at 7.41 UT, around 17 hours after the burst. The radio afterglow
of the GRB is undetected at the SWIFT-XRT position (GCN 6421). The
2-sigma uppler limit on the GRB flux density is 64 uJy.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
GCN Circular 6426
Subject
GRB 070518: TNG observations
Date
2007-05-20T21:23:06Z (18 years ago)
From
Stefano Covino at Brera Astronomical Observatory <stefano.covino@gmail.com>
S. Covino, G. Tagliaferri, G. Chincarini (INAF/OABr), L.A. Antonelli,
G.L. Israel (INAF/Rome), G. Andreuzzi, A. Garcia de Gurtubai Escudero
(INAF/TNG) on behalf of the CIBO collaboration, report:
We observed the field of GRB070518 (GCN 6415, Guidorzi et al.) with
the Italian Telescopio Nazionale Galileo (TNG) equipped with Dolores
in the R band at about 10 and 35 hours from the burst. We clearly
detected the optical afterglow (GCN 6415, Guidorzi et al.; GCN 6418,
Jelinek et al.; GCN 6419, Cucchiara et al.).
At about 35 hours from the burst the afterglow magnitude was R ~
23.3. The decay index between the two epochs was about 0.5,
significantly shallower than what reported at earlier times by
Cucchiara et al. (GCN 6419). At about 2.5 arcsec NE of the afterglow
we also detect a fainter source with no evidence of extended emission.
Further observations are in progress.
This message may be cited.
GCN Circular 6443
Subject
GRB070518: Optical/NIR observation
Date
2007-05-21T23:40:21Z (18 years ago)
From
Paul Price at IfA,UH <price@ifa.hawaii.edu>
P.A. Price (IfA, Hawaii) and T. Minezaki (IoA, Tokyo) report on behalf
of a larger collaboration:
We observed the optical afterglow of GRB070518 with the MAGNUM telescope
+ MIPS dual-beam camera. Observations commenced 10.6 minutes after the
trigger, with a mid-point time of 2007 May 18.614 UTC. Based on
calibration using a single USNO star (optical image; as for GCN #6418)
and single 2MASS star (NIR image), we find:
R ~ 19.5 mag
J ~ 18.8 mag
This message may be cited.
GCN Circular 6458
Subject
GRB 070518: optical observation
Date
2007-05-23T15:53:05Z (18 years ago)
From
Giuseppe Greco at U Bologna <giuseppe.greco2@studio.unibo.it>
F. Terra (Second University of Roma "Tor Vergata"), G. Greco, C. Bartolini,
A. Guarnieri, A. Piccioni (Bologna University), G. Pizzichini (INAF/IASF
Bologna), D. Nanni (INAF/OAR and Second University of Rome "Tor Vergata"),
S. Karpov (Special Astrophysical Observatory, Russia),
S. Galetti and R. Gualandi (Bologna Observatory) report:
During the night of 07/05/18 we observed the OT of GRB070518
(Guidorzi et al., GCN 6415) with the 1.52 cm telescope
of the Bologna Observatory in Loiano under moderate
sky conditions (seeing ~ 2").
The OT flux was slightly blended with a nearby star (R ~ 18.7).
To correct for the blending we employed difference image analysis techniques.
By adding two consecutive 30 min exposures in the Rc filter at
mean time 23.5 UT we find Rc = 22.3 +/- 0.2 based on the USNO-A2.0 catalog.
Our coadded image have been posted in our public directory
from where they can be retrieved by sftp using
hostname: ermione.bo.astro.it
username: publicGRB
password: GRB_bo.
GCN Circular 6461
Subject
GRB 070518: MARGE Observations
Date
2007-05-25T21:03:22Z (18 years ago)
From
Heather Swan at U.of Michigan/ROTSE <hflewell@umich.edu>
H. Swan (U Mich), I. Smith (Rice), C. Akerlof (U Mich), and M. Skinner
(Boeing) report on behalf of the MARGE collaboration:
The AEOS Burst Camera (ABC) on the AEOS telescope, located at the Maui
Space Surveillance System on Haleakala, observed the fading counterpart
to GRB070518 (Swift trigger 279592(GCN 6415)). The images are
unfiltered 10s exposures which started at 14:55:49 UT (~29 minutes after
the trigger) and ended at 15:04:00 UT.
After coadding our images in sets of 5, we detect the OT first
identified by C. Guidorzi et al (GCN 6415). A preliminary analysis gives
a magnitude of approximately 20.0 +/-0.1 at a mid time of 14:56:32 UT.
We calibrated the OT to the USNO-A2.0 R band magnitude of the nearby
18.7 mag star located at (J2000) RA = 16:56:47.4373, DEC =
+55:17:45.610. Our observations are consistent with the other optical
observations. Using our data, and the optical data from P. A. Price and
T. Minezaki (GCN 6443), L. P. Xin et al. (GCN 6416), M. Jelinek et al.
(GCN 6418), F. Terra et al. (GCN 6458), and S. Covino et al. (GCN 6426),
we find that the OT has a power-law decay index of 0.74.
GCN Circular 6462
Subject
GRB 070518, deep LBT photometry
Date
2007-05-25T21:45:51Z (18 years ago)
From
Peter Garnavich at U of Notre Dame <pgarnavi@nd.edu>
P. Garnavich (Notre Dame), N. Bouche, P. Buschkamp (MPE),
O. Kuhn (LBTO/UAz), X. Fan, (U Ariz), X. Dai, J. Prieto,
K. Z. Stanek (Ohio State), J. Hill (LBTO/UAz), J. Bechtold,
J. Kern (U Ariz), R. M. Wagner (LBTO/OSU), J. Rhoads (Ariz State)
report:
The Large Binocular Telescope (LBT) imaged the position of the GRB 070518
afterglow (Guidorzi et al, GCN 6415; Xin et al. GCN 6416) with the
LBC-blue CCD camera (http//lbc.mporzio.astro.it) and 8.4-m SX mirror on
three epochs beginning 2007 May 19.32 (UT) (17.2 hours after the burst).
A fading source is clearly detected at the position of the afterglow
at all three epochs. Assuming the USNO-B.1 star at 16:56:47.39
+55:17:45.8 (J2000) has an R2=19.12 mag, we estimate the total brightness
of the source (shown in the table below) using a 1.3" radius aperture.
UT Date Age (hr) Exposures Seeing R2 mag Error
-----------------------------------------------------------
May 19.32 17.2 5x200s 0.75" 23.03 0.05
May 20.31 41.0 5x200s 1.0" 23.36 0.05
May 22.21 86.4 15x200s 1.1" 23.56 0.05
The slow fading implies significant contribution from a host
galaxy, and in good seeing the source appears elongated to the
southwest.
Combining observations from Price et al. (GCN 6443), Covino et al.
(GCN 6426) and Jelinek et al. (GCN 6418, corrected to USNO-B.1 catalog)
with the LBT estimates shows that a single power-law decline with index
0.95+/-0.05 added to a host galaxy of R=23.8+/-0.1 mag fits all the
observations spanning 10 minutes to 100 hours after the burst.
The May 19 LBT image can be found at:
http://www.nd.edu/~pgarnavi/grb070518/grb070518_LBT.jpg
The LBT is an international collaboration among institutions in the
United States, Italy and Germany. The LBT Corporation partners are:
* The University of Arizona on behalf of the Arizona university system
* Istituto Nazionale di Astrofisica, Italy
* LBT Beteiligungsgesellschaft, Germany, representing the Max Planck
Society, the Astrophysical Institute Potsdam, and Heidelberg University
* The Ohio State University
* The Research Corporation, on behalf of The University of Notre Dame,
University of Minnesota and University of Virginia
This message may be cited
GCN Circular 6483
Subject
GRB070518: optical observation
Date
2007-06-02T16:32:24Z (18 years ago)
From
Vasilij Rumjantsev at CrAO <rum@crao.crimea.ua>
V. Rumyantsev (CrAO), V. Biryukov (CrAO, SAI MSU), A. Pozanenko (IKI)
on behalf of larger GRB follow up collaboration report:
We observed error box of GRB070518 with 1-m Zeiss (Simeiz) telescopes
of CrAO in R-band on May 18 between (UT)19:35 and 20:30. Due to
blending of the nearby star (USNO-A2.0 R=3D18.7) and poor seeing (~4.5")
we do not resolve clearly optical transient (Guidorzi et al., GCN
6415) in a combined image. More sophisticated photometry estimation is
underway. A limiting magnitude of the combined image is based on USNO
A2.0:
Mid time (UT), Exposure, R_Lim (3sigma), Seeing
May 18.835 50x60 22.0 4.5"
This message may be cited.
[GCN OPS NOTE(02jun07): The binary attachment was removed as well as the
diagnostics from MIMEDefang reacting to that binary.]