GRB 060904A
GCN Circular 5512
Subject
GRB 060904A: P60 Observations
Date
2006-09-04T07:40:17Z (19 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. B. Cenko and A. Rau (Caltech) report on behalf of a larger
collaboration:
We have imaged the error circle of GRB 060904a (Grupe et al; GCN 5502)
with the automated Palomar 60-inch telescope. Observations began at
4:57 UT 4 September (3.9 hours after the burst) and consisted of 12 x 180
s images in the Kron R and Sloan i' and z' filters. We find no sources
inside the XRT error circle, to a limiting magnitude of R > 22.0
(estimated by comparison with several USNO-B objects in the field).
GCN Circular 5514
Subject
GRB 060904A: Suzaku-XIS and -HXD observation plan
Date
2006-09-04T10:33:57Z (19 years ago)
From
Makoto Tashiro at Saitama U/Swift <tashiro@phy.saitama-u.ac.jp>
Kazuhisa Mitsuda on behalf of Suzaku team
We have just started to observe GRB 060904A (GCN 5502: D. Grupe et al.)
at location (RA, Dec)={15h 50m 58s, +44d 57' 57"} (J2000)
with the Suzaku narrow field instruments (the XIS and HXD).
The observation has started at 10:30 UT, on 4 September (UT),
and continue until 05:04 of 5 September, 2006 (UT).
We encourage further follow-up observations with other wavelengths.
GCN Circular 5515
Subject
GRB 060904A: Swift-XRT refined analysis
Date
2006-09-04T10:50:28Z (19 years ago)
From
Dirk Grupe at PSU/Swift-XRT <grupe@astro.psu.edu>
D. Grupe (PSU) reports on behalf of the Swift/XRT team
We have analyzed the first orbit with a total observing time
of 2.06 ks of Swift XRT data of GRB 060904A (Grupe et al., GCN 5502).
The X-ray light curve displays the end of a giant flare with a
flattening of the light curve at 200s after the burst. The initial
decay slope is 3.8+/-0.2 followed by 1.3+/-0.2.
Spectral fits to the Windowed Timing mode data during the flare phase
suggest a significant absorption column density in excess of the
Galactic value (1.41e20 cm**-2). The spectrum can be fitted by a
single power law with a photon index Gamma=1.93+/-0.04 and an
absorption column density NH=1.7+/-0.1e21.
Due to the detection of GRB 060904B (Grupe et al., GCN 5505) about
about 1.5 hours after the trigger of GRB 060904A, only one orbit has
been observed on GRB 060904A and the data were only taken in Windowed
Timing mode. Therefore no photon counting mode data exist currently
and no improved position can be given yet.
This circular is an official product of the Swift XRT Team.
GCN Circular 5516
Subject
GRB 060904A: Refined analysis of the Swift-BAT burst
Date
2006-09-04T12:33:22Z (19 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/UMD), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Grupe (PSU), D. Hullinger (BYU-Idaho), 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-110 to T+843 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 060904 (trigger #227996)
(Grupe, et al., GCN Circ. 5502). The BAT ground-calculated position
is (RA,Dec) = 237.730, 44.984 deg {15h 50m 55.3s, 44d 59' 3.7"} (J2000)
+- 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 94%.
The mask-weighted lightcurve shows the emission starting at a very low level
at ~T-70 sec, then increasing slightly at ~T-7 sec for the trigger with several
small peaks until the main peak. The main emission peak starts at T+45,
peaking at T+56, and ending at ~T+125 sec. T90 (15-350 keV) is 80 +- 2 sec
(estimated error including systematics). Note that the spacecraft slewed
to the field of view containing the burst approximately 110 seconds
before the trigger, so there is no BAT data before this time.
The time-averaged spectrum from T-23.9 to T+108.7 is best fit by
a simple power-law model. The power law index of the time-averaged spectrum
is 1.52 +- 0.04. The fluence in the 15-150 keV band is 7.9 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+55.34 sec in the 15-150 keV
band is 4.9 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90%
confidence level.
GCN Circular 5518
Subject
Konus-Wind observation of GRB 060904A
Date
2006-09-04T13:36:59Z (19 years ago)
From
Valentin Pal'shin at Ioffe Inst <val@mail.ioffe.ru>
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and
T. Cline on behalf of the Konus-Wind team report:
The most intense part of the long GRB 060904A
(Swift-BAT trigger #227996; Grupe et al., GCN 5502;
Krimm et al., GCN 5516)
triggered Konus-Wind at T0=3853.821 s UT (01:04:13.821).
As observed by Konus-Wind the burst emission
started at T-T0 ~-56 s, peaked at T-T0 ~0 s,
and ended at T-T0 ~26 s, so the total burst duration
is ~80 s.
The burst fluence is 1.59(-0.21, +0.40)x10^-5 erg/cm2,
and the 256-ms peak flux measured from T0-0.128 s
1.38(-0.33, +0.46)x10^-6 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).
The spectrum of the main pulse
(from T0 to T0+16.64 s)
is well fitted (in the 20 keV - 2 MeV range)
by GRBM (Band) model for which:
the low-energy photon index is alpha = -1.00(-0.17, +0.23),
the high energy photon index beta = -2.57(-1.00, 0.37),
the break energy E0 = 163 (-54, +65) keV (chi2 = 40/61 dof).
The peak energy Ep = 163 +/- 31 keV.
All the quoted errors are at the 90% confidence level.
GCN Circular 5521
Subject
GRB 060904A: pseudo-z from spectral parameters of the prompt emission
Date
2006-09-04T16:07:09Z (19 years ago)
From
Alexandre Pelangeon at LATT,OMP,Toulouse <apelange@ast.obs-mip.fr>
A. Pelangeon & J-L. Atteia (LATT-OMP) report:
We have used the spectral parameters of GRB 060904A
provided by Golenetskii et al. (GCNC 5518) to
compute the spectral pseudo-redshift** of this burst
detected by SWIFT-BAT (trigger #227996:
Grupe et al., GCNC 5502; Krimm et al., GCN 5516).
We find a pseudo-redshift pz= 1.84 � 0.85
We thank V. Pal'shin for providing the fluence of this GRB
during the main pulse (from T0 to T0+16.64 s, KONUS time).
** cf. http://www.ast.obs-mip.fr/grb/pz
GCN Circular 5522
Subject
GRB 060904A: Subaru NIR observation
Date
2006-09-04T16:14:48Z (19 years ago)
From
Nobuyuki Kawai at Tokyo Tech <nkawai@hp.phys.titech.ac.jp>
K. Aoki, I. Tanaka (Subaru Telescope, NAOJ) and N. Kawai (Tokyo Tech)
report on behalf of the Subaru GRB team:
"We began observing the field of GRB 060904A (Grupe et al., GCN 5502)
with MOIRCS on the 8.2m Subaru Telescope at ~6 UT (5 hours after the
burst).
In the stacked image of the 18 x 120 sec exposure (mid time UT 6:24)
in Ks band, we detected an object with 20.2 mag in the XRT error
circle, though the object may be extended. In the the J band image
of 21 x 120 sec exposure (mid time UT 7:13), we did not detect an
object brighter than 21.0 mag in the XRT error circle. The magnitudes
were estimated based on the 2 MASS objects in the field."
GCN Circular 5523
Subject
GRB060904A: Swift/UVOT optical observations
Date
2006-09-04T19:26:56Z (19 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S.R. Oates (UCL-MSSL), D. Grupe (PSU) report on behalf of the
Swift/UVOT team:
The Swift/UVOT began observing the field of GRB 060904A at
01:04:36 on 2006-09-04, 75 s after the BAT trigger (Grupe
et al., GCN 5502). No new source was detected within the XRT error
circle
in coadded images in any filter down to the following 3-sigma
magnitude upper limits:
Filter Tstart Tstop Exposure 3-sigma UL
-------------------------------------------------
V 55 1888 1680 20.11
B 658 1984 97 19.85
U 634 1959 117 19.49
UVW1 610 1936 117 19.91
UVM2 586 1911 117 19.95
UVW2 687 2014 128 20.55
White 75 1997 352.2 21.69
------------------------------------------------
These upper limits are not corrected for Galactic extinction
E(B-V) = 0.018.
GCN Circular 5527
Subject
GRB 060904A Milagro GeV/TeV Observations
Date
2006-09-05T17:57:46Z (19 years ago)
From
Pablo Saz Parkinson at UCSC/Milagro <pablo@scipp.ucsc.edu>
Pablo Saz Parkinson (UC Santa Cruz) on behalf of the Milagro
collaboration reports:
We have searched Milagro data for emission at GeV/TeV energies from the
bright GRB 060904A detected by Swift (GCN Circ 5502, D. Rupe et al.),
during the main period of emission lasting 80s (GCN Circ 5516, H. Krimm et
al.). No evidence for prompt GeV/TeV emission was found. A preliminary
analysis, assuming a differential photon spectral index of -2.4, gives an
upper limit on E^2dN/dE at 99% confidence of:
E^2dN/dE at 2 TeV < 2.9 * 10^(-7) erg cm^(-2) (No EBL absorption)
TeV photons are attenuated by pair production with infrared photons in
intergalactic space. We calculate an upper limit assuming a
redshift of 0.5 using the extragalactic infrared background light (EBL)
absorption model of Primack et al. 2005 (AIP Conf. Proc. 745, p. 23).
We find 99% confidence level upper limits on E^2dN/dE of:
E^2dN/dE at 200 GeV < 5.5 * 10^(-5) erg cm^(-2) (Primack et al. EBL model)
The energies quoted represent the approximate median energy of the
events that would be detected assuming a power law spectrum with
differential index -2.4 convolved with the absorption model.
These upper limits are preliminary and will be refined with further
analysis.
GCN Circular 5543
Subject
GRB 060904A: Suzaku/WAM observation of the prompt emission
Date
2006-09-08T04:47:19Z (19 years ago)
From
Makoto Tashiro at Saitama U/Swift <tashiro@phy.saitama-u.ac.jp>
M. Tashiro, K. Abe, K. Onda, Y. Sato, M. Suzuki, Y. Urata (Saitama U.),
M. Ohno, T. Takahashi, T. Asano, T. Uehara, Y. Fukazawa (Hiroshima U.),
K. Yamaoka, S. Sugita (Aoyama Gakuin U.), T. Enoto, R. Miyawaki,
K. Kokubun, K. Makishima (Univ. of Tokyo), K. Nakazawa, T. Takahashi
(ISAS/JAXA), M. Suzuki, Y. Terada, T. Tamagawa (RIKEN),
S. Hong (Nihon U.), on behalf of the Suzaku WAM team report:
The bright, long burst, GRB 060904A (Swift-BAT trigger #227996;
D. Grupe et al., GCN 5502; Krimm et al., GCN 5516), triggered
the Suzaku Wideband All-sky Monitor (WAM) which covers an energy
range of 50 keV - 5 MeV at 01:04:09.040 (UT).
The three little peaks and following large peak (GCN 5502) are
clearly seen in the light curve observed with the WAM.
The T90 duration was ~79 seconds.
The fluence in 100 - 1000 keV was 8.66(-4.19 +0.39)x10-6 erg/cm2,
while the 1-s peak flux was 2.07(-1.12 +0.09) photons/cm2/s in the
same energy range.
Preliminary result shows that the time-averaged spectrum is
well described with a single power-law model with the energy index
of 1.16 (-0.18 0.20).
All the quoted errors are at statistical 90% confidence level,
in which systematic errors are not included.
GCN Circular 5547
Subject
GRB 060904A : Optical limit
Date
2006-09-08T11:53:10Z (19 years ago)
From
Yuji Urata at Saitama U <urata@crystal.heal.phy.saitama-u.ac.jp>
H. Mito, T. Soyano, (Tokyo Univ.) and Y. Urata (Saitama Univ.)
on behalf of EAFON report:
"We have observed the position of X-ray afterglow using Kiso 1.05m
Schmited telescope. The observation was started at 10:20 UT September
4, 2006. The combined image from 20 frames taken with 300 sec exposure
shows no optical afterglow associated with the X-ray afterglow
position brighter than 22.4 (R) mag.
-------------------------------------------
Start time Exposure Limit(SN=3)
10:20 300 sec x 20 frame > 22.4
-------------------------------------------
This message may be cited."