GRB 090107B
GCN Circular 8786
Subject
GRB 090107B: a long GRB localized by INTEGRAL
Date
2009-01-07T17:05:19Z (16 years ago)
From
Diego Gotz at CEA <diego.gotz@cea.fr>
D. Gotz (CEA-Saclay), S.Mereghetti, A.Paizis (IASF-Milano), C. Ferrigno,
V.Beckmann, M. Beck (ISDC, Versoix), and J. Borkowski (CAMK, Torun) on
behalf of the IBAS Localization Team report:
A GRB lasting about 20 s has been detected by IBAS in IBIS/ISGRI data at
16:20:36 UT on January 7th. The refined coordinates (J2000) are:
RA = 284.8075 [degrees]
DEC= 59.5924 [degrees]
with an uncertainty of 1.5 arcmin (90% c.l.).
A preliminary analysis gives a peak flux in the 20-200 keV range of
about 1.6 ph/cmsq/s (1-s integration time) and a fluence over the
same energy
range of about 1.5e-6 erg/cmsq. Both values have to be considered
lower limits,
since the burst is affected by telemetry saturation.
A plot of the light curve will be posted at
http://ibas.iasf-milano.inaf.it/IBAS_Results.html
This message can be cited.
GCN Circular 8787
Subject
GRB 090107B: ROTSE-III Optical Limits
Date
2009-01-07T17:48:17Z (16 years ago)
From
Tolga Guver at UA <tolga@physics.arizona.edu>
GRB 090107B: ROTSE-III Optical Limits
T. Guver (U Arizona), H. Swan (U Mich), report on behalf of the ROTSE
collaboration:
ROTSE-IIId, located at the TUBITAK National Observatory at
Bakirlitepe, Turkey, responded to GRB 090107B (INTEGRAL trigger 5398;
D. Gotz, GCN 8786), producing images beginning 0.0 s after the GCN
notice time. An automated response took the first image at 16:20:40.7
UT, 4.7 s after the burst, and during the gamma-ray emission, under
fair conditions. We took 10 5-sec, 10 20-sec and 63 60-sec exposures.
These unfiltered images are calibrated relative to USNO A2.0 (R).
Imaging is on going.
Comparison to the DSS (second epoch) reveals no new sources within the
3-sigma INTEGRAL/IBIS error circle, for both single images and
coadding into sets of 10. Individual images have limiting magnitudes
ranging from 16.2-16.6; we set the following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
16:26:35.8 16:26:55.8 20 16.6 359.8 N
16:28:03.0 16:32:41.6 278 17.7 447.0 Y
GCN Circular 8788
Subject
GRB 090107B optical observations
Date
2009-01-07T17:53:05Z (16 years ago)
From
Arne A. Henden at AAVSO <arne@aavso.org>
Arto Oksanen (Hankasalmi Obs., Hankasalmi, Finland) reports via the
AAVSO High Energy Network the following optical observations of the
INTEGRAL burst GRB 090107B (Gotz et al., GCN Circular #8786):
Unfiltered observations were made using a 0.4-meter RC telescope
with an SBIG STL-1001E CCD. The full INTEGRAL error box was
observed unfiltered starting at 16:35UT, 15 minutes after the
burst. Combining ten 60-second exposures, we do not see any
optical afterglow to a limiting magnitude of 20.5 (compared
with the DSS2 red plate).
A FITS image of this observation is available at the following URL:
ftp://ftp.aavso.org/grb/ArtoOksanen_GRB090107_2454839.23238_.fits
The AAVSO thanks the Curry Foundation for their continued support of the
AAVSO International High Energy Network.
GCN Circular 8789
Subject
GRB 090107B: Swift-XRT detection of possible afterglow
Date
2009-01-07T21:09:39Z (16 years ago)
From
Matteo Perri at ISAC/ASDC <perri@asdc.asi.it>
M. Perri (ASDC) and P. Evans (U. Leicester) report on behalf of the
Swift-XRT team:
Swift began observing the field of the INTEGRAL GRB 090107B (Gotz et
al., GCN Circ. 8786) 4.2 ks after the trigger. A single uncatalogued
source was identified within the IBIS/ISGRI error circle.
Using 1314 s of XRT Photon Counting mode data and 2 UVOT images, we find
an astrometrically corrected X-ray position (using the XRT-UVOT alignment
and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec =
284.81750, 59.59510 which is equivalent to:
RA (J2000): 18 59 16.21
Dec (J2000): +59 35 42.3
with an uncertainty of 1.8 arcsec (radius, 90% confidence). The source
lies 21 arcsec from the IBIS/ISGRI centroid and has a count rate of
~0.25 counts/s during this observation.
Currently we cannot determine if this source is fading, and therefore
cannot confirm if this source is associated with GRB 090107B.
Observations of this source are on-going.
This circular is an official product of the Swift-XRT team.
GCN Circular 8790
Subject
GRB 090107B: Swift/UVOT Observations
Date
2009-01-07T21:41:56Z (16 years ago)
From
Frank Marshall at GSFC <marshall@milkyway.gsfc.nasa.gov>
F.E. Marshall (NASA/GSFC)
reports on behalf of the Swift/UVOT team:
The Swift/UVOT observed the field of GRB 090107B starting 4396 s after
the INTEGRAL trigger (Gotz et al., GCN Circ. 8786). No optical afterglow
is detected in the initial UVOT exposures at the position
of the candidate X-ray afterglow (Perri et al., GCN Circ. 8789).
There is also no obvious optical afterglow candidate
elsewhere in the INTEGRAL error circle.
The 3-sigma upper limits in the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627) for detecting
a source at the position of the XRT candidate are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 5420 5535 113 >20.9
v 4396 4595 197 >19.6
b 5216 5415 197 >20.3
u 5010 5209 197 >20.1
uvw1 4806 5005 197 >20.3
uvm2 4600 4799 197 >20.3
uvw2 4191 4390 197 >20.6
The values quoted above are not corrected for the Galactic extinction due
to the reddening of E(B-V) = 0.046 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 8791
Subject
GRB 090107B: Swift XRT afterglow confirmation
Date
2009-01-09T16:08:56Z (16 years ago)
From
Matteo Perri at ISAC/ASDC <perri@asdc.asi.it>
G. Stratta (ASDC), M. Perri (ASDC) and J. R. Cummings (GSFC/UMBC)
report on behalf of the Swift-XRT team:
The Swift ToO observations of GRB 090107B started on 2009 Jan 7th
at 17:30:50 UT. XRT data set consists of 5.7 ks exposure in PC mode.
The single, uncatalogued X-ray source observed in the field
of INTEGRAL, previously reported by Perri et al. (GCN Circ. 8789),
shows fading flux, confirming its afterglow nature.
The 0.3-10 keV light curve from T + 4.2 ks to T + 96.4 ks
possibly indicates evidence for a plateau phase
followed by a steeper decay, but the available data prevented
us from constraining the parameters (i.e. the temporal break and
the two decay indexes). Assuming a simple power law model,
the best fit decay index is alpha = 1.3 +/- 0.1.
The average spectrum accumulated in the same time interval
was fitted with an absorbed power law. The best fit photon
index is 1.8 +/- 0.4. The spectrum shows evidence of absorption
at the level of (9 +/- 1)e20 cm-2, in excess of the
estimated Galactic value (5e20 cm-2, Kalberla et al. 2005).
The average observed[unabsorbed] 0.3-10 keV average flux is
about 2.8[3.6]e-12 ergs cm-2 s-1.
The predicted count rate 48 hours after the trigger is 0.002 cts/s
The count-rate-to-flux conversion factor is 5.2e-11 ergs cm-2 cts-1
All quoted errors are at 90% confidence level.
Burst Advocate for this burst is J. R. Cummings.
This circular is an official product of the Swift-XRT team.
GCN Circular 8793
Subject
GRB090107B: Fermi GBM Detection
Date
2009-01-09T23:33:40Z (16 years ago)
From
Adam Goldstein at Fermi-GBM/UAH <adam.m.goldstein@msfc.nasa.gov>
A. Goldstein (UAH), R. Preece (UAH), and A.J. van der Horst (NASA/ORAU)
report on behalf of the Fermi GBM Team:
"At 16:20:42.77 UT on 07 January 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090107B (trigger 25303844 / 090107681).
This burst was also detected by the INTEGRAL IBAS
(D. Gotz et al. 2009, GCN 8786)
The GBM on-ground location is consistent with the INTEGRAL position.
The GBM light curve consists of two main emission peaks and apparent
substructure with a duration (T90) of about 24.1 s (8-1000 keV).
The time-averaged spectrum from T0-4.1 s to T0+20.5 s is
best fit by a power law function with an exponential
high energy cutoff. The power law index is -0.68 +/- 0.26 and
the cutoff energy, parameterized as Epeak, is 106.1 +/- 14.8 keV
(chi squared 530.4 for 486 d.o.f.).
The event fluence (8-1000 keV) in this time interval is
(1.75 +/- 0.37)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+6.1 s in the 8-1000 keV band
is 3.68 +/- 0.27 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 8794
Subject
GRB 090107B: Suzaku WAM observation of the prompt emission
Date
2009-01-10T14:30:59Z (16 years ago)
From
Yujin E. Nakagawa at RIKEN <yujin@crab.riken.jp>
Y. E. Nakagawa, T. Tamagawa (RIKEN), H. Hayashi, E. Sonoda, M. Yamauchi,
H. Tanaka, R. Hara, N. Ohmori, K. Kono (Univ. of Miyazaki), A. Endo,
M. Tashiro, Y. Terada, Y. Urata, K. Onda, N. Kodaka, K. Morigami,
T. Sugasahara, W. Iwakiri (Saitama U.), T. Enoto, K. Nakazawa,
K. Makishima (Univ. of Tokyo), S. Sugita, K. Yamaoka (Aoyama Gakuin U.),
M. Ohno, M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), Y. Hanabata,
T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira (Hiroshima U.),
S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report:
The long GRB 090107B (Gotz et al., GCN 8786) was detected by the
Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range
of 50 keV - 5 MeV at 2009-01-07 16:20:35 UT (=T0).
The observed light curve shows a double-peaked structure lasting from
T0-1 s to T0+20 s with a duration (T90) of about 14 seconds. The fluence
in 100 - 1000 keV was 1.3 (+0.7, -0.9) * 10^-6 erg/cm^2. The 1-s peak
flux measured from T0+13 s was 0.4 +/- 0.3 photons/cm^2/s in the same
energy range.
Preliminary result shows that the time-averaged spectrum from T0-1 s
to T0+20 s is well fitted by a single power-law with a photon index
of 2.0 +/- 0.4 (chi^2/d.o.f = 6/10).
All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.
The light curves with 1-sec time resolution for this burst will be appeared at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/untrig/grb_table.html