- GCN Circular #10171
J. R. Cummings (GSFC/CRESST),
V. Pal'shin (Ioffe Inst.),
K. Yamaoka (Aoyama Gakuin U.),
P. Evans (U. Leicester)
on behalf of the Swift-BAT, Konus-Wind, and Suzaku-WAM teams
The Suzaku WAM alerted the IPN to a short hard burst that occurred at
17:44:29 UT on November 17th. The burst was seen in detector rates
with Suzaku, Konus-Wind, INTEGRAL SPI ACS, and Swift-BAT. A source
was found in ground analysis of BAT data (trigger 376211) at 12% coding.
The BAT ground position was RA, Dec 30.945, -16.944, which is
RA (J2000) 02h 03m 46.9s
Dec (J2000) -16d 56' 38.0"
with an estimated 90% containment radius of 2.6 arcmin.
As seen in BAT, the burst had a weak precursor at T0, and the main spike
at T+2.7 sec. The precursor was about 0.12 sec and the main spike was
about 0.4 seconds long. The BAT peak count rate was about
700 counts/0.064 sec in the 15-350 keV band.
There is an AGN 2.5 arcmin from this position, 2MASX J02035665-1656585
at z = 0.092.
The BAT position is inside the error box of a triangulation performed
using Konus-Wind, BAT, Suzaku-WAM, and INTEGRAL-SPI-ACS data.
A Swift TOO observation has been requested and approved.
- GCN Circular #10172
V. Casanova (OSN), A.J. Castro-Tirado (IAA-CSIC), A. de Ugarte Postigo
(INAF/OAB), J. Gorosabel (IAA-CSIC), report on behalf of a larger
collaboration:
"We carried out I-band observations of the GRB 091117 error box
(Cummings et al., GCNC 10171) with the 1.5m OSN telescope. The
observations were performed on Nov 18.895-18.958 UT (27.7-29.3 hours
post GRB). Visual comparison with the DSS does not reveal any new
source in the error box brighter than I~20.5."
- GCN Circular #10173
E. Berger (Harvard) reports:
"Inspection of Swift/XRT observations of the short GRB 091117 (GCN
#10171) reveals an X-ray source coincident with an extended object in
DSS images. The DSS object (APMUKS B020129.84-171252.3) is located at
the following coordinates (J2000):
RA = 02:03:53.35
DEC = -16:58:30.6
Optical observations are in progress."
- GCN Circular #10174
E. Berger (Harvard) and J. Mulchaey (OCIW) report:
"We obtained optical r-band observations of the BAT error circle of GRB
091117 (GCN #10171) with IMACS on the Magellan/Baade 6.5-m telescope
starting on 2009 Nov 19.06 UT. A comparison to DSS images reveals no
new sources brighter than the DSS limit of about 21 mag.
The galaxy coincident with the XRT source within the BAT error circle
(GCN #10173) has a face-on spiral morphology. We find a single apparent
point source coincident with one of the spiral arms. This object may be
the optical afterglow of GRB091117 or an unrelated bright HII region.
Additional observations are planned to determine if the source exhibits
fading behavior.
An image of the galaxy is available from:
http://www.cfa.harvard.edu/~eberger/GRB091117_Magellan.gif
- GCN Circular #10175
S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:
The short hard GRB 091117A (localized by Swift-BAT and IPN,
Cummings et al., GCN 10171) triggered Konus-Wind
at T0=63869.513 s UT (17:44:29.513).
The burst light curve consists of a single peak with a total
duration of ~0.3 s. The Konus-Wind light curve of this GRB
is available at http://www.ioffe.ru/LEA/GRBs/GRB091117_T63869/
As observed by Konus-Wind the burst
had a fluence of 1.9(-0.5, +0.7)x10-6 erg/cm2,
and a 16-ms peak flux measured from T0
of 1.4(-0.4. +0.7)x10-5 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).
The time-integrated spectrum of the burst
(from T0 to T0+0.256 s) can be fitted
(in the 20 keV - 5 MeV range) by a power law
with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.42(-0.41, +0.64),
and Ep = 663(-225, +396) keV (chi2 = 29/23 dof).
Fitting by GRB (Band) model yields the same alpha
and Ep values with the high energy photon index
beta = -9.4 (< -1.9).
All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level.
- GCN Circular #10176
R. Chornock and E. Berger (Harvard) report:
We obtained spectra of the DSS galaxy coincident with the XRT source (GCN 10173)
seen in the Swift observations of the short GRB 091117 (GCN 10171) using GMOS on
Gemini-North. A pair of 1800s exposures using the R400 grating were taken
starting at 07:27 UT on Nov. 19. Numerous emission lines are present at
z=0.096. The slit was aligned through both the nucleus and the point source on
the spiral arm (GCN 10174). The off-nuclear point source exhibits the
high-equivalent-width nebular emission lines expected of an H II region and is
therefore unlikely to be related to the afterglow of GRB 091117. In addition,
the nuclear spectrum shows a broad component to the H-alpha line (FWHM ~ 1670
km/sec), indicative of an AGN. The AGN could also be responsible for the
observed X-ray emission.
- GCN Circular #10177
V. D'Elia, G. Stratta, M. Perri (ASDC), P.A. Evans and M.R. Goad (U.
Leicester),
J. Cummings (GSFC/CRESST), S. Campana (INAF-OAB) report on behalf of
the Swift-XRT team:
We have analysed 3.85 ks of XRT data for GRB 091117 (Cummings et al.
et al.
GCN Circ. 10171), from 96765 s to 119.4 ks after the Suzaku trigger. The
data are entirely in Photon Counting (PC) mode. Two sources are detected
at the edge of the BAT error circle.
Source #1:
using 722 s of XRT Photon Counting mode data and 1 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 = 30.97240, -16.97490 deg which is equivalent to:
RA (J2000): 02 03 53.38
Dec (J2000): -16 58 29.8
with an uncertainty of 3.6 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
The source is at a count rate level of (4.8+/-1.4)e-3 counts/s.
The light curve does not allow us to assess if the source is fading.
This source has been reported by Berger et al. (GCN Circ. 10173)
to be coincident with the DSS galaxy APMUKS B020129.84-171252.3
at redshift z=0.096 (Chornock & Berger 2009, GCN Circ. 10176)
We can't distinguish if this is nuclear emission from the AGN
discussed by Berger et al. (GCN Circ. 10176)
Source #2:
the other source has a count rate level of
(2.7+/-1.1)e-3 counts/s and is at RA, Dec= 30.988333, -16.948583 deg
which is equivalent to
RA (J2000): 02 03 57.2
Dec(J2000): -16 56 54.9
with an uncertainty of 7.7 arcsec (radius, 90% confidence).
The light curve does not allow us to assess if the source is fading.
We note that there is a known source (2MASX J02035665-1656585 at
z=0.096220)
located 8.8 arcsec from Source #2.
Further observations are planned for this field.
This circular is an official product of the Swift-XRT team.
- GCN Circular #10178
S. B. Cenko, J. S. Bloom, D. A. Perley (UC Berkeley) report on behalf of a
larger collaboration:
We have imaged the field of GRB091117 (Cummings et al., GCN 10171) with
the Gemini Multi-Object Spectrograph on the 8 m Gemini South telescope
beginning at 7:07 UT on 19 November (~ 37 hours after the burst trigger
time). Observations were conducted in the Sloan g', r', and i' filters
under poor seeing conditions (~ 2" FWHM).
We find no new point sources at the location of either candidate X-ray
afterglow (Berger, GCN 10173; D'Elia et al., GCN 10177). The limiting
magnitude of our images is g' >~ 24 mag for isolated point sources;
however we note that both XRT positions fall close to nearby galaxies and
are contaminated by galaxy light.
The galaxy system near source 2 appears to be highly disturbed, possibly
indicative of recent merger activity.
- GCN Circular #10179
D. B. Fox (Penn State) reports:
"Analysis of the first 3.85 ks of Swift XRT exposure (D'Elia et al.,
GCN 10177) on the field of GRB 091117 (Cummings et al., GCN 10171), as
reduced via standard XRT pipeline processing, yields a total of 13
photons from Source #1 (Berger, GCN 10173) and 7 photons from Source
#2 (D'Elia et al., GCN 10177).
The resulting distribution of photon arrival times for Source #1 is
inconsistent with a constant count rate at roughly 93% confidence,
according to a single-sample KS test, suggesting fading or variable
behavior of this X-ray source. The maximum deviation from a constant
count rate model occurs after 35% of the integrated exposure, when 9
of 13 photons (70% of total counts) have been collected.
The same test applied to the arrival times for Source #2 indicates
consistency with a constant count rate (p-value of 0.90), however, the
sensitivity of the test is more strongly limited by photon statistics
in this case, such that we would not expect fading/variability at the
level suggested in Source #1 to be apparent in Source #2, even if
present."
- GCN Circular #10180
T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC),
G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC),
T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-0.16 to T+10 sec, we report further analysis
of BAT/IPN GRB 091117 (trigger #376211) (Cummings, et al.,
GCN Circ.# 10171). The BAT ground-calculated position is as reported
before, RA, Dec = 30.945, -16.944, which is
RA (J2000) 02h 03m 46.9s
Dec (J2000) -16d 56' 38.0"
with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 12%.
The mask-weighted light curve shows two peaks. The first is a weak spike
at T+0 lasting for 0.15 sec. The second is the main spike at T+2.7
lasting for 0.4 sec. T90 (15-350 keV) is 0.43 +- 0.05 sec (estimated
error including systematics). There is an indication of possible
extended-time soft emission in the mask-weighted image covering ~1 minute
in the 15-50 keV band following the burst (2.6 sigma). There is no
indication of a persistent source in the BAT energy band at this position
at other times.
The time-averaged spectrum from T-2.5 to T+3.2 sec is best fit by a
simple power-law model. The power law index of the time-averaged
spectrum is 0.8 +- 0.3. The fluence in the 15-150 keV band is
3.5 +- 1.2 x 10-7 erg/cm2**. The 1-sec peak photon flux measured from
T+2.3 sec in the 15-150 keV band is 2.5 +- 0.5 ph/cm2/sec. All the
quoted errors are at the 90% confidence level.
Because of the ground-detected nature of this burst, the usual automated
data products are not currently available.
- GCN Circular #10181
V. D'Elia, M. Perri (ASDC), J. Cummings (GSFC/CRESST) report
on behalf of the Swift-XRT team:
We have analysed further 4.0 ks of XRT data for GRB 091117 (Cummings
et al. GCN Circ. 10171), from 161.3 ks to 172.4 ks after the trigger.
The data are entirely in Photon Counting (PC) mode.
We found that Source #1 (Berger, GCN Circ. 10173; D'Elia et al.,
GCN Circ. 10177; Fox, GCN Circ. 10179) is detected with a count rate of
(1.9+/-0.9)e-3 cts/s, thus showing some evidence of fading with respect
to the first Swift follow-up observation (errors are given at the
1-sigma level). We note that the photon statistics is low and further
observations are needed to firmly assess that this source is the X-ray
afterglow of the burst.
Source #2 (D'Elia et al., GCN Circ. 10177; Fox, GCN Circ. 10179) is
instead
not detected. The derived 3-sigma upper limit value on its count rate,
~3.3e-3 cts/s, does not allow to constrain the temporal behavior of this
source.
This circular is an official product of the Swift-XRT team.
- GCN Circular #10182
E. Berger and W. Fong (Harvard) report:
"We imaged the BAT error circle of the short GRB 091117 (GCN #10171)
with the VLA at a frequency of 8.46 GHz starting on 2009 Nov 20.07 UT.
In the 1 hour observation only a single source is detected within the
BAT error circle, in coincidence with the galaxy near XRT Source #2
(GCNs #10177,10178). However, inspection of the NRAO VLA Sky Survey
(NVSS) reveals a coincident archival source, indicating that this is not
the afterglow of GRB 091117. No other sources are detected within the
BAT error circle to a 3-sigma limit of about 120 microJy."
- GCN Circular #10183
E. Berger (Harvard) and I. Momcheva (OCIW) report:
"We obtained a second set of optical r-band observations of the BAT
error circle of GRB 091117 (GCN #10171) with IMACS on the Magellan/Baade
6.5-m telescope starting on 2009 Nov 20.03 UT. A comparison to our
first epoch of Magellan observations (GCN #10174) reveals no variable
sources within the BAT error circle or in coincidence with the two XRT
sources (GCNs #10173,10177,10181) to a limit of r~24 mag. The point
source identified as an HII region (GCN #10176) has not varied in
brightness. Further analysis is in progress."
- GCN Circular #10184
A. Breeveld (MSSL/UCL), M. De Pasquale (MSSL/UCL) and J. R. Cummings=20
(GSFC/UMBC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 091117A=20
96767s (~27 hours) after the BAT trigger (Cummings et al., GCN Circ.=20
10171). The galaxy described by Berger and Mulchaey (GCN Circ. 10174)=20
as being a possible host, is clearly seen as an extended object in the=20
UVOT data. There is no evidence of a fading source at either of the=20
two XRT source positions (D'Elia et al., GCN Circ. 10177) when=20
compared with data taken ~47 hours after the burst. In the case of=20
source 1, which is coincident with the spiral galaxy, we checked for=20
fading using an aperture of 2" at the refined XRT position as well as=20
using an aperture of 8" to contain the whole galaxy.
Magnitudes measured with a non-standard 8" aperture to include the=20
whole galaxy, using the UVOT photometric system (Poole et al. 2008,=20
MNRAS, 383, 627), for the initial summed exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 97197 113850 875 17.56 =B1 0.01
v 109296 109642 340 17.05 =B1 0.06
u 96767 119064 2614 17.60 =B1 0.02
Upper limits (3 sigma) obtained at the position of source 2 (D'Elia et=20
al., GCN Circ. 10181) are as follows:
white 97197 113850 875 21.89 (UL)
v 109296 109642 340 19.72 (UL)
u 96767 119064 2614 21.52 (UL)
None of the values quoted above are corrected for the Galactic extinction
due to the reddening of E(B-V) =3D 0.03 in the direction of the burst
(Schlegel et al. 1998).
- GCN Circular #10185
P. D'Avanzo (INAF-OAB), L.A. Antonelli (INAF-OAR), A. de Ugarte Postigo
(INAF-OAB), A.J. Castro-Tirado (IAA-CSIC), J. Gorosabel (IAA-CSIC), E.
Palazzi (IANF-IASFBo), S. Covino (INAF/OAB), J.M. de Leon Cruz,
(IAA-CSIC), C. Padilla (TNG) report:
We observed the field of GRB 091117 (Cummings et al. GCN 10171) with the
Italian 3.6m TNG telescope, sited in Canary Islands (Spain) with the
DOLORES camera in imaging mode on Nov 19.995 UT. Observations were carried
out in V, R and I band.
We compared our 900 s I-band image with the one obtained in the same band
with the 1.5m OSN telescope on Nov 18.9 UT (Casanova et al., GCN 10172).
Image subtraction performed with the ISIS package does not show any
variable source in the overlap region covered by the two images (about 90%
of the BAT error circle; Sakamoto et al, GCN 10180). In particular we note
that no variability is detected for XRT source #1 (Berger, GCN. 10173;
D'Elia et al., GCN 10177; Fox, GCN 10179) while no conclusion can be drawn
for XRT source #2 (D'Elia et al., GCN 10177; Fox, GCN 10179) because it is
saturated in the TNG image.
An image showing the result of image subtraction is available here:
http://www.brera.inaf.it/utenti/davanzo/grb/GRB091117_subtraction.jpg
The 3sigma limiting magnitudes are I~22.9 and I~23.6 for the OSN and TNG
images respectively.
- GCN Circular #10186
H. Hayashi, N. Ohmori, A. Daikyuji,E. Sonoda, K. Kono,
K. Noda, Y. Nishioka, M. Yamauchi (Univ. of Miyazaki)
T. Sugasahara, M. Tashiro, Y. Terada, A. Endo, K. Onda,
W. Iwakiri (Saitama U.), S. Sugita(Nagoya U.), K. Yamaoka (Aoyama
Gakuin U.),
M. Ohno, M. Suzuki, M. Kokubun, T. Takahashi (ISAS/JAXA),
Y. E. Nakagawa, T. Tamagawa (RIKEN), N. Ohmori, A. Daikyuji,
E. Sonoda, K. Kono, H. Hayashi, K. Noda, Y. Nishioka, M. Yamauchi
(Univ. of Miyazaki), N. Vasquez (Tokyo Tech.), Y. Urata, H.M Lin (NCU),
Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa (Hiroshima U.),
T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), S. Hong
(Nihon U.), on behalf of the Suzaku WAM team, report
The short GRB 091117A (Swift/BAT Detected in ground analysis ; Cummings et al.,
GCN 10171) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 2009-11-17 17:44:25.253 UT (=T0).
The observed light curve shows a single peak starting at T0 s, ending
at T0+1 s with a duration (T90) of about 0.4 seconds.
The fluence in 100 - 1000 keV was 1.54 (-0.26/+0.25) x10^-6 erg/cm^2.
The 1-s peak flux measured from T0 s was 2.78 (-0.30,+0.37) photons/cm^2/s
in the same energy range.
Preliminary result shows that the time-averaged spectrum from T0 s to
T0+1 s is well fitted by a single power-law with a photon index
of 1.29 (-0.13,+0.13) (chi^2/d.o.f. = 42/33).
All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.
The light curves for this burst are available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html
- GCN Circular #10232
D. B. Fox (Penn State) and E. Berger (Harvard) report:
"We observed the Swift/BAT localization region for GRB 091117
(Cummings et al., GCN 10171; Sakamoto et al., GCN 10180) with the
Chandra X-ray Observatory + ACIS, positioned at the ACIS-S3 aimpoint,
in a 20.1 ksec integration with mean epoch Nov 21.85 UT, 4.1 days
after the burst trigger.
Analysis of these data reveals the presence of nine X-ray sources
within and near the BAT localization region, including the two X-ray
sources identified in previous Swift XRT observations (Berger, GCN
10173; D'Elia et al., GCN 10177). Comparison to deep optical imaging
of the region from Magellan (Berger & Mulchaey, GCN 10174; Berger &
Momcheva, GCN 10183) reveals point-like (nuclear, stellar, or
unresolved galactic) optical counterparts to all but three of these
sources:
# CXOU J Sigma Cts Unc Comments
==========================================================
1 020353.36-165830.0 54.0 119 11 XRT-1; Nuclear
2 020356.65-165659.1 44.5 101 10 XRT-2; Nuclear
3 020353.68-165428.1 14.7 34.9 6.5 Stellar
4 020338.35-165547.3 8.7 23.0 5.0 Stellar
5 020347.45-165927.6 6.2 13.4 3.7 (not imaged)
6 020342.46-165706.7 4.8 9.7 3.2 Stellar
7 020345.74-165817.1 4.2 8.7 3.0 Near galaxy
8 020345.21-165818.2 3.8 7.7 2.8 Stellar
9 020349.61-165430.5 3.7 7.6 2.8 No counterpart
==========================================================
The table above provides source names/coordinates (J2000) as
determined from the Chandra astrometric solution, the significance of
detection in "wavdetect" analysis over the 0.3-8.0 keV bandpass, and
estimated counts and uncertainties (0.3-8.0 keV) for each source. The
nature of the optical counterpart, if any, is also provided.
We note that the two brightest X-ray sources, also observed by Swift,
are coincident to within <1 arcsec with the active nuclei of the two
brightest galaxies in the region: Chandra source #1 (XRT-1) with the
active nucleus of the face-on spiral galaxy at z=0.096 (Chornock &
Berger, GCN 10176), and Chandra source #2 (XRT-2) with the active
nucleus of 2MASX J02035665-1656585 at z=0.092. Source #1 appears
(2.8-sigma confidence) to have faded since the first epoch of Swift
observations, consistent with inferences from Swift XRT data (Fox, GCN
10179); however, the coincidence of sources #1 and #2 with AGN
suggests that neither of these objects is associated with GRB 091117.
Chandra source #7 is notable for being located 2.4 arcsec from the
center of an edge-on galaxy that is resolved in our Magellan imaging."
- GCN Circular #10292
V. D'Elia, G. Stratta, M. Perri (ASDC), J. Cummings (GSFC/CRESST) report
on behalf of the Swift-XRT team:
Swift-XRT has observed the field of GRB 091117 about one month after
the burst
(Cummings et al. GCN Circ. 10171). The data set consists of two
further
observations, 9.7 ks and 9.2 ks, from 32.8 to 34.2 days after the
trigger.
The data are entirely in Photon Counting (PC) mode.
We found that Source #1 (Berger, GCN Circ. 10173; D'Elia et al.,
GCN Circ. 10177; Fox, GCN Circ. 10179, D'Elia et al., GCN Circ 10181)
is still detected with a count rate of (2.95+/-0.70)e-3 cts/s (first
observation) and (3.42+/-0.75)e-3 cts/s (second observation),
thus showing no evidence of fading with respect to the first Swift
follow-up observations. Thus evidence of possible fading of Source #1,
reported in Fox (GCN Circ. 10179), D'Elia et al. (GCN Circ.10181) and
Fox & Berger (GCN Circ. 10232), is not confirmed by these measurements.
Source #2 (D'Elia et al., GCN Circ. 10177; Fox, GCN Circ. 10179,
D'Elia et al.,
GCN Circ 10181) is also detected, and the derived count rate is
(2.03+/-0.55)e-3 cts/s (first observation) and (1.85+/-0.54)e-3 cts/s
(second observation). No evidence of a fading behavior is found for
this
source either.
All quoted errors are given at the 1-sigma level.
In view of these XRT observations, we can safely conclude that neither
source is the X-ray afterglow of GRB091117.
This circular is an official product of the Swift-XRT team.
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