GRB 091117
GCN Circular 10292
Subject
GRB 091117: Swift-XRT late time observations
Date
2009-12-23T16:17:58Z (16 years ago)
From
Valerio D'Elia at INAF-OAR <delia@mporzio.astro.it>
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.
GCN Circular 10232
Subject
GRB 091117: Chandra Observations
Date
2009-12-02T19:36:40Z (16 years ago)
From
Derek Fox at PSU <dfox@astro.psu.edu>
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 10185
Subject
GRB 091117: TNG optical observations
Date
2009-11-21T01:24:23Z (16 years ago)
From
Paolo D'Avanzo at INAF-OAB <paolo.davanzo@brera.inaf.it>
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 10183
Subject
GRB 091117: 2nd epoch of Magellan optical observations
Date
2009-11-20T06:00:05Z (16 years ago)
From
Edo Berger at Harvard <eberger@cfa.harvard.edu>
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 10182
Subject
GRB 091117: VLA radio observations
Date
2009-11-20T04:08:09Z (16 years ago)
From
Edo Berger at Harvard <eberger@cfa.harvard.edu>
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 10181
Subject
GRB 091117: Swift-XRT observations
Date
2009-11-19T23:47:45Z (16 years ago)
From
Matteo Perri at ISAC/ASDC <perri@asdc.asi.it>
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 10180
Subject
GRB 091117 BAT refined analysis
Date
2009-11-19T19:18:16Z (16 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <james.r.cummings@nasa.gov>
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 10179
Subject
GRB 091117: Evidence for Variability of XRT Source #1
Date
2009-11-19T16:49:49Z (16 years ago)
From
Derek Fox at PSU <dfox@astro.psu.edu>
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 10178
Subject
GRB091117: Gemini South Observations
Date
2009-11-19T16:17:09Z (16 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
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 10177
Subject
GRB 091117: Swift XRT refined analysis
Date
2009-11-19T15:58:16Z (16 years ago)
From
Valerio D'Elia at INAF-OAR <delia@mporzio.astro.it>
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 10176
Subject
GRB 091117: Gemini-North spectroscopy of DSS galaxy
Date
2009-11-19T11:01:41Z (16 years ago)
From
Ryan Chornock at UC Berkeley <chornock@astro.berkeley.edu>
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 10174
Subject
GRB 091117: Magellan optical observations
Date
2009-11-19T06:06:15Z (16 years ago)
From
Edo Berger at Harvard <eberger@cfa.harvard.edu>
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 10173
Subject
GRB 091117: XRT source coincident with a DSS galaxy
Date
2009-11-19T04:56:34Z (16 years ago)
From
Edo Berger at Harvard <eberger@cfa.harvard.edu>
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 10172
Subject
GRB 091117: OSN I-band observations
Date
2009-11-18T23:37:29Z (16 years ago)
From
Javier Gorosabel at IAA-CSIC <jgu@iaa.es>
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."