GRB 060923C
GCN Circular 5591
Subject
GRB 060923C: Swift detection of a burst
Date
2006-09-23T13:48:45Z (19 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
M. Stamatikos (NASA/ORAU), S. D. Barthelmy (GSFC),
D. N. Burrows (PSU), M. Capalbi (ASDC), M.L. Conciatore (ASDC),
C. Guidorzi (Univ Bicocca&INAF-OAB), S. T. Holland (GSFC/USRA),
J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL),
M. Perri (ASDC), T. Sakamoto (NASA/ORAU), D. E. Vanden Berk (PSU) and
H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team:
At 13:33:02 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 060923C (trigger=230711). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA,Dec 346.127, +3.942 {23h 04m 30s, +03d 56' 32"} (J2000)
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). This is an image-trigger (88 sec), and as such,
the BAT TDRSS lightcurve does not show significant activity.
The XRT began observing the field at 13:36:25 UT, 203 seconds after the
BAT trigger. XRT found a bright, fading, uncatalogued X-ray source
located at RA(J2000) = 23h 04m 28.1s, Dec(J2000) = +03d 55' 30.3", with an
estimated uncertainty of 8.1 arcseconds (90% confidence radius).
This location is 70 arcseconds from the BAT on-board position, within
the BAT error circle. The initial flux in the 2.5s image was
8.5e-10 erg/cm2/s (0.2-10 keV).
There is a 4th magnitude star 12 arcmin from the XRT error circle.
Therefore, UVOT will not and can not observe this burst.
GCN Circular 5592
Subject
GRB 060923C: optical observation
Date
2006-09-23T14:38:23Z (19 years ago)
From
Ken ichi Torii at Osaka U <torii@ess.sci.osaka-u.ac.jp>
K. Torii (Osaka U.) reports on behalf of the ART collaboration:
The error region of GRB 060923C (Stamatikos et al. GCN 5591) was
observed with the ART-3 telescopes in Toyonaka, Osaka.
Preliminary analysis does not reveal an optical afterglow candidate
brighter than R~15 at 6 minutes after the trigger.
===
GCN Circular 5593
Subject
GRB060923C: Faulkes Telescope North optical observations
Date
2006-09-23T15:21:20Z (19 years ago)
From
Andreja Gomboc at LT,ARI,Liverpool JMU <ag@astro.livjm.ac.uk>
A. Gomboc (University of Ljubljana), C. Guidorzi (Univ Bicocca &
INAF-OAB), A. Melandri, I.A. Steele, R.J. Smith, C.G. Mundell, A. Monfardini,
D. Carter, S. Kobayashi, D. Bersier, M. Bode (Liverpool JMU), P. O'Brien,
E. Rol, N. Bannister (Leicester) report:
The 2m Faulkes North Telescope (Hawaii) automatically reacted to
the Swift burst GRB060923C (trigger 230711, Stamatikos et al. GCN 5591).
Observations started about 4.2 min after the trigger time and were
performed in R and i' bands. From the stacked images we do not detect
any new source down to:
Filter Start(min from GRB) End(min from GRB) TotExp(s) Lim
---------------------------------------------------------------------
R 4.22 20.00 220 19.0
i' 6.52 22.70 220 17.5
----------------------------------------------------------------------
GCN Circular 5594
Subject
GRB060923C : Faulkes Telescope South optical limits
Date
2006-09-23T16:08:08Z (19 years ago)
From
Andrea Melandri at Liverpool John Moores U <axm@astro.livjm.ac.uk>
A. Melandri (Liverpool JMU), C. Guidorzi (Univ Bicocca & INAF-OAB),
A. Gomboc (University of Ljubljana), I.A. Steele, R.J. Smith,
C.G. Mundell, A. Monfardini, D. Carter, S. Kobayashi, D. Bersier,
M. Bode (Liverpool JMU), P. O'Brien, E. Rol, N. Bannister (Leicester)
report:
The 2m Faulkes Telescope South (Siding Spring, Australia) automatically
reacted to the Swift burst GRB 060923C (trigger 230711, Stamatikos et al.,
GCN 5591).
Observations were performed in the R-band. From t=19.38 min to t=20.27 min
(after the burst event) a 3x10s stacked image gives a limiting magnitude
R > 19.5 inside the XRT error circle (Stamatikos et al. GCN 5591).
This message can be cited.
GCN Circular 5596
Subject
GRB 060923C: Xinglong TNT optical observations
Date
2006-09-23T16:24:00Z (19 years ago)
From
W.K. Zheng at NAOC <zwk@bao.ac.cn>
M.Zhai, L.P. Xing, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng and
W.K. Zheng on behalf of EAFON report:
We have imaged the field of GRB 060923C with the TNT 0.8m telescope
at Xinglong Observatory.The first image was taken at 13:36:37 UT, 215s
after the burst. A series of White and R band images were obtained. No
new source were detected in our combined images down to:
Filter Mid_Time(s) 3 sigma limit
---------------------------------
White 487 19.2
R 1210 20.0
This message may be cited.
GCN Circular 5598
Subject
GRB 060923C: Keck Observations
Date
2006-09-23T18:20:56Z (19 years ago)
From
Derek Fox at PSU <dfox@astro.psu.edu>
A. Rau (Caltech), E.O. Ofek (Caltech) and D.B. Fox (Penn State) report
on behalf of a larger collaboration:
We imaged the position of GRB060923C (Stamatikos et al., GCN 5591) on
UT 2006 Sep 23.58 (30 minutes post trigger) with the Low Resolution
Imager and Spectrograph at Keck-I. Observations were performed at high
airmass (3.1).
Within the XRT error circle, we detect a single point-like object,
with I~21 mag, at coordinates:
R.A. 23:04:28.4, Dec. +03:55:29 (J2000)
We note that this source is marginally detected in the Palomar Optical
Sky Survey (DSS) at a similar brightness.
GCN Circular 5600
Subject
GRB 060923C, Swift-BAT partial refined analysis
Date
2006-09-23T22:42:57Z (19 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), L. Barbier (GSFC), J. Cummings (GSFC/UMBC),
E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (BYU-Idaho),
H. Krimm (GSFC/USRA), 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 a partial data set from T-119 to T+183 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 060923C (trigger #230711)
(Stamatikos, et al., GCN Circ. 5591). The BAT ground-calculated position
is RA,Dec = 346.123, 3.963 deg {23h 4m 29.4s, 3d 57' 47.4"} (J2000)
+- 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 17%.
With only a partial data set downlinked (there is a gap in the data
between T+51 to +62 sec), the mask-weighted lightcurve has a single long
emision from T+0 to T+110 sec.
The lower limit to the fluence in the 15-150 keV band is
1.3 +- 0.2 x 10^-6 erg/cm2. We repeat that there is an 11-sec gap
in the data in the middle of this burst used for this analysis.
When the full data set is downlinked, we will report the usual numbers.
GCN Circular 5601
Subject
GRB 060923C: Swift XRT refined analysis
Date
2006-09-24T00:14:00Z (19 years ago)
From
Matteo Perri at ISAC/ASDC <perri@asdc.asi.it>
M. Perri, M. Capalbi, M.L. Conciatore (ASDC), D.N. Burrows (PSU)
and M. Stamatikos (NASA/ORAU) report on behalf of the Swift XRT team:
We have analysed the first four orbits of Swift XRT data on the BAT GRB
060923C (Stamatikos, et al., GCN Circ. 5591). A 5.5 ks Photon Counting
mode image provides a refined XRT position:
RA(J2000) = 23h 04m 28.49s
Dec(J2000) = +03d 55' 26.6"
with an uncertainty of 5.9" (90% containment). This is 2.4' away from
the center of the BAT refined position (Barthelmy et al., GCN Circ. 5600)
and 6.9" away from the first XRT position quoted in GCN Circ. 5591
(Stamatikos, et al.). This position lies 2.8" from the object reported
by Rau et al. (GCN Circ. 5598).
The 0.3-10 keV X-ray light curve from T+212 s to T+13 ks can be fit by
a broken power law model with temporal break at T+780s (+/-120s) and
decay indices -3.4 (+/-0.2) and -0.6 (+/-0.2) before and after the break,
respectively.
The X-ray spectrum covering the time period from T+212s to T+275s is
well fit by an absorbed power-law with a photon index of 1.85 (+/-0.13)
and a column density consistent with the Galactic value in the
direction of the burst (5.3e20 cm**-2).
Assuming the X-ray emission continues to decline at the same rate, we
predict a 0.3-10 keV XRT count rate of ~0.01 count/s at T+24hr, which
corresponds to an observed 0.3-10 keV flux of ~5e-13 erg/cm**2/s.
This circular is an official product of the Swift XRT Team.
GCN Circular 5604
Subject
GRB 060923C: VLT J-band observations
Date
2006-09-24T18:11:53Z (19 years ago)
From
Daniele Malesani at SISSA-ISAS,Trieste,Italy <malesani@sissa.it>
Stefano Covino (INAF/OABr), Daniele Malesani (SISSA/ISAS), and Gianpiero
Tagliaferri (INAF/OABr), report on behalf of the MISTICI collaboration:
We imaged the field of GRB 060923C (Stamatikos et al., GCN 5591) on 2006
Sep 24 from 3:39 to 4:16 UT with the ESO VLT+ISAAC in the J band under
good seeing conditions.
Within the refined XRT error circle (Perri et al., GCN 5601) we detect
three sources with the following positions (RA, DEC, J2000) and magnitudes:
A: 23:04:28.40, +03:55:29.1 19.23 +- 0.03
B: 23:04:28.31, +03:55:29.0 22.87 +- 0.12
C: 23:04:28.18, +03:55:28.5 21.33 +- 0.07
Source C could be extended. Absolute magnitudes are calibrated with
respect to two 2MASS stars in the field. The reported errors are only
statistical; the absolute calibration error may be of the order of ~0.15
mag. At this stage, we cannot say whether any of these sources is
related to GRB 060923C. A finding chart is posted at the followin URL:
http://www.sissa.it/~malesani/GRB/060923C/finder_ISAAC.jpg
Source A has been reported by Rau et al. (GCN 5598) and could also be
marginally visible in the DSS.
We acknowledge support from the ESO observing staff at Paranal, in
particular Christophe Dumas and Emmanuel Jehin.
This message may be cited.
GCN Circular 5606
Subject
GRB 060923C, optical observation
Date
2006-09-25T01:20:00Z (19 years ago)
From
Shouta Maeno at U.of Miyazaki <shouta@astro.miyazaki-u.ac.jp>
S.Maeno, E.Sonoda, M.Yamauchi
(University of Miyazaki)
We have observed the field covering the error circle of
GRB 060923C (GCN 5591) with the unfiltered CCD camera on
the 30-cm telescope at University of Miyazaki.
The observation was started 15:01:30 UT on Sep. 23.
We have compared our data of 30 sec exposures
with the USNO-A2.0 catalog, there is no new source
at the position reported by GCN 5591.
The upper limit is as follows:
--------------------------------------------------------------
Start(UT) End(UT) Num. of frames Limit (mag.)
--------------------------------------------------------------
15:01:30 15:32:39 17 ~17.5
---------------------------------------------------------------
GCN Circular 5607
Subject
GRB 060923C: Gemini Observations and Afterglow Candidate
Date
2006-09-25T03:32:08Z (19 years ago)
From
Derek Fox at PSU <dfox@astro.psu.edu>
D.B. Fox (Penn State) reports on behalf of a larger collaboration:
"We have imaged the XRT position of GRB060923C (Stamtikos et al., GCN
5591) in the K-band with Gemini-North + NIRI on two occasions with
mean epochs of 05:39 UT and 08:34 UT, respectively, on 24 Sep 2006.
We detect the (I-band) source of Rau et al. (GCN 5598; hereafter
source "A") as well the additional (J-band) sources "B" and "C" of
Covino et al. (GCN 5604). At both epochs, these are the only sources
consistent with the XRT localization.
Although we lack an absolute photometric calibration at this time, we
observe a relative decline of Source B by ~0.4 mag in K-band between
these two epochs. The magnitudes of Sources A and C are not observed
to vary, being consistent across our two epochs to within 0.1 mag.
Noting as well the indication for Source A in the DSS (GCN 5598), and
that Source C is clearly extended in our images, we suggest that
Source B is the afterglow of GRB060923C. In this case, the absence
of detectable afterglow light in the early Keck+LRIS I-band images may
indicate a high-redshift origin or high line-of-sight extinction for
this burst."
GCN Circular 5608
Subject
GRB060923C: AROMA optical obsevation
Date
2006-09-25T12:45:25Z (19 years ago)
From
Atsumasa Yoshida at Aoyama Gakuin U <grbalert-ylab@phys.aoyama.ac.jp>
T.Uehara, I.Takahashi, K.Yoshida, A.Kobayashi,
D.Oyamada, Y.E.Nakagawa, S.Sugita, K.Yamaoka,
A.Yoshida (AGU) report:
We have observed the feild of GRB060923C (Stamatikos et al. GCN 5591)
from 13:35:46 (UT) with 0.3m AROMA robotic telescope with R-band filter
at Aoyama Gakuin University.
Although the weather condition was not good, we have taken 60 frames of
image with 20s exposure each. The photometric calibration was made
by first 5 and every 20 frames by comparing with USNO A2.0 stars
in the same field. No new source was found. The 3 sigma
limiting magnitude of each combined image is as below.
number mean time since limiting magnitude
of frames time (UT) GRB (s) in R (3 sigma)
========================================================================
5 13:36:39 217 15.4
20 13:40:20 436 15.8
20 13:54:06 1264 16.8
20 14:10:26 2244 17.5
GCN Circular 5609
Subject
GRB 060923C: NIR afterglow confirmed
Date
2006-09-25T17:09:07Z (19 years ago)
From
Daniele Malesani at SISSA-ISAS,Trieste,Italy <malesani@sissa.it>
Paolo D'Avanzo (INAF-OABr), Stefano Covino (INAF-OABr), Daniele
Malesani (SISSA/ISAS), and Gianpiero Tagliaferri (INAF-OABr), report on
behalf of the MISTICI collaboration:
We imaged again the field of GRB 060923C (Stamatikos et al., GCN 5591)
on 2006 Sep 25 from 0:51 to 1:36 UT with the ESO VLT+ISAAC in the J
band. Seeing conditions were comparable to our previous observation
(Covino et al., GCN 5604).
With respect to the first epoch of imaging, we detect sources A and C,
with the same brightness. Source B has faded significantly and is barely
detectable. Image subtraction performed with ISIS also confirms the fading.
We therefore fully confirm the identification by Fox (GCN 5607) of
source B as the afterglow of GRB 060923C.
We acknowledge support from the ESO observing staff at Paranal.
This message may be cited.
GCN Circular 5610
Subject
GRB 060923C: VLA Observation
Date
2006-09-25T18:46:31Z (19 years ago)
From
Poonam Chandra at U Virginia/NRAO <pc8s@virginia.edu>
P. Chandra (UVA/NRAO) and D. A. Frail (NRAO) report on behalf of
the Caltech-NRAO-Carnegie GRB Collaboration:
"We observed the field centered on the BAT position of the Swift burst GRB
060923C (GCN#5591) using the VLA at a frequency of 8.46 GHz and starting
at 6.02 UT on Sept 25, about 2 days after the burst. There is no
detection of
the GRB with 2-sigma upper limit of 100 microJy.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
GCN Circular 5611
Subject
GRB 060923C, Swift-BAT refined analysis
Date
2006-09-25T19:51:01Z (19 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori@milkyway.gsfc.nasa.gov>
T. Sakamoto (GSFC/ORAU), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
D. Palmer (LANL), A. Parsons (GSFC), G. Sato (GSFC/ISAS),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
on behalf of the Swift-BAT team:
Using the data set from T-239 to T+963 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 060923
(trigger #230711) (Stamatikos, et al., GCN Circ. 5591;
Barthelmy, et al., GCN Circ 5600). The BAT ground-calculated position
is RA,Dec = 346.122, 3.943 deg {23h 4m 29.3s, 3d 56' 33.8"} (J2000)
+- 2.1 arcmin, (radius, sys+stat, 90% containment). The partial
coding was 17%.
The mask-weighted lightcurve has a single long emision from T+0 to T+110 sec.
T90 (15-350 keV) is 76 +- 2 sec (estimated error including systematics).
The long duration and smooth profile of the lightcurve suggest,
but do not prove, that this is a high redshift burst.
The time-averaged spectrum from T+6.8 to T+90.7 is best fit by
a simple power-law model. The power law index of the time-averaged
spectrum is 2.27 +- 0.24. The fluence in the 15-150 keV band is
1.6 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from
T+27.54 sec in the 15-150 keV band is 1.0 +- 0.4 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.
GCN Circular 5648
Subject
GRB060923C: optical limit
Date
2006-09-28T16:38:13Z (19 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
G. Kornienko, A. Erofeeva (UAPhO), A.Pozanenko (IKI), V.Rumyantsev (CrAO) on
behalf of larger GRB follow up collaboration report:
We observed the error box of GRB060923C (Stamatikos et al., GCN 5591)
with 0.4m telescope of Ussuriysk Astrophysical Observatory in R-band
starting Sep.23 (UT) 13:51:55. We do not detect the optical transient
detected by Fox (GCN 5607). Upper limits of the first image (exposure 60 s)
and combined image (exp. 10x60 s) are based on USNOA2.0:
Mid time, Exposure, Limiting mag (3 sigma)
(UT) (s)
Sep. 23.5781 1x60 16.0
Sep. 23.5829 10x60 17.3
This message may be cited.