- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 03 Oct 09 04:36:03 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 45
TRIGGER_NUM: 276237347
GRB_RA: 253.133d {+16h 52m 32s} (J2000),
253.215d {+16h 52m 52s} (current),
252.713d {+16h 50m 51s} (1950)
GRB_DEC: +39.600d {+39d 36' 00"} (J2000),
+39.584d {+39d 35' 03"} (current),
+39.682d {+39d 40' 54"} (1950)
GRB_ERROR: 5.12 [deg radius, statistical plus systematic]
GRB_INTEN: 505 [cnts/sec]
DATA_SIGNIF: 22.50 [sigma]
INTEG_TIME: 1.024 [sec]
GRB_DATE: 15107 TJD; 276 DOY; 09/10/03
GRB_TIME: 16545.58 SOD {04:35:45.58} UT
GRB_PHI: 260.00 [deg]
GRB_THETA: 15.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO: 0.65
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 94% GRB
2nd_MOST_LIKELY: 3% Generic Transient
DETECTORS: 1,0,0, 0,0,0, 0,0,0, 1,0,0, 0,0,
SUN_POSTN: 189.29d {+12h 37m 09s} -4.00d {-04d 00' 04"}
SUN_DIST: 72.94 [deg] Sun_angle= -4.3 [hr] (East of Sun)
MOON_POSTN: 356.04d {+23h 44m 09s} +2.96d {+02d 57' 32"}
MOON_DIST: 97.93 [deg]
MOON_ILLUM: 99 [%]
GAL_COORDS: 63.36, 39.10 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 242.14, 61.42 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 177.05,-25.23 [deg].
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 03 Oct 09 04:36:15 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 58
TRIGGER_NUM: 276237347
GRB_RA: 251.867d {+16h 47m 28s} (J2000),
251.956d {+16h 47m 50s} (current),
251.407d {+16h 45m 38s} (1950)
GRB_DEC: +34.317d {+34d 18' 60"} (J2000),
+34.300d {+34d 17' 59"} (current),
+34.404d {+34d 24' 16"} (1950)
GRB_ERROR: 5.17 [deg radius, statistical plus systematic]
GRB_INTEN: 491 [cnts/sec]
DATA_SIGNIF: 52.10 [sigma]
INTEG_TIME: 4.096 [sec]
GRB_DATE: 15107 TJD; 276 DOY; 09/10/03
GRB_TIME: 16545.58 SOD {04:35:45.58} UT
GRB_PHI: 270.00 [deg]
GRB_THETA: 10.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO: 0.63
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 95% GRB
2nd_MOST_LIKELY: 3% Generic Transient
DETECTORS: 1,0,0, 0,0,0, 0,0,0, 1,0,0, 0,0,
SUN_POSTN: 189.29d {+12h 37m 09s} -4.00d {-04d 00' 04"}
SUN_DIST: 70.18 [deg] Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN: 356.04d {+23h 44m 10s} +2.96d {+02d 57' 34"}
MOON_DIST: 99.89 [deg]
MOON_ILLUM: 99 [%]
GAL_COORDS: 56.43, 39.46 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 242.60, 56.04 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 177.05,-25.23 [deg].
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 03 Oct 09 04:36:26 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 70
TRIGGER_NUM: 276237347
GRB_RA: 247.683d {+16h 30m 44s} (J2000),
247.769d {+16h 31m 05s} (current),
247.245d {+16h 28m 59s} (1950)
GRB_DEC: +38.167d {+38d 09' 60"} (J2000),
+38.146d {+38d 08' 46"} (current),
+38.273d {+38d 16' 24"} (1950)
GRB_ERROR: 4.12 [deg radius, statistical plus systematic]
GRB_INTEN: 1195 [cnts/sec]
DATA_SIGNIF: 58.60 [sigma]
INTEG_TIME: 1.024 [sec]
GRB_DATE: 15107 TJD; 276 DOY; 09/10/03
GRB_TIME: 16545.58 SOD {04:35:45.58} UT
GRB_PHI: 280.00 [deg]
GRB_THETA: 15.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO: 0.67
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 96% GRB
2nd_MOST_LIKELY: 3% Generic Transient
DETECTORS: 1,0,0, 0,0,0, 0,0,0, 1,0,0, 0,0,
SUN_POSTN: 189.29d {+12h 37m 09s} -4.00d {-04d 00' 04"}
SUN_DIST: 68.47 [deg] Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN: 356.04d {+23h 44m 10s} +2.96d {+02d 57' 37"}
MOON_DIST: 102.38 [deg]
MOON_ILLUM: 99 [%]
GAL_COORDS: 61.05, 43.23 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 234.69, 58.90 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 177.05,-25.23 [deg].
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 03 Oct 09 04:36:22 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 57
TRIGGER_NUM: 276237347
GRB_RA: 250.960d {+16h 43m 50s} (J2000),
251.043d {+16h 44m 10s} (current),
250.535d {+16h 42m 08s} (1950)
GRB_DEC: +39.310d {+39d 18' 36"} (J2000),
+39.292d {+39d 17' 32"} (current),
+39.402d {+39d 24' 06"} (1950)
GRB_ERROR: 1.08 [deg radius, statistical only]
DATA_SIGNIF: 46.10 [sigma]
DATA_INTERVAL: 4.096 [sec]
GRB_DATE: 15107 TJD; 276 DOY; 09/10/03
GRB_TIME: 16545.58 SOD {04:35:45.58} UT
GRB_PHI: 267.00 [deg]
GRB_THETA: 15.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 413 (Gnd S/W Version number)
SUN_POSTN: 189.29d {+12h 37m 09s} -4.00d {-04d 00' 04"}
SUN_DIST: 71.27 [deg] Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN: 356.04d {+23h 44m 10s} +2.96d {+02d 57' 36"}
MOON_DIST: 99.63 [deg]
MOON_ILLUM: 99 [%]
GAL_COORDS: 62.81, 40.75 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 238.94, 60.71 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: Fermi-GBM Ground-calculated Coordinates.
COMMENTS: This Notice was ground-generated -- not flight-generated.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 03 Oct 09 04:36:27 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 60
TRIGGER_NUM: 276237347
GRB_RA: 250.760d {+16h 43m 02s} (J2000),
250.845d {+16h 43m 23s} (current),
250.327d {+16h 41m 18s} (1950)
GRB_DEC: +38.230d {+38d 13' 48"} (J2000),
+38.212d {+38d 12' 43"} (current),
+38.323d {+38d 19' 21"} (1950)
GRB_ERROR: 1.00 [deg radius, statistical only]
DATA_SIGNIF: 54.50 [sigma]
DATA_INTERVAL: 4.096 [sec]
GRB_DATE: 15107 TJD; 276 DOY; 09/10/03
GRB_TIME: 16545.58 SOD {04:35:45.58} UT
GRB_PHI: 269.00 [deg]
GRB_THETA: 14.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 413 (Gnd S/W Version number)
SUN_POSTN: 189.29d {+12h 37m 09s} -4.00d {-04d 00' 04"}
SUN_DIST: 70.72 [deg] Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN: 356.04d {+23h 44m 10s} +2.96d {+02d 57' 37"}
MOON_DIST: 100.01 [deg]
MOON_ILLUM: 99 [%]
GAL_COORDS: 61.37, 40.82 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 239.20, 59.63 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: Fermi-GBM Ground-calculated Coordinates.
COMMENTS: This Notice was ground-generated -- not flight-generated.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 03 Oct 09 04:36:37 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 72
TRIGGER_NUM: 276237347
GRB_RA: 253.640d {+16h 54m 34s} (J2000),
253.726d {+16h 54m 54s} (current),
253.198d {+16h 52m 48s} (1950)
GRB_DEC: +36.610d {+36d 36' 36"} (J2000),
+36.595d {+36d 35' 41"} (current),
+36.689d {+36d 41' 22"} (1950)
GRB_ERROR: 1.00 [deg radius, statistical only]
DATA_SIGNIF: 125.30 [sigma]
DATA_INTERVAL: 1.024 [sec]
GRB_DATE: 15107 TJD; 276 DOY; 09/10/03
GRB_TIME: 16545.58 SOD {04:35:45.58} UT
GRB_PHI: 263.00 [deg]
GRB_THETA: 12.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 413 (Gnd S/W Version number)
SUN_POSTN: 189.29d {+12h 37m 09s} -4.00d {-04d 00' 04"}
SUN_DIST: 72.30 [deg] Sun_angle= -4.3 [hr] (East of Sun)
MOON_POSTN: 356.04d {+23h 44m 11s} +2.96d {+02d 57' 39"}
MOON_DIST: 98.06 [deg]
MOON_ILLUM: 99 [%]
GAL_COORDS: 59.61, 38.37 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 244.28, 58.60 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: Fermi-GBM Ground-calculated Coordinates.
COMMENTS: This Notice was ground-generated -- not flight-generated.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 03 Oct 09 04:36:36 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 73
TRIGGER_NUM: 276237347
GRB_RA: 247.733d {+16h 30m 56s} (J2000),
247.819d {+16h 31m 17s} (current),
247.295d {+16h 29m 11s} (1950)
GRB_DEC: +38.183d {+38d 10' 60"} (J2000),
+38.163d {+38d 09' 46"} (current),
+38.290d {+38d 17' 23"} (1950)
GRB_ERROR: 3.68 [deg radius, statistical plus systematic]
GRB_INTEN: 2401 [cnts/sec]
DATA_SIGNIF: 112.50 [sigma]
INTEG_TIME: 1.024 [sec]
GRB_DATE: 15107 TJD; 276 DOY; 09/10/03
GRB_TIME: 16545.58 SOD {04:35:45.58} UT
GRB_PHI: 280.00 [deg]
GRB_THETA: 15.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO: 0.52
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 95% GRB
2nd_MOST_LIKELY: 4% Generic Transient
DETECTORS: 1,0,0, 0,0,0, 0,0,0, 1,0,0, 0,0,
SUN_POSTN: 189.29d {+12h 37m 09s} -4.00d {-04d 00' 04"}
SUN_DIST: 68.51 [deg] Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN: 356.04d {+23h 44m 10s} +2.96d {+02d 57' 39"}
MOON_DIST: 102.34 [deg]
MOON_ILLUM: 99 [%]
GAL_COORDS: 61.08, 43.19 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 234.75, 58.93 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 177.05,-25.23 [deg].
- GCN notice
TITLE: GCN/INTEGRAL NOTICE
NOTICE_DATE: Sat 03 Oct 09 04:36:54 UT
NOTICE_TYPE: INTEGRAL SPI ACS Trigger
TRIGGER_NUM: 5933, Sub_Num: 0
GRB_INTEN: 9.77 [sigma]
GRB_TIME: 16543.90 SOD {04:35:43.90} UT
GRB_DATE: 15107 TJD; 276 DOY; 09/10/03
COMMENTS: INTEGRAL SPI_ACS GRB Trigger.
COMMENTS:
+ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2009-10/2009-10-03T04-35-43.6785-00486-00007-0.lc
- GCN Circular #9983
Arne Rau (MPE) reports on behalf of the Fermi GBM Team:
"At 04:35:45.58 UT on 03 September 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 091003A (trigger 276237347 / 091003191).
The on-ground calculated location, using the GBM trigger
data, is RA = 251.1, DEC = 37.2 (J2000 degrees,
equivalent to 16h 44m, 37d 12'), with an uncertainty
of 1.0 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
The angle from the Fermi LAT boresight is 13 degrees.
This burst was also independently detected by INTEGRAL SPI-ACS.
The GBM light curve consists of multiple peaks
with a duration (T90) of about 21.1 +/- 0.5s (8-1000 keV).
The time-averaged spectrum from T0-0.384s to T0+23.168s is
best fit by a Band function with Epeak = 486.2 +/- 23.6 keV,
alpha = -1.13 +/- 0.01, and beta = -2.64 +/- 0.24
(chi squared 851 for 611 d.o.f.).
The event fluence (8-1000 keV) in this time interval is
(3.76 +/- 0.04)E-05 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+18.048 s in the 8-1000 keV band
is 31.8 +/- 0.4 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
- GCN Circular #9985
Julie McEnery (NASA/GSFC), Jim Chiang (SLAC) and Yoshitaka Hanabata (Hiroshima) report on behalf of the Fermi LAT team:
At 04:35:45 (UT) on 03 Oct 2009, the Fermi Large Area Telescope (LAT) detected gamma rays from the long GRB 091003, which was triggered and located by the Fermi Gamma-ray Burst Monitor (GBM) (trigger 2756237347 / 091003191, GCN9983). The angle of the GBM best position (RA, Dec= 251.1, 37.2) with respect to the LAT boresight was ~13 degrees at the time of the trigger, which is close to the center of our field of view.
This burst was bright enough to initiate a Fermi spacecraft repointing maneuver resulting in 5 hours of pointed observations of the burst position following the GBM trigger.
The data from the Fermi LAT shows a significant increase in the event rate after the GBM trigger that is spatially and temporally correlated with the GBM emission with high significance (>10 sigma).
The best LAT on-ground localization is found to be (RA, Dec = 251.39, 36.58) with a 90% containment radius of 0.21 deg (statistical; 68% containment radius: 0.15 deg, preliminary systematic error is less than 0.1 deg) which is consistent with the GBM localization.
A Swift TOO request has been issued.
Further analysis is ongoing.
The point of contact for this burst is
Julie McEnery : julie.mcenery@nasa.gov
The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
This message can be cited.
- GCN Circular #9986
R.L.C. Starling and A.P. Beardmore (U. Leicester) report on behalf
of the Swift-XRT team:
The Swift X-ray Telescope (XRT) observed the Fermi GBM/LAT and
Integral-detected GRB 091003 (Rau GCN Circ. 9983; McEnery et al. GCN
Circ. 9985) on 2009 October 3 at 20:07:28 UT, 15.5 hours after the
Fermi trigger.
In 2.5 ks of photon counting mode data we detect an uncatalogued
X-ray source at RA, Dec = 251.52047, 36.62548 degrees, which is
equivalent to:
RA (J2000) = 16:46:04.9
Dec (J2000) = +36:37:31.74
with an uncertainty of 3.7 arcsec (radius, 90% containment). This
is 6.85 arcmin from the Fermi LAT position and within its error circle.
A spectrum formed from these data can be fit with an absorbed power law of
photon index 1.7+/-0.3, with nH < 2e21 cm-2, and has an observed 0.3-10 keV
count rate of 0.087+/-0.007 count/s corresponding to a flux of 3.6e-12
erg/cm2/s.
At this stage we do not have enough data to tell if the source is fading.
This circular is an official product of the Swift-XRT team.
- GCN Circular #9987
C. Gronwall (PSU) and R.L.C. Starling (U. Leicester) report on behalf
of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 091003
approximately 15.5 hours after the Fermi/GBM trigger (Rau,
GCN Circ. 9983). In a 885 sec observation in the uvw2 filter, we
find a faint candidate fading UV afterglow within the XRT error circle
(Starling & Beardmore, GCN Circ. 9986). The estimated magnitude is
21.02 +/- 0.27. This value is not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.02 in the direction of
the burst (Schlegel et al. 1998).
- GCN Circular #9988
R.L.C. Starling, P.A. Evans, A.P. Beardmore and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team:
Using 4881 s of XRT Photon Counting mode data and 11 UVOT
images for GRB 091003, 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 =
251.51980, 36.62470 which is equivalent to:
RA (J2000): 16 46 4.75
Dec (J2000): +36 37 29.0
with an uncertainty of 1.7 arcsec (radius, 90% confidence). The UV
counterpart reported in Gronwall & Starling (GCN Circ.9987) is consistent
with this position.
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).
This circular is an official product of the Swift-XRT team.
- GCN Circular #9989
J. Haislip, D. Reichart, A. Smith, D. Caton, L. Hawkins, K. Ivarsen, A.
LaCluyze, A. Foster, J. Moore, A. Oza, M. Schubel, J. Styblova, A. Trotter,
J. A. Crain, and M. Nysewander report:
Skynet observed the Fermi/LAT localization (McEnery, Chiang & Hanabata, GCN
9985) of GRB 091003 (Rau, GCN 9935) with the 14" Dark Sky Observatory
telescope in North Carolina beginning 20.2 hours after the trigger in BVRI.
We do not detect the afterglow (Starling & Beardmore, GCN 9986; Gronwall &
Starling, GCN 9987). Stacking only images that increase the limiting
magnitude yields:
mean 1-sig. 1-sig.
time 3-sig. sys. stat.
since lim. cal. cal. cal.
trig. tel. exp. fil. mag. stars* unc. unc.
(h) (# x s) (mag) (mag)
21.0 DSO-14 16 x 80 V 19.6 58 SDSS 7 0.076 0.000
21.0 DSO-14 17 x 80 B 19.5 33 SDSS 7 0.087 0.001
21.0 DSO-14 16 x 80 R 19.8 64 SDSS 7 0.064 0.000
21.0 DSO-14 16 x 80 I 19.3 45 SDSS 7 0.049 0.000
* Transformed using Jester et al., 2005, ApJ, 130, 873.
- GCN Circular #9990
T. A. Pritchard (PSU) , E.A. Hoversten (PSU), and
R.L.C. Starling (U. Leicester) report on behalf of the
Swift/UVOT team:
The Swift/UVOT began settled observations of the field of
GRB 091003 approximately 15.5 hours after the FERMI/GBM Trigger (Rau,
GCN Circ. 9983) A faint source is detected with 3.9-sigma confidence
in the summed UVOT observations at the Swift UVOT-enhanced XRT
position (R.L.C. Starling, et al. GCN Circ. 9988).
The observed magnitudes and upper limits using the UVOT photometric
system (Poole etal. 2008, MNRAS, 383, 627) for the initial exposures
are:
Filter T_start(s) T_stop(s) Exp(s) Mag
w2 56820 64169 1150 21.08 =B1 0.28 (3.9 sigma)
w1 103712 104474 750 20.70 =B1 0.32 (3.4 sigma)
b 92252 92954 685 20.80 =B1 0.26 (4.1 sigma)
m2 98013 98715 691 > 21.63
v 86432 87195 741 > 20.27
The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) =3D 0.02 in the direction of the burst
(Schlegel et al. 1998).
- GCN Circular #9991
K.L. Page, R.L.C. Starling, P.A. Evans & A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team:
We have now collected 15 ks of Swift-XRT Photon Counting mode data on the
Fermi burst GRB 091003 (Rau, GCN Circ. 9983; McEnery, Chiang & Hanabata,
GCN Circ. 9985), between 56 and 168 ks after the trigger. The light-curve
is fading, with alpha = 1.02 +0.21/-0.20. We therefore confirm that the
source given by Starling et al. in GCN Circ. 9986 and 9988 is, indeed, the
X-ray afterglow.
This circular is an official product of the Swift-XRT team.
- GCN Circular #9994
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the
Konus-Wind team, report:
The long bright GRB 091003A (Fermi-GBM trigger 276237347 / 091003191:
Rau, GCN 9983) localized by Fermi-LAT (McEnery et al., GCN 9985)
triggered Konus-Wind at T0=16543.801 s UT (04:35:43.801).
The burst light curve shows a multipeaked structure with a total
duration of ~23 s.
As observed by Konus-Wind the burst
had a fluence of 3.44(-0.19, +0.20)x10^-5 erg/cm2,
and a 16-ms peak flux measured from T0+18.592 s
of (1.68 +/- 0.32)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+26.880 s) is well fitted (in the 20 keV - 2 MeV
range) by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), with
alpha = -1.04 +/- 0.06, and
Ep = 381(-36, +44) keV (chi2 = 58.4/61 dof).
Fitting by GRB (Band) model yields the same alpha and Ep,
and only an upper limit on the high energy
photon index: beta < -2.22 (chi2 = 56.2/60 dof).
All the quoted errors are at the 90% confidence level.
The Konus-Wind light curve of this GRB is available
at http://www.ioffe.ru/LEA/GRBs/GRB091003_T16543/
- GCN Circular #9995
K. Wiersema, N. Tanvir (Leicester), A. Levan (Warwick) and C. Benn (ING)
report on behalf of a larger collaboration:
We observed the afterglow of Fermi GRB 091003 (Rau GCN 9983; McEnery et al
GCN 9985; Starling & Beardmore GCN 9986) with the William Herschel
Telescope, using the ACAM instrument. We took a 60 and a 250 second
exposure in imaging mode, starting at 21:11 UT, October 4 (1.69 days after
burst).
The afterglow is clearly detected, with r =3D 21.33 +/- 0.11 (calibrated
to
SDSS field stars), at position:
RA (J2000) = 16:46:04.687
Dec (J2000) = +36:37:30.76
with uncertainty 0.3 arcseconds.
We obtained spectroscopy with ACAM immediately after, at high airmass. Two
900 second exposures were obtained using the 400V grism and a 1 arcsecond
slit. Faint continuum emission is detected over the 4000-9300 A range. No
strong absorption or emission lines are detected. The detection of=20
continuum at 4000A gives a upper limit to the redshift of 2.3.
- GCN Circular #9997
D. A. Perley, J. Choi, A. J. L. Morton, and M. Ganeshalingam (UC
Berkeley) report:
We observed the position of Fermi GRB 091003 (Rau et al., GCN9983) using
the Nickel 1m telescope at Lick Observatory on the night of 2009-10-06
(UT) starting at 04:06 for a series of five 600-second exposures in
R-band. The afterglow (Starling and Beardmore, GCN 9986; Gronwall and
Starling, GCN 9987) is marginally detected in the combined frame.
Calibrating to nearby SDSS stars transformed to R-band using the
equations of Lupton et al. (2005) we estimate a magnitude of
R = 21.2 +/- 0.4 (t_mid = 3.00 days)
This suggests only limited fading since the observations of Wiersama et
al. (GCN 9995).
Further, we note that a source coincident with this position is detected
in the SDSS survey imaging. The object (SDSS J164604.70+363731.1) has a
magnitude of r = 23.2 and is classified as a star, but could represent
the host galaxy of this event. A low redshift would also be consistent
with the absence of absorption signatures in the spectrum of Wiersema et
al. and with the Swift UVW2 detection (Pritchard et al., GCN 9990). We
encourage further observations, in particular additional spectroscopy,
of this object.
- GCN Circular #9998
K. Kono, E. Sonoda, N. Ohmori, K. Noda, H. Hayashi,
A. Daikyuji, Y. Nishioka, M. Yamauchi (Univ. of Miyazaki),
Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa (Hiroshima U.),
M. Ohno, M. Suzuki, M. Kokubun, T. Takahashi (ISAS/JAXA),
W. Iwakiri, M. Tashiro, Y. Terada, A. Endo, K. Onda,
T. Sugasahara (Saitama U.), Y. Urata (NCU),
T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo),
K. Yamaoka, S. Sugita (Aoyama Gakuin U.), Y. E. Nakagawa,
T. Tamagawa (RIKEN), S. Hong (Nihon U.), N. Vasquez (Tokyo Tech.),
on behalf of the Suzaku WAM team, report:
The long GRB 091003A
(Fermi-GBM trigger 276237347 / 091003191 ; A. Rau et al., GCN 9983 ; J.
McEnery et al., GCN 9985)
triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 04:35:45.586 UT (=T0).
The observed light curve shows a multi-peaked structure
starting at T0-2 s and ending at T0+23 s, with a total duration (T90) of
about 21 s.
The fluence in 100 - 1000 keV was 1.98(-0.14, +0.08)x10-5 erg/cm2.
The 1-s peak flux measured from T0+18 s was 7.53(-1.28, +0.39)
photons/cm2/s in the same energy range.
Preliminary result shows that the time-averaged spectrum from
T0-2 s to T0+23 s is well fitted by a power-law with exponential cutoff
model:
dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
alpha 1.19(-0.36, +0.29), and
Epeak 576(-72, +106) keV (chi2/d.o.f. = 21.5/24).
Due to the brightness of this burst, a 3% systematic error
was added for low energy channels.
All the quoted errors are at 90% confidence level,
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 #10031
A. Cucchiara, D. B. Fox (PSU), S. B. Cenko (U. Berkeley), N. Tanvir (U.
Leicester),
E. Berger (Harvard U.) report on behalf of a larger collaboration:
"On October 17.20 UT we observed the possible host galaxy of the Fermi/LAT
GRB 091003 (McEnery at al, GCN 9985 and Perley et al. GCN 9997) with
Gemini GMOS-N.
We took a sequence of 2 spectra of 1800s each covering the 6000-10000A
wavelength range. The spectra clearly show emission lines which we
interpreted
as [OII]3727, Hbeta and we resolved the [OIII]4959,5007 doublet.
All these identifications are consistent with redshift z = 0.8969 for
this galaxy.
The galaxy is detected in our 300s R-band acquisition image.
The estimated magnitude, calibrated using 3 SDSS stars is:
R = 22.65 +- 0.05 mag
This value is brighter than the cataloged magnitude, which may indicate a
contribution of the afterglow. After subtracting the contribution
of the galaxy we derive an estimate of the OT flux, R = 23.65 +- 0.05 mag.
We thank the Gemini staff for performing these observations."
- GCN Circular #10032
S. T. Holland (CRESST/USRA/GSFC) reports:
The excess light from the z = 0.8969 host galaxy candidate for
GRB 091003 (Cucchiara et al. 2009, GCNC 10031) correspond to a
rest-frame B-band absolute magnitude of approximately M_B = -20 mag.
This is approximately consistent with the peak rest-frame B-band
absolute magnitude of SN1998bw. The Cucchiara et al. (2009, GCNC
10031) observation was taken on 2009 Oct 17, which corresponds to
approximately seven days after the burst in the rest frame, which is
approximately the expected time of maximum light for a SN Ib/c.
Therefore, we suggest that the excess light seen in this galaxy may be
due to a supernova component of GRB 091003. The lack of an observed
optical afterglow at earlier times supports this interpretation.
Further spectroscopic observations are encouraged to test this
hypothesis.
- GCN Circular #10033
S. T. Holland (CRESST/USRA/GSFC) reports:
I would like to retract GCNC 10032 (Holland 2009). It was sent
in error due to a confusion between GRB 091003 and GRB 091010. I
apologize for the error and any confusion that it may have caused.
- GCN Report 253.1
GCN_Report 253.1 has been posted:
http://gcn.gsfc.nasa.gov/reports/report_253_1.pdf
by R.L.C. Starling
at U. Leicester
titled: "Swift Observations on GRB 091003"
- 1308.2819 from 14 Aug 13
Rupal Basak et al.: A lingering non-thermal component in the GRB prompt emission: predicting GeV emission from the MeV spectrum
The high energy GeV emission of gamma-ray bursts (GRBs), detected by \emph{Fermi}/LAT, has a significantly different morphology compared to the
lower energy MeV emission, detected by \emph{Fermi}/GBM. Though the late time GeV emission is believed to be synchrotron radiation produced via
an external shock, this emission as early as the prompt phase is puzzling. Meaningful connection between these two emissions can be drawn only
by an accurate description of the prompt MeV spectrum. We perform a time-resolved spectroscopy of the GBM data of long GRBs having significant
GeV emission, using a model consisting of 2 blackbodies and a power-law. We examine in detail the evolution of the spectral components and
found that GRBs having high GeV emission (GRB 090902B and GRB 090926A) have a delayed onset of the power-law component, in the GBM spectrum,
which lingers at the later part of the prompt emission. This behaviour mimics the flux evolution in LAT. In contrast, bright GBM GRBs with an
order of magnitude lower GeV emission (GRB 100724B and GRB 091003) show a coupled variability of the total and the power-law flux. Further, by
analyzing the data for a set of 17 GRBs, we find a strong correlation between the power-law fluence in the MeV and the LAT fluence (Pearson
correlation: r=0.88 and Spearman correlation: $\rho=0.81$). We demonstrate that this correlation is not influenced by the correlation between
the total and the power-law fluences at a confidence level of 2.3$\sigma$. We speculate the possible radiation mechanisms responsible for the
correlation.
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