- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 24 Oct 09 09:06:44 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 46
TRIGGER_NUM: 278067991
GRB_RA: 337.833d {+22h 31m 20s} (J2000),
337.929d {+22h 31m 43s} (current),
337.346d {+22h 29m 23s} (1950)
GRB_DEC: +55.500d {+55d 30' 00"} (J2000),
+55.551d {+55d 33' 02"} (current),
+55.243d {+55d 14' 33"} (1950)
GRB_ERROR: 19.83 [deg radius, statistical plus systematic]
GRB_INTEN: 60 [cnts/sec]
DATA_SIGNIF: 5.00 [sigma]
INTEG_TIME: 4.096 [sec]
GRB_DATE: 15128 TJD; 297 DOY; 09/10/24
GRB_TIME: 32789.36 SOD {09:06:29.36} UT
GRB_PHI: 120.00 [deg]
GRB_THETA: 15.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO: 0.73
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 91% GRB
2nd_MOST_LIKELY: 5% Cyg X-1
DETECTORS: 0,0,0, 0,0,0, 1,0,0, 1,0,0, 0,0,
SUN_POSTN: 208.95d {+13h 55m 48s} -11.85d {-11d 51' 04"}
SUN_DIST: 121.17 [deg] Sun_angle= -8.6 [hr] (East of Sun)
MOON_POSTN: 284.59d {+18h 58m 22s} -23.75d {-23d 45' 00"}
MOON_DIST: 91.32 [deg]
MOON_ILLUM: 35 [%]
GAL_COORDS: 103.95, -2.12 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 14.10, 57.26 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 143.57,22.93 [deg].
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 24 Oct 09 09:07:03 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 57
TRIGGER_NUM: 278067991
GRB_RA: 332.610d {+22h 10m 26s} (J2000),
332.698d {+22h 10m 48s} (current),
332.160d {+22h 08m 38s} (1950)
GRB_DEC: +56.050d {+56d 02' 60"} (J2000),
+56.099d {+56d 05' 55"} (current),
+55.803d {+55d 48' 12"} (1950)
GRB_ERROR: 4.72 [deg radius, statistical only]
DATA_SIGNIF: 5.40 [sigma]
DATA_INTERVAL: 4.096 [sec]
GRB_DATE: 15128 TJD; 297 DOY; 09/10/24
GRB_TIME: 32789.36 SOD {09:06:29.36} UT
GRB_PHI: 108.00 [deg]
GRB_THETA: 15.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 413 (Gnd S/W Version number)
SUN_POSTN: 208.95d {+13h 55m 48s} -11.85d {-11d 51' 05"}
SUN_DIST: 118.28 [deg] Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN: 284.59d {+18h 58m 23s} -23.75d {-23d 44' 58"}
MOON_DIST: 89.62 [deg]
MOON_ILLUM: 35 [%]
GAL_COORDS: 101.78, -0.06 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 10.76, 59.69 [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 24 Oct 09 09:06:56 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 58
TRIGGER_NUM: 278067991
GRB_RA: 28.733d {+01h 54m 56s} (J2000),
28.934d {+01h 55m 44s} (current),
27.723d {+01h 50m 54s} (1950)
GRB_DEC: +70.500d {+70d 30' 00"} (J2000),
+70.548d {+70d 32' 52"} (current),
+70.255d {+70d 15' 17"} (1950)
GRB_ERROR: 14.57 [deg radius, statistical plus systematic]
GRB_INTEN: 79 [cnts/sec]
DATA_SIGNIF: 6.40 [sigma]
INTEG_TIME: 4.096 [sec]
GRB_DATE: 15128 TJD; 297 DOY; 09/10/24
GRB_TIME: 32789.36 SOD {09:06:29.36} UT
GRB_PHI: 240.00 [deg]
GRB_THETA: 15.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO: 1.14
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 97% GRB
2nd_MOST_LIKELY: 1% Generic SGR
DETECTORS: 0,0,0, 0,0,0, 1,0,0, 1,0,0, 0,0,
SUN_POSTN: 208.95d {+13h 55m 48s} -11.85d {-11d 51' 04"}
SUN_DIST: 121.30 [deg] Sun_angle= -12.0 [hr] (East of Sun)
MOON_POSTN: 284.59d {+18h 58m 23s} -23.75d {-23d 44' 59"}
MOON_DIST: 117.08 [deg]
MOON_ILLUM: 35 [%]
GAL_COORDS: 128.23, 8.28 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 60.73, 53.23 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 143.57,22.93 [deg].
- GCN/BACODINE POSITION NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 24 Oct 09 08:56:19 UT
NOTICE_TYPE: Swift-BAT GRB Position
TRIGGER_NUM: 373674, Seg_Num: 0
GRB_RA: 339.207d {+22h 36m 50s} (J2000),
339.303d {+22h 37m 13s} (current),
338.718d {+22h 34m 52s} (1950)
GRB_DEC: +56.874d {+56d 52' 28"} (J2000),
+56.926d {+56d 55' 32"} (current),
+56.615d {+56d 36' 53"} (1950)
GRB_ERROR: 3.00 [arcmin radius, statistical only]
GRB_INTEN: 4850 [cnts] Image_Peak=195 [image_cnts]
TRIGGER_DUR: 1.024 [sec]
TRIGGER_INDEX: 155 E_range: 50-350 keV
BKG_INTEN: 28198 [cnts]
BKG_TIME: 32146.80 SOD {08:55:46.80} UT
BKG_DUR: 8 [sec]
GRB_DATE: 15128 TJD; 297 DOY; 09/10/24
GRB_TIME: 32161.26 SOD {08:56:01.26} UT
GRB_PHI: 179.66 [deg]
GRB_THETA: 44.44 [deg]
SOLN_STATUS: 0x20000003
RATE_SIGNIF: 19.39 [sigma]
IMAGE_SIGNIF: 9.06 [sigma]
MERIT_PARAMS: +1 +0 +0 +0 +3 +0 +0 +1 +51 +0
SUN_POSTN: 208.94d {+13h 55m 47s} -11.85d {-11d 50' 55"}
SUN_DIST: 121.19 [deg] Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN: 284.50d {+18h 58m 00s} -23.77d {-23d 45' 57"}
MOON_DIST: 92.86 [deg]
MOON_ILLUM: 35 [%]
GAL_COORDS: 105.30, -1.32 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 16.89, 57.73 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SWIFT-BAT GRB Coordinates.
COMMENTS: This is a rate trigger.
COMMENTS: A point_source was found.
COMMENTS: This does not match any source in the on-board catalog.
COMMENTS: This does not match any source in the ground catalog.
COMMENTS: This is a GRB.
COMMENTS: This trigger occurred at longitude,latitude = 300.45,19.85 [deg].
COMMENTS:
COMMENTS: NOTE: This BAT event is temporally(3.0<100sec) coincident with the FERMI_GBM event (trignum=278067360).
- red DSS finding chart
ps-file
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 24 Oct 09 08:56:40 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 68
TRIGGER_NUM: 278067360
GRB_RA: 347.500d {+23h 10m 00s} (J2000),
347.611d {+23h 10m 27s} (current),
346.937d {+23h 07m 45s} (1950)
GRB_DEC: +51.770d {+51d 46' 12"} (J2000),
+51.823d {+51d 49' 24"} (current),
+51.498d {+51d 29' 55"} (1950)
GRB_ERROR: 4.14 [deg radius, statistical only]
DATA_SIGNIF: 17.70 [sigma]
DATA_INTERVAL: 4.096 [sec]
GRB_DATE: 15128 TJD; 297 DOY; 09/10/24
GRB_TIME: 32158.47 SOD {08:55:58.47} UT
GRB_PHI: 232.00 [deg]
GRB_THETA: 99.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 413 (Gnd S/W Version number)
SUN_POSTN: 208.94d {+13h 55m 47s} -11.85d {-11d 50' 56"}
SUN_DIST: 128.00 [deg] Sun_angle= -9.2 [hr] (East of Sun)
MOON_POSTN: 284.50d {+18h 58m 01s} -23.77d {-23d 45' 55"}
MOON_DIST: 93.49 [deg]
MOON_ILLUM: 35 [%]
GAL_COORDS: 107.41, -8.02 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 17.42, 50.71 [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 24 Oct 09 08:56:36 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 57
TRIGGER_NUM: 278067360
GRB_RA: 343.170d {+22h 52m 41s} (J2000),
343.272d {+22h 53m 05s} (current),
342.650d {+22h 50m 36s} (1950)
GRB_DEC: +55.990d {+55d 59' 24"} (J2000),
+56.042d {+56d 02' 32"} (current),
+55.724d {+55d 43' 26"} (1950)
GRB_ERROR: 3.14 [deg radius, statistical only]
DATA_SIGNIF: 16.60 [sigma]
DATA_INTERVAL: 4.096 [sec]
GRB_DATE: 15128 TJD; 297 DOY; 09/10/24
GRB_TIME: 32158.47 SOD {08:55:58.47} UT
GRB_PHI: 237.00 [deg]
GRB_THETA: 99.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 413 (Gnd S/W Version number)
SUN_POSTN: 208.94d {+13h 55m 47s} -11.85d {-11d 50' 55"}
SUN_DIST: 123.53 [deg] Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN: 284.50d {+18h 58m 00s} -23.77d {-23d 45' 55"}
MOON_DIST: 93.97 [deg]
MOON_ILLUM: 35 [%]
GAL_COORDS: 106.82, -3.12 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 18.69, 55.58 [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/SWIFT NOTICE
NOTICE_DATE: Sat 24 Oct 09 08:59:38 UT
NOTICE_TYPE: Swift-BAT GRB Lightcurve
TRIGGER_NUM: 373674, Seg_Num: 0
GRB_RA: 339.207d {+22h 36m 50s} (J2000),
339.303d {+22h 37m 13s} (current),
338.718d {+22h 34m 52s} (1950)
GRB_DEC: +56.874d {+56d 52' 28"} (J2000),
+56.926d {+56d 55' 32"} (current),
+56.615d {+56d 36' 53"} (1950)
GRB_DATE: 15128 TJD; 297 DOY; 09/10/24
GRB_TIME: 32161.26 SOD {08:56:01.26} UT
TRIGGER_INDEX: 155
GRB_PHI: 179.66 [deg]
GRB_THETA: 44.44 [deg]
DELTA_TIME: -5.00 [sec]
TRIGGER_DUR: 1.024 [sec]
SOLN_STATUS: 0x3
RATE_SIGNIF: 19.39 [sigma]
IMAGE_SIGNIF: 9.06 [sigma]
LC_URL: sw00373674000msb.lc
SUN_POSTN: 208.95d {+13h 55m 47s} -11.85d {-11d 50' 58"}
SUN_DIST: 121.19 [deg] Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN: 284.53d {+18h 58m 07s} -23.76d {-23d 45' 39"}
MOON_DIST: 92.84 [deg]
MOON_ILLUM: 35 [%]
GAL_COORDS: 105.30, -1.32 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 16.89, 57.73 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SWIFT-BAT GRB Lightcurve.
COMMENTS:
COMMENTS: The next comments were copied from the BAT_POS Notice:
COMMENTS: This is a rate trigger.
COMMENTS: A point_source was found.
COMMENTS: This does not match any source in the on-board catalog.
COMMENTS: This does not match any source in the ground catalog.
COMMENTS: This is a GRB.
COMMENTS: This trigger occurred at longitude,latitude = 300.45,19.85 [deg].
- GCN Circular #10062
F. E. Marshall (NASA/GSFC), W. H. Baumgartner (GSFC/UMBC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
S. Campana (INAF-OAB), P. A. Evans (U Leicester),
S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU),
C. B. Markwardt (CRESST/GSFC/UMD), P. T. O'Brien (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
T. Sakamoto (NASA/UMBC), B. Sbarufatti (INAF-IASFPA),
R. L. C. Starling (U Leicester) and T. N. Ukwatta (GSFC/GWU) report on
behalf of the Swift Team:
At 08:56:01 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 091024 (trigger=373674). The BAT on-board calculated
location is RA, Dec 339.207, +56.874 which is
RA(J2000) = 22h 36m 50s
Dec(J2000) = +56d 52' 28"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a double-peaked
structure with the first peak at T=0 and a second smaller peak at T=40s
with a total duration of about 50 sec. The peak count rate
was ~5000 counts/sec (15-350 keV), at ~0 sec after the trigger.
Due to an observing constraint, Swift will not slew until
T0+50.0 minutes. There will be no XRT or UVOT data until
this time.
Burst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.nasa.gov).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
- GCN Circular #10063
C.G. Mundell, Z. Cano (Liverpool, JMU), C. Guidorzi (U. Ferrara),
I. A. Steele, A. Melandri, D. Bersier, S. Kobayashi, C.J. Mottram,
R.J. Smith (Liverpool, JMU), A. Gomboc, D. Kopac (U. Ljubljana),
P. O'Brien (U. Leicester) report:
"The 2-m Faulkes Telescope North robotically followed up GRB091024 (SWIFT
trigger 373674; Marshall et al. GCN 10062) 3.27 min after the GRB trigger
time. The automatic "detection mode" procedure detected an uncatalogued
afterglow candidate at:
22:36:59.7 +56:53:23.4 (J2000) uncertainty 0.5"
with magnitude R = 18.1 +/-mag (vs USNOB1)
Observations and analysis are ongoing.
This message may be cited"
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 24 Oct 09 09:48:54 UT
NOTICE_TYPE: Swift-XRT Nack-Position
TRIGGER_NUM: 373674, Seg_Num: 0
POINT_RA: 339.112d {+22h 36m 27s} (J2000)
POINT_DEC: +56.763d {+56d 45' 45"} (J2000)
IMG_START_DATE: 15128 TJD; 297 DOY; 09/10/24
IMG_START_TIME: 35325.87 SOD {09:48:45.87} UT, 3164.6 [sec] since BAT Trigger Time
COUNTS: 55 Min_needed= 20
STD_DEV: 0.00 Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER: 4 Max_iter_allowed= 4
ERROR_CODE: 2
COMMENTS: SWIFT-XRT Nack Position.
COMMENTS: Algorithm did not converge; too many iterations.
- GCN Circular #10064
Markku Nissinen (Taurus Hill Observatory) and Veli-Pekka Hentunen (Taurus
Hill Observatory) report:
We used Global-rent-a-scope GRAS004 Epsilon 250 telescope with ST-8XE CCD
at RAS Observatory Mayhill H06 (New Mexico, USA) for follow-up observations
of GRB091024 (D.Palmer et al. , GCN 10062). The observations were started
on October 24, at 09:44 UTC (48 min after the burst) and stopped on October,
at 09:58 UTC. One unfiltered 120 seconds image and one unfiltered 600 seconds image
were taken. We detected a very dim uncatalogued optical afterglow object at the position
of RA 22h 36min 59s.68 and DEC +56o 53' 22".6 with respect to POSSII F
(J2000) which is in good correlation with Carole Mundell et al. observation
(GCN 10063). Upper limit for our observations is >18.7 mag. Quoted upper
limit has been derived using POSSII F and USNO-B1.0 field stars as reference.
Filter Tmid(s) Exp(s) OA Mag (CR) USNO-B1.0
unfiltered 09:53:11 600 18.2+/-0.4
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 24 Oct 09 13:33:00 UT
NOTICE_TYPE: Swift-XRT Position
TRIGGER_NUM: 373674, Seg_Num: 0
GRB_RA: 339.2517d {+22h 37m 00.40s} (J2000),
339.3478d {+22h 37m 23.46s} (current),
338.7634d {+22h 35m 03.20s} (1950)
GRB_DEC: +56.8892d {+56d 53' 21.1"} (J2000),
+56.9403d {+56d 56' 25.0"} (current),
+56.6293d {+56d 37' 45.3"} (1950)
GRB_ERROR: 6.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN: 1.00e-10 [erg/cm2/sec]
GRB_SIGNIF: 10.00 [sigma]
IMG_START_DATE: 15128 TJD; 297 DOY; 09/10/24
IMG_START_TIME: 35353.00 SOD {09:49:13.00} UT, 78582.2 [sec] since BAT Trigger Time
TAM[0-3]: 327.61 237.19 261.35 242.66
AMPLIFIER: 2
WAVEFORM: 134
SUN_POSTN: 209.13d {+13h 56m 31s} -11.92d {-11d 54' 55"}
SUN_DIST: 121.18 [deg] Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN: 286.95d {+19h 07m 49s} -23.33d {-23d 19' 30"}
MOON_DIST: 91.50 [deg]
MOON_ILLUM: 36 [%]
GAL_COORDS: 105.33, -1.32 [deg] galactic lon,lat of the burst
ECL_COORDS: 16.94, 57.72 [deg] ecliptic lon,lat of the burst
COMMENTS: SWIFT-XRT Coordinates.
COMMENTS: This Notice was ground-generated -- not flight-generated.
COMMENTS: TAM values are not valid.
- GCN Circular #10065
A. Cucchiara, D. Fox (PSU) & N. Tanvir (U. Leicester) report:
We observed the afterglow of GRB 091024 (Marshall et al. GCN 10062;
Mundell et al. GCN 10063) with the GMOS-N spectrograph on Gemini North
beginning at 10.43 UT. The resultant spectrum, which spans 5925A to 10200A,
shows a strong continuum and well detected lines of CaII H & K, MgI (2853A)
at a common redshift of z=1.092. Further analysis is ongoing.
We thank the Gemini-N support staff, in particular R. Pike, for
obtaining these observations.
- GCN Circular #10066
Z. Cano (Liverpool JMU), C. Guidorzi (U. Ferrara), C.G. Mundell, D.
Bersier, N.R. Clay, S. Kobayashi, A. Melandri, C.J. Mottram, R.J. Smith,
I.A. Steele (Liverpool JMU), A. Gomboc (U. Ljubljana), P. O'Brien, N.R.
Tanvir (U. Leicester) on behalf of a larger collaboration report:
The Faulkes Telescope North (Hawaii) continued observing the field of GRB
091024 (Swift trigger=373674, Marshall et al., GCN 10062).
We have detected an initial rise in the R & I LCs, peaking around To+600s
with 16.7 Rmag, which was followed by flaring activity that lasted
approximate 6ks. After 6ks we estimate from our data a power-law decay
index alpha = 1.7 +/- 0.2.
As calibrated against nearby USNO objects, we find:
Filter mag merr T-To (hr)
---------------------------------------
R 17.55 0.05 0.98
R 17.98 0.05 1.84
R 19.09 0.08 3.30
We also note the large amount of foreground extinction, E(B-V) = 0.98 mag
(Schlegel et al. 98), corresponding to AV=3.0 mag.
- GCN Circular #10067
H.Li, L.P. Xin, J. Wang, Y.L. Qiu, J.Y. Wei, W. K. Zheng,
J.S. Deng, and C. Wu, J.Y. Hu on behalf of EAFON report:
We have observed GRB 091024 (Marshall et al. GCN 10062)
with Xinglong TNT telescope from Oct. 24, 10:27:11 (UT),
1.3 hour after the burst. The optical afterglow
(Cano et al. GCN 10066; Cucchiara et al. GCN 10065;
Mundell et al. GCN 10063) has been detected in our images.
The brightness is estimated to be about R~18.5 mag
derived from USNO-A1.0 R magnitude, at the mean time
of 1.38 hour since the trigger.
The observation is still going.
This message may be cited.
For more information about Xinglong GRBs Follow-up
observations, please visit the website:
http://www.xinglong-naoc.org/grb/
- GCN Circular #10069
K.L. Page (U. Leicester) and F.E. Marshall (NASA/GSFC) report on behalf of
the Swift-XRT team:
Following an Earth-limb constraint, Swift-XRT began observing the field of
GRB 091024 at 09:49:13, about 53 minutes after the BAT trigger. We detect
a bright, uncatalogued X-ray source at a position of RA, Dec = 339.25167,
56.88928, which is equivalent to
RA (J2000): 22 37 00.40
Dec (J2000): 56 53 21.4
with an uncertainty of 6 arcsec (radius, 90% confidence). This is 6.1
arcsec from the optical afterglow candidate given by Mundell et al. (GCN
Circ. 10063) and 6.0 arcsec from the position given by Nissinen & Hentunen
(GCN Circ. 10064).
Only one orbit of data has been collected thus far (spanning 3.2-5.4 ks
after the burst), but the source does appear to be fading, albeit with a
relatively large uncertainty: alpha = 1.2 +/- 0.4.
The spectrum of the source, extracted from the 2.2 ks of Photon Counting
mode data, can be fitted by an absorbed power-law with Gamma = 1.70 +/-
0.17, the Galactic column of NH = 4.86 x 10^21 cm^-2 and an intrinsic
column of (2.3 +1.0/-0.9) x 10^22 at a redshift of 1.092 (Cucchiara, Fox &
Tanvir, GCN Circ. 10065). The observed (unabsorbed) flux over this time is
7.23 x 10^-11 (1.15 x 10^-10) erg cm^-2 s^-1, corresponding to a counts to
observed (unabsorbed) flux conversion of 7.5 x 10^-11 (1.2 x 10^-10) erg
cm^-2 count^-1.
If the source continues to fade with alpha ~ 1.2, the predicted count rate
at 24 hours will be 0.034 count s^-1, corresponding to an observed
(unabsorbed) flux of 2.6x10^-12 (4.1x10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00373674.
This circular is an official product of the Swift-XRT team.
- GCN Circular #10070
Elisabetta Bissaldi (MPE) and Valerie Connaughton (UAH)
report on behalf of the Fermi GBM Team:
"At 08:55:58.47 UT on 24 October 2009, the Fermi Gamma-Ray Burst Monitor
(GBM) triggered and located GRB 091024 (trigger 278067360 / 091024372),
which was also detected by the Swift-BAT (Marshall et al. 2009, GCN 10062).
The GBM on-ground location is consistent with the Swift position. At
09:06:29.36, GBM triggered on what appears to be the continuation of this
burst (trigger 278067991 / 091024380). The GBM on-ground location for
this
second trigger is also consistent with the Swift position for GRB 091024.
The angle from the Fermi LAT boresight at the time of the
first trigger is 97 degrees and at the time of the second trigger
it is 14 degrees. Furthermore, at 09:12:14.28, the Fermi spacecraft
executed
a maneuver to place the burst near the center of the Large Area Telescope
(LAT) field-of-view and observe this region for 5 hours subject to
Earth angle constraints.
The first emission episode appears to last about 50 s, with 2 peaks
separated
by a few seconds. A brighter emission periods starts at the time of the
2nd
trigger, 630 s later, and persists for at least 400 s. This second
emission period
shows an initial pulse (at 630 s) lasting about 40 s, followed by a
multi-peaked
episode starting 210 s later (840 s from the first trigger) and lasting
over 100 s.
There is evidence for lower-level emission beyond this time. The Fermi
spacecraft entered the South Atlantic Anomaly 2200 s after trigger
091024380,
by which time there was no obvious emission in GBM.
In a first, preliminary analysis, we have fit time-integrated spectra
for each of the
3 main emission blocks. The first trigger appears to have an EPeak of
about
400 keV; the first peak of the second trigger is quite weak and best
fit using
a power-law of index around -1.5; the long and brighter emission period of
the second trigger has an EPeak of around 300 keV. Detailed spectral
analyses and fluence values will be given in a future circular.
The POC for this burst is Elisabetta Bissaldi (ebs@mpe.mpg.de).
- GCN Circular #10072
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), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC),
T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-239 to T+483 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 091024 (trigger #373674)
(Mashall, et al., GCN Circ. 10062). The BAT ground-calculated position is
RA, Dec = 339.240, 56.885 deg, which is
RA(J2000) = 22h 36m 57.6s
Dec(J2000) = +56d 53' 07.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 39%.
The mask-weighted light curve shows two slightly overlapping FRED peaks.
The first starts at ~T-20 sec, peaks at ~T+2 sec. The second peaks at ~T+42 sec
and long-term low-level emission extends out to ~T+400 sec.
T90 (15-350 keV) is 109.8 +- 16.7 sec (estimated error including systematics).
The time-averaged spectrum from T-15.2 to T+135.8 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.20 +- 0.08. The fluence in the 15-150 keV band is 6.1 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.23 sec in the 15-150 keV band
is 2.0 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/373674/BA/
- GCN Circular #10073
A. Henden (AAVSO), J. Gross (SRO), B. Denny (DC-3), D. Terrell (SwRI), and
W. Cooney (SRO) report:
We obtained photometry of the GRB091024 afterglow reported by Mundell et
al. (GCN 10063) using the Sonoita Research Observatory (SRO) 35cm telescope
in southern Arizona, utilizing an automatic VOevent trigger. The Rc-band
exposures began about 9 minutes after the burst and continued for approximately
one hour. Ten Rc-band, nine V-band, and one Ic-band exposures were acquired.
Photometry, assuming that USNO-B1.0 1468-0448363 (RA: 22:36:44.11 ,
Dec: +56:52:42.6) has the following magnitudes: V=13.46, R=12.93, I=12.71
UT(mid) delT exp mag err filter
09.1122 642 180 17.177 0.030 Rc
09.1667 839 180 17.510 0.037 Rc
09.2192 1028 180 17.827 0.049 Rc
09.2722 1218 180 17.993 0.044 Rc
09.3247 1407 180 18.136 0.056 Rc
09.4123 1723 300 18.008 0.046 Rc
09.5000 2038 300 17.764 0.045 Rc
09.5859 2348 300 17.737 0.033 Rc
09.6717 2657 300 17.665 0.037 Rc
09.7575 2965 300 17.776 0.045 Rc
09.8609 3338 300 19.029 0.111 V
09.9486 3653 300 19.267 0.120 V
10.0348 3964 300 19.290 0.132 V
10.1206 4273 300 19.320 0.126 V
10.2064 4581 300 19.237 0.091 V
10.2923 4891 300 19.345 0.151 V
10.4642 5510 300 19.163 0.107 V
10.5500 5818 300 19.293 0.123 V
10.6359 6128 300 19.350 0.163 V
10.8439 6877 180 17.550 0.074 Ic
Where delT is the time in seconds from the burst (Marshall et al., GCN
10062), and the exposure is in seconds.
Astrometry from the Rc frames, using UCAC3, yields a precise position of
22:36:59.68 +56:53:23.3 J2000 (+/- 100mas). A full BVRcIc calibration
is in the Sonoita queue and will be released when photometric conditions
permit.
The AAVSO thanks the Curry Foundation for its support of the AAVSO
International High Energy Network.
- GCN Circular #10074
Adria C. Updike, Dieter H. Hartmann (Clemson University), Peter A. Milne
(Steward Observatory), and Grant G. Williams (MMT Observatory) report:
The 0.6m Super-LOTIS telescope located at Kitt Peak National Observatory
began observing the field of GRB 091024 (Marshall et al., GCN 10062) 58
seconds after the BAT trigger under good conditions. We detect the
afterglow (Mundell et al., GCN 10063) in early stacked 20s exposures and
individual 60s exposures beginning 5 min after the trigger. At 3.62 min
after the trigger, we measure the magnitude to be R = 17.7 +/- 0.1
relative to field stars and the USNO B1.0 catalog. Observations continued
for 36 minutes.
- GCN Circular #10075
R. Chornock, W. Li, and A. V. Filippenko (UC Berkeley) report on behalf of the
KAIT GRB team:
The Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory automatically
responded to the Swift BAT trigger for GRB 091024 (Marshall et al., GCN 10062)
with a sequence of observations starting 82 s after the BAT trigger. The
afterglow is not initially detected. Our first detection of the optical
afterglow (Mundell et al., GCN 10063) is in a 20 s I band observation starting
at 08:58:45 UT. The KAIT position is
(J2000) 22:36:59.64 +56:53:24.0
which is consistent the positions reported by Mundell et al. (GCN 10063) and
Henden et al. (GCN 10073). The optical afterglow is thereafter detected in a
sequence of V, I, and unfiltered images as it rose to a peak at an unfiltered
magnitude of 16.2 (preliminarily calibrated to USNO-B1) at t=404s and then
declined to mag 17.0 at t=988s, similar to the behavior described by Cano et al.
(GCN 10066). After this time observations ceased due to a pointing limit.
- GCN Circular #10077
D. A. Kann, and U. Laux (TLS Tautenburg) report:
We observed the afterglow of the ultra-long Swift/GBM GRB 091024 (Marshall
et al., GCN 10062, Mundell et al., GCN 10063, Bissaldi & Connaughton, GCN
10070) with the 1.34m Schmidt telescope of the Thueringer
Landessternwarte Tautenburg, Germany, 0.6 days after the GRB. We obtained
6 x 600 sec images in Rc.
As a comparison star, we use the USNOB1.0 star at:
RA (J2000) = 22:37:31.11
Dec. (J2000) = +56:59:26.23
which has R2 = 17.78 mag. This was one of the rare non-blended stars that
was bright enough to be detected in the catalog.
At the afterglow position, we do not detect any source which is not
detected anyway in the DSS2 red plate. We place the following 2 sigma
upper limit on the afterglow:
dt Filter UL
____________________________________
0.602309 Rc 21.0
and note that the true upper limit may be less deep due to crowding (the
afterglow pretty much conincides with a ~20th mag object detected in the
DSS).
No further observations are planned.
This message may be cited.
- GCN Circular #10078
S. R. Oates (MSSL-UCL) and F. E. Marshall (NASA/GSFC) report on behalf
of the Swift/UVOT team:
The Swift/UVOT began observerving the field of GRB 091024 ~3ks
after the BAT trigger (Marshall et al., GCN Circ. 10062). No
optical afterglow is detected in the UVOT exposures at
the refined position of the X-ray afterglow (Page et al.,
GCN Circ. 10069) and the position reported by Faulkes
Telescope North (Mundell., et al., GCN Circ. 10063).
The 3 sigma upper limits for the b, u, uvw2 and summed uvw1
exposures are reported below.
Filter T_start(s) T_stop(s) Exposure(s) 3sigma Upper Limit
-------------------------------------------------------------------
b 45981 45984 3 > 17.31
u 32984 33055 70 > 19.03
uvw1 26617 38935 1283 > 20.37
uvw2 3151 3161 10 > 17.28
-------------------------------------------------------------------
The above magnitudes are not corrected for the Galactic extinction
corresponding to a significant reddening of E_{B-V} = 0.99 mag
(Schlegel et al.,
1998, ApJS, 500, 525). The photometry is on the UVOT photometric system
described in Poole et al. (2008, MNRAS, 383,627).
- GCN Circular #10083
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks,
P. Oleynik, M. Ulanov, and D. Svinkin on behalf of
the Konus-Wind and Konus-RF teams, and
T. Cline on behalf of the Konus-Wind team, report:
The long GRB 091024 (Swift-BAT trigger #373674: Marshall et al. GCN
10062, Sakamoto et al. GCN 10072) was observed by Konus-Wind in the
waiting mode. The emission was detected in all three Konus-Wind energy
bands: G1 (18-70 keV), G2 (70-360 keV) and G3 (360-1360 keV) with high
S/N.
The burst light curve shows three pulses: the first pulse starts at
~T0-10 s and has a duration of ~90 s, the second starts at ~T0+600 s and
has a duration of ~100 s, and the most intense third pulse starts at
T0+840 s and has a duration of ~400 s; there is a low-level emission
between the first and second pulses.
The most intense part of the third pulse was also detected by Konus-RF,
while Coronas-F was exiting the SAA.
The GBM localizations suggest a common origin of these events (Bissaldi
& Connaughton, GCN 10070). Both the K-W light curve and the K-W ecliptic
latitude response confirms this suggestion. So, we believe all these
pulses belong to the extremely long burst, GRB 091024, which has a total
duration of ~1200 s. Hence, some optical observations of this burst were
performed during the most intense part of the prompt emission, but no
bright optical flares have been reported.
Modeling of the K-W 3-channel spectra by
a power law with exponential cutoff model:
dN/dE ~ E^(-alpha)*exp(-E*(2-alpha)/Ep)
yields the following parameters:
--------------------------------------------------
Tstart Tstop alpha Ep (keV)
--------------------------------------------------
P1 -7 80 -1.1+/-0.2 500+/-160
P2 606 703 -1.6+/-0.2 200+/-120
P3 835 1194 -1.4+/-0.2 230+/-50
Total -7 1194 -1.5+/-0.4 280+/-120
--------------------------------------------------
Tstart, Tstop - seconds since the BAT trigger time
As observed by Konus-Wind, the burst had a fluence of (1.13 +/-
0.12)x10^-4 erg/cm2 (in the 20 - 1300 keV energy range).
Assuming z = 1.092 (Cucchiara, Fox & Tanvir, GCN 10065) and a standard
cosmology model with H_0 = 70 km/s/Mpc, Omega_M=0.27, Omega_\Lambda =
0.7, the isotropic energy release E_iso ~3.2x10^53 erg.
All the quoted errors are estimated at the 1 sigma confidence level.
The K-W light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB091024/
- GCN Circular #10086
T. Sakamoto (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
on behalf of the Swift-BAT team:
We reported the BAT refined analysis based on the event-by-event
data only up to T+483 sec (T. Sakamoto et al., GCN Circ. GCN 10072).
Since the Swift spacecraft slewed to the pre-planned target (GRB 091020)
at T+415 sec, GRB 091024 became <5% coding by BAT at T+461 sec. This
is the reason why we only have the mask-weighted light curve data up
to T+483 sec.
However, we do see the 2nd and 3rd episodes reported by Fermi-GBM
(Bissaldi et al., GCN Circ. 10070) and by Konus-Wind and Konus-RF
(Golenetskii et al., GCN Circ. 10083) in the BAT raw light curve data.
Although we can not confirm whether these 2nd and 3rd episodes are
associated with GRB 091024 by the BAT imaging capability, the BAT
observations are consistent with the later peaks being part of GRB 091024.
- GCN Circular #10092
J. Mao (YNAO & INAF-OAB), S. Li and J. Bai (YNAO) report on behalf of the GMG group:
We observed the optical afterglow of GRB 091024 (Marshall et al., GCN 10062) using one 2.4-m telescope located at Gao-Mei-Gu (GMG, Yunnan Observatory) about 3 hours after the trigger. Some preliminary results are shown below:
Start UT Filter mag err
-------------------------------------
11:52:13 R 19.66 0.02
12:54:35 R 20.18 0.03
15:11:33 R 21.03 0.05
All the calibrations were processed by nearby USNO stars in the images and without extinction correction. The detailed analysis is ongoing.
This message might be cited.
- GCN Circular #10093
S. B. Cenko (UC Berkeley), M. M. Kasliwal and S. R. Kulkarni (Caltech)
report on behalf of a larger collaboration:
We have obtained optical spectra of the afterglow of GRB091024 (Marshall
et al., GCN 10062) with the Low Resolution Imaging Spectrometer mounted on
the 10-m Keck I telescope. Observations began at 11:01 UT on 24 October
2009 (~ 2.1 hours after the burst) and covered the wavelength range from ~
3500 - 10000 A.
In addition to the features identified by Cucchiara, Fox, and Tanvir (CaII
H & K, Mg I), we also find strong absorption features we identify as Mg
II (2796 / 2803) and Fe II (2344, 2374, 2382, 2586, and 2600) at a common
redshift of z = 1.091. The lack of Lyman-alpha absorption places an upper
limit of z <~ 1.9 on the redshift of GRB091024.
- GCN Circular #10101
A. Moskvitin, T. Fatkhullin (SAO-RAS Niznijh Arkhyz, Russia),
on behalf of a larger colaboration, report:
We observed the field of the GRB 091024 afterglow (Marshall et al., GCN
10062) with the Zeiss-1000 telescope of SAO RAS, Russia. The observations
were carried out starting from October, 24.651 (15:37 UT) till October,
24.976 (23:26 UT). In total 29 * 300 sec. exposures in the Rc-band and
29 * 300 sec. exposures in the V-band were obtained. During the observations
we detected a faint fading object at the position reported by Mundell et al.
(GCN 10063) as well as a small extended object with R~20.8 in ~2 arcseconds
to the North-West from the afterglow (see also Kann and Laux GCN 10077).
The brightness of the OT in the first stacked R-band images (the mean epoch
is 16:52 UT) is R = 20.7 +/- 0.2 (we admit some contribution in flux from
the extended object). It is not clear at this stage if the extended object
is a host galaxy or a foreground galaxy responsible for the absorption line
system reported by Cucchiara et al. (GCN 10065) and Cenko et al.
(GCN 10093). The data analysis is in progress. Photometry was carried out
using nearby USNO B1.0 stars (R2 magnitudes).
This message may be cited.
- GCN Circular #10114
Aurelien Bouvier (SLAC), Julie McEnery (NASA/GSFC), Jim Chiang
(SLAC), Dan Kocevski (SLAC), Elena Moretti (INFN Trieste), Vlasios
Vasileiou (NASA/GSFC & UMBC) and Frederic Piron (LPTA) report on
behalf of the Fermi LAT team:
We present the flux and fluence upper limits based on the non-
detection of GRB 091024 (trigger 278067360 / 091024372) by the Fermi
Large Area Telescope (Fermi LAT) in the 0.1-300 GeV energy range.
This burst was detected by Swift (GCN 10062) and the Fermi Gamma-ray
Burst Monitor with a first emission interval lasting ~50 sec and a
second emission interval starting ~630 sec after trigger and lasting
more than 400 sec (GCN 10070). The spacecraft performed a repointing
maneuver for this burst which resulted in pointed observation for 5
hours starting ~350 sec after trigger.
No significant emission was detected in the LAT energy range during
any of the time intervals in which the burst was in the LAT field of
view. We computed the 95% CL upper limits using a bayesian method
(Helene O., 1983, N.I.M. 212, 319) and our background estimation tool
(described in Abdo et al. 2009: arXiv:0910.4192) on the LAT energy
flux and fluence for the time interval T0+350 to T0+2000 sec with
respect to the GRB trigger time T0 (08:55:58.47 UT, October 24th
2009) and with an assumed spectral index of -2.2:
- 95% Energy Flux Upper Limit = 9.4e-10 erg/cm^2/sec
- 95% Energy Fluence Upper Limit = 1.5e-6 erg/cm^2
The upper limit results presented above are preliminary; final
results will be published in the Fermi LAT GRB Catalog. 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.
- GCN Circular #10116
V. Rumyantsev, V. Biryukov (CrAO), A. Pozanenko (IKI) report on behalf of
larger GRB follow-up collaboration:
We observed the field of the Swift GRB 091024 (Marshall et al., GCN 10062)
with ZTE telescope of Crimean branch of SAI MSU in R-filter on Oct.24
between (UT) 16:18:50 - 00:04:47 and Oct.25 19:07:19 - 19:48:19 under
moderate seeing of about 3". In initial images we detect fading afterglow
(Mundell et al., GCN 10063). In a combined image of the Oct. 24 the
afterglow looks like extended due to the nearby NW object reported by
Moskvitin et al. (GCN 10101).
In a preliminary data reduction we do not separate afterglow and nearby
object. The astrometry of the afterglow + nearby object is following
Oct.24
RA(J2000): 22 36 59.61
Dc(J2000): +56 53 23.1
with uncertainty of 0.5 arcsec
Oct.25
RA(J2000): 22 36 59.33
Dc(J2000): +56 53 24.5
with uncertainty of 0.5 arcsec
The coordinates of Oct. 24 consistent with afterglow coordinates (Mundell et
al., GCN 10063, Henden et al. GCN 10073, Chornock et al. GCN 10075). The
angular distance between astrometry results is 2.7" suggests a prevalence
of the afterglow on Oct.24 and nearby object on Oct.25. Taking into account
the redshift of z = 1.091 (Cucchiara et al. GCN 10065, Cenko et al. GCN
10093) one can estimate the distance between afterglow and object as 22 kpc
and the nearby object could be the host galaxy of GRB 091024 as suggested
early (Moskvitin et al. GCN 10101).
A preliminary photometry of the afterglow+nearby object is based on
reference star USNO B1.0 1468-0448529 (22 36 55.66 +56 53 04.2) assuming
R=17.30:
T0+ Filter, Exposure, mag., err.
(d) (s)
0.3210 R 600 18.31 +/-0.07
0.3283 R 600 18.56 +/-0.08
0.3356 R 600 18.72 +/-0.08
0.3429 R 600 18.56 +/-0.08
0.3522 R 600 18.73 +/-0.08
0.3595 R 600 18.80 +/-0.09
0.3668 R 600 18.89 +/-0.11
0.3741 R 600 18.70 +/-0.08
0.3814 R 600 19.20 +/-0.16
0.3887 R 600 19.16 +/-0.16
0.3960 R 600 18.86 +/-0.15
0.4076 R 780 19.44 +/-0.34
0.5706 R 1260 19.11 +/-0.08
0.5873 R 1320 19.15 +/-0.09
1.4386 R 2340 20.7 +/- 0.2
We caution that afterglow photometry above is contaminated by the nearby
object which we suggest as a candidate of host galaxy. The combined image
can be found at http://grb.rssi.ru/GRB091024/GRB091024a_091024_R_ZTE.gif
where vertical tick points out the afterglow and horizontal one points out
the nearby object.
- 1101.1099 from 7 Jan 11
D. Gruber et al.: Fermi/GBM observations of the ultra-long GRB 091024: A burst with an optical flash
Briggs, J. M. Burgess, V. L. Chaplin, V. Connaughton, R. Diehl, G. J. Fishman, M. H. Gibby, M. M. Giles, A. Goldstein, S. Guiriec, A. J. van
der Horst, R. M. Kippen, C. Kouveliotou, L. Lin, C. A. Meegan, W. S. Paciesas, R. D. Preece, D. Tierney, C. Wilson-Hodge
In this paper we examine gamma-ray and optical data of GRB 091024, a gamma-ray burst (GRB) with an extremely long duration of T90~1020 s, as
observed with the Fermi Gamma-Ray Burst Monitor (GBM). We present spectral analysis of all three distinct emission episodes using data from
Fermi/GBM. Because of the long nature of this event, many ground-based optical telescopes slewed to its location within a few minutes and thus
were able to observe the GRB during its active period. We compare the optical and gamma-ray light curves. Furthermore, we estimate a lower
limit on the bulk Lorentz factor from the variability and spectrum of the GBM light curve and compare it with that obtained from the peak time
of the forward shock of the optical afterglow. From the spectral analysis we note that, despite its unusually long duration, this burst is
similar to other long GRBs, i.e. there is spectral evolution (both the peak energy and the spectral index vary with time) and spectral lags are
measured. We find that the optical light curve is highly anti-correlated to
the prompt gamma-ray emission, with the optical emission reaching
the maximum during an epoch of quiescence in the prompt emission. We interpret this behavior as the reverse shock (optical flash), expected in
the internal-external shock model of GRB emission but observed only in a handful of GRBs so far. The lower limit on the initial Lorentz factor
deduced from the variability time scale ($\Gamma_{min}=195_{-110}^+{90}$)is consistent within the error to the one obtained using the peak time
of the forward shock ($\Gamma_0=120$) and is also consistent with Lorentz factors of other long GRBs.
- 1310.0313 from 2 Oct 13
F.J. Virgili et al.: GRB 091024A and the nature of ultra-long gamma-ray bursts
We present a broadband study of gamma-ray burst (GRB) 091024A within the context of other ultra-long-duration GRBs. An unusually long burst
detected by Konus-Wind, Swift, and Fermi, GRB 091024A has prompt emission episodes covering ~1300 s, accompanied by bright and highly
structured optical emission captured by various rapid-response facilities, including the 2-m autonomous robotic Faulkes North and Liverpool
Telescopes, KAIT, S-LOTIS, and SRO. We also observed the burst with 8- and 10-m class telescopes and determine the redshift to be z = 1.0924
\pm 0.0004. We find no correlation between the optical and gamma-ray peaks and interpret the optical light curve as being of external origin,
caused by the reverse and forward shock of a highly magnetized jet (R_B ~ 100-200). Low-level emission is detected throughout the
near-background quiescent period between the first two emission episodes of the Konus-Wind data, suggesting continued central-engine activity;
we discuss the implications of this ongoing emission and its impact on the afterglow evolution and predictions. We summarize the varied sample
of historical GRBs with exceptionally long durations in gamma-rays (>~ 1000 s) and discuss the likelihood of these events being from a separate
population.
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