Gamma-ray Burst 081101

(All information courtesy of the instrument teams.)

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Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 01 Nov 08 11:46:48 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      47
TRIGGER_NUM:     247232793
GRB_RA:           93.567d {+06h 14m 16s} (J2000),
                  93.689d {+06h 14m 45s} (current),
                  92.873d {+06h 11m 29s} (1950)
GRB_DEC:         +10.900d {+10d 54' 00"} (J2000),
                 +10.897d {+10d 53' 49"} (current),
                 +10.916d {+10d 54' 56"} (1950)
GRB_ERROR:       14.25 [deg radius, statistical only]
GRB_INTEN:       334 [cnts/sec]
DATA_SIGNIF:     7.80 [sigma]
INTEG_TIME:      0.256 [sec]
GRB_DATE:        14771 TJD;   306 DOY;   08/11/01
GRB_TIME:        42392.06 SOD {11:46:32.06} UT
GRB_PHI:         141.00 [deg]
GRB_THETA:        40.00 [deg]
HARD_RATIO:      0.78
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      79%  GRB
2nd_MOST_LIKELY:  13%  GRO_J0422_32
DETECTORS:       0,0,0, 0,0,0, 0,0,0, 1,1,0, 0,0,
SUN_POSTN:       217.03d {+14h 28m 07s}  -14.63d {-14d 37' 56"}
SUN_DIST:        124.75 [deg]   Sun_angle= 8.2 [hr] (West of Sun)
MOON_POSTN:      257.16d {+17h 08m 38s}  -27.02d {-27d 00' 57"}
MOON_DIST:       157.60 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      198.99, -3.15 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       93.59,-12.49 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 01 Nov 08 11:46:58 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     333320,   Seg_Num: 0
GRB_RA:           95.826d {+06h 23m 18s} (J2000),
                  95.940d {+06h 23m 46s} (current),
                  95.186d {+06h 20m 45s} (1950)
GRB_DEC:          -0.082d {-00d 04' 55"} (J2000),
                  -0.087d {-00d 05' 13"} (current),
                  -0.055d {-00d 03' 19"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1914 [cnts]    Image_Peak=170 [image_cnts]
TRIGGER_DUR:     0.256 [sec]
TRIGGER_INDEX:   123     E_range: 25-100 keV
BKG_INTEN:       31417 [cnts]
BKG_TIME:        42380.77 SOD {11:46:20.77} UT
BKG_DUR:         8 [sec]
GRB_DATE:        14771 TJD;   306 DOY;   08/11/01
GRB_TIME:        42391.97 SOD {11:46:31.97} UT
GRB_PHI:          66.13 [deg]
GRB_THETA:        26.17 [deg]
SOLN_STATUS:     0xD
RATE_SIGNIF:     28.17 [sigma]
IMAGE_SIGNIF:    11.53 [sigma]
MERIT_PARAMS:     +0  +0 +100  -2  +2 +10  +0  +1 +49  +0
SUN_POSTN:       217.03d {+14h 28m 07s}  -14.63d {-14d 37' 56"}
SUN_DIST:        119.95 [deg]   Sun_angle= 8.1 [hr] (West of Sun)
MOON_POSTN:      257.16d {+17h 08m 38s}  -27.02d {-27d 00' 57"}
MOON_DIST:       147.43 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      209.79, -6.29 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       96.35,-23.39 [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 matches a source in the on-board catalog: Num=10030=A0620-00,   delta=0.308 [deg].
COMMENTS:        This does not match any source in the ground catalog.
COMMENTS:        This is not a GRB.
COMMENTS:        This is an interesting source.
COMMENTS:        This trigger occurred at longitude,latitude = 237.25,15.94 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 01 Nov 08 11:47:33 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     247232793
GRB_RA:           91.920d {+06h 07m 41s} (J2000),
                  92.043d {+06h 08m 10s} (current),
                  91.225d {+06h 04m 54s} (1950)
GRB_DEC:         +11.100d {+11d 05' 60"} (J2000),
                 +11.098d {+11d 05' 54"} (current),
                 +11.108d {+11d 06' 28"} (1950)
GRB_ERROR:       11.46 [deg radius, statistical only]
DATA_SIGNIF:     8.30 [sigma]
DATA_INTERVAL:   0.256 [sec]
GRB_DATE:        14771 TJD;   306 DOY;   08/11/01
GRB_TIME:        42392.06 SOD {11:46:32.06} UT
GRB_PHI:         143.00 [deg]
GRB_THETA:        41.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   1 (Gnd S/W Version number)
SUN_POSTN:       217.03d {+14h 28m 07s}  -14.63d {-14d 37' 57"}
SUN_DIST:        126.37 [deg]   Sun_angle= 8.3 [hr] (West of Sun)
MOON_POSTN:      257.17d {+17h 08m 40s}  -27.02d {-27d 00' 57"}
MOON_DIST:       158.80 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      198.04, -4.47 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       91.93,-12.33 [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 01 Nov 08 11:50:14 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     333320,   Seg_Num: 0
GRB_RA:           95.826d {+06h 23m 18s} (J2000),
                  95.940d {+06h 23m 46s} (current),
                  95.186d {+06h 20m 45s} (1950)
GRB_DEC:          -0.082d {-00d 04' 55"} (J2000),
                  -0.087d {-00d 05' 13"} (current),
                  -0.055d {-00d 03' 19"} (1950)
GRB_DATE:        14771 TJD;   306 DOY;   08/11/01
GRB_TIME:        42391.97 SOD {11:46:31.97} UT
TRIGGER_INDEX:   123
GRB_PHI:          66.13 [deg]
GRB_THETA:        26.17 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     0.256 [sec]
SOLN_STATUS:     0xD
RATE_SIGNIF:     28.17 [sigma]
IMAGE_SIGNIF:    11.53 [sigma]
LC_URL:          sw00333320000msb.lc
SUN_POSTN:       217.03d {+14h 28m 08s}  -14.63d {-14d 37' 59"}
SUN_DIST:        119.95 [deg]   Sun_angle= 8.1 [hr] (West of Sun)
MOON_POSTN:      257.19d {+17h 08m 46s}  -27.02d {-27d 01' 01"}
MOON_DIST:       147.45 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      209.79, -6.29 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       96.35,-23.39 [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 matches a source in the on-board catalog.
COMMENTS:        This does not match any source in the ground catalog.
COMMENTS:        This is not a GRB.
COMMENTS:        This is an interesting source.
COMMENTS:        This trigger occurred at longitude,latitude = 237.25,15.94 [deg].

GCN Circular #8457
M. Stamatikos (NASA/ORAU), S. D. Barthelmy (GSFC), N. Gehrels (NASA/GSFC), N. P. M. Kuin (MSSL), V. La Parola (INAF-IASFPA), C. B. Markwardt (CRESST/GSFC/UMD), D. M. Palmer (LANL) and P. Romano (INAF-IASFPA) report on behalf of the Swift Team:
At 11:46:31 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 081101 (trigger=333320). Swift did not slew because of the low merit value assignment because of the chance spatial coincidence with the A0620-00 blackhole candidate source. The BAT on-board calculated location is RA, Dec 95.826, -0.082 which is
```
   RA(J2000)  =  06h 23m 18s
   Dec(J2000) = -00d 04' 55"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single hard spike with a duration of less than 128 msec. The peak count rate was ~7000 counts/sec (15-350 keV), at ~0 sec after the trigger. We can not rule out that this was from A0620-00, although the position is a very unlikely 18 arcmin away. Thus, we believe this to be a gamma-ray burst, or possibly a new SGR (although the spectrum is harder than typical SGR bursts).
Burst Advocate for this burst is M. Stamatikos (michael 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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 01 Nov 08 13:41:56 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     333320,   Seg_Num: 0
POINT_RA:         95.847d {+06h 23m 23s} (J2000)
POINT_DEC:        -0.088d {-00d 05' 14"} (J2000)
POINT_ROLL:      107.080d
IMG_START_DATE:  14771 TJD;   306 DOY;   08/11/01
IMG_START_TIME:  49085.73 SOD {13:38:05.73} UT,   6693.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.784
N_STARS:         190
X_OFFSET:        337 [pixels]
Y_OFFSET:        648 [pixels]
X_MAX:           1296 [pixels]
Y_MAX:           1607 [pixels]
DET_THRESH:      18
PHOTO_THRESH:    11
SL_URL:          sw00333320000msufc6693.fits
SUN_POSTN:       217.11d {+14h 28m 26s}  -14.66d {-14d 39' 28"}
SUN_DIST:        120.00 [deg]   Sun_angle= 8.1 [hr] (West of Sun)
MOON_POSTN:      258.22d {+17h 12m 54s}  -27.05d {-27d 02' 57"}
MOON_DIST:       147.95 [deg]
MOON_ILLUM:      12 [%]
GAL_COORDS:      209.80, -6.28 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       96.37,-23.40 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 01 Nov 08 13:38:09 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     333320,   Seg_Num: 0
POINT_RA:         95.847d {+06h 23m 23s} (J2000)
POINT_DEC:        -0.087d {-00d 05' 14"} (J2000)
IMG_START_DATE:  14771 TJD;   306 DOY;   08/11/01
IMG_START_TIME:  49081.49 SOD {13:38:01.49} UT,   6689.5 [sec] since BAT Trigger Time
COUNTS:          1    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        0    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 01 Nov 08 13:42:36 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     333320,   Seg_Num: 0
POINT_RA:         95.847d {+06h 23m 23s} (J2000)
POINT_DEC:        -0.088d {-00d 05' 14"} (J2000)
POINT_ROLL:      107.080d
IMG_START_DATE:  14771 TJD;   306 DOY;   08/11/01
IMG_START_TIME:  49085.73 SOD {13:38:05.73} UT,   6693.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.784
N_STARS:         190
X_OFFSET:        337 [pixels]
Y_OFFSET:        648 [pixels]
X_MAX:           1296 [pixels]
Y_MAX:           1607 [pixels]
DET_THRESH:      18
PHOTO_THRESH:    11
SL_URL:          sw00333320000msufc6693.fits
SUN_POSTN:       217.11d {+14h 28m 26s}  -14.66d {-14d 39' 28"}
SUN_DIST:        120.00 [deg]   Sun_angle= 8.1 [hr] (West of Sun)
MOON_POSTN:      258.23d {+17h 12m 55s}  -27.05d {-27d 02' 58"}
MOON_DIST:       147.95 [deg]
MOON_ILLUM:      12 [%]
GAL_COORDS:      209.80, -6.28 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       96.37,-23.40 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 01 Nov 08 13:43:25 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     333320,   Seg_Num: 0
POINT_RA:         95.847d {+06h 23m 23s} (J2000)
POINT_DEC:        -0.088d {-00d 05' 14"} (J2000)
ROLL:            107.080d
IMG_START_DATE:  14771 TJD;   306 DOY;   08/11/01
IMG_START_TIME:  49085.73 SOD {13:38:05.73} UT,   6693.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     247239488
X_OFFSET:        656 [pixels]
Y_OFFSET:        967 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       816
Y_GRB_POS:       1127
BINNING_INDEX:   1
IM_URL:          sw00333320000msuni6693.fits
SUN_POSTN:       217.11d {+14h 28m 26s}  -14.66d {-14d 39' 29"}
SUN_DIST:        120.00 [deg]   Sun_angle= 8.1 [hr] (West of Sun)
MOON_POSTN:      258.24d {+17h 12m 57s}  -27.05d {-27d 02' 59"}
MOON_DIST:       147.95 [deg]
MOON_ILLUM:      12 [%]
GAL_COORDS:      209.80, -6.28 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       96.37,-23.40 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 01 Nov 08 13:43:47 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     333320,   Seg_Num: 0
POINT_RA:         95.847d {+06h 23m 23s} (J2000)
POINT_DEC:        -0.088d {-00d 05' 14"} (J2000)
ROLL:            107.080d
IMG_START_DATE:  14771 TJD;   306 DOY;   08/11/01
IMG_START_TIME:  49085.73 SOD {13:38:05.73} UT,   6693.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     247239488
X_OFFSET:        656 [pixels]
Y_OFFSET:        967 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       816
Y_GRB_POS:       1127
BINNING_INDEX:   1
IM_URL:          sw00333320000msuni6693.fits
SUN_POSTN:       217.11d {+14h 28m 26s}  -14.66d {-14d 39' 29"}
SUN_DIST:        120.00 [deg]   Sun_angle= 8.1 [hr] (West of Sun)
MOON_POSTN:      258.24d {+17h 12m 58s}  -27.05d {-27d 03' 00"}
MOON_DIST:       147.95 [deg]
MOON_ILLUM:      12 [%]
GAL_COORDS:      209.80, -6.28 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       96.37,-23.40 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_sources_image.fits.gz file does not exist; skipping the attachment.

GCN Circular #8458
S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), M. Stamatikos (GSFC/ORAU), J. Kennea (PSU), V. Mangano (INAF-IASFPa), V. LaParola (INAF-IASFPA), P. Romano (INAF-IASFPA), N. P. M. Kuin (MSSL) (on behalf of the Swift-BAT/-XRT teams):
Using the data set from T-239 to T+963 sec from recent telemetry downlinks, we report further analysis of BAT GRB 081101 (trigger #333320) (Stamatikos, et al., GCN Circ. 8457). The BAT ground-calculated position is RA, Dec = 95.836, -0.112 deg, which is
```
   RA(J2000)  =  06h 23m 20.7s 
   Dec(J2000) = -00d 06' 41.5" 
```
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 50%.
The mask-weighted light curve shows a single spike starting at ~T-0.05 sec, peaking at ~T+0.1 sec, and ending by ~T+0.3 sec. T90 (15-350 keV) is 0.20 +- 0.02 sec (estimated error including systematics).
The time-averaged spectrum from T+0.0 to T+0.2 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index -0.24 +- 1.12, and Epeak of 78 +- 34 keV (chi squared 62.8 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 6.2 +- 1.0 x 10^-8 erg/cm2 and the 1-sec peak flux measured from T-0.38 sec in the 15-150 keV band is 3.6 +- 0.5 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.25 +- 0.20 (chi squared 69.9 for 57 d.o.f.). All the quoted errors are at the 90% confidence level.
The BAT results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/333320/BA/
Swift/XRT began observing the field at 13:37:56 UT, 111 minutes after the BAT trigger, and observed the field in photon counting mode for 200 sec. No point sources were detected in the field of view. Observations of this field are ongoing.
Given the short single spike form of the BAT lightcurve and the somewhat soft spectral values, this suggests that this is an SGR. We can not rule out a GRB explanation of this event.
GCN Circular #8459
V. La Parola, V. Mangano, B. Sbarufatti (INAF-IASF PA) report on behalf of the Swift-XRT team
We have analysed the Swift-XRT follow-up observation of the source (trigger #333320; Stamatikos, et al., GCN Circ. 8457) started on 2008-11-01 14:49:13 UT (about 11 ks after the trigger). In the first 3.4 ks of data no source is detected within the BAT refined error circle (Barthelmy, et al., GCN Circ. 8458) down to a limiting flux of 1.4e-13 erg cm^-2 s^-1.
This is an official product of the Swift-XRT team.
GCN Circular #8460
A. von Kienlin (MPE), E. Bissaldi (MPE), M.S. Briggs (UAHuntsville) and C. Kouveliotou (NASA/MSFC) report on behalf of the Fermi GBM Team:
"At 11:46:32 UT on 01 November 2008, the Fermi GBM triggered and located an event (trigger 247232793 / 081101491) which was also seen by SWIFT (Stamatikos et al. 2008, GCN 8457, Barthelmy et al. 2008, GCN 8458). The GBM on-ground location is consistent with the Swift position.
The GBM light curve shows a single peak with duration of about 224 ms. The event is significantly detected with GBM between 40 - 200 keV. The time-averaged spectrum from T0-0.103 s to T0+0.121 s is best fit by a single power law with index -1.14 +/- 0.07 (chi squared 212 for 234 d.o.f.). The event fluence (50-300 keV) in the same time interval is (1.6 +/- 0.08) E-07 erg/cm^2.
The Swift team suggested that the event could be a possible new Soft Gamma Repeater (SGR 0623-0006). The GBM spectrum is more consistent with that of a faint short GRB; the lack of photons below 40 keV is rather unusual for an SGR.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."

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Jochen Greiner, last update: 02-Nov-2008 [Disclaimer]