Gamma-ray Burst 051001

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 01 Oct 05 11:12:54 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     157870,   Seg_Num: 0
GRB_RA:          350.973d {+23h 23m 53s} (J2000),
                 351.049d {+23h 24m 12s} (current),
                 350.304d {+23h 21m 13s} (1950)
GRB_DEC:         -31.528d {-31d 31' 39"} (J2000),
                 -31.496d {-31d 29' 45"} (current),
                 -31.802d {-31d 48' 08"} (1950)
GRB_ERROR:       4.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=1401 [image_cnts]
TRIGGER_DUR:     64.000 [sec] 
TRIGGER_INDEX:   20000     E_range: 15-50 keV
BKG_INTEN:       0 [cnts]
BKG_TIME:        0.00 SOD {00:00:00.00} UT
BKG_DUR:         0 [sec]
GRB_DATE:        13644 TJD;   274 DOY;   05/10/01
GRB_TIME:        40296.24 SOD {11:11:36.24} UT
GRB_PHI:          13.30 [deg]
GRB_THETA:        29.33 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    7.29 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  -3  +0  +0 +78  +1 
SUN_POSTN:       187.69d {+12h 30m 47s}   -3.32d {-03d 19' 16"}
SUN_DIST:        141.75 [deg]
MOON_POSTN:      168.38d {+11h 13m 32s}   +7.73d {+07d 43' 44"}
MOON_DIST:       156.10 [deg]
MOON_ILLUM:      4 [%]
GAL_COORDS:       14.69,-70.45 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      338.55,-25.25 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
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.

red DSS finding chart ps-file

GCN/SWIFT NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 01 Oct 05 11:15:18 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     157870,   Seg_Num: 0
GRB_RA:          350.9546d {+23h 23m 49.1s} (J2000),
                 351.0313d {+23h 24m 07.5s} (current),
                 350.2861d {+23h 21m 08.6s} (1950)
GRB_DEC:         -31.5210d {-31d 31' 15.6"} (J2000),
                 -31.4894d {-31d 29' 21.7"} (current),
                 -31.7957d {-31d 47' 44.4"} (1950)
GRB_ERROR:       5.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       2099.07 [arb]
GRB_SIGNIF:      10.67 [sigma]
GRB_DATE:        13644 TJD;   274 DOY;   05/10/01
GRB_TIME:        40481.84 SOD {11:14:41.84} UT     [Start of CCD integration]
TAM[0-3]:        327.68 237.15 261.30 243.04
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       187.70d {+12h 30m 47s}   -3.32d {-03d 19' 19"}
SUN_DIST:        141.75 [deg]
MOON_POSTN:      168.41d {+11h 13m 38s}   +7.72d {+07d 43' 01"}
MOON_DIST:       156.10 [deg]
MOON_ILLUM:      4 [%]
GAL_COORDS:       14.72,-70.44 [deg] galactic lon,lat of the burst
ECL_COORDS:      338.54,-25.24 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        WARNING: XRT alignment calibration is on-going, and there may be  
COMMENTS:        residual systematic offsets of several arcseconds not accounted for yet  
COMMENTS:        by our on-board position determination algorithm.  We have increased  
COMMENTS:        the estimated error circle radius to take this into account.

GCN/SWIFT NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 01 Oct 05 11:15:55 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     157870,   Seg_Num: 0
GRB_RA:          350.973d {+23h 23m 53s} (J2000),
                 351.049d {+23h 24m 12s} (current),
                 350.304d {+23h 21m 13s} (1950)
GRB_DEC:         -31.528d {-31d 31' 39"} (J2000),
                 -31.496d {-31d 29' 45"} (current),
                 -31.802d {-31d 48' 08"} (1950)
GRB_DATE:        13644 TJD;   274 DOY;   05/10/01
GRB_TIME:        40296.24 SOD {11:11:36.24} UT
TRIGGER_INDEX:   20000
GRB_PHI:          13.30 [deg]
GRB_THETA:        29.33 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     64.000 [sec] 
LC_URL:          sw00157870000msb.lc
SUN_POSTN:       187.69d {+12h 30m 47s}   -3.32d {-03d 19' 16"}
SUN_DIST:        141.75 [deg]
MOON_POSTN:      168.38d {+11h 13m 32s}   +7.73d {+07d 43' 44"}
MOON_DIST:       156.10 [deg]
MOON_ILLUM:      4 [%]
GAL_COORDS:       14.69,-70.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      338.55,-25.25 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-BAT GRB Lightcurve.  
COMMENTS:           
COMMENTS:        The next comments were copied from the BAT_POS Notice:  
COMMENTS:        This is an image 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.

GCN/SWIFT NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 01 Oct 05 11:16:47 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     157870,   Seg_Num: 0
POINT_RA:        350.952d {+23h 23m 49s} (J2000)
POINT_DEC:       -31.476d {-31d 28' 34"} (J2000)
POINT_ROLL:      207.593d
GRB_DATE:        13644 TJD;   274 DOY;   05/10/01
GRB_TIME:        40485.31 SOD {11:14:45.31} UT
FILTER:          3, V
BKG_MEAN:        0.364
N_STARS:         16
X_OFFSET:        541 [pixels]
Y_OFFSET:        658 [pixels]
X_MAX:           1500 [pixels]
Y_MAX:           1617 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw00157870000msufc.fits
SUN_POSTN:       187.70d {+12h 30m 47s}   -3.32d {-03d 19' 19"}
SUN_DIST:        141.79 [deg]
MOON_POSTN:      168.41d {+11h 13m 38s}   +7.72d {+07d 43' 00"}
MOON_DIST:       156.15 [deg]
MOON_ILLUM:      4 [%]
GAL_COORDS:       14.85,-70.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      338.56,-25.20 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN/SWIFT NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 01 Oct 05 11:17:44 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     157870,   Seg_Num: 0
POINT_RA:        350.952d {+23h 23m 49s} (J2000)
POINT_DEC:       -31.476d {-31d 28' 34"} (J2000)
ROLL:            207.593d
GRB_DATE:        13644 TJD;   274 DOY;   05/10/01
GRB_TIME:        40485.31 SOD {11:14:45.31} UT
FILTER:          3, V
EXPOSURE_ID:     149858085
X_OFFSET:        861 [pixels]
Y_OFFSET:        978 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1021
Y_GRB_POS:       1138
BINNING_INDEX:   1
IM_URL:          sw00157870000msuni.fits
SUN_POSTN:       187.70d {+12h 30m 47s}   -3.32d {-03d 19' 19"}
SUN_DIST:        141.79 [deg]
MOON_POSTN:      168.41d {+11h 13m 38s}   +7.72d {+07d 43' 00"}
MOON_DIST:       156.15 [deg]
MOON_ILLUM:      4 [%]
GAL_COORDS:       14.85,-70.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      338.56,-25.20 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN/SWIFT NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 01 Oct 05 11:18:24 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     157870,   Seg_Num: 0
POINT_RA:        350.952d {+23h 23m 49s} (J2000)
POINT_DEC:       -31.476d {-31d 28' 34"} (J2000)
ROLL:            207.593d
GRB_DATE:        13644 TJD;   274 DOY;   05/10/01
GRB_TIME:        40485.31 SOD {11:14:45.31} UT
FILTER:          3, V
EXPOSURE_ID:     149858085
X_OFFSET:        861 [pixels]
Y_OFFSET:        978 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1021
Y_GRB_POS:       1138
BINNING_INDEX:   1
IM_URL:          sw00157870000msuni.fits
SUN_POSTN:       187.70d {+12h 30m 47s}   -3.32d {-03d 19' 19"}
SUN_DIST:        141.79 [deg]
MOON_POSTN:      168.41d {+11h 13m 38s}   +7.72d {+07d 43' 00"}
MOON_DIST:       156.15 [deg]
MOON_ILLUM:      4 [%]
GAL_COORDS:       14.85,-70.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      338.56,-25.20 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_sources_image.fits file does not exist; skipping the attachment.  
COMMENTS:        The uvot_catalog_image.fits file does not exist; skipping the attachment.

GCN/SWIFT NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 01 Oct 05 11:18:25 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     157870,   Seg_Num: 0
POINT_RA:        350.952d {+23h 23m 49s} (J2000)
POINT_DEC:       -31.476d {-31d 28' 34"} (J2000)
POINT_ROLL:      207.593d
GRB_DATE:        13644 TJD;   274 DOY;   05/10/01
GRB_TIME:        40485.31 SOD {11:14:45.31} UT
FILTER:          3, V
BKG_MEAN:        0.364
N_STARS:         16
X_OFFSET:        541 [pixels]
Y_OFFSET:        658 [pixels]
X_MAX:           1500 [pixels]
Y_MAX:           1617 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw00157870000msufc.fits
SUN_POSTN:       187.70d {+12h 30m 47s}   -3.32d {-03d 19' 19"}
SUN_DIST:        141.79 [deg]
MOON_POSTN:      168.41d {+11h 13m 38s}   +7.72d {+07d 43' 00"}
MOON_DIST:       156.15 [deg]
MOON_ILLUM:      4 [%]
GAL_COORDS:       14.85,-70.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      338.56,-25.20 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_sources_srclist.fits file does not exist; skipping the attachment.  
COMMENTS:        The uvot_catalog_srclist.fits file does not exist; skipping the attachment.

GCN notice #4050
E.S. Rykoff (U Mich), H. Swan (U Mich), B. Schaefer (Louisiana State), S.A. Yost (U Mich), F. Yuan (U Mich) report on behalf of the ROTSE collaboration:
ROTSE-IIIa, located at Siding Spring Observatory, Australia, responded to GRB 051001 (Swift trigger 157870), producing images beginning 7.9 s after the GCN notice time. An automated response took the first image at 11:13:01.9 UT, 85.6 s after the burst, under fair conditions. We took 10 5-sec, 10 20-sec and 20+ 60-sec eposures. Observations are ongoing. These unfiltered images are calibrated relative to USNO A2.0 (R).
Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma BAT error circle (or the possible X-ray position from the GCN notice), for both single images and coadding into sets of 10. Individual images have limiting magnitudes ranging from 16.1-17.4; we set the following specific limits.
```
start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
11:13:01.9   11:13:06.9         5     16.2           85.6       N
11:13:01.9   11:15:25.9       144     17.7           85.6       Y     
11:15:26.6   11:20:19.6       293     18.1          230.3       Y
```
GCN notice #4051
A. Moretti (OAB), J. Cummings (GSFC-NRC), N. Gehrels (GSFC), S. Hunsberger (PSU), H. Krimm (GSFC-USRA), C. Markwardt (GSFC-UMD), F. Marshall (GSFC), D. Palmer (LANL), P. Romano (OAB), on behalf of the Swift team:
GRB 051001: Swift Detection of a Burst
At 11:11:36 UT, Swift-BAT triggered and located GRB051001 (trigger=157870). The spacecraft slewed immediately, which in this case was 75 seconds after the image trigger. The BAT on-board calculated location is RA,Dec 350.973d, -31.528d {23h 23m 53s, -31d 31' 39"} (J2000), with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). Since this was an image trigger there is no obvious information in the light curve.
XRT began observing the field at 11:14:42, 185 seconds after the BAT trigger. Onboard centroiding found a bright fading uncatalogued X-ray source in the field of view at the following coordinates:
```
RA(J2000):   23h 23m 49.1
Dec(J2000):  -31d 31' 15.6"
```
We estimate the uncertainty of this position to be 6 arcseconds (radius, 90% containment). This position is 61 arcseconds from the BAT position above.
UVOT began observing the field 189 seconds after the trigger. The small image does not overlap the XRT error circle. No new source was seen in the list of sources from the entire UVOT field of view.
We are currently in the portion of the orbits where the spacecraft does not pass over the Malindi downlink station. Therefore, it will be at least four hours before we have access to the full data set for the refined analyses.
GCN notice #4052
T. Sakamoto (GSFC/NRC), L. Angelini (GSFC-JHU), L. Barbier (GSFC), S. Barthelmy (GSFC), M. Chester (PSU), J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), G. Sato (ISAS), J. Tueller (GSFC), on behalf of the Swift-BAT team:
Using the data set from T-300 to T+300 sec from the recent telemetry downlink, we report further analysis of Swift-BAT GRB 051001 (trigger #157870) (Moretti, et al., GCN 4051). The refined BAT ground position is (RA,Dec) = 350.990,-31.523 {23h 23m 57.7s, -31d 31' 23.6"} [deg; J2000] +-2.3 arcmin, (radius, sys+stat, 90% containment). This is 1.8 arcmin from the XRT flight centroid and 0.9 arcmin from the BAT position derived onboard. The partial coding was 74 %.
The mask-weighted light curve shows very broad emission starting at ~10 sec before the trigger and extending to T+195 sec. There are two main peaks: from T-10 to T+60 sec, and a stronger one from T+80 to T+180 and weak peaks ~T+185 to T+195 and T+230 to T+240 sec. There is no significant emission in the BAT energy range after T+240 out to T+1400 sec. With such a low level light curve it is difficult to estimate the duration, but our best estimate of T90 (15-350 keV) is 190 +- 10 sec (estimated error including systematics).
The power law index of the time-averaged spectrum is 2.10 +- 0.15. The fluence in the 15-150 keV band is (1.8 +- 0.15) x 10^6 erg/cm2. The 1-sec peak photon flux measured from T0+153.3 sec in the 15-150 keV band is (0.51 +- 0.12) ph/cm2/sec. All the quoted errors are at the 90% confidence level.
GCN notice #4053
E. Rol (U. of Leicester), A. Levan, N. Tanvir (U. of Hertfordshire), report on behalf of a larger collaboration:
We have observed the field of GRB 051001 (Moretti, GCN 4051) with the IRIS2 instrument on the Anglo-Australian Telescope. Two epochs of observations were performed in each of the ZJHKs bands, roughly 2 hours and 6 hours after the trigger, respectively. Our observations covered the entire BAT error box, albeit with a small section (<5%) on the edge of the FOV. Comparison between the two epochs shows no variable sources.
Inside the XRT error circle, one source is visible, which appears to be extended. Its location is, calibrated to the 2MASS:
```
  RA    23:23:49.04    (J2000)
  Dec  -31:31:18.8     (J2000)
```
with an estimated error of 0.16" in each coordinate.
Magnitude estimates for the first epoch, calibrated with respect to the 2MASS, are as follows:
```
 filter   mid-time      exposure     magnitude        limiting
         after trigger    time      of extended        magnitude
           (hours)      (minutes)    source           (3 sigma)
   Ks       1.40           20         18.7 (0.1)        20.3
   H        1.85           20         20.0 (0.1)        20.7
   J        2.36           10         20.9 (0.3)        20.7
```
The first epoch Ks image can be seen at http://www.star.le.ac.uk/~er45/grb051001/
GCN notice #4054
D.B. Fox (Penn State), N.E.D. Noel (Instituto de Astrofisica de Canarias), and S.L. Prior (RSAA/ANU), with B.A. Peterson and B.P. Schmidt (RSAA/ANU) report:
"We have observed the Swift XRT localization region for GRB 051001 (Swift Trigger 157870; Moretti et al., GCN 4051) with the 40-inch telescope at Siding Spring Observatory. A coadded I-band image with mean epoch 1 October 11:53 UT (52 minutes after the burst) reveals no sources within this region, to a limiting magnitude of I>20.8 mag as calibrated against the photometry of the USNO-B1.0 catalog.
In particular, we do not detect the extended object of Rol, Levan & Tanvir (GCN 4053) to the quoted limit."
GCN notice #4055
P. Tristram (Univ. of Canterbury), M. Jelinek, A. J. Castro-Tirado, A. de Ugarte Postigo, S. Guziy, J. Gorosabel (IAA-CSIC, Granada) and Ph. Yock (Univ. of Auckland)
report:
"Following the detection of GRB 051001 by SWIFT (Krimm et al. GCN 4052), we have imaged the entire error box with the 0.6-m (+MOA camera) at Mt. John Observatory in wide R- and B-band filters (8 x 300-s each) starting on Oct 1.48 UT (i.e. 45 min after the event). We do not detect the object reported by Rol et al. (GCNC 4053) within the SWIFT/XRT error box (Moretti et al. GCN 4051) down to R about 21.5 ."
GCN notice #4056
A. Moretti (INAF-OAB), P. Romano (INAF-OAB), G. Tagliaferri (INAF-OAB), S. Campana (INAF-OAB), G. Chincarini (INAF-OAB), M. Chester (PSU), P. Boyd (GSFC-UMBC), on behalf of the Swift-XRT Team report.
We have analyzed the Swift XRT data from the first day of observation of GRB 051001 (Moretti et al., GCN 4051). As already reported an uncatalogued, fading X-ray source was detected by XRT. The refined position of the source is
```
RA(J2000): 23 23 48.8   
Dec(J2000):-31 31 17.0
```
We estimate an uncertainty of 6 arcseconds radius (90% containment).
The observations started in Windowed Timing (WT) 192 seconds from the BAT trigger. The light curve shows a fast decay in the first orbit with a slope of -2.9+-0.1. Since the second orbit onward the decay has been flatter, with a power law slope of -0.65+-0.10. The spectral fit (simple absorbed power-law) to the WT data yields a photon index of 1.48-/+0.02 in the [0.2-10] keV band. The derived NH is (1.3)E21 cm^-2, which is higher than the Galactic value (1.4E+20 cm-2; Dickey & Lockman 1990).
The unabsorbed 0.5-10.0 keV flux of the afterglow at 24 hours after the burst is then estimated to be 2E-13 ergs/s/cm2.
GCN notice #4058
F. Marshall(GSFC), A. Moretti (OAB), J. Nousek (PSU), W. Voges (MPE), N. Gehrels (GSFC) report on behalf of the Swift/UVOT team.
The Swift/UVOT instrument began observing the field of the burst GRB051001 at 11:14:45 UT, 189 seconds after the BAT trigger (Moretti et al., GCN 4051).
Within the 6 arcsec radius XRT error circle (GCN 4051), no new optical/UV source is detected. We derive the following 3-sigma upper limit magnitudes on any optical/UV counterpart in the summed images in each UVOT filter (from 6" radius apertures centered on the XRT location, which is representative of the local background).
```
     Filter    T_range(sec)  Exp(sec)  3-sig UL

       V           189-289       100     18.9
       V         189-11522      1189     20.1
       B          335-6646      1077     21.2
       U          321-5738      1106     21.0
       UVW1      307-13221       952     20.9
       UVW2    11530-12429       900     21.4
       UVM2      6655-7435       780     21.5
```
New/revised redshift from the TOUGH project, in particular: 1205.3162 1205.3490 1205.3779 1205.4036

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Jochen Greiner, last update: 08-Jul-2012 [Disclaimer]