Gamma-ray Burst 060728

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 28 Jul 06 22:25:49 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     221627,   Seg_Num: 0
GRB_RA:           16.694d {+01h 06m 46s} (J2000),
                  16.768d {+01h 07m 04s} (current),
                  16.123d {+01h 04m 29s} (1950)
GRB_DEC:         -41.386d {-41d 23' 10"} (J2000),
                 -41.351d {-41d 21' 04"} (current),
                 -41.653d {-41d 39' 11"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=1452 [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:        13944 TJD;   209 DOY;   06/07/28
GRB_TIME:        80670.65 SOD {22:24:30.65} UT
GRB_PHI:         158.43 [deg]
GRB_THETA:         7.12 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    7.18 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  -3  +0  +0 +47  +1 
SUN_POSTN:       128.06d {+08h 32m 15s}  +18.85d {+18d 50' 46"}
SUN_DIST:        118.13 [deg]   Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN:      168.56d {+11h 14m 15s}   +5.71d {+05d 42' 39"}
MOON_DIST:       136.38 [deg]
MOON_ILLUM:      13 [%]
GAL_COORDS:      291.45,-75.40 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      354.81,-43.81 [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.  
COMMENTS:        This trigger occurred at longitude,latitude = 141.90,-1.63 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 28 Jul 06 22:27:45 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     221627,   Seg_Num: 0
POINT_RA:         16.711d {+01h 06m 51s} (J2000)
POINT_DEC:       -41.382d {-41d 22' 52"} (J2000)
IMG_START_DATE:  13944 TJD;   209 DOY;   06/07/28
IMG_START_TIME:  80795.17 SOD {22:26:35.17} UT,   124.5 [sec] since BAT Trigger Time
COUNTS:          3    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 28 Jul 06 22:29:40 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     221627,   Seg_Num: 0
GRB_RA:           16.694d {+01h 06m 46s} (J2000),
                  16.768d {+01h 07m 04s} (current),
                  16.123d {+01h 04m 29s} (1950)
GRB_DEC:         -41.386d {-41d 23' 10"} (J2000),
                 -41.351d {-41d 21' 04"} (current),
                 -41.653d {-41d 39' 11"} (1950)
GRB_DATE:        13944 TJD;   209 DOY;   06/07/28
GRB_TIME:        80670.65 SOD {22:24:30.65} UT
TRIGGER_INDEX:   20000
GRB_PHI:         158.43 [deg]
GRB_THETA:         7.12 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     64.000 [sec] 
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    7.18 [sigma]
LC_URL:          sw00221627000msb.lc
SUN_POSTN:       128.07d {+08h 32m 16s}  +18.85d {+18d 50' 44"}
SUN_DIST:        118.13 [deg]   Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN:      168.59d {+11h 14m 21s}   +5.70d {+05d 41' 45"}
MOON_DIST:       136.39 [deg]
MOON_ILLUM:      13 [%]
GAL_COORDS:      291.45,-75.40 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      354.81,-43.81 [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 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.  
COMMENTS:        This trigger occurred at longitude,latitude = 141.90,-1.63 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 28 Jul 06 22:35:32 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     221627,   Seg_Num: 0
POINT_RA:         16.711d {+01h 06m 51s} (J2000)
POINT_DEC:       -41.382d {-41d 22' 54"} (J2000)
POINT_ROLL:      89.061d
IMG_START_DATE:  13944 TJD;   209 DOY;   06/07/28
IMG_START_TIME:  80791.73 SOD {22:26:31.73} UT,   121.1 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        2.463
N_STARS:         13
X_OFFSET:        404 [pixels]
Y_OFFSET:        621 [pixels]
X_MAX:           1363 [pixels]
Y_MAX:           1580 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00221627000msufc0121.fits
SUN_POSTN:       128.07d {+08h 32m 17s}  +18.84d {+18d 50' 41"}
SUN_DIST:        118.12 [deg]   Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN:      168.63d {+11h 14m 32s}   +5.67d {+05d 40' 24"}
MOON_DIST:       136.38 [deg]
MOON_ILLUM:      13 [%]
GAL_COORDS:      291.40,-75.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      354.83,-43.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 28 Jul 06 22:37:42 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     221627,   Seg_Num: 0
POINT_RA:         16.711d {+01h 06m 51s} (J2000)
POINT_DEC:       -41.382d {-41d 22' 54"} (J2000)
ROLL:            89.061d
IMG_START_DATE:  13944 TJD;   209 DOY;   06/07/28
IMG_START_TIME:  80791.73 SOD {22:26:31.73} UT,   121.1 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     175818393
X_OFFSET:        723 [pixels]
Y_OFFSET:        940 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       883
Y_GRB_POS:       1100
BINNING_INDEX:   1
IM_URL:          sw00221627000msuni0121.fits
SUN_POSTN:       128.07d {+08h 32m 17s}  +18.84d {+18d 50' 39"}
SUN_DIST:        118.12 [deg]   Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN:      168.65d {+11h 14m 36s}   +5.66d {+05d 39' 53"}
MOON_DIST:       136.38 [deg]
MOON_ILLUM:      13 [%]
GAL_COORDS:      291.40,-75.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      354.83,-43.82 [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:     Fri 28 Jul 06 22:38:50 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     221627,   Seg_Num: 0
POINT_RA:         16.711d {+01h 06m 51s} (J2000)
POINT_DEC:       -41.382d {-41d 22' 54"} (J2000)
ROLL:            89.061d
IMG_START_DATE:  13944 TJD;   209 DOY;   06/07/28
IMG_START_TIME:  80791.73 SOD {22:26:31.73} UT,   121.1 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     175818393
X_OFFSET:        723 [pixels]
Y_OFFSET:        940 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       883
Y_GRB_POS:       1100
BINNING_INDEX:   1
IM_URL:          sw00221627000msuni0121.fits
SUN_POSTN:       128.07d {+08h 32m 18s}  +18.84d {+18d 50' 39"}
SUN_DIST:        118.12 [deg]   Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN:      168.66d {+11h 14m 38s}   +5.66d {+05d 39' 38"}
MOON_DIST:       136.38 [deg]
MOON_ILLUM:      13 [%]
GAL_COORDS:      291.40,-75.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      354.83,-43.82 [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:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 28 Jul 06 22:39:52 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     221627,   Seg_Num: 0
POINT_RA:         16.711d {+01h 06m 51s} (J2000)
POINT_DEC:       -41.383d {-41d 22' 57"} (J2000)
POINT_ROLL:      89.062d
IMG_START_DATE:  13944 TJD;   209 DOY;   06/07/28
IMG_START_TIME:  81544.00 SOD {22:39:04.00} UT,   873.4 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        0.521
N_STARS:         5
X_OFFSET:        404 [pixels]
Y_OFFSET:        621 [pixels]
X_MAX:           1363 [pixels]
Y_MAX:           1580 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00221627000msufc0873.fits
SUN_POSTN:       128.07d {+08h 32m 18s}  +18.84d {+18d 50' 38"}
SUN_DIST:        118.12 [deg]   Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN:      168.66d {+11h 14m 39s}   +5.66d {+05d 39' 23"}
MOON_DIST:       136.38 [deg]
MOON_ILLUM:      13 [%]
GAL_COORDS:      291.40,-75.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      354.83,-43.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 28 Jul 06 22:40:31 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     221627,   Seg_Num: 0
POINT_RA:         16.711d {+01h 06m 51s} (J2000)
POINT_DEC:       -41.383d {-41d 22' 57"} (J2000)
ROLL:            89.062d
IMG_START_DATE:  13944 TJD;   209 DOY;   06/07/28
IMG_START_TIME:  81544.00 SOD {22:39:04.00} UT,   873.4 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     175819145
X_OFFSET:        723 [pixels]
Y_OFFSET:        940 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       883
Y_GRB_POS:       1100
BINNING_INDEX:   1
IM_URL:          sw00221627000msuni0873.fits
SUN_POSTN:       128.07d {+08h 32m 18s}  +18.84d {+18d 50' 38"}
SUN_DIST:        118.12 [deg]   Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN:      168.67d {+11h 14m 41s}   +5.65d {+05d 39' 14"}
MOON_DIST:       136.38 [deg]
MOON_ILLUM:      13 [%]
GAL_COORDS:      291.40,-75.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      354.83,-43.82 [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:     Fri 28 Jul 06 22:41:37 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     221627,   Seg_Num: 0
POINT_RA:         16.711d {+01h 06m 51s} (J2000)
POINT_DEC:       -41.383d {-41d 22' 57"} (J2000)
ROLL:            89.062d
IMG_START_DATE:  13944 TJD;   209 DOY;   06/07/28
IMG_START_TIME:  81544.00 SOD {22:39:04.00} UT,   873.4 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     175819145
X_OFFSET:        723 [pixels]
Y_OFFSET:        940 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       883
Y_GRB_POS:       1100
BINNING_INDEX:   1
IM_URL:          sw00221627000msuni0873.fits
SUN_POSTN:       128.08d {+08h 32m 18s}  +18.84d {+18d 50' 37"}
SUN_DIST:        118.12 [deg]   Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN:      168.68d {+11h 14m 42s}   +5.65d {+05d 38' 59"}
MOON_DIST:       136.38 [deg]
MOON_ILLUM:      13 [%]
GAL_COORDS:      291.40,-75.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      354.83,-43.82 [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_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 28 Jul 06 22:41:25 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     221627,   Seg_Num: 0
POINT_RA:         16.711d {+01h 06m 51s} (J2000)
POINT_DEC:       -41.383d {-41d 22' 57"} (J2000)
POINT_ROLL:      89.062d
IMG_START_DATE:  13944 TJD;   209 DOY;   06/07/28
IMG_START_TIME:  81544.00 SOD {22:39:04.00} UT,   873.4 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        0.521
N_STARS:         5
X_OFFSET:        404 [pixels]
Y_OFFSET:        621 [pixels]
X_MAX:           1363 [pixels]
Y_MAX:           1580 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00221627000msufc0873.fits
SUN_POSTN:       128.08d {+08h 32m 18s}  +18.84d {+18d 50' 37"}
SUN_DIST:        118.12 [deg]   Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN:      168.68d {+11h 14m 42s}   +5.65d {+05d 39' 02"}
MOON_DIST:       136.38 [deg]
MOON_ILLUM:      13 [%]
GAL_COORDS:      291.40,-75.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      354.83,-43.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN Circular #5360
C. Pagani (PSU), L. M. Barbier (NASA/GSFC), S. D. Barthelmy (GSFC), M. M. Chester (PSU), J. R. Cummings (NASA/UMD), C. B. Markwardt (GSFC/UMD), K. M. McLean (LANL/UTD), A. N. Morgan (PSU), D. M. Palmer (LANL) and M. Stamatikos (NASA/ORAU) report on behalf of the Swift Team:
At 22:24:30 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 060728 (trigger=221627). Swift slewed immediately to the burst. The BAT on-board calculated location is RA,Dec 16.694, -41.386 {01h 06m 46s, -41d 23' 10"} (J2000) with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). This is an 64-sec image trigger so there is very little information in the TDRSS lightcuve.
The XRT began taking data at 22:26:35 UT, 124 seconds after the BAT trigger. The XRT on-board centroid algorithm did not find a source in the image and no prompt position is available. We are waiting for down-linked data to detect and determine a position for the source.
The UVOT began observing at 22:26:31.7 UT, 121.1 seconds after the BAT trigger. Images have been taken in V only, not in white, due to a bright source in the field-of-view. Ground processing indicates an uncataloged, non-fading source, V=16.93, 58 arcsecs from the BAT position.
We are currently in the Malindi gap in data downlinks, so it will be about 6 hours until we get the full data set.
GCN Circular #5361
C. Pagani (PSU), J.L. Racusin and D.N. Burrows (PSU) report on behalf of the Swift XRT team:
XRT started observing the field of GRB060728 at 22:26:35 UT, 124 seconds after the BAT trigger. In the first 4.5ks of PC mode data no new point source was detected within the BAT error circle (GCN 5360) up to a limiting flux of about 2.e-13 erg cm^-2 s^-1. Swift observations are continuing, further analysis will be issued as the data becomes available.
This circular is an official product of the Swift-XRT team.
GCN Circular #5362
B. E. Cobb, part of the larger SMARTS consortium, reports:
Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 060728 (Pagani et al. GCN 5360) with a mid-exposure time of ~6.8 hours post-burst (2006-07-29 05:13 UT). Optical imaging in V and I has a field of view of 6'x6' and, therefore, covers the entire GRB error circle. IR imaging in J and K has a smaller field of view (2.4'x2.4') and covers a region totaling 5.8 square arcminutes in the middle of the quoted BAT error region. Total summed exposure times amounted to 15 minutes in I and V and 12 minutes in J and K.
Preliminary visual comparison of the optical and IR images to the DSS does not reveal any new sources. Our I-band limiting magnitude is I ~ 22 (in comparison with several USNO-B1.0 stars). Our J-band images does not contain any 2MASS stars, but the few sources detected in the J-band image are all consistent with sources found in the DSS.
GCN Circular #5363
D. Palmer (LANL), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/ORAU), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), M. Koss (GSFC/UMD), C. Markwardt (GSFC/UMD), C. Pagani (PSU), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC) on behalf of the Swift-BAT team:
Using the data set from T-239 to T+963 sec from recent telemetry downlinks, we report further analysis of BAT GRB 060728 (trigger #221627) (Pagani, et al., GCN Circ. 5360). The BAT ground-calculated position is RA,Dec = 16.646,-41.390 deg {1h 6m 35.1s, -41d 23' 23.1"} (J2000) +- 3.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%.
The mask-weighted lightcurve shows a smooth (at 10-sec binning) single peak starting at T_zero and ending at ~T+70 sec. T90 (15-350 keV) is 60 +- 10 sec (estimated error including systematics).
The time-averaged spectrum from T+0.0 to T+64.0 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.40 +- 0.45. The fluence in the 15-150 keV band is 2.4 +- 0.7 x 10^-07 erg/cm2. All the quoted errors are at the 90% confidence level.
Given (a) the weakness of this event and (b) the lack of an x-ray counterpart (Pagani et al., GCN Circ 5361) and optical counterpart (Pagani et al., 5360), we can not rule out the possibility that this is a hard x-ray transient, but is most likely a burst. We note that Swift has not had a long GRB with no XRT detection when a prompt slew occurred.
GCN Circular #5364
A. N. Morgan, M. M. Chester, and C. Pagani (PSU) report on behalf of the Swift/UVOT team:
The Swift UVOT began taking data on the field of GRB 060728 121s after the BAT trigger (Pagani et al., GCN Circ 5360). No new source, relative to the DSS, is seen inside the refined BAT error circle (Palmer et al., GCN Circ 5363). Images were not taken in all filters due to a bright source in the field-of-view. The 3-sigma limiting magnitudes for the first finding chart and the coadded images are listed below.
Finding chart:
```
Filter  Midpoint (s)  Exposure (s)    3-sigma LM
V       319           393             19.3
```
Coadded images:
```
Filter  T_range(s)    EXPOSURE (s)    3-sigma LM
V       121-6586      1113            19.9
UVW1    551-10828     1553            21.2
UVM2    527-6690      765             20.9
UVW2    578-11225     1029            21.2
```
T_range is calculated from the time of the burst. These upper limits have not been corrected for the estimated Galactic reddening of E(B-V) = 0.012 mag (Schlegel et al. 1998).
GCN Circular #5393
C. Pagani (PSU), D. Morris (PSU) and D.N. Burrows (PSU) report on behalf of the Swift-XRT team:
The XRT performed 2 observations of the field of GRB 060728 (GCN 5360), starting at 2006-07-28-22:26:35 UT (124 seconds after the BAT trigger) to 2006-07-29-19:06:56 UT and from 2006-08-02-01:41:22 to 2006-08-02-22:57:56 UT, collecting 17.8 and 13.2ks of data in PC mode respectively.
No new source is detected within the BAT refined error circle (GCN 5363) in either of the two exposures. The 3 sigma upper limit on the count-rate is 1.0e-3 counts/sec for the first observation, which corresponds to an unabsorbed flux of 4.0e-14 erg cm-2 s-1 in the energy range 0.3-10 keV, assuming a Crab-like spectrum, and 1.2e-3 counts/sec for the second observation (unabsorbed flux of 4.8e-14 erg cm-2 s-1). Combining the two observations the 3 sigma upper limit is 9.2e-4 counts/sec, corresponding to an unabsorbed flux of 3.7e-14 erg cm-2 s-1.
This is the first case of a long GRB for which Swift performed a prompt slew without a decection of the afterglow by the XRT. The only previously undetected X-ray afterglow of a long GRB discovered by Swift is GRB 050911 (Page et al. 2006), for which the XRT observations started 4.6 hours after the BAT trigger.

Back to JG's homepage

Jochen Greiner, last update: 03-Aug-2006 [Disclaimer]