Gamma-ray Burst 080906

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:33:32 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     323984,   Seg_Num: 0
GRB_RA:          227.890d {+15h 11m 34s} (J2000),
                 228.216d {+15h 12m 52s} (current),
                 226.048d {+15h 04m 11s} (1950)
GRB_DEC:         -80.486d {-80d 29' 09"} (J2000),
                 -80.518d {-80d 31' 05"} (current),
                 -80.296d {-80d 17' 45"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       5308 [cnts]    Image_Peak=166 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   148     E_range: 25-100 keV
BKG_INTEN:       36027 [cnts]
BKG_TIME:        48780.92 SOD {13:33:00.92} UT
BKG_DUR:         8 [sec]
GRB_DATE:        14715 TJD;   250 DOY;   08/09/06
GRB_TIME:        48796.34 SOD {13:33:16.34} UT
GRB_PHI:         -109.86 [deg]
GRB_THETA:        26.30 [deg]
SOLN_STATUS:     0x83
RATE_SIGNIF:     10.63 [sigma]
IMAGE_SIGNIF:    6.72 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  +0  +0  +0  +2  +1 
SUN_POSTN:       165.56d {+11h 02m 14s}   +6.17d {+06d 10' 12"}
SUN_DIST:         91.76 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.21d {+16h 00m 49s}  -25.78d {-25d 46' 37"}
MOON_DIST:        54.97 [deg]
MOON_ILLUM:      40 [%]
GAL_COORDS:      308.70,-19.22 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      257.62,-58.88 [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:        Since the IMAGE_SIGNIF is less than 7 sigma, this is a questionable detection.  
COMMENTS:        This trigger occurred at longitude,latitude = 75.55,-20.43 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:34:58 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     323984,   Seg_Num: 0
GRB_RA:          228.0514d {+15h 12m 12.3s} (J2000),
                 228.3788d {+15h 13m 30.9s} (current),
                 226.2019d {+15h 04m 48.4s} (1950)
GRB_DEC:         -80.5183d {-80d 31' 05.8"} (J2000),
                 -80.5505d {-80d 33' 01.8"} (current),
                 -80.3288d {-80d 19' 43.7"} (1950)
GRB_ERROR:       4.7 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       7.17e-09 [erg/cm2/sec]
GRB_SIGNIF:      13.30 [sigma]
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  48867.61 SOD {13:34:27.61} UT,   71.3 [sec] since BAT Trigger Time
TAM[0-3]:        327.68 237.24 261.41 243.62
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       165.56d {+11h 02m 14s}   +6.17d {+06d 10' 11"}
SUN_DIST:         91.80 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.22d {+16h 00m 52s}  -25.78d {-25d 46' 44"}
MOON_DIST:        54.99 [deg]
MOON_ILLUM:      40 [%]
GAL_COORDS:      308.70,-19.27 [deg] galactic lon,lat of the burst
ECL_COORDS:      257.69,-58.89 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 2.50 arcmin from the BAT position.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:35:08 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     323984,   Seg_Num: 0
GRB_RA:          228.0514d {+15h 12m 12.3s} (J2000),
                 228.3788d {+15h 13m 30.9s} (current),
                 226.2019d {+15h 04m 48.4s} (1950)
GRB_DEC:         -80.5183d {-80d 31' 05.8"} (J2000),
                 -80.5505d {-80d 33' 01.8"} (current),
                 -80.3288d {-80d 19' 43.7"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       177 [cnts]
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  48867.61 SOD {13:34:27.61} UT,   71.3 [sec] since BAT Trigger Time
CENTROID_X:      328.72,  raw= 329  [pixels]
CENTROID_Y:      321.75,  raw= 322  [pixels]
ROLL:            298.12 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   55.99
GRB_POS_XRT_Z:   62.29
IMAGE_URL:       sw00323984000msxps_rw.img
SUN_POSTN:       165.56d {+11h 02m 14s}   +6.17d {+06d 10' 11"}
SUN_DIST:         91.80 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.22d {+16h 00m 53s}  -25.78d {-25d 46' 45"}
MOON_DIST:        54.99 [deg]
MOON_ILLUM:      40 [%]
GAL_COORDS:      308.70,-19.27 [deg] galactic lon,lat of the burst
ECL_COORDS:      257.69,-58.89 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:35:14 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     323984,   Seg_Num: 0
GRB_RA:          228.0514d {+15h 12m 12.3s} (J2000),
                 228.3788d {+15h 13m 30.9s} (current),
                 226.2019d {+15h 04m 48.4s} (1950)
GRB_DEC:         -80.5183d {-80d 31' 05.8"} (J2000),
                 -80.5505d {-80d 33' 01.8"} (current),
                 -80.3288d {-80d 19' 43.7"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       177 [cnts]
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  48867.61 SOD {13:34:27.61} UT,   71.3 [sec] since BAT Trigger Time
CENTROID_X:      328.72,  raw= 329  [pixels]
CENTROID_Y:      321.75,  raw= 322  [pixels]
ROLL:            298.12 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   55.99
GRB_POS_XRT_Z:   62.29
IMAGE_URL:       sw00323984000msxps_rw.img
SUN_POSTN:       165.56d {+11h 02m 14s}   +6.17d {+06d 10' 11"}
SUN_DIST:         91.80 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.22d {+16h 00m 53s}  -25.78d {-25d 46' 46"}
MOON_DIST:        54.99 [deg]
MOON_ILLUM:      40 [%]
GAL_COORDS:      308.70,-19.27 [deg] galactic lon,lat of the burst
ECL_COORDS:      257.69,-58.89 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:36:48 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     323984,   Seg_Num: 0
POINT_RA:        228.001d {+15h 12m 00s} (J2000)
POINT_DEC:       -80.496d {-80d 29' 46"} (J2000)
POINT_ROLL:      298.123d
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  48878.51 SOD {13:34:38.51} UT,   82.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.697
N_STARS:         136
X_OFFSET:        323 [pixels]
Y_OFFSET:        503 [pixels]
X_MAX:           1282 [pixels]
Y_MAX:           1462 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00323984000msufc0082.fits
SUN_POSTN:       165.56d {+11h 02m 15s}   +6.17d {+06d 10' 09"}
SUN_DIST:         91.78 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.23d {+16h 00m 56s}  -25.78d {-25d 46' 54"}
MOON_DIST:        54.97 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.71,-19.24 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.66,-58.88 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:38:05 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     323984,   Seg_Num: 0
POINT_RA:        228.001d {+15h 12m 00s} (J2000)
POINT_DEC:       -80.496d {-80d 29' 46"} (J2000)
ROLL:            298.123d
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  48878.51 SOD {13:34:38.51} UT,   82.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     242400881
X_OFFSET:        643 [pixels]
Y_OFFSET:        823 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       803
Y_GRB_POS:       983
BINNING_INDEX:   1
IM_URL:          sw00323984000msuni0082.fits
SUN_POSTN:       165.56d {+11h 02m 15s}   +6.17d {+06d 10' 08"}
SUN_DIST:         91.78 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.25d {+16h 00m 59s}  -25.78d {-25d 47' 00"}
MOON_DIST:        54.97 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.71,-19.24 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.66,-58.88 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:38:23 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     323984,   Seg_Num: 0
POINT_RA:        228.001d {+15h 12m 00s} (J2000)
POINT_DEC:       -80.496d {-80d 29' 46"} (J2000)
ROLL:            298.123d
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  48878.51 SOD {13:34:38.51} UT,   82.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     242400881
X_OFFSET:        643 [pixels]
Y_OFFSET:        823 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       803
Y_GRB_POS:       983
BINNING_INDEX:   1
IM_URL:          sw00323984000msuni0082.fits
SUN_POSTN:       165.56d {+11h 02m 15s}   +6.17d {+06d 10' 08"}
SUN_DIST:         91.78 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.25d {+16h 01m 00s}  -25.78d {-25d 47' 02"}
MOON_DIST:        54.97 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.71,-19.24 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.66,-58.88 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position 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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:38:15 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     323984,   Seg_Num: 0
GRB_RA:          227.890d {+15h 11m 34s} (J2000),
                 228.216d {+15h 12m 52s} (current),
                 226.048d {+15h 04m 11s} (1950)
GRB_DEC:         -80.486d {-80d 29' 09"} (J2000),
                 -80.518d {-80d 31' 05"} (current),
                 -80.296d {-80d 17' 45"} (1950)
GRB_DATE:        14715 TJD;   250 DOY;   08/09/06
GRB_TIME:        48796.34 SOD {13:33:16.34} UT
TRIGGER_INDEX:   148
GRB_PHI:         -109.86 [deg]
GRB_THETA:        26.30 [deg]
DELTA_TIME:      58.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x83
RATE_SIGNIF:     10.63 [sigma]
IMAGE_SIGNIF:    6.72 [sigma]
LC_URL:          sw00323984000msb.lc
SUN_POSTN:       165.56d {+11h 02m 15s}   +6.17d {+06d 10' 08"}
SUN_DIST:         91.76 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.25d {+16h 00m 59s}  -25.78d {-25d 47' 01"}
MOON_DIST:        54.96 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.70,-19.22 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      257.62,-58.88 [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:        Since the IMAGE_SIGNIF is less than 7 sigma, this is a questionable detection.  
COMMENTS:        This trigger occurred at longitude,latitude = 75.55,-20.43 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:44:45 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     323984,   Seg_Num: 0
POINT_RA:        228.017d {+15h 12m 04s} (J2000)
POINT_DEC:       -80.497d {-80d 29' 47"} (J2000)
POINT_ROLL:      298.108d
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  48984.49 SOD {13:36:24.49} UT,   188.2 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        1.643
N_STARS:         155
X_OFFSET:        323 [pixels]
Y_OFFSET:        503 [pixels]
X_MAX:           1282 [pixels]
Y_MAX:           1462 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00323984000msufc0188.fits
SUN_POSTN:       165.57d {+11h 02m 16s}   +6.17d {+06d 10' 02"}
SUN_DIST:         91.78 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.31d {+16h 01m 14s}  -25.79d {-25d 47' 35"}
MOON_DIST:        54.96 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.71,-19.24 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.66,-58.88 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:45:25 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     323984,   Seg_Num: 0
GRB_RA:          228.0442d {+15h 12m 10.60s} (J2000),
                 228.3716d {+15h 13m 29.17s} (current),
                 226.1949d {+15h 04m 46.76s} (1950)
GRB_DEC:         -80.5177d {-80d 31' 03.7"} (J2000),
                 -80.5499d {-80d 32' 59.6"} (current),
                 -80.3282d {-80d 19' 41.5"} (1950)
GRB_ERROR:       0.4 [arcsec radius, statistical only]
GRB_MAG:         19.70 +/- 0.50 [mag]
FILTER:          10, White
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  48880.00 SOD {13:34:40.00} UT,   83.7 [sec] since BAT Trigger Time
SUN_POSTN:       165.57d {+11h 02m 16s}   +6.17d {+06d 10' 01"}
SUN_DIST:         91.80 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.31d {+16h 01m 15s}  -25.79d {-25d 47' 39"}
MOON_DIST:        54.98 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.70,-19.26 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      257.69,-58.89 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The UVOT position is 4.7 arcsec from the XRT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:46:01 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     323984,   Seg_Num: 0
POINT_RA:        228.017d {+15h 12m 04s} (J2000)
POINT_DEC:       -80.497d {-80d 29' 47"} (J2000)
ROLL:            298.108d
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  48984.49 SOD {13:36:24.49} UT,   188.2 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     242400987
X_OFFSET:        643 [pixels]
Y_OFFSET:        823 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       803
Y_GRB_POS:       983
BINNING_INDEX:   1
IM_URL:          sw00323984000msuni0188.fits
SUN_POSTN:       165.57d {+11h 02m 16s}   +6.17d {+06d 10' 01"}
SUN_DIST:         91.78 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.32d {+16h 01m 16s}  -25.80d {-25d 47' 42"}
MOON_DIST:        54.96 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.71,-19.24 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.66,-58.88 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:46:28 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     323984,   Seg_Num: 0
POINT_RA:        228.017d {+15h 12m 04s} (J2000)
POINT_DEC:       -80.497d {-80d 29' 47"} (J2000)
ROLL:            298.108d
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  48984.49 SOD {13:36:24.49} UT,   188.2 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     242400987
X_OFFSET:        643 [pixels]
Y_OFFSET:        823 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       803
Y_GRB_POS:       983
BINNING_INDEX:   1
IM_URL:          sw00323984000msuni0188.fits
SUN_POSTN:       165.57d {+11h 02m 16s}   +6.17d {+06d 10' 00"}
SUN_DIST:         91.78 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.32d {+16h 01m 17s}  -25.80d {-25d 47' 44"}
MOON_DIST:        54.96 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.71,-19.24 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.66,-58.88 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position 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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:50:08 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     323984,   Seg_Num: 0
POINT_RA:        228.018d {+15h 12m 04s} (J2000)
POINT_DEC:       -80.497d {-80d 29' 47"} (J2000)
POINT_ROLL:      298.107d
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  49674.97 SOD {13:47:54.97} UT,   878.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.752
N_STARS:         141
X_OFFSET:        323 [pixels]
Y_OFFSET:        503 [pixels]
X_MAX:           1282 [pixels]
Y_MAX:           1462 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00323984000msufc0878.fits
SUN_POSTN:       165.57d {+11h 02m 17s}   +6.17d {+06d 09' 57"}
SUN_DIST:         91.78 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.35d {+16h 01m 25s}  -25.80d {-25d 48' 03"}
MOON_DIST:        54.96 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.71,-19.24 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.66,-58.88 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:51:29 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     323984,   Seg_Num: 0
POINT_RA:        228.018d {+15h 12m 04s} (J2000)
POINT_DEC:       -80.497d {-80d 29' 47"} (J2000)
ROLL:            298.107d
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  49674.97 SOD {13:47:54.97} UT,   878.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     242401678
X_OFFSET:        642 [pixels]
Y_OFFSET:        822 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       802
Y_GRB_POS:       982
BINNING_INDEX:   1
IM_URL:          sw00323984000msuni0878.fits
SUN_POSTN:       165.57d {+11h 02m 17s}   +6.17d {+06d 09' 55"}
SUN_DIST:         91.78 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.37d {+16h 01m 28s}  -25.80d {-25d 48' 10"}
MOON_DIST:        54.95 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.71,-19.24 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.66,-58.88 [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 06 Sep 08 13:51:50 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     323984,   Seg_Num: 0
POINT_RA:        228.018d {+15h 12m 04s} (J2000)
POINT_DEC:       -80.497d {-80d 29' 47"} (J2000)
ROLL:            298.107d
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  49674.97 SOD {13:47:54.97} UT,   878.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     242401678
X_OFFSET:        642 [pixels]
Y_OFFSET:        822 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       802
Y_GRB_POS:       982
BINNING_INDEX:   1
IM_URL:          sw00323984000msuni0878.fits
SUN_POSTN:       165.57d {+11h 02m 17s}   +6.17d {+06d 09' 55"}
SUN_DIST:         91.78 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.37d {+16h 01m 29s}  -25.80d {-25d 48' 12"}
MOON_DIST:        54.95 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.71,-19.24 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.66,-58.88 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:52:19 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     323984,   Seg_Num: 0
POINT_RA:        228.018d {+15h 12m 04s} (J2000)
POINT_DEC:       -80.497d {-80d 29' 47"} (J2000)
POINT_ROLL:      298.107d
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  49780.88 SOD {13:49:40.88} UT,   984.5 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        0.257
N_STARS:         77
X_OFFSET:        323 [pixels]
Y_OFFSET:        503 [pixels]
X_MAX:           1282 [pixels]
Y_MAX:           1462 [pixels]
DET_THRESH:      5
PHOTO_THRESH:    2
SL_URL:          sw00323984000msufc0984.fits
SUN_POSTN:       165.57d {+11h 02m 17s}   +6.17d {+06d 09' 55"}
SUN_DIST:         91.78 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.37d {+16h 01m 30s}  -25.80d {-25d 48' 14"}
MOON_DIST:        54.95 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.71,-19.24 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.66,-58.88 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:51:50 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     323984,   Seg_Num: 0
GRB_RA:          228.0455d {+15h 12m 10.9s} (J2000),
                 228.3729d {+15h 13m 29.4s} (current),
                 226.1961d {+15h 04m 47.0s} (1950)
GRB_DEC:         -80.5180d {-80d 31' 04.8"} (J2000),
                 -80.5502d {-80d 33' 00.7"} (current),
                 -80.3285d {-80d 19' 42.6"} (1950)
GRB_ERROR:       3.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  49130.00 SOD {13:38:50.00} UT,   333.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       165.57d {+11h 02m 17s}   +6.17d {+06d 09' 55"}
SUN_DIST:         91.80 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.37d {+16h 01m 29s}  -25.80d {-25d 48' 12"}
MOON_DIST:        54.97 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.70,-19.26 [deg] galactic lon,lat of the burst
ECL_COORDS:      257.69,-58.89 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        This position was enhanced using UVOT field astrometry

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Sep 08 13:53:25 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     323984,   Seg_Num: 0
POINT_RA:        228.018d {+15h 12m 04s} (J2000)
POINT_DEC:       -80.497d {-80d 29' 47"} (J2000)
ROLL:            298.107d
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  49780.88 SOD {13:49:40.88} UT,   984.5 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     242401783
X_OFFSET:        642 [pixels]
Y_OFFSET:        822 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       802
Y_GRB_POS:       982
BINNING_INDEX:   1
IM_URL:          sw00323984000msuni0984.fits
SUN_POSTN:       165.57d {+11h 02m 17s}   +6.16d {+06d 09' 54"}
SUN_DIST:         91.78 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.38d {+16h 01m 32s}  -25.81d {-25d 48' 20"}
MOON_DIST:        54.95 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.71,-19.24 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.66,-58.88 [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 06 Sep 08 13:53:53 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     323984,   Seg_Num: 0
POINT_RA:        228.018d {+15h 12m 04s} (J2000)
POINT_DEC:       -80.497d {-80d 29' 47"} (J2000)
ROLL:            298.107d
IMG_START_DATE:  14715 TJD;   250 DOY;   08/09/06
IMG_START_TIME:  49780.88 SOD {13:49:40.88} UT,   984.5 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     242401783
X_OFFSET:        642 [pixels]
Y_OFFSET:        822 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       802
Y_GRB_POS:       982
BINNING_INDEX:   1
IM_URL:          sw00323984000msuni0984.fits
SUN_POSTN:       165.57d {+11h 02m 17s}   +6.16d {+06d 09' 53"}
SUN_DIST:         91.78 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      240.39d {+16h 01m 33s}  -25.81d {-25d 48' 22"}
MOON_DIST:        54.95 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      308.71,-19.24 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.66,-58.88 [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 #8186
L. Vetere (PSU), S. D. Barthelmy (GSFC), P. J. Brown (PSU), D. N. Burrows (PSU), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), H. A. Krimm (CRESST/GSFC/USRA), J. Mao (INAF-OAB), C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), D. M. Palmer (LANL), J. L. Racusin (PSU), B. Sbarufatti (INAF-IASFPA), M. Stamatikos (NASA/ORAU), G. Tagliaferri (INAF-OAB), E. Troja (INAF-IASFPA) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:
At 13:33:16 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080906 (trigger=323984). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 227.890, -80.486 which is
```
   RA(J2000) = 15h 11m 34s
   Dec(J2000) = -80d 29' 09"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed one major peak of duration ~50 sec, with possible smaller peaks. The peak count rate was ~2000 counts/sec (15-350 keV), at ~10 sec after the trigger.
The XRT began observing the field at 13:34:27.6 UT, 71.3 seconds after the BAT trigger. XRT found a bright, fading, uncatalogued X-ray source located at RA, Dec 228.0514, -80.5183 which is equivalent to:
```
   RA(J2000)  = 15h 12m 12.3s
   Dec(J2000) = -80d 31' 05.8"
```
with an uncertainty of 4.7 arcseconds (radius, 90% containment). This location is 150 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy.
UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 82 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	15:12:10.63 = 228.0443
  DEC(J2000) = -80:31:04.1  = -80.5178
```
with a 1-sigma error radius of about 0.5 arc sec. This position is 4.6 arc sec. from the center of the XRT error circle. The estimated magnitude is 19.7 with a 1-sigma error of about 0.5 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.30.
Burst Advocate for this burst is L. Vetere (vetere AT astro.psu.edu). 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 #8194
GRB 080906: GROND observations of the optical/NIR afterglow
P.Afonso, T. Kruehler, J. Greiner, C.Clemens, A. Yoldas (all MPE Garching) and A. Kuepcue Yoldas (ESO) report on behalf of the GROND team:
We observed the field of GRB 080906 (Swift trigger 323984; L. Vetere et al., GCN #8186), simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile).
Observations started at 00:12 UT on September 7th, 2008, 10.7 hrs after the GRB trigger.We detect the optical afterglow reported by L. Vetere et al. (GCN #8186) at a position consistent with the UVOT detection in all bands, implying a redshift smaller than 3.5.
Preliminary photometry yields the following magnitudes calibrated against USNO-B1 and 2MASS field stars in stacked images:
```
Band  Exp(min)   Mag 

g'    24         22.2 +- 0.1
r'    24         21.4 +- 0.1
i'    24         21.2 +- 0.1
z'    24         21.2 +- 0.1
J     20         20.2 +- 0.1
H     20         19.2 +- 0.1
K     20         18.5 +- 0.1 
```
not corrected for the expected Galactic foreground reddening of E(B-V) = 0.30 mag (Schlegel et al., 1998).
GCN Circular #8196
M. Stamatikos (GSFC/ORAU), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), J. Tueller (GSFC), T. Ukwatta (GWU), L. Vetere (PSU) (i.e. 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 080906 (trigger #323984) (Vetere, et al., GCN Circ. 8186). The BAT ground-calculated position is RA, Dec = 228.055, -80.540 deg, which is
```
   RA(J2000)  =  15h 12m 13.3s 
   Dec(J2000) = -80d 32' 24.9" 
```
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 58%.
The mask-weighted light curve shows a roughly symmetrical peak starting at ~T-100 sec, peaking around T+10 sec, and tailing off to about T+100 sec. T90 (15-350 keV) is 147 +- 21 sec (estimated error including systematics).
The time-averaged spectrum from T-105 to T+104 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.59 +- 0.09. The fluence in the 15-150 keV band is 3.5 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.06 sec in the 15-150 keV band is 1.0 +- 0.2 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/323984/BA/
GCN Circular #8197
L. Vetere, J.L. Racusin, C. Pagani (PSU), J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team:
The XRT began observing the field of GRB 080906 (trigger=323984; Vetere et al., GCN Circ 8186) at 13:34:27.6 UT, 71.3 seconds after the BAT trigger.
Using 1224 s of XRT Photon Counting mode data and 2 UVOT images, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching to the USNO-B1 catalogue): RA, Dec = 228.04211, -80.51787 which is equivalent to:
```
 RA (J2000): 15 12 10.11
 Dec (J2000): -80 31 04.3
```
with an uncertainty of 1.8 arcsec (90% confidence).
This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an extension of this method.
This position is 80 arcsec away from the ground-processed BAT position given in GCN Circ. 8196 (Stamatikos et al.) inside BAT error circle.
The WT mode lightcurve shows a number of flares, with the strongest peaking around 186, 598 and 907 s after the trigger. The PC data in later orbits shows some flaring activity and decays as a single power-law with alpha = 1.25 +/- 0.11.
The WT spectrum of the first 80 s (before the first peak) can be fitted with a power-law of Gamma = 1.82 +/-0.08 and absorption consistent with the Galactic value along the line of sight (9.7x10^20 cm^-2). The observed (unabsorbed) flux over this time is 1.98 (2.7)x10^-9 erg cm^-2 s^-1. A spectrum extracted from the PC mode data (11.6-75.6 ks after the trigger) can be fitted with a power-law of Gamma = 2.3 +0.1/-0.2 and total NH = (1.7 +/- 0.5)x10^22 cm^-2, slightly in excess of the Galactic value. The observed (unabsorbed) flux over this time is 1.7 (3.1)x10^-11 erg cm^-2 s^-1.
If the decay continues with alpha = 1.25, the predicted count-rate at 48 hours is 0.007 count s^-1, corresponding to an observed (unabsorbed) flux of 2.6 (4.8)x10^-13 erg cm^-2 s^-1.
This Circular is an official product of the Swift-XRT team.
GCN Circular #8198
S. T. Holland (CRESST/USRA/GSFC) & L. Vetere (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT observed the field of GRB 080906 starting 62 s after the BAT trigger (Vetere et al., 2008, GCNC. 8186). Settled observations started at T + 82 s. We detect the optical afterglow (Vetere et al., GCNC 8186) in the v, b, u, and white filters. The refined UVOT source position is
```
  RA (J2000.0) =  15:12:10.65
Dec (J2000.0) = -80:31:03.2
```
with an estimated uncertainty of 0.64 arcsec (radius, 90% confidence).
Magnitudes and upper limits are reported below.
```
Filter   TSTART   TSTOP   Exposure     Mag  Err  Comment
  white       82     182         98   19.71 0.15
    v        188     588        393   18.61 0.12
    b        668    6204        216   21.02 0.44
    u        643    5998        236   20.37 0.34
   uvw1      619    5793        236  >20.9        2-sigma upper limit
   uvm2      594    5588        236  >20.5        2-sigma upper limit
   uvw2      698    6614        235  >21.1        2-sigma upper limit
```
The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0.30 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).
The detection in the u filter, coupled with the non-detections in the uvw1, uvm2, and uvw2 filters, are consistent with a redshift of approximately z < 2.6. The power-law decay index in the v band between 338 and 6719 s is -0.50 +/- 0.04.
Please update my e-mail address in your Address Book to .
GCN Circular #8212
Stephen Holland (CRESST/USRA/GSFC) reports, on behalf of the Swift/UVOT team:
We have performed UVOT photometry on the optical afterglow of GRB 080906 (Vetere et al., 2008, GCNC 8186) at approximately 6000 s after the BAT trigger. This data was used to estimate the photometric redshift of the afterglow assuming a reddened power-law spectrum with a Lyman cut-off. We find a best-fit value for the photometric redshift of z = 2.0 +/- 0.4 (90% confidence). Combining this redshift with the BAT fluence given in Stamatikos et al. (2008, GCNC 8196) yields a total energy of (8.4 +/- 0.5) x 10^51 erg (90% confidence) in the observed energy range 15-150 keV. The assumed cosmology is (H_0,Omega_matter,Omega_lambda) = (70,0.3,0.7).
GCN Circular #8216
Alejandro Ferrero (UCD School of Physics), John French (UCD School of Physics, DARK/NBI), Gary Melady (UCD School of Physics) report on behalf of a larger collaboration:
The Watcher 40 cm robotic telescope at Boyden Observatory, South Africa, began imaging the field of GRB 080906 (Vetere et al. GCN 8186) at 16:51:15.5 UT, 3.6 h after the Swift triggger. We do not detect the afterglow reported by Holland et al. (GCN 8198) and Afonso et al. (GCN 8194). Our first 120s exposure has a limiting magnitude of 16.9, while a stacked sequence of 10 120s images, with an exposure mid-time of 3.8 hrs after the trigger, results in a limiting magnitude of 18.4. Unfiltered magnitudes are transformed to R-band by comparison with the USNO-B1 catalog.
1011.1205 from 5 Nov 10
T. Kr�hler et al.: Photometric redshifts for GRB afterglows from GROND and Swift/UVOT
We present a framework to obtain photometric redshifts (photo-zs) for gamma-ray burst afterglows. Using multi-band photometry from GROND and Swift/UVOT, photo-zs are derived for five GRBs for which spectroscopic redshifts are not available. We use UV/optical/NIR data and synthetic photometry based on afterglow observations and theory to derive the photometric redshifts of GRBs and their accuracy. Taking into account the afterglow synchrotron emission properties, we investigate the application of photometry to derive redshifts in a theoretical range between z~1 and z~12. The measurement of photo-zs for GRB afterglows provides a quick, robust and reliable determination of the distance scale to the burst, particularly in those cases where spectroscopic observations in the optical/NIR range cannot be obtained. Given a sufficiently bright and mildly reddened afterglow, the relative photo-z accuracy is better than 10% between z=1.5 and z~7 and better than 5% between z=2 and z=6. We detail the approach on 5 sources without spectroscopic redshifts observed with UVOT on-board Swift and/or GROND. The distance scale to those same afterglows is measured to be $z=4.31^{+0.14}_{-0.15}$ for GRB 080825B, $z=2.13^{+0.14}_{-0.20}$ for GRB 080906, $z=3.44^{+0.15}_{-0.32}$ for GRB 081228, $z=2.03^{+0.16}_{-0.14}$ for GRB 081230 and $z=1.28^{+0.16}_{-0.15}$ for GRB 090530. Combining the response from UVOT with ground-based observatories and in particular GROND operating in the optical/NIR wavelength regime, reliable photo-zs can be obtained from z ~ 1.0 out to z ~ 10, and possibly even at higher redshifts in some favorable cases, provided that these GRBs exist, are localized quickly, have sufficiently bright afterglows and are not heavily obscured.

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Jochen Greiner, last update: 05-Nov-2010 [Disclaimer]