Gamma-ray Burst 080503

(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 03 May 08 12:26:29 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     310785,   Seg_Num: 0
GRB_RA:          286.617d {+19h 06m 28s} (J2000),
                 286.609d {+19h 06m 26s} (current),
                 286.662d {+19h 06m 39s} (1950)
GRB_DEC:         +68.778d {+68d 46' 41"} (J2000),
                 +68.791d {+68d 47' 29"} (current),
                 +68.698d {+68d 41' 54"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       558 [cnts]    Image_Peak=75 [image_cnts]
TRIGGER_DUR:     0.064 [sec] 
TRIGGER_INDEX:   10418     E_range: 25-100 keV
BKG_INTEN:       29386 [cnts]
BKG_TIME:        44757.23 SOD {12:25:57.23} UT
BKG_DUR:         8 [sec]
GRB_DATE:        14589 TJD;   124 DOY;   08/05/03
GRB_TIME:        44773.23 SOD {12:26:13.23} UT
GRB_PHI:          -6.72 [deg]
GRB_THETA:        32.33 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     20.19 [sigma]
IMAGE_SIGNIF:    8.79 [sigma]
MERIT_PARAMS:     +1  +0  +0  -2  +2  +8  +0  +0 -11  +1 
SUN_POSTN:        40.98d {+02h 43m 56s}  +15.87d {+15d 52' 17"}
SUN_DIST:         83.61 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.80d {+00h 51m 11s}   +9.75d {+09d 44' 45"}
MOON_DIST:        79.54 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.83 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       26.92, 83.33 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is a rate trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 188.59,20.13 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 03 May 08 12:28:07 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     310785,   Seg_Num: 0
GRB_RA:          286.6174d {+19h 06m 28.1s} (J2000),
                 286.6095d {+19h 06m 26.2s} (current),
                 286.6629d {+19h 06m 39.1s} (1950)
GRB_DEC:         +68.7934d {+68d 47' 36.2"} (J2000),
                 +68.8067d {+68d 48' 24.0"} (current),
                 +68.7137d {+68d 42' 49.2"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       163 [cnts]
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  44848.13 SOD {12:27:28.13} UT,   74.9 [sec] since BAT Trigger Time
CENTROID_X:      298.01,  raw= 298  [pixels]
CENTROID_Y:      318.30,  raw= 318  [pixels]
ROLL:            61.87 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   47.87
GRB_POS_XRT_Z:   -10.09
IMAGE_URL:       sw00310785000msxps_rw.img
SUN_POSTN:        40.98d {+02h 43m 56s}  +15.87d {+15d 52' 18"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.81d {+00h 51m 15s}   +9.75d {+09d 45' 11"}
MOON_DIST:        79.54 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.69, 23.83 [deg] galactic lon,lat of the burst
ECL_COORDS:       27.05, 83.33 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 03 May 08 12:28:13 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     310785,   Seg_Num: 0
GRB_RA:          286.6174d {+19h 06m 28.1s} (J2000),
                 286.6095d {+19h 06m 26.2s} (current),
                 286.6629d {+19h 06m 39.1s} (1950)
GRB_DEC:         +68.7934d {+68d 47' 36.2"} (J2000),
                 +68.8067d {+68d 48' 24.0"} (current),
                 +68.7137d {+68d 42' 49.2"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       163 [cnts]
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  44848.13 SOD {12:27:28.13} UT,   74.9 [sec] since BAT Trigger Time
CENTROID_X:      298.01,  raw= 298  [pixels]
CENTROID_Y:      318.30,  raw= 318  [pixels]
ROLL:            61.87 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   47.87
GRB_POS_XRT_Z:   -10.09
IMAGE_URL:       sw00310785000msxps_rw.img
SUN_POSTN:        40.98d {+02h 43m 56s}  +15.87d {+15d 52' 18"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.81d {+00h 51m 15s}   +9.75d {+09d 45' 13"}
MOON_DIST:        79.54 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.69, 23.83 [deg] galactic lon,lat of the burst
ECL_COORDS:       27.05, 83.33 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 03 May 08 12:27:57 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     310785,   Seg_Num: 0
GRB_RA:          286.6174d {+19h 06m 28.1s} (J2000),
                 286.6095d {+19h 06m 26.2s} (current),
                 286.6629d {+19h 06m 39.1s} (1950)
GRB_DEC:         +68.7934d {+68d 47' 36.2"} (J2000),
                 +68.8067d {+68d 48' 24.0"} (current),
                 +68.7137d {+68d 42' 49.2"} (1950)
GRB_ERROR:       4.7 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       7.82e-09 [erg/cm2/sec]
GRB_SIGNIF:      12.76 [sigma]
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  44848.13 SOD {12:27:28.13} UT,   74.9 [sec] since BAT Trigger Time
TAM[0-3]:        327.66 237.25 261.41 243.52
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:        40.98d {+02h 43m 56s}  +15.87d {+15d 52' 18"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.81d {+00h 51m 15s}   +9.75d {+09d 45' 08"}
MOON_DIST:        79.54 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.69, 23.83 [deg] galactic lon,lat of the burst
ECL_COORDS:       27.05, 83.33 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.92 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 03 May 08 12:29:42 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     310785,   Seg_Num: 0
POINT_RA:        286.628d {+19h 06m 31s} (J2000)
POINT_DEC:       +68.779d {+68d 46' 46"} (J2000)
POINT_ROLL:      61.872d
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  44856.88 SOD {12:27:36.88} UT,   83.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.128
N_STARS:         74
X_OFFSET:        454 [pixels]
Y_OFFSET:        584 [pixels]
X_MAX:           1413 [pixels]
Y_MAX:           1543 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00310785000msufc0083.fits
SUN_POSTN:        40.98d {+02h 43m 56s}  +15.87d {+15d 52' 19"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.83d {+00h 51m 18s}   +9.76d {+09d 45' 36"}
MOON_DIST:        79.54 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       26.92, 83.33 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 03 May 08 12:30:22 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     310785,   Seg_Num: 0
POINT_RA:        286.628d {+19h 06m 31s} (J2000)
POINT_DEC:       +68.779d {+68d 46' 46"} (J2000)
POINT_ROLL:      61.872d
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  44856.88 SOD {12:27:36.88} UT,   83.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.128
N_STARS:         74
X_OFFSET:        454 [pixels]
Y_OFFSET:        584 [pixels]
X_MAX:           1413 [pixels]
Y_MAX:           1543 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00310785000msufc0083.fits
SUN_POSTN:        40.98d {+02h 43m 56s}  +15.87d {+15d 52' 20"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.83d {+00h 51m 20s}   +9.76d {+09d 45' 47"}
MOON_DIST:        79.53 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       26.92, 83.33 [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 03 May 08 12:30:55 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     310785,   Seg_Num: 0
POINT_RA:        286.628d {+19h 06m 31s} (J2000)
POINT_DEC:       +68.779d {+68d 46' 46"} (J2000)
ROLL:            61.872d
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  44856.88 SOD {12:27:36.88} UT,   83.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     231510459
X_OFFSET:        774 [pixels]
Y_OFFSET:        794 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       934
Y_GRB_POS:       954
BINNING_INDEX:   1
IM_URL:          sw00310785000msuni0083.fits
SUN_POSTN:        40.98d {+02h 43m 56s}  +15.87d {+15d 52' 20"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.84d {+00h 51m 21s}   +9.77d {+09d 45' 56"}
MOON_DIST:        79.53 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       26.92, 83.33 [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 03 May 08 12:31:05 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     310785,   Seg_Num: 0
GRB_RA:          286.617d {+19h 06m 28s} (J2000),
                 286.609d {+19h 06m 26s} (current),
                 286.662d {+19h 06m 39s} (1950)
GRB_DEC:         +68.778d {+68d 46' 41"} (J2000),
                 +68.791d {+68d 47' 29"} (current),
                 +68.698d {+68d 41' 54"} (1950)
GRB_DATE:        14589 TJD;   124 DOY;   08/05/03
GRB_TIME:        44773.42 SOD {12:26:13.42} UT
TRIGGER_INDEX:   10418
GRB_PHI:          -6.72 [deg]
GRB_THETA:        32.33 [deg]
DELTA_TIME:      -18.00 [sec]
TRIGGER_DUR:     0.064 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     20.19 [sigma]
IMAGE_SIGNIF:    8.79 [sigma]
LC_URL:          sw00310785000msb.lc
SUN_POSTN:        40.98d {+02h 43m 56s}  +15.87d {+15d 52' 20"}
SUN_DIST:         83.61 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.84d {+00h 51m 22s}   +9.77d {+09d 45' 59"}
MOON_DIST:        79.54 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.83 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       26.92, 83.33 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Lightcurve.  
COMMENTS:           
COMMENTS:        The next comments were copied from the BAT_POS Notice:  
COMMENTS:        This is a rate trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 188.59,20.13 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 03 May 08 12:31:25 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     310785,   Seg_Num: 0
POINT_RA:        286.628d {+19h 06m 31s} (J2000)
POINT_DEC:       +68.779d {+68d 46' 46"} (J2000)
ROLL:            61.872d
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  44856.88 SOD {12:27:36.88} UT,   83.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     231510459
X_OFFSET:        774 [pixels]
Y_OFFSET:        794 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       934
Y_GRB_POS:       954
BINNING_INDEX:   1
IM_URL:          sw00310785000msuni0083.fits
SUN_POSTN:        40.98d {+02h 43m 56s}  +15.87d {+15d 52' 21"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.84d {+00h 51m 22s}   +9.77d {+09d 46' 04"}
MOON_DIST:        79.53 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       26.92, 83.33 [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 03 May 08 12:38:31 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     310785,   Seg_Num: 0
POINT_RA:        286.626d {+19h 06m 30s} (J2000)
POINT_DEC:       +68.782d {+68d 46' 56"} (J2000)
POINT_ROLL:      61.869d
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  44962.88 SOD {12:29:22.88} UT,   189.6 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        1.043
N_STARS:         120
X_OFFSET:        454 [pixels]
Y_OFFSET:        474 [pixels]
X_MAX:           1413 [pixels]
Y_MAX:           1433 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00310785000msufc0189.fits
SUN_POSTN:        40.99d {+02h 43m 57s}  +15.87d {+15d 52' 26"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.91d {+00h 51m 38s}   +9.80d {+09d 47' 58"}
MOON_DIST:        79.53 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       26.95, 83.33 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 03 May 08 12:39:05 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     310785,   Seg_Num: 0
POINT_RA:        286.626d {+19h 06m 30s} (J2000)
POINT_DEC:       +68.782d {+68d 46' 56"} (J2000)
POINT_ROLL:      61.869d
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  44962.88 SOD {12:29:22.88} UT,   189.6 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        1.043
N_STARS:         120
X_OFFSET:        454 [pixels]
Y_OFFSET:        474 [pixels]
X_MAX:           1413 [pixels]
Y_MAX:           1433 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00310785000msufc0189.fits
SUN_POSTN:        40.99d {+02h 43m 58s}  +15.87d {+15d 52' 26"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.91d {+00h 51m 40s}   +9.80d {+09d 48' 07"}
MOON_DIST:        79.53 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       26.95, 83.33 [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 03 May 08 12:39:41 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     310785,   Seg_Num: 0
POINT_RA:        286.626d {+19h 06m 30s} (J2000)
POINT_DEC:       +68.782d {+68d 46' 56"} (J2000)
ROLL:            61.869d
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  44962.88 SOD {12:29:22.88} UT,   189.6 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     231510565
X_OFFSET:        774 [pixels]
Y_OFFSET:        794 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       934
Y_GRB_POS:       954
BINNING_INDEX:   1
IM_URL:          sw00310785000msuni0189.fits
SUN_POSTN:        40.99d {+02h 43m 58s}  +15.87d {+15d 52' 27"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.92d {+00h 51m 41s}   +9.80d {+09d 48' 17"}
MOON_DIST:        79.53 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       26.95, 83.33 [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 03 May 08 12:40:12 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     310785,   Seg_Num: 0
POINT_RA:        286.626d {+19h 06m 30s} (J2000)
POINT_DEC:       +68.782d {+68d 46' 56"} (J2000)
ROLL:            61.869d
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  44962.88 SOD {12:29:22.88} UT,   189.6 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     231510565
X_OFFSET:        774 [pixels]
Y_OFFSET:        794 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       934
Y_GRB_POS:       954
BINNING_INDEX:   1
IM_URL:          sw00310785000msuni0189.fits
SUN_POSTN:        40.99d {+02h 43m 58s}  +15.87d {+15d 52' 27"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.93d {+00h 51m 42s}   +9.81d {+09d 48' 25"}
MOON_DIST:        79.53 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       26.95, 83.33 [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 03 May 08 12:42:32 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     310785,   Seg_Num: 0
POINT_RA:        286.626d {+19h 06m 30s} (J2000)
POINT_DEC:       +68.782d {+68d 46' 56"} (J2000)
POINT_ROLL:      61.869d
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  45626.35 SOD {12:40:26.35} UT,   853.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.168
N_STARS:         93
X_OFFSET:        454 [pixels]
Y_OFFSET:        474 [pixels]
X_MAX:           1413 [pixels]
Y_MAX:           1433 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00310785000msufc0853.fits
SUN_POSTN:        40.99d {+02h 43m 58s}  +15.87d {+15d 52' 29"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.95d {+00h 51m 47s}   +9.82d {+09d 49' 02"}
MOON_DIST:        79.53 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       26.95, 83.33 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 03 May 08 12:43:11 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     310785,   Seg_Num: 0
POINT_RA:        286.626d {+19h 06m 30s} (J2000)
POINT_DEC:       +68.782d {+68d 46' 56"} (J2000)
POINT_ROLL:      61.869d
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  45626.35 SOD {12:40:26.35} UT,   853.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.168
N_STARS:         93
X_OFFSET:        454 [pixels]
Y_OFFSET:        474 [pixels]
X_MAX:           1413 [pixels]
Y_MAX:           1433 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00310785000msufc0853.fits
SUN_POSTN:        40.99d {+02h 43m 58s}  +15.87d {+15d 52' 29"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.95d {+00h 51m 49s}   +9.82d {+09d 49' 13"}
MOON_DIST:        79.53 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       26.95, 83.33 [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 03 May 08 12:44:06 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     310785,   Seg_Num: 0
POINT_RA:        286.626d {+19h 06m 30s} (J2000)
POINT_DEC:       +68.782d {+68d 46' 56"} (J2000)
ROLL:            61.869d
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  45626.35 SOD {12:40:26.35} UT,   853.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     231511229
X_OFFSET:        773 [pixels]
Y_OFFSET:        793 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       933
Y_GRB_POS:       953
BINNING_INDEX:   1
IM_URL:          sw00310785000msuni0853.fits
SUN_POSTN:        40.99d {+02h 43m 58s}  +15.87d {+15d 52' 30"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.96d {+00h 51m 51s}   +9.82d {+09d 49' 27"}
MOON_DIST:        79.53 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       26.95, 83.33 [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 03 May 08 12:43:39 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     310785,   Seg_Num: 0
POINT_RA:        286.626d {+19h 06m 30s} (J2000)
POINT_DEC:       +68.782d {+68d 46' 56"} (J2000)
ROLL:            61.869d
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  45626.35 SOD {12:40:26.35} UT,   853.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     231511229
X_OFFSET:        773 [pixels]
Y_OFFSET:        793 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       933
Y_GRB_POS:       953
BINNING_INDEX:   1
IM_URL:          sw00310785000msuni0853.fits
SUN_POSTN:        40.99d {+02h 43m 58s}  +15.87d {+15d 52' 29"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.96d {+00h 51m 50s}   +9.82d {+09d 49' 20"}
MOON_DIST:        79.53 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       26.95, 83.33 [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 03 May 08 12:43:28 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     310785,   Seg_Num: 0
GRB_RA:          286.6204d {+19h 06m 28.8s} (J2000),
                 286.6125d {+19h 06m 27.0s} (current),
                 286.6659d {+19h 06m 39.8s} (1950)
GRB_DEC:         +68.7937d {+68d 47' 37.3"} (J2000),
                 +68.8070d {+68d 48' 25.1"} (current),
                 +68.7140d {+68d 42' 50.2"} (1950)
GRB_ERROR:       2.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  45056.00 SOD {12:30:56.00} UT,   282.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        40.99d {+02h 43m 58s}  +15.87d {+15d 52' 29"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       12.96d {+00h 51m 49s}   +9.82d {+09d 49' 17"}
MOON_DIST:        79.53 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.69, 23.83 [deg] galactic lon,lat of the burst
ECL_COORDS:       27.05, 83.33 [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 03 May 08 12:49:14 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     310785,   Seg_Num: 0
POINT_RA:        286.625d {+19h 06m 30s} (J2000)
POINT_DEC:       +68.782d {+68d 46' 55"} (J2000)
POINT_ROLL:      61.869d
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  45732.25 SOD {12:42:12.25} UT,   959.0 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        1.288
N_STARS:         116
X_OFFSET:        454 [pixels]
Y_OFFSET:        474 [pixels]
X_MAX:           1413 [pixels]
Y_MAX:           1433 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00310785000msufc0959.fits
SUN_POSTN:        41.00d {+02h 43m 59s}  +15.88d {+15d 52' 33"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       13.01d {+00h 52m 02s}   +9.85d {+09d 50' 50"}
MOON_DIST:        79.52 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       26.95, 83.33 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 03 May 08 12:49:43 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     310785,   Seg_Num: 0
POINT_RA:        286.625d {+19h 06m 30s} (J2000)
POINT_DEC:       +68.782d {+68d 46' 55"} (J2000)
POINT_ROLL:      61.869d
IMG_START_DATE:  14589 TJD;   124 DOY;   08/05/03
IMG_START_TIME:  45732.25 SOD {12:42:12.25} UT,   959.0 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        1.288
N_STARS:         116
X_OFFSET:        454 [pixels]
Y_OFFSET:        474 [pixels]
X_MAX:           1413 [pixels]
Y_MAX:           1433 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00310785000msufc0959.fits
SUN_POSTN:        41.00d {+02h 43m 59s}  +15.88d {+15d 52' 34"}
SUN_DIST:         83.60 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       13.01d {+00h 52m 03s}   +9.85d {+09d 50' 57"}
MOON_DIST:        79.52 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       99.68, 23.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       26.95, 83.33 [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 03 May 08 12:51:55 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     5955576,   Seg_Num: 66
POINT_RA:          0.000d {+00h 00m 00s} (J2000)
POINT_DEC:       -214748.365d {-214748d 21' 52"} (J2000)
ROLL:            -214748.365d
IMG_START_DATE:  30162 TJD;   15697 DOY;   08/135293677/137615576
IMG_START_TIME:  86165.00 SOD {23:56:05.00} UT,   41391.8 [sec] since BAT Trigger Time
FILTER:          0, illegal value
EXPOSURE_ID:     788549324
X_OFFSET:        0 [pixels]
Y_OFFSET:        68 [pixels]
WIDTH:           0 [pixels]
HEIGHT:          256 [pixels]
X_GRB_POS:       1728
Y_GRB_POS:       107
BINNING_INDEX:   2
IM_URL:          sw00310785000msuni1345548591.fits
SUN_POSTN:        41.00d {+02h 43m 60s}  +15.88d {+15d 52' 35"}
SUN_DIST:        133.42 [deg]   Sun_angle= 2.7 [hr] (West of Sun)
MOON_POSTN:       13.03d {+00h 52m 08s}   +9.86d {+09d 51' 33"}
MOON_DIST:       158.23 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       87.58, 67.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      356.65,  7.67 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        WARNING: This Notice was received with 1 (or more) critical values out of range.  
COMMENTS:        This Notice is generated as a result of an uploaded TOO on an old GRB -- this is not a newly detected burst.  
COMMENTS:        And the IMG_START_DATE/TIME fields are the current epoch -- not the original detection.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 4x4 binning (compression).  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 03 May 08 12:52:18 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     5955576,   Seg_Num: 66
POINT_RA:          0.000d {+00h 00m 00s} (J2000)
POINT_DEC:       -214748.365d {-214748d 21' 52"} (J2000)
ROLL:            -214748.365d
IMG_START_DATE:  30162 TJD;   15697 DOY;   08/135293677/137615576
IMG_START_TIME:  86165.00 SOD {23:56:05.00} UT,   41391.8 [sec] since BAT Trigger Time
FILTER:          0, illegal value
EXPOSURE_ID:     788549324
X_OFFSET:        0 [pixels]
Y_OFFSET:        68 [pixels]
WIDTH:           0 [pixels]
HEIGHT:          256 [pixels]
X_GRB_POS:       1728
Y_GRB_POS:       107
BINNING_INDEX:   2
IM_URL:          sw00310785000msuni1345548591.fits
SUN_POSTN:        41.00d {+02h 43m 60s}  +15.88d {+15d 52' 36"}
SUN_DIST:        133.42 [deg]   Sun_angle= 2.7 [hr] (West of Sun)
MOON_POSTN:       13.04d {+00h 52m 09s}   +9.86d {+09d 51' 39"}
MOON_DIST:       158.23 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:       87.58, 67.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      356.65,  7.67 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        WARNING: This Notice was received with 1 (or more) critical values out of range.  
COMMENTS:        This Notice is generated as a result of an uploaded TOO on an old GRB -- this is not a newly detected burst.  
COMMENTS:        And the IMG_START_DATE/TIME fields are the current epoch -- not the original detection.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 4x4 binning (compression).  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_sources_image.fits.gz file does not exist; skipping the attachment.  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN Circular #7665
J. Mao (INAF-OAB), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), C. Guidorzi (INAF-OAB), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-IASFPA), T. N. Ukwatta (GSFC/GWU) and D. E. Vanden Berk (PSU) report on behalf of the Swift Team:
At 12:26:13 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080503 (trigger=310785). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 286.617, +68.778 which is
```
   RA(J2000) = 19h 06m 28s
   Dec(J2000) = +68d 46' 41"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single spike structure with a duration of about 0.5 sec, although there may be further activity during the slew. The peak count rate was ~6500 counts/sec (15-350 keV), at ~0.1 sec after the trigger.
The XRT began observing the field at 12:27:28.1 UT, 74.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 286.62049, 68.79379 which is equivalent to:
```
   RA(J2000)  = 19h 06m 28.92s
   Dec(J2000) = +68d 47' 37.6"
```
with an uncertainty of 2.7 arcseconds (radius, 90% containment). This location is 57 arcseconds from the BAT onboard position, within the BAT error circle.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 5.56e+20 cm^-2 (Kalberla et al. 2005), so we cannot constrain the redshift at this time using the relation from Grupe et al. (2007). A summary of the promptly downlinked data is given at http://www.swift.ac.uk/sper/310785/.
The initial flux in the 2.5 s image was 7.82e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 84 seconds after the BAT trigger. No afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The 3-sigma upper limit is about 20th mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.06.
Burst Advocate for this burst is J. Mao (jirong.mao AT brera.inaf.it). 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 #7666
D. A. Perley (UC Berkeley), D. Lai, C. Rockosi (UCSC/Lick), and J. S. Bloom (UC Berkeley) report:
After the GRB alert we slewed to the position with the Keck I telescope, equipped with LRIS. We detect a possible new source at a position consistent with the XRT position in the LRIS guider camera near the detection limit of the guider (~20-21st mag). Spectroscopic observations began at ~13:01 UT. Results will be reported in forthcoming circulars.
GCN Circular #7667
J. S. Bloom and D. A. Perley (UC Berkeley) report on behalf of a larger collaboration:
We obtained a sequence of images of the field of GRB 080503 (Mao et al. GCN 7665) from Gemini North using GMOS. In a stack of five 180s exposures starting 2008-05-03 13:23:39 UT, we detect a faint source ("s1") consistent with the Mao et al. XRT position at:
19:06:28.694 +68:47:37.71 J2000
With a positional uncertainty of about 250 mas. Given the faintness of the source, we can claim neither variability nor that the source is pointlike, but it is possible that the source is the host and/or the afterglow. Note that s1 is not the source we originally identified as the possible afterglow in Perley et al. (GCN 7666); we now believe that that object identified in the Keck guider image was outside the XRT error circle and unrelated to the GRB.
This and other sources of interest near the XRT position are encircled in green in the finder:
http://lyra.berkeley.edu/~jbloom/grb080503.png
We thank Rachel Mason of Gemini for her assistance.
GCN Circular #7668
Y.A. Mori, Y. Kudou, T. Shimokawabe and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:
We observed the error box of GRB 080503 (Mao et al. GCN 7665) with the 3-color 50cm MITSuME Telescope at Akeno, Japan starting at 2008-05-03 12:31:53 UT, 5.4 min after the trigger. In the co-added images of Ic, Rc, and g' bands, we did not detect any afterglow candidate in the XRT error circle. The 3-sigma limiting magnitudes based on USNO-B1.0 (I-band) and NOMAD (R-band,g'-band) stars are following.
```
Filter  start (UT)  end (UT)    Exposure   LimitMag
---------------------------------------------------
g'      12:31:53    12:41:03    9 x 60 s     18.8
Rc      12:31:53    12:41:03    9 x 60 s     19.2
Ic      12:31:53    12:41:03    9 x 60 s     18.1
----------------------------------------------------
```
GCN Circular #7669
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 307 s of overlapping XRT Photon Counting mode and UVOT data for GRB 080503, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 286.61961, +68.79330 which is equivalent to:
```
RA (J2000): 19h 06m 28.71s
Dec (J2000): +68d 47' 35.9"
```
with an uncertainty of 1.8 arcsec (radius, 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 circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #7673
T. Ukwatta (GWU), 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), J. Mao (INAF-OAB), D. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC) (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 080503 (trigger #310785) (Mao, et al., GCN Circ. 7665). The BAT ground-calculated position is RA, Dec = 286.686, 68.803 deg, which is
```
   RA(J2000)  =  19h 06m 44.7s 
   Dec(J2000) = +68d 48' 09.2" 
```
with an uncertainty of 3.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 75%.
The mask-weighted light curve shows an initial spike starting at ~T+0.1 sec with a fast rise to a peak at ~T+0.2 sec, with a roughly exponential decay down to background at ~T+0.7 sec. The softer emission starts at about T+10 sec, rising with two peaks at about T+26 and +37 sec, and then falling to background levels at T+220+/-20 sec. T90 (15-350 keV) is 170 +- 40 sec (estimated error including systematics).
The time-averaged spectrum from T+0.2 to T+220.6 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.00 +- 0.13. The fluence in the 15-150 keV band is 2.0 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+26.58 sec in the 15-150 keV band is 0.9 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
As to whether this burst is a SHB with extended emission or a Long burst with a partcularly short pulse at the beginning, we can not say yet. Looking at the 4-band lightcurves, the initial spike is harder than the later emission. We are waiting for (a) separate spectral analysis on the two portions of the lightcurve, and (b) for the lag analysis. We are currently in an 8-hour gap in the downlink sessions, so it will be a while before we can say with better confidence if this is truely a SHB or not. We will issue another circular.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/310785/BA/
GCN Circular #7674
GRB 080503: Swift-XRT refined analysis
C. Guidorzi & J. Mao (INAF-OAB) report on behalf of the Swift-XRT team:
The Swift-XRT began observing GRB 080503 (trigger=3D310785, Mao et al., GCN Circ. 7665) in Window Timing mode, 81 s after the BAT trigger. The enhanced XRT position was given in Goad et al. (GCN Circ. 7669).
The light curve from 81 s to 13.2 ks can be modelled with the combination of an exponential with a power law taking over at late time, with the following best-fitting parameters: e-folding time=3D (72 =B1 4) s, power-law index alpha=3D 2.2 (-1.1, +0.6). The chisq/dof=3D202/151 is due to short-term variability superposed to the model.
The WT mode spectrum spanning from 81 to 282 s can be fit by a power-law model, with a photon index of 1.27 =B1 0.03 and column density consistent with the average Galactic column density in this direction of 5.6e20 cm^-2. The PC mode spectrum, starting from 282 s and totalling 6.3 ks of exposure, is fit with a power law with a photon index of 2.45+/-0.25 and no evidence for any additional column density with respect to the Galactic one. The corresponding observed (unabsorbed) 0.3-10 keV flux is 2.9e-12 (3.9e-12) erg cm^-2 s^-1.
If the burst continues to decay at the same rate, we predict an XRT count rate of 1.7e-6 count/s at T+24 hours, which corresponds to an observed 0.3-10 keV flux of approximately 4e-17 erg cm^-2 s^-1.
This circular is an official product of the Swift-XRT team.
GCN Circular #7675
P. J. Brown (PSU) and J. Mao(INAF-OAB), on behalf of the Swift/UVOT team.
The Swift Ultra-Violet/Optical Telescope (UVOT) began settled observations of GRB 080503 (trigger 310785) 84 seconds after the BAT trigger (Mao et al.,GCN Circ. 7639). No afterglow is detected at the enhanced XRT position (Goad et al., GCN Circ. 7665) in the initial white finding chart or subsequent summed images. The limiting magnitudes (3-sigma in 5" radius apertures) in each of the UVOT filters are as follows:
```
Filter  T_start(s)  T_stop(s)  Exp(s)  Mag UL (3sig)

white       85       184        98     >20.0
white       85     12500      1314     >22.3
v          191      6749      1219     >20.5
b          671     11588      1203     >21.4
u          646      7365       471     >20.3
uvw1       622      7160       471     >20.4
uvm2       597      6954       471     >20.3
uvw2       701     13219      1133     >21.0
```
The values quoted above are in the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627). They are not corrected for the expected Galactic extinction corresponding to a reddening of E(B-V)=0.06 mag in the direction of the burst (Schlegel et al. 1998).
GCN Circular #7676
D. Kuroda, K. Yanagisawa (NAOJ) and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:
We observed the error box of GRB 080503 (Mao et al. GCN 7665) with the 3-color 105cm Telescope at Ishigakijima Astronomical Observatory starting at 2008-05-03 13:49:55 UT, 1.4 hours after the trigger. In the co-added images of Ic, Rc, and g' bands, we did not detect any afterglow candidate. The 3-sigma limiting magnitudes based on USNO-B1.0 (I-band) and NOMAD (R-band,g'-band) stars are following.
```
Filter  start (UT)  end (UT)    Exposure   LimitMag
---------------------------------------------------
g'      13:49:55    13:59:19    9 x 60 s     20.5
Rc      13:49:55    13:59:19    9 x 60 s     20.2
Ic      13:49:55    13:59:19    9 x 60 s     20.1
----------------------------------------------------
```
GCN Circular #7677
T. Ukwatta (GWU), M. Stamatikos (GSFC/ORAU), T. Sakamoto (GSFC/UMBC), J. Norris (U. of Denver), S. D. Barthelmy (GSFC) (for the Swift-BAT team):
For GRB 080503 (Trigger 310785, GCNs 7665 & 7673), the spectral lag analysis of the data from T-1 sec to T+1 sec (the initial spike), yields a lag of -13 +/- 9 msec for the 15-25 to 50-100 keV bands using lightcurve binnings of 4, 8 and 16 msec. For the on-going emission (T+10 to T+220 sec), the signal is too weak and lacking sufficient structure to yield a significant lag measurement.
Expanding on the total-burst spectral analysis in GCN 7673, we have divided the burst into an initial phase (T+0.0 to T+0.7 sec) and the extended phase (T+10 to T+170 sec). The simple power law fits are:
```
  Phase     PLI            Norm(@50keV)         Chi2/DoF
  Initial   1.59 +/-0.28  (8.15 +- 1.5)E-3      69/59
  Extended  1.91 +/-0.12  (1.19 +- 0.08)E-3     52/59
```
The units of Normalization are ph/cm2/s/keV.
This lag value plus the spectral results puts this burst in the short hard burst category.
GCN Circular #7678
D. A. Perley, J. S. Bloom (UC Berkeley), and J. X. Prochaska (UCO/Lick) report:
Further to Bloom et al. (GCN 7667), we acquired additional imaging of the probable short-hard (Ukwatta et al., GCN 7677) GRB 080503 (Mao et al., GCN 7665) with extended emission the night after the burst. A total of 10 exposures of 180 seconds each were taken in r-band between UT 14:08 and 14:46 (2008-05-04), 26 hours after the BAT trigger, using GMOS on Gemini-North. In addition, we report analysis of additional imaging taken between 1.0-2.5 hours after the burst in g, r, i, and z filters.
The source noted in our previous circular, s1, does not appear to be variable between images, and no other sources are detected in the XRT error circle to a very deep limit of r >~ 26.5 during the first night. However, a new source ("s2") appears in the second night's observation that was not detected in our r-band imaging during the first night. If this source is associated with GRB 080319B this would be extremely unusual behavior for a short gamma-ray burst. It is possible that the rebrightening is the first example of the detection of a Li-Paczynski "mini"-supernova (1998ApJ...507L..59L; see also Kulkarni astro-ph/0510256). More tentatively, we note that s1 may the host galaxy (we note that all previous SHB's with extended emission have been seen at small offset from their host galaxies: Troja et al., astro-ph/0711.3034).
The source is located near the center of the enhanced XRT error circle (Goad et al, GCN 7669) at:
RA=19:06:28.766 Dec=+68:47:35.53 (J2000)
(uncertainty is 250 mas in both coordinates relative to the ICRS)
And can be seen at the following links:
```
http://lyra.berkeley.edu/~jbloom/grb080503-comp.png

http://lyra.berkeley.edu/~jbloom/grb080503-rebrightening.mpeg

http://lyra.berkeley.edu/~dperley/080503/080503_s2b.png
```
We report the following photometry, calibrated relative to USNO-B1.0:
```
Acquisition r-band image (t=0.98 hr)
s1: R = 25.56 +/- 0.33
s2: R > 25.6

First night r-band stack (t=1.5 hr)
s1: R = 26.00 +/- 0.18
s2: R >~ 26.5

Second night r-band stack (t=26.0 hr)
s1: R = 25.70 +/- 0.12
s2: R = 25.28 +/- 0.09

UT_start exposure   filter magnitude
13:23    1x180      r      R = 24.8 +/- 0.3
13:38    1x30+2x300 R      R > 25.5 (2-sigma)
13:47    5x180      r      R = 25.4 +/- 0.2
```
Photometric uncertainties do not include calibration uncertainties relative to USNO-B1.0, which are at the level of 0.1 magnitude. (This does not affect the relative magnitudes between the images).
In our images in other filters, s2 is not detected in i-band or z-band during the first night. It may be marginally detected in g-band imaging near the limiting magnitude of that observation.
Further observations of this source are planned and strongly encouraged.
GCN Circular #7679
D. A. Perley, J. S. Bloom (UC Berkeley), and J. X. Prochaska (UCO/Lick) report:
The line that states:
"If this source is associated with GRB 080319B this would be extremely unusual behavior for a short gamma-ray burst."
Should of course read:
"If this source is associated with GRB 080503 this would be extremely unusual behavior for a short gamma-ray burst."
We apologize for any confusion, and thank R. Chornock for pointing out the error.
GCN Circular #7680
D. A. Perley and J. S. Bloom (UC Berkeley) report on behalf of a larger collaboration:
Starting at UT 11:32 on the night of 2008-05-05, we began a series of additional r-band imaging follow-up observations of the optical counterpart associated with GRB 080503 (GCN 7665, Mao et al.), using Gemini-North (+GMOS).
The new source (s2) reported in our previous circular (GCN 7678) is still present at about the same magnitude. Using a stack of 9x180s images, we present the following measurement of the magnitudes of s1 and s2:
```
s1: R = 26.33 +/- 0.20
s2: R = 25.46 +/- 0.09
```
This is consistent (within about 2-sigma) with the previous night's measurement and suggests neither additional rebrightening nor dramatic fading. We continue to strongly encourage follow-up with large-aperture instruments.
We also issue the following correction to GCN 7678: the data table at the bottom (with heading "UT_start exposure filter magnitude") is not valid. This is photometry of s1 based on an older calibration, and including a Keck R-band limiting magnitude that will be refined in a future circular. The preceding photometry of s1 and s2 in that circular is still valid.
To reiterate, the r-band evolution of the optical counterpart (s2) to date, calibrated to USNO B1.0 R-band, is given by:
```
t(hr)  magnitude
0.98   R > 25.6
1.5    R > 26.5
26.0   R = 25.28 +/- 0.09
47.4   R = 25.46 +/- 0.09
```
Further observations are ongoing.
GCN Circular #7682
From: Arnon Dar at Technion-Israel Inst. of Tech
Many long GRBs have optical light-curves which are initially slowly rising. The optical light curve of the short hard burst (SHB) 080503 (Mao et al. GCN 7665; Ukwatta et al. GCN 7673; Guidorzi et al. GCN 7674) discovered by Perley et al. (GCNs 7678, 7680) may be their analog slow-rise optical afterglow (AG) changing to a plateau phase and entering the gradual transition to an asymptotic decline, which, in the CB model, has roughly the form,
Fnu ~ [1/(t+t_b}^{\beta_O+1/2}] * nu^{-beta_O}
for a constant low-density SHB environment, or
Fnu ~ [1/ (t+t_b)^{beta_O+1}] * nu^{-beta_O}
for an isothermal sphere environment with a density propto 1/r^2. t_b is the bending time of its canonical AG, and beta_O = Gamma - 1 ~ 1.1 is the spectral index above the bend frequency. In the CB model, the initial increase of the CB's radius, R^2 ~ t^2/(t^2+t_exp^2), where t_exp is the time beyond which the CB's radius settles to its approximate constant value, produces the initial rise of the synchrotron AG. The low density environments of SHBs yields typically, t_b~ 10^5 s, and a long expansion time, t_exp, of the CB's radius relative to its values in slow-rise optical AGs of long GRB such as 071010A (Covino et el. arXiv:0804.4367).
GCN Circular #7683
A. de Ugarte Postigo, (ESO), C. C. Th=F6ne, D. Malesani, J. P. U. Fynbo (DARK) and T. Purismo (NOT) on behalf of a larger collaboration report:
We have observed the field of GRB 080503 (Mao et al., GCN 7665) from the 2.5m NOT (+MOSCA) under bad atmospheric conditions. We do not detect the object reported by Perley et al. (GCN 7678) down to a 3-sigma limiting magnitude of R~21.7 at a mean time of 6.091 May 2008 UT (2.573 days after the burst).
GCN Circular #7684
Dale A. Frail (NRAO) and Poonam Chandra (NRAO/UVA) report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration:
"We used the Very Large Array to observe the field of view toward GRB 080503 (GCN 7665) at a frequency of 8.46 GHz at 2008 May 6.57 UT. We do not detect the GRB afterglow in 2.5 hours of VLA observations. The 3-sigma upper limit on the afterglow flux is 54 uJy (rms 18 uJy).
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc."
GCN Circular #7691
H. Tanaka, N. Ohmori, H. Hayasi, R. Hara, K. Kono, M. Yamauchi (University of Miyazaki)
We have observed the field covering the error circle of GRB080503 (GCN 7669, M.R. Goad et al.) with the unfiltered CCD camera on the 30-cm telescope at University of Miyazaki. The observation was started 15:25:55 UT; about 180 minutes after the Swift trigger time.
We have compared our data of 30 sec exposures with the USNO-A2.0 catalog,there is no new source at the reported position
the upper limits are as follows:
```
--------------------------------------------------------------
Start(UT) End(UT)	Num. of frames 	Limit (mag.)
--------------------------------------------------------------
15:26:57 15:27:27 	1 		~16.82
15:26:57 16:24:33 	57 		~17.43
---------------------------------------------------------------
```
GCN Circular #7695
D. A. Perley, J. S. Bloom, and W. Li (UC Berkeley), on behalf of a larger collaboration, report:
We have continued to monitor the optical transient (Perley et al., GCN 7678) associated with GRB 080503 (Mao et al., GCN 7665) using Gemini-N (+GMOS) with additional exposures in r-band nightly since the event.
The optical counterpart remains detected in all images to date (through 2008-05-07 UT) and is significantly, but slowly, fading. This confirms the lack of further rebrightening (see also Perley et al., GCN 7680) and further distinguishes the behavior of the transient from ordinary long- and short-burst afterglows. Alternatively, a faint host galaxy could be contributing to the later exposures somewhat; further follow-up may help resolve this ambiguity.
GCN Circular #7703
J. S. Bloom (UC Berkeley), W. Li (UC Berkeley), A. J. Levan (U. Warwick), D. A. Perley (UCB), N. R. Tanvir (U. Leicester), N. R. Butler (UCB), H-W. Chen (U. Chicago), R. Chornock (UCB), J. X. Prochaska (UCO/Lick), C. D. Bailyn (Yale), A. Bunker (U. Exeter), R. Chornock (UCB), B. Cobb (Yale), P. B. Hall (York U.), A. V. Filippenko (UCB), N. Gehrels (NASA/GSFC), K. Glazebrook (Swinburne), J. Granot (U. Hertfordshire), K. C. Hurley (UCB), D. Kocevski (UCB), B. Metzger (UCB), M. Modjaz (UCB), A. Miller (UCB), W. Lee (I. de Astronomia), S. Lopez (U. Chile), J. Norris (NASA/Ames), P. E. Nugent (LBNL), M. Pettini (U. Cambridge), D. Poznanski (UCB), A. L. Piro (UCB), E. Quataert (UCB), E. Ramirez-Ruiz (UCSC), J. Shiode (UCB), and T. Sakamoto (GSFC/UMBC) report:
Under Director's Discretionary Proposal (#11551), we acquired observations of GRB 080503 (Mao et al., GCN 7665) with the Hubble Space Telescope (HST+WFPC2), starting at 15:08 and lasting until 20:45 (UT 2008-05-08), approximately 5.2 days after the GRB. The total integration time was 2x1200s + 2x1100s (2 orbits) in F606W, 3x700s (1 orbit) in F814W, and 3x700s (1 orbit) in F450W. The data were collected in a small dither pattern around the WFALL position to mitigate against CTE losses.
We clearly detect a point source at a location consistent with the optical transient (Perley et al., GCN 7678) in F606W, and marginally detect a source at this position in 450W. The transient is not detected in F814W. We report the following preliminary magnitudes:
```
F450W_AB = 26.95 +/- 0.27
F606W_AB = 26.86 +/- 0.15
F814W_AB > 26.6
```
The nearby source s1 (see Perley et al., GCN 7667) is also detected, and appears visibly extended, though this extension does not reach s2. Two other faint, extended sources ("s3" and "s4") are detected about 1 arcsecond to the northwest and southeast of the transient, respectively. There is no obviously extended source detected at the position of s2.
The source is significantly fainter than observed in our Gemini measurements, which may suggest a break (as expected from an off-axis jet) or an exponential decline (as expected from an LP mini-supernova). However, LP mini-SN models also predict a red late-time color, which is not observed. We note also the detection of an X-ray afterglow in late-time Chandra observations (Butler et al., GCN in prep.)
An additional epoch of HST imaging will be obtained starting 15:05 12-May-2008 UT.
An preliminary image with less-than-optimal cosmic ray reduction is posted to: http://lyra.berkeley.edu/~dperley/080503/080503_hst660w_ep1.png
We are grateful to all the people STSCI that made such a rapid ToO possible.
GCN Circular #7704
N. R. Butler (UC Berkeley), J. S. Bloom (UCB), W. Li (UCB), A. J. Levan (U. Warwick), D. A. Perley (UCB), N. R. Tanvir (U. Leicester), H-W. Chen (U. Chicago), R. Chornock (UCB), J. X. Prochaska (UCO/Lick), C. D. Bailyn (Yale), A. Bunker (U. Exeter), R. Chornock (UCB), B. Cobb (Yale), P. B. Hall (York U.), A. V. Filippenko (UCB), N. Gehrels (NASA/GSFC), D. Burrows (PSU), K. Glazebrook (Swinburne), J. Granot (U. Hertfordshire), K. C. Hurley (UCB), D. Kocevski (UCB), B. Metzger (UCB), M. Modjaz (UCB), A. Miller (UCB), W. Lee (I. de Astronomia), S. Lopez (U. Chile), J. Norris (NASA/Ames), P. E. Nugent (LBNL), M. Pettini (U. Cambridge), D. Poznanski (UCB), A. L. Piro (UCB), E. Quataert (UCB), E. Ramirez-Ruiz (UCSC), J. Shiode (UCB), and T. Sakamoto (GSFC/UMBC) report:
From 2008/05/07 19:18:23 UT to 2008/05/08 04:09:59 UT (4.29 - 4.66 days post burst), Chandra Director's Discretionary Time observations with ACIS-S were conducted of the field of GRB 080503 (Mao et al. 2008; GCN7665) for a total exposure of 29.8 ksec (livetime). We find a highly significant detection of one X-ray point source in the XRT error circle (Goad et al. 2008; GCN7669) at:
RA, Dec = 19:06:28.76, +68:47:35.3 +/- 0.5" (J2000).
The source is 0.2" away from the Gemini optical source (S2) in Perley et al. (2008; GCN7678), and is 0.7" away from the center of the XRT error circle. The X-ray source is therefore highly likely to be associated with S2, which is in turn highly likely to be associated with GRB 080503. Astrometry is established using Chandra field sources also detected in the Gemini images.
We detect 40+/-6 counts in the 0.5-8.0 keV band. There is weak evidence in favor of variability. During the first half of the exposure, we measure 21+/-5 cts, as compared to 19+/-4 counts in the second half. Testing against the NULL hypothesis of a steady source, we find KS-prob=0.23.
The Chandra flux implies a flattening of the X-ray flux relative to the rapid decay observed prior to ~13 ksec by the Swift XRT (Guidorzi et al. 2008; GCN7674). We note also that XRT observations at late time (2.4-3.2 days post burst) exhibit a flux consistent with that of Chandra, yielding a marginal (~1-sigma) XRT detection.
Minimizing the Cash (1976) statistic, we find the Chandra spectrum to be acceptably fit by an absorbed powerlaw with photon index Gamma=1.5+/-0.5 and unabsorbed flux Fx(0.3-10 keV) = (1.5+/-0.7) x 10^(-14) erg/cm^2/s. We assume Galactic absorption only, as observed for the Swift XRT spectrum (Guidorzi et al. 2008; GCN7674).
Roughly, the X-ray flux is consistent with an extrapolation of the optical flux as observed by HST (Bloom et al. 2008; GCN7703), assuming the X-ray spectral index. If the optical flux is due to a a Li-Paczynski "mini"-supernova (1998ApJ...507L..59L) as suggested by Perley et al. (2008; GCN7678), then the X-ray light curve may be more easily explained by invoking a separate emission mechanism. Alternatively, both the optical and X-ray fluxes may be due to shock energy re-injection or flaring occuring on timescales ~1-4 days post burst.
More detailed analyses are ongoing.
We thank Harvey Tananbaum, Patrick Slane, Andrea Prestwich, and the rest of the Chandra observatory staff for their impressive rapid scheduling and execution of this observation.
This message can be cited.
GCN Circular #7749
D. A. Perley (UC Berkeley), J. S. Bloom (UCB), A. J. Levan (U. Warwick), W. Li (UCB), N. R. Tanvir (U. Leicester), N. R. Butler (UCB), H-W. Chen (U. Chicago), R. Chornock (UCB), J. X. Prochaska (UCO/Lick), C. D. Bailyn (Yale), A. Bunker (U. Exeter), R. Chornock (UCB), B. Cobb (Yale), P. B. Hall (York U.), A. V. Filippenko (UCB), N. Gehrels (NASA/GSFC), K. Glazebrook (Swinburne), J. Granot (U. Hertfordshire), K. C. Hurley (UCB), D. Kocevski (UCB), B. Metzger (UCB), M. Modjaz (UCB), A. Miller (UCB), W. Lee (I. de Astronomia), S. Lopez (U. Chile), J. Norris (NASA/Ames), P. E. Nugent (LBNL), M. Pettini (U. Cambridge), D. Poznanski (UCB), A. L. Piro (UCB), E. Quataert (UCB), E. Ramirez-Ruiz (UCSC), J. Shiode (UCB), and T. Sakamoto (GSFC/UMBC) report:
Further to GCN 7703 (Bloom et al.), we obtained additional imaging using the Hubble Space Telescope (+WFPC2) of GRB 080503 (Mao et al., GCN 7665) starting at 15:05:05 on UT 2008-05-12, about 9.2 days after the trigger. Four exposures of 1000s each were acquired in F606W and in F814W.
The afterglow has faded significantly since the previous HST epoch, and is not detected in either filter, or in a combined stack of the imaging from both filters. The approximate limiting magnitude is F606W(AB) > 28.0, confirming the rapid fading observed previously. No sign of host-galaxy emission is present in either filter.
GCN Report 138.1
GCN_Report 138.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_138_1.pdf by J. Mao at INAF-OAB titled: "Final Swift Observations of GRB 080503"
GCN Circular #7775
N. R. Butler (UC Berkeley), J. S. Bloom (UCB), W. Li (UCB), A. J. Levan (U. Warwick), D. A. Perley (UCB), N. R. Tanvir (U. Leicester), H-W. Chen (U. Chicago), R. Chornock (UCB), J. X. Prochaska (UCO/Lick), C. D. Bailyn (Yale), A. Bunker (U. Exeter), B. Cobb (Yale), P. B. Hall (York U.), A. V. Filippenko (UCB), N. Gehrels (NASA/GSFC), D. Burrows (PSU), K. Glazebrook (Swinburne), J. Granot (U. Hertfordshire), K. C. Hurley (UCB), D. Kocevski (UCB), B. Metzger (UCB), M. Modjaz (UCB), A. Miller (UCB), W. Lee (I. de Astronomia), S. Lopez (U. Chile), J. Norris (NASA/Ames), P. E. Nugent (LBNL), M. Pettini (U. Cambridge), D. Poznanski (UCB), A. L. Piro (UCB), E. Quataert (UCB), E. Ramirez-Ruiz (UCSC), J. Shiode (UCB), and T. Sakamoto (GSFC/UMBC) report:
From 2008/05/25 18:11:36 UT to 2008/05/26 03:04:28 UT (22.24 - 22.61 days post burst), Chandra Director's Discretionary Time observations with ACIS-S were conducted of the field of GRB 080503 (e.g., Mao et al. 2008; GCN 7665) for a total exposure of 29.8 ksec (livetime). In a 3-pixel radius source extraction region centered around the first epoch Chandra source (Butler et al. 2008; GCN 7704), we find no source counts in the 0.5-8.0 keV band.
We derive a 2-sigma upper limit to the source flux of Fx(0.3-10 keV) < 9.9 x 10^(-16) erg/cm^2/s. Relative to the first epoch flux ~18 days earlier, the 2nd epoch flux implies a fade steeper in time than t^(-1.6). A similarly steep or steeper fade is implied in the optical band from Gemini and HST observations of this source (Perley et al. 2008; GCNs 7667, 7678, 7679, 7680, 7695, 7703, 7749). Combined with a rough agreement in the extrapolated flux levels assuming a GRB afterglow external shock model (e.g., GCN 7704), the lightcurve similarity supports an interpretation where the external shock is responsible for both the X-ray and optical emission.
More detailed analyses are ongoing.
We thank Harvey Tananbaum and the Chandra observatory staff for their impressive rapid scheduling and execution of this observation.
This message can be cited.
0811.1044from 7 Nov 2008
Perley: GRB 080503: Implications of a Naked Short Gamma-Ray Burst Dominated by Extended Emission
Abstract: We report on observations of GRB 080503, a short gamma-ray burst with very bright extended emission (about 30 times the gamma-ray fluence of the initial spike) in conjunction with a thorough comparison to other short Swift events. In spite of the prompt-emission brightness, however, the optical counterpart is extraordinarily faint, never exceeding 25 mag in deep observations starting at ~1 hr after the BAT trigger. The optical brightness peaks at ~1 day and then falls sharply in a manner similar to the predictions of Li & Paczynski (1998) for supernova-like emission following compact-binary mergers. However, a shallow spectral index and similar evolution in X-rays inferred from Chandra observations are more consistent with an afterglow interpretation. The extreme faintness of this probable afterglow relative to the bright gamma-ray emission argues for a very low-density medium surrounding the burst (a "naked" GRB), consistent with the lack of a coincident host galaxy down to 28.5 mag in deep HST imaging. Our observations reinforce the notion that short GRBs generally occur outside regions of active star formation, but demonstrate that in some cases the luminosity of the extended prompt emission can greatly exceed that of the short spike, which may constrain theoretical interpretation of this class of events. Because most previous BAT short bursts without observed extended emission are too faint for this signature to have been detectable even if it were present at typical level, conclusions based solely on the observed presence or absence of extended emission in the existing Swift sample are premature. (abridged)
1204.0941 from 5 Apr 12
R. Hasco�t et al.: The origin of the late rebrightening in GRB 080503
GRB 080503, detected by Swift, belongs to the class of bursts whose prompt phase consists of an initial short spike followed by a longer soft tail. It did not show any transition to a regular afterglow at the end of the prompt emission but exhibited a surprising rebrightening after one day. We aim to explain this rebrightening with two different scenarios - refreshed shocks or a density clump in the circumburst medium - and two models for the origin of the afterglow, the standard one where it comes from the forward shock, and an alternative one where it results from a long-lived reverse shock. We computed afterglow light curves either using a single-zone approximation for the shocked region or a detailed multizone method that more accurately accounts for the compression of the material. We find that in several of the considered cases the detailed model must be used to obtain a reliable description of the shock dynamics. The density clump scenario is not favored. We confirm previous results that the presence of the clump has little effect on the forward shock emission, except if the microphysics parameters evolve when the shock enters the clump. Moreover, we find that the rebrightening from the reverse shock is also too weak when it is calculated with the multi-zone method. On the other hand, in the refreshed-shock scenario both the forward and reverse shock models provide satisfactory fits of the data under some additional conditions on the distribution of the Lorentz factor in the ejecta and the beaming angle of the relativistic outflow.
1311.1519 from 8 Nov 13
Brian D. Metzger et al.: Optical and X-ray emission from stable millisecond magnetars formed from the merger of binary neutron stars
The coalescence of binary neutron stars (NSs) may in some cases produce a stable massive NS remnant rather than a black hole. Due to the substantial angular momentum from the binary, such a remnant is born rapidly rotating and likely acquires a strong magnetic field (a `millisecond magnetar'). Magnetic spin-down deposits a large fraction of the rotational energy from the magnetar behind the small quantity of mass ejected during the merger. This has the potential for creating a bright transient that could be useful for determining whether a NS or black hole was formed in the merger. We investigate the expected signature of such an event, including for the first time the important impact of electron/positron pairs injected by the millisecond magnetar into the surrounding nebula. These pairs cool via synchrotron and inverse Compton emission, producing a pair cascade and hard X-ray spectrum. A fraction of these X-rays are absorbed by the ejecta walls and re-emitted as thermal radiation, leading to an optical/UV transient peaking at a luminosity of ~1e43-1e44 erg/s on a timescale of several hours to days. This is dimmer than predicted by simpler analytic models because the large optical depth of electron/positron pairs across the nebula suppresses the efficiency with which the magnetar spin down luminosity is thermalized. Nevertheless, the optical/UV emission is more than two orders of magnitude brighter than a radioactively powered `kilonova.' In some cases nebular X-rays are sufficiently luminous to re-ionize the ejecta, in which case non-thermal X-rays escape the ejecta unattenuated with a similar peak luminosity and timescale as the optical radiation. We discuss the implications of our results for the temporally extended X-ray emission that is observed to follow some short gamma-ray bursts (GRBs), including the kilonova candidates GRB 080503 and GRB 130603B.
1508.05093 from 24 Aug 15
Shota Kisaka et al.: X-ray-powered macronovae
A macronova (or kilonova) was observed as an infrared excess several days after short gamma-ray burst, GRB 130603B. Although the $r$-process radioactivity is widely discussed as an energy source, it requires huge mass of ejecta from a neutron star (NS) binary merger. We propose that the X-ray excess simultaneously observed with the infrared excess can naturally heat the ejecta, leading to the thermal re-emission as observed in infrared. This X-ray-powered model explains both the X-ray and infrared excesses with a single energy source by the central engine like a black hole, and allows for broader parameter region, in particular smaller ejecta mass $\sim10^{-3}-10^{-2}M_{\odot}$ with iron mixed as suggested by general relativistic simulations for typical NS-NS mergers, than the previous models. We also discuss the other macronova candidates in GRB 060614 and GRB 080503, and implications for the search of electromagnetic counterparts to gravitational waves.

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Jochen Greiner, last update: 24-Aug-2015 [Disclaimer]