Gamma-ray Burst 070420

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:18:40 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     276321,   Seg_Num: 0
GRB_RA:          121.253d {+08h 05m 01s} (J2000),
                 121.311d {+08h 05m 15s} (current),
                 120.855d {+08h 03m 25s} (1950)
GRB_DEC:         -45.561d {-45d 33' 38"} (J2000),
                 -45.582d {-45d 34' 54"} (current),
                 -45.417d {-45d 25' 01"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       12944 [cnts]    Image_Peak=331 [image_cnts]
TRIGGER_DUR:     2.048 [sec] 
TRIGGER_INDEX:   263     E_range: 50-350 keV
BKG_INTEN:       114962 [cnts]
BKG_TIME:        22662.09 SOD {06:17:42.09} UT
BKG_DUR:         24 [sec]
GRB_DATE:        14210 TJD;   110 DOY;   07/04/20
GRB_TIME:        22693.52 SOD {06:18:13.52} UT
GRB_PHI:         146.80 [deg]
GRB_THETA:        48.28 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     23.93 [sigma]
IMAGE_SIGNIF:    10.94 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +3 +14  +0  +1 +18  +1 
SUN_POSTN:        27.72d {+01h 50m 53s}  +11.40d {+11d 24' 07"}
SUN_DIST:        100.61 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.39d {+04h 25m 34s}  +26.82d {+26d 49' 24"}
MOON_DIST:        87.90 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.87, -7.41 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      143.87,-63.27 [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 = 134.64,-13.06 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:20:29 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     276321,   Seg_Num: 0
GRB_RA:            0.0000d {+00h 00m 00.0s} (J2000),
                   0.0935d {+00h 00m 22.4s} (current),
                  -0.6405d {-00h 02m 33.7s} (1950)
GRB_DEC:          +0.0000d {+00d 00' 00.0"} (J2000),
                  +0.0406d {+00d 02' 26.2"} (current),
                  -0.2784d {-00d 16' 42.2"} (1950)
GRB_ERROR:       -773094113.3 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       0 [cnts]
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  22792.39 SOD {06:19:52.39} UT,   98.9 [sec] since BAT Trigger Time
CENTROID_X:      0.00,  raw= 0  [pixels]
CENTROID_Y:      0.00,  raw= 0  [pixels]
ROLL:            0.00 [deg]
GAIN:            0
MODE:            0, illegal mode
WAVEFORM:        0
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -11.64
GRB_POS_XRT_Z:   61.28
IMAGE_URL:       sw00276321000msxps_rw.img
SUN_POSTN:        27.72d {+01h 50m 54s}  +11.40d {+11d 24' 09"}
SUN_DIST:         29.70 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:       66.41d {+04h 25m 38s}  +26.83d {+26d 49' 35"}
MOON_DIST:        68.98 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:       96.34,-60.19 [deg] galactic lon,lat of the burst
ECL_COORDS:        0.00,  0.00 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:21:41 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     276321,   Seg_Num: 0
GRB_RA:          121.253d {+08h 05m 01s} (J2000),
                 121.311d {+08h 05m 15s} (current),
                 120.855d {+08h 03m 25s} (1950)
GRB_DEC:         -45.561d {-45d 33' 38"} (J2000),
                 -45.582d {-45d 34' 54"} (current),
                 -45.417d {-45d 25' 01"} (1950)
GRB_DATE:        14210 TJD;   110 DOY;   07/04/20
GRB_TIME:        22693.52 SOD {06:18:13.52} UT
TRIGGER_INDEX:   263
GRB_PHI:         146.80 [deg]
GRB_THETA:        48.28 [deg]
DELTA_TIME:      58.00 [sec]
TRIGGER_DUR:     2.048 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     23.93 [sigma]
IMAGE_SIGNIF:    10.94 [sigma]
LC_URL:          sw00276321000msb.lc
SUN_POSTN:        27.72d {+01h 50m 54s}  +11.40d {+11d 24' 10"}
SUN_DIST:        100.61 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.42d {+04h 25m 42s}  +26.83d {+26d 49' 43"}
MOON_DIST:        87.89 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.87, -7.41 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      143.87,-63.27 [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 = 134.64,-13.06 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:22:21 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.557d {-45d 33' 26"} (J2000)
POINT_ROLL:      275.565d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  22801.17 SOD {06:20:01.17} UT,   107.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.320
N_STARS:         190
X_OFFSET:        256 [pixels]
Y_OFFSET:        656 [pixels]
X_MAX:           1215 [pixels]
Y_MAX:           1615 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    6
SL_URL:          sw00276321000msufc0107.fits
SUN_POSTN:        27.72d {+01h 50m 54s}  +11.40d {+11d 24' 10"}
SUN_DIST:        100.58 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.43d {+04h 25m 43s}  +26.83d {+26d 49' 47"}
MOON_DIST:        87.86 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.85, -7.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.29 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:22:52 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.557d {-45d 33' 26"} (J2000)
POINT_ROLL:      275.565d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  22801.17 SOD {06:20:01.17} UT,   107.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.320
N_STARS:         190
X_OFFSET:        256 [pixels]
Y_OFFSET:        656 [pixels]
X_MAX:           1215 [pixels]
Y_MAX:           1615 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    6
SL_URL:          sw00276321000msufc0107.fits
SUN_POSTN:        27.73d {+01h 50m 54s}  +11.40d {+11d 24' 11"}
SUN_DIST:        100.58 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.44d {+04h 25m 45s}  +26.83d {+26d 49' 50"}
MOON_DIST:        87.85 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.85, -7.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.29 [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:     Fri 20 Apr 07 06:23:45 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.557d {-45d 33' 26"} (J2000)
ROLL:            275.565d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  22801.17 SOD {06:20:01.17} UT,   107.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     198742803
X_OFFSET:        689 [pixels]
Y_OFFSET:        941 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       849
Y_GRB_POS:       1101
BINNING_INDEX:   1
IM_URL:          sw00276321000msuni0107.fits
SUN_POSTN:        27.73d {+01h 50m 54s}  +11.40d {+11d 24' 12"}
SUN_DIST:        100.58 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.45d {+04h 25m 47s}  +26.83d {+26d 49' 56"}
MOON_DIST:        87.85 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.85, -7.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.29 [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:     Fri 20 Apr 07 06:24:09 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.557d {-45d 33' 26"} (J2000)
ROLL:            275.565d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  22801.17 SOD {06:20:01.17} UT,   107.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     198742803
X_OFFSET:        689 [pixels]
Y_OFFSET:        941 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       849
Y_GRB_POS:       1101
BINNING_INDEX:   1
IM_URL:          sw00276321000msuni0107.fits
SUN_POSTN:        27.73d {+01h 50m 54s}  +11.40d {+11d 24' 12"}
SUN_DIST:        100.58 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.45d {+04h 25m 48s}  +26.83d {+26d 49' 58"}
MOON_DIST:        87.85 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.85, -7.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.29 [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:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:31:21 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.555d {-45d 33' 16"} (J2000)
POINT_ROLL:      275.566d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  22907.01 SOD {06:21:47.01} UT,   213.5 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        1.810
N_STARS:         190
X_OFFSET:        369 [pixels]
Y_OFFSET:        621 [pixels]
X_MAX:           1328 [pixels]
Y_MAX:           1580 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    6
SL_URL:          sw00276321000msufc0213.fits
SUN_POSTN:        27.73d {+01h 50m 55s}  +11.41d {+11d 24' 18"}
SUN_DIST:        100.57 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.53d {+04h 26m 08s}  +26.85d {+26d 50' 43"}
MOON_DIST:        87.82 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.84, -7.43 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:31:51 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.555d {-45d 33' 16"} (J2000)
POINT_ROLL:      275.566d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  22907.01 SOD {06:21:47.01} UT,   213.5 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        1.810
N_STARS:         190
X_OFFSET:        369 [pixels]
Y_OFFSET:        621 [pixels]
X_MAX:           1328 [pixels]
Y_MAX:           1580 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    6
SL_URL:          sw00276321000msufc0213.fits
SUN_POSTN:        27.73d {+01h 50m 55s}  +11.41d {+11d 24' 18"}
SUN_DIST:        100.57 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.54d {+04h 26m 09s}  +26.85d {+26d 50' 46"}
MOON_DIST:        87.81 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.84, -7.43 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.28 [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:     Fri 20 Apr 07 06:32:52 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.555d {-45d 33' 16"} (J2000)
ROLL:            275.566d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  22907.01 SOD {06:21:47.01} UT,   213.5 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     198742908
X_OFFSET:        689 [pixels]
Y_OFFSET:        941 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       849
Y_GRB_POS:       1101
BINNING_INDEX:   1
IM_URL:          sw00276321000msuni0213.fits
SUN_POSTN:        27.73d {+01h 50m 56s}  +11.41d {+11d 24' 19"}
SUN_DIST:        100.57 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.55d {+04h 26m 12s}  +26.85d {+26d 50' 52"}
MOON_DIST:        87.81 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.84, -7.43 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.28 [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:     Fri 20 Apr 07 06:33:06 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.555d {-45d 33' 16"} (J2000)
ROLL:            275.566d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  22907.01 SOD {06:21:47.01} UT,   213.5 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     198742908
X_OFFSET:        689 [pixels]
Y_OFFSET:        941 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       849
Y_GRB_POS:       1101
BINNING_INDEX:   1
IM_URL:          sw00276321000msuni0213.fits
SUN_POSTN:        27.73d {+01h 50m 56s}  +11.41d {+11d 24' 20"}
SUN_DIST:        100.57 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.55d {+04h 26m 12s}  +26.85d {+26d 50' 54"}
MOON_DIST:        87.81 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.84, -7.43 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.28 [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:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:36:48 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.555d {-45d 33' 16"} (J2000)
POINT_ROLL:      275.566d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  23550.62 SOD {06:32:30.62} UT,   857.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.149
N_STARS:         190
X_OFFSET:        369 [pixels]
Y_OFFSET:        621 [pixels]
X_MAX:           1328 [pixels]
Y_MAX:           1580 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00276321000msufc0857.fits
SUN_POSTN:        27.73d {+01h 50m 56s}  +11.41d {+11d 24' 23"}
SUN_DIST:        100.57 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.59d {+04h 26m 22s}  +26.85d {+26d 51' 17"}
MOON_DIST:        87.79 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.84, -7.43 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:37:13 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.555d {-45d 33' 16"} (J2000)
POINT_ROLL:      275.566d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  23550.62 SOD {06:32:30.62} UT,   857.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.149
N_STARS:         190
X_OFFSET:        369 [pixels]
Y_OFFSET:        621 [pixels]
X_MAX:           1328 [pixels]
Y_MAX:           1580 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00276321000msufc0857.fits
SUN_POSTN:        27.73d {+01h 50m 56s}  +11.41d {+11d 24' 23"}
SUN_DIST:        100.57 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.60d {+04h 26m 23s}  +26.86d {+26d 51' 19"}
MOON_DIST:        87.79 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.84, -7.43 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.28 [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:     Fri 20 Apr 07 06:38:24 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.555d {-45d 33' 16"} (J2000)
ROLL:            275.566d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  23550.62 SOD {06:32:30.62} UT,   857.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     198743552
X_OFFSET:        688 [pixels]
Y_OFFSET:        940 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       848
Y_GRB_POS:       1100
BINNING_INDEX:   1
IM_URL:          sw00276321000msuni0857.fits
SUN_POSTN:        27.74d {+01h 50m 56s}  +11.41d {+11d 24' 24"}
SUN_DIST:        100.57 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.61d {+04h 26m 26s}  +26.86d {+26d 51' 26"}
MOON_DIST:        87.79 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.84, -7.43 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:38:40 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.555d {-45d 33' 16"} (J2000)
ROLL:            275.566d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  23550.62 SOD {06:32:30.62} UT,   857.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     198743552
X_OFFSET:        688 [pixels]
Y_OFFSET:        940 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       848
Y_GRB_POS:       1100
BINNING_INDEX:   1
IM_URL:          sw00276321000msuni0857.fits
SUN_POSTN:        27.74d {+01h 50m 57s}  +11.41d {+11d 24' 24"}
SUN_DIST:        100.57 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.61d {+04h 26m 27s}  +26.86d {+26d 51' 28"}
MOON_DIST:        87.79 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.84, -7.43 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:40:05 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     276321,   Seg_Num: 0
GRB_RA:          121.2300d {+08h 04m 55.2s} (J2000),
                 121.2881d {+08h 05m 09.1s} (current),
                 120.8321d {+08h 03m 19.7s} (1950)
GRB_DEC:         -45.5553d {-45d 33' 19.0"} (J2000),
                 -45.5764d {-45d 34' 34.9"} (current),
                 -45.4118d {-45d 24' 42.4"} (1950)
GRB_ERROR:       4.7 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-09 [erg/cm2/sec]
GRB_SIGNIF:      5.00 [sigma]
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  22794.20 SOD {06:19:54.20} UT,   100.7 [sec] since BAT Trigger Time
TAM[0-3]:        327.61 237.19 261.35 242.66
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:        27.74d {+01h 50m 57s}  +11.41d {+11d 24' 26"}
SUN_DIST:        100.59 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.63d {+04h 26m 31s}  +26.86d {+26d 51' 37"}
MOON_DIST:        87.79 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.85, -7.42 [deg] galactic lon,lat of the burst
ECL_COORDS:      143.84,-63.28 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values are not valid.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:43:15 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.555d {-45d 33' 16"} (J2000)
POINT_ROLL:      275.566d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  23656.36 SOD {06:34:16.36} UT,   962.8 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        1.745
N_STARS:         190
X_OFFSET:        369 [pixels]
Y_OFFSET:        621 [pixels]
X_MAX:           1328 [pixels]
Y_MAX:           1580 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00276321000msufc0962.fits
SUN_POSTN:        27.74d {+01h 50m 57s}  +11.41d {+11d 24' 28"}
SUN_DIST:        100.57 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.66d {+04h 26m 39s}  +26.87d {+26d 51' 56"}
MOON_DIST:        87.77 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.84, -7.43 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:43:38 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.555d {-45d 33' 16"} (J2000)
POINT_ROLL:      275.566d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  23656.36 SOD {06:34:16.36} UT,   962.8 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        1.745
N_STARS:         190
X_OFFSET:        369 [pixels]
Y_OFFSET:        621 [pixels]
X_MAX:           1328 [pixels]
Y_MAX:           1580 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00276321000msufc0962.fits
SUN_POSTN:        27.74d {+01h 50m 57s}  +11.41d {+11d 24' 29"}
SUN_DIST:        100.57 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.67d {+04h 26m 40s}  +26.87d {+26d 51' 59"}
MOON_DIST:        87.76 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.84, -7.43 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.28 [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:     Fri 20 Apr 07 06:44:46 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.555d {-45d 33' 16"} (J2000)
ROLL:            275.566d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  23656.36 SOD {06:34:16.36} UT,   962.8 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     198743658
X_OFFSET:        688 [pixels]
Y_OFFSET:        940 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       848
Y_GRB_POS:       1100
BINNING_INDEX:   1
IM_URL:          sw00276321000msuni0962.fits
SUN_POSTN:        27.74d {+01h 50m 57s}  +11.41d {+11d 24' 30"}
SUN_DIST:        100.57 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.68d {+04h 26m 43s}  +26.87d {+26d 52' 06"}
MOON_DIST:        87.76 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.84, -7.43 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:45:05 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     276321,   Seg_Num: 0
POINT_RA:        121.205d {+08h 04m 49s} (J2000)
POINT_DEC:       -45.555d {-45d 33' 16"} (J2000)
ROLL:            275.566d
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  23656.36 SOD {06:34:16.36} UT,   962.8 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     198743658
X_OFFSET:        688 [pixels]
Y_OFFSET:        940 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       848
Y_GRB_POS:       1100
BINNING_INDEX:   1
IM_URL:          sw00276321000msuni0962.fits
SUN_POSTN:        27.74d {+01h 50m 58s}  +11.41d {+11d 24' 30"}
SUN_DIST:        100.57 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.68d {+04h 26m 44s}  +26.87d {+26d 52' 08"}
MOON_DIST:        87.76 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      260.84, -7.43 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      143.80,-63.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN Circular #6330
M. Stamatikos (NASA/ORAU), D. N. Burrows (PSU), G. Cusumano (INAF-IASFPA), P. A. Evans (U Leicester), C. Gronwall (PSU), V. Mangano (INAF-IASFPA), C. B. Markwardt (GSFC/UMD), P. T. O'Brien (U Leicester), D. M. Palmer (LANL), A. M. Parsons (GSFC), M. Perri (ASDC) and G. Stratta (ASDC) report on behalf of the Swift Team:
At 06:18:13 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 070420 (trigger=276321). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 121.253, -45.561 which is
```
   RA(J2000) = 08h 05m 01s
   Dec(J2000) = -45d 33' 38"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multiply-peaked structure with a duration of at least 70 sec starting at T-50s. The peak count rate was ~4000 counts/sec (15-350 keV), at ~7 sec after the trigger.
XRT began observing the field at 06:19:52 UT, 99 seconds after the BAT trigger. XRT found a bright, fading, previously uncatalogued X-ray source in the field of view at the following coordinates:
```
  RA(J2000) =  08h 04m 55.3s
  Dec(J2000)= -45d 33' 23.2"
```
with an uncertainty of 4 arcseconds radius (90% containment). This is a ground calculated position based on prompt downlinked data. This position lies 62 arcseconds from the center of the BAT error circle.
UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 108 seconds after the BAT trigger. An afterglow candidate has been found in the initial data products. The 2.7'x2.7' region for the list of sources generated on-board covers 100% of the XRT error circle. A source is detected at
```
 RA(J2000) = 08h 04m 55.25s 
 Dec(J2000)= -45d 33' 21.0"   
```
with an estimated uncertainty of +/-0.5 arcsec. This position is 2.0 arcsec from the XRT position. The estimated magnitude in the White filter is 17.3. No correction has been made for the expected extinction correspondingto E(B-V) of 0.52.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Apr 07 06:59:42 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     276321,   Seg_Num: 0
GRB_RA:          121.2300d {+08h 04m 55.20s} (J2000),
                 121.2881d {+08h 05m 09.13s} (current),
                 120.8321d {+08h 03m 19.71s} (1950)
GRB_DEC:         -45.5600d {-45d 33' 36.0"} (J2000),
                 -45.5811d {-45d 34' 51.9"} (current),
                 -45.4165d {-45d 24' 59.3"} (1950)
GRB_ERROR:       0.4 [arcsec radius, statistical only]
GRB_MAG:         17.29 +/- 3.00 [mag]
FILTER:          10, White
IMG_START_DATE:  14210 TJD;   110 DOY;   07/04/20
IMG_START_TIME:  22802.00 SOD {06:20:02.00} UT,   108.5 [sec] since BAT Trigger Time
SUN_POSTN:        27.75d {+01h 50m 60s}  +11.41d {+11d 24' 42"}
SUN_DIST:        100.58 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:       66.85d {+04h 27m 23s}  +26.89d {+26d 53' 37"}
MOON_DIST:        87.71 [deg]
MOON_ILLUM:      12 [%]
GAL_COORDS:      260.86, -7.42 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      143.84,-63.28 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN Circular #6331
P. D'Avanzo, L.A. Antonelli, L. Calzoletti, S. Campana, G. Chincarini, M.L. Conciatore, S. Covino, S. Cutini, P. D'Avanzo, V. D'Elia, F. Dalessio, F. Fiore, D. Fugazza, P. Goldoni, D. Guetta, C. Guidorzi, G.L. Israel, D. Malesani, N. Masetti, A. Melandri, E. Meurs, L. Nicastro, E. Palazzi, E. Pian, S. Piranomonte, D. Rizzuto, L. Stella, G. Stratta, G. Tagliaferri, G. Tosti, V. Testa, S.D. Vergani, F. Vitali report on behalf of the REM team:
We observed the field of the GRB 070420 (Stamatikos et al. GCN 6330) with the robotic 60-cm REM telescope located at La Silla (Chile). A set of observations was performed automatically in the optical and near infrared filters (V, R, I and J, H, K, z) starting on 2007 April 20 at 06:19:32 UT, 42s after the Swift trigger and 79s after the GRB time.
Although the observations were performed under thin clouds and at very high airmass (~ 7.5) we clearly detect the NIR and optical afterglow at the coordinates reported by UVOT (GCN 6330).
Preliminary analysis gives an approximate magnitude about 5 minutes after the burst time was H = 13.1 +/- 0.2.
Observations were then soon interrupted due to excessive airmass.
This message may be cited.
GCN Circular #6332
Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report:
We imaged the field of GRB 070420 detected by SWIFT (trigger 276321) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile.
The observations started 34s after the GRB trigger (8s after the notice) when the GRB was still active. The elevation of the field decreased from from 7 degrees above horizon and weather conditions were good but with some thin clouds in the sky.
The date of trigger : t0 = 2007-04-20T06:18:13.824
The first image is trailed with a duration of 60.0s (see the description in Klotz et al., 2006, A&A 451, L39). We do not detect the OT mentioned by Stamatikos et al. (GCNC 6330) with a limiting magnitude of: t0+34s to t0+94s : R > 16.1
The second image is 30.0s exposure in tracking mode. We detect the OT: t0+100s to t0+130s : R = 16.2
The third image is 30.0s exposure in tracking mode: t0+136s to t0+166s : R = 16.4
Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction.
It seems that this afterglow is very red compared to values published by Stamatikos et al. (GCNC 6330) and by D'Avanzo et al. GCNC 6331).
N.B. Galactic coordinates are lon=260.8667 lat= -7.4088 and the galactic extinction in R band is 0.7 magnitudes estimated from D. Schlegel et al. 1998ApJ...500..525S.
This message may be cited.
GCN Circular #6334
C. Guidorzi (Uni-Bicocca/INAF-OAB), R.J. Smith, D.F. Bersier, I.A. Steele= , C.G. Mundell, S.N. Fraser, C.J. Mottram, A. Melandri, M.F. Bode (Liverpool JMU), A. Gomboc (Ljubljana), P. O'Brien, E. Rol, N. Tanvir (U. Leicester) report on behalf of the RoboNet GRB collaboration:
"The 2-m Faulkes Telescope South (Australia) started observing the field = of the Swift burst GRB 070420 (Stamatikos et al. GCN Circ. 6330) about 3 hours after the trigger time in BVRi filters.
We detect the UVOT optical transient reported by Stamatikos et al (GCN Circ. 6330) and confirmed in IR by REM (D'Avanzo et al., GCN Circ. 6331) in V, R and i' band filters at the following position:
```
RA(J2000) =3D 08:04:55.18
Dec(J2000)=3D -45:33:20.0
```
with an error of 0.7", and 1.2" away from the UVOT position.
```
Start Time   End Time    Exposure  Filter   Mag
(min)        (min)         (s)
--------------------------------------------------------
175.5        185.9        4x150      R      19.7 =B1 0.4
211.3        221.8        4x150      i'     19.3 =B1 0.5
--------------------------------------------------------
```
Magnitudes are calibrated with respect to USNOB1 R2 and I magnitudes. Further observations are ongoing."
GCN Circular #6336
S. Immler (USRA/GSFC), F. E. Marshall (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), and M. Stamatikos (NASA/ORAU) report on behalf of the Swift/UVOT team:
The UVOT position sent out as a GCN notice gave an invalid position while GCN 6330 had the correct position. We regret any confusion this might have caused. The revised UVOT position of the afterglow is
```
RA(J2000) = 08h04m55.17s, Dec(J2000) = -45d33'20.0".
```
We estimate a statistical accuracy of 0.2 arcsec radius (90% confidence) but with a systematic uncertainty of the aspect solution of about 0.5 arcsec.
The Swift/UVOT began taking data in the field of GRB070420 90s after the BAT trigger (Stamatikos et al., GCN 6330). The afterglow is detected in all UVOT optical filters. The large reddening, E(B-V) = 0.52, might explain the non-detection in the UV. The flux is decaying with t**-0.7 in the White for times between T+500 and T+10000 seconds. The photometry results are given for the 7 UVOT filters below.
```
V                T+(s)          Exp(s)       Mag

White          109            99           17.4+/-0.1
                  7125           197          20.8+/-0.1
V                    90           10            17.9+/-0.1
B                  693          10            18.8+/-0.1
U                  669          20            21.1+/-0.1
UVW1         645          20            >20.4 (3-sigma)
UWM2         620          20            >20.8 (3-sigma)
UVW2             723          20            >20.8 (3-sigma)
```
GCN Circular #6337
G. Stratta (ASDC), M. Perri (ASDC), D.N. Burrows (PSU) and M. Stamatikos (NASA/ORAU) report on behalf of the Swift XRT team:
We have analyzed the first four orbits of Swift-XRT data on GRB 070420 (Stamatikos et al. GCN 6330), with a total exposure of 573 s in Windowed Timing (WT) mode and of 7.5 ks in Photon Counting (PC) mode. This provides a refined XRT position at RA,Dec(deg)=121.230194683,-45.5562815181 which is:
```
RA(J2000)=08h 04m 55.22s
Dec(J2000)=-45d 33' 22.6"
```
with an estimated error radius of 3.5 arcseconds (90% confidence). This position is 62.3 arcseconds from the BAT position (Stamatikos et al. GCN 6330), 0.8 arcseconds from the initial XRT position (Stamatikos et al. GCN 6330) and 2.6 arcseconds from the UVOT refined optical counterpart position (Holland et al. GCN 6336).
The 0.3-10 keV X-ray light curve presents a steep decay between T+106 s and T+300 s followed by a plateau phase up to about T+2ks (end of the first orbit). The last three orbits of data taken in PC mode show a new steepening of the light curve, from T+5ks to T+18.5 ks (end of the third orbit). The light curve from T+106 s to T+18.5 ks is well fit by a double broken power law model with decay indices: d1=-4.4+/-0.2, d2=-0.2+/-0.1 and d3=-1.5+/-0.1 and with the first break at about t1=230s and the second break at about t2=3200s.
The 0.3-10.0 keV X-ray spectrum from the XRT/WT data during the decay phase is well fit by an absorbed power law with a photon index of 2.6 +/- 0.1 and a total column density of NH=(4.1+/-0.3)e21 cm**-2. The X-ray spectrum from the XRT/PC data during the flat decay phase (corrected from the pileup effects) can be fit by an absorbed power law with a photon index of 2.0+/-0.2 and a total column density of NH=(5.0+/-1.0)e21 cm**-2. We note that the Galactic column density in the direction of the source is 3.7e21 cm**-2 (Dickey & Lockman 1990).
Assuming the X-ray emission continues to decline with decay index d3, we predict a 0.3-10.0 keV XRT count rate of 1.3e-2 count/s at T+24h and 4.7e-3 count/s at T+48h, which corresponds to an observed 0.3-10.0 keV flux of 7e-13 erg/cm**2/s and 2.5e-13 erg/cm**2/s, respectively.
This circular is an official product of the Swift Team.
GCN Circular #6338
M. Jel=EDnek (IAA-CSIC Granada), P. Tristram (MOA, Univ. of Canterbury), A. de Ugarte Postigo, J. Gorosabel, (IAA-CSIC), F. Hale (Earth & Sky, Tekapo), A. Gilmore, P. Kilmartin (Univ. of Canterbury) and A. J. Castro-Tirado (IAA-CSIC),=20 on behalf of a larger collaboration,
report:
"Following the detection by Swift of the GRB070420 (Stamatikos et al. GCNC 6330), we obtained V(26), R (14) and I (1) -band images at the 0.6m B&C telescope at the Mt. John Observatory on Lake Tekapo. They were taken starting on Apr 20.33 UT (i.e. 1.6 hr post-burst) and continued until Apr 20.51 UT (~6 hours after the burst).
Our preliminary V-band lightcurve shows a simple powerlaw decay between 1.6 and 3.5 hours after the burst with alpha~-1.2+-0.2 which is somewhat stee- per than the value reported from UVOT (Stamatikos et al. GCNC 6330).
At 4 hours after the GRB we see a sudden rebrigh- tening of the order of 1 magnitude in 40min above the value extrapolated from the previous decay.
Further analysis is in progress."
This message can be quoted.
GCN Circular #6342
A. Parsons (GSFC), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC) on behalf of the Swift-BAT team:
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 070420 (trigger #276321) (Stamatikos, et al., GCN Circ. 6330). The BAT ground-calculated position is RA, Dec = 121.245, -45.564 deg which is
```
   RA(J2000) = 8h 4m 58.7s 
   Dec(J2000) = -45d 33' 50.6" 
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 8%.
The light curve is described by a slow rise to double-peaks at T+2 and T+8 sec, with subsequent gradual decay spanning from T-50 to T+70 sec. The T90 (15-350 keV) is 77 +- 4 sec (estimated error including systematics).
The time-averaged spectrum from T-29 to T+100 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.16 +- 0.24, and Epeak of 114 +- 42 keV (chi squared 50.74 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.40 +- 0.04 x 10-5 erg/cm2 and the 1-sec peak flux measured from T+1.40 sec in the 15-150 keV band is 7.1 +- 0.8 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.59 +- 0.05 (chi squared 61.25 for 57 d.o.f.). All the quoted errors are at the 90% confidence level.
GCN Report 48.1
GCN_Report 48.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_48_1.pdf by M. Stamatikos at GSFC/ORAU titled: "Swift Observations of GRB 070420"
GCN Circular #6344
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind team report:
The long GRB 070420 (Stamatikos et al., GCN 6330; Parsons et al., GCN 6342), triggered Konus-Wind at T0=22693.706 s UT (06:18:13.706).
The burst started at T-T0 ~-50 s and had a duration of ~120 s. As observed by Konus-Wind the burst had a fluence of 2.64(-0.88, +0.11)x10^-5 erg/cm2, and a 256-ms peak flux measured from T0-0.144 s 1.28(-0.29, +0.19)x10^-6 erg/cm2/s (both in the 20 keV - 1 MeV energy range).
The spectrum of the most intense part integrated from T0 to T0+16.640 s is well fitted (in the 20 keV - 1 MeV range) by a power law with exponential cutoff model: dN/dE ~ E^(-alpha) * exp(-(2-alpha)*E/Ep) with alpha = 1.08(-0.13, +0.12) and Ep = 167(-16, +20) keV (chi2 = 40/52 dof). The fluence of this part is 1.06(-0.19, +0.04)x10^5 erg/cm2.
The spectrum integrated from T0 to T0+65.792 s is well fitted (in the 20 keV - 1 MeV range) by a power law with exponential cutoff model with alpha = 1.23(-0.18, +0.17) and Ep = 147(-19, +29) keV (chi2 = 54/52 dof).
All the quoted errors are at the 90% confidence level.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB070420_T22693/
GCN Circular #6345
A. Pelangeon & J-L. Atteia (LATT-OMP) report:
We have used the spectral parameters of the most intense part of GRB 070420 provided by Golenetskii et al. (GCNC 6344) to compute the spectral pseudo-redshift** of this burst detected by SWIFT-BAT (Stamatikos et al., GCNC 6330).
We find a pseudo-redshift pz= 1.56 +/- 0.35
** cf. http://www.ast.obs-mip.fr/grb/pz
GCN Circular #6347
B. E. Cobb (Yale), part of the larger SMARTS consortium, reports:
Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 070420 (GCN 6330, Stamatikos et al.) with a mid-exposure time of 2007-04-21 01:15 UT (~18.9 hrs post-burst) and again at 2007-04-23 00:52 UT (~66.6 hrs post-burst). For each set of observations, total summed exposure times amounted to 36 minutes in I and 30 minutes in J.
The afterglow of GRB 070420 (GRB 6330, Stamatikos et al.) is detected in the first epoch images and is observed to fade between the first and second epochs by approximately 1 magnitude. This indicates a decay rate of alpha ~ 0.7 (afterglow flux proportional to t^-alpha), which is consistent with early-time UVOT observations (GCN 6336, Immler et al.).
We note that there is a source with constant brightness only 1 arcseconds West and 0.7 arcseconds North of the afterglow of GRB 070420. This source has magnitudes I~20 and J~18.5 (magnitudes are calibrated using USNO-B1.0 values in the optical and 2MASS stars in the IR.). The source appears to have a stellar profile and is most likely just a coincident star.
0803.0505from 4 Mar 2008
Klotz: Early emission of rising optical afterglows: The case of GRB 060904B and GRB 070420
Abstract: We present the time-resolved optical emission of gamma-ray bursts GRB 060904B and GRB 070420 during their prompt and early afterglow phases. We used time resolved photometry from optical data taken by the TAROT telescope and time resolved spectroscopy at high energies from the Swift spacecraft instrument. The optical emissions of both GRBs are found to increase from the end of the prompt phase, passing to a maximum of brightness at t_{peak}=9.2 min and 3.3 min for GRB 060904B and GRB 070420 respectively and then decrease. GRB 060904B presents a large optical plateau and a very large X-ray flare. We argue that the very large X-flare occurring near t_{peak} is produced by an extended internal engine activity and is only a coincidence with the optical emission. GRB 070420 observations would support this idea because there was no X-flare during the optical peak. The nature of the optical plateau of GRB 060904B is less clear and might be related to the late energy injection.

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Jochen Greiner, last update: 23-Apr-2007 [Disclaimer]