Gamma-ray Burst 130418A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Apr 13 19:02:13 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     553847,   Seg_Num: 0
GRB_RA:          149.043d {+09h 56m 10s} (J2000),
                 149.223d {+09h 56m 54s} (current),
                 148.367d {+09h 53m 28s} (1950)
GRB_DEC:         +13.649d {+13d 38' 58"} (J2000),
                 +13.586d {+13d 35' 09"} (current),
                 +13.887d {+13d 53' 15"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=1715 [image_cnts]
TRIGGER_DUR:     64.000 [sec] 
TRIGGER_INDEX:   20000     E_range: 15-50 keV
BKG_INTEN:       0 [cnts]
BKG_TIME:        0.00 SOD {00:00:00.00} UT
BKG_DUR:         0 [sec]
GRB_DATE:        16400 TJD;   108 DOY;   13/04/18
GRB_TIME:        68453.54 SOD {19:00:53.54} UT
GRB_PHI:           8.94 [deg]
GRB_THETA:        23.43 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    9.78 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  +0  +0  +0 +46  +0 
SUN_POSTN:        26.86d {+01h 47m 27s}  +11.08d {+11d 04' 60"}
SUN_DIST:        117.74 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      122.87d {+08h 11m 29s}  +14.78d {+14d 46' 40"}
MOON_DIST:        25.56 [deg]
MOON_ILLUM:      53 [%]
GAL_COORDS:      222.19, 47.03 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      146.46,  1.01 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 78.79,-18.39 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Apr 13 19:03:34 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     553847,   Seg_Num: 0
GRB_RA:          149.0377d {+09h 56m 09.04s} (J2000),
                 149.2173d {+09h 56m 52.14s} (current),
                 148.3617d {+09h 53m 26.80s} (1950)
GRB_DEC:         +13.6654d {+13d 39' 55.4"} (J2000),
                 +13.6019d {+13d 36' 06.7"} (current),
                 +13.9033d {+13d 54' 11.8"} (1950)
GRB_ERROR:       5.3 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.55e-09 [erg/cm2/sec]
GRB_SIGNIF:      6.92 [sigma]
IMG_START_DATE:  16400 TJD;   108 DOY;   13/04/18
IMG_START_TIME:  68583.24 SOD {19:03:03.24} UT,   129.7 [sec] since BAT Trigger Time
TAM[0-3]:        327.69 237.23 261.68 243.63
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:        26.86d {+01h 47m 28s}  +11.08d {+11d 05' 01"}
SUN_DIST:        117.72 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      122.88d {+08h 11m 32s}  +14.78d {+14d 46' 30"}
MOON_DIST:        25.54 [deg]
MOON_ILLUM:      53 [%]
GAL_COORDS:      222.17, 47.03 [deg] galactic lon,lat of the burst
ECL_COORDS:      146.45,  1.03 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.01 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Apr 13 19:03:45 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     553847,   Seg_Num: 0
GRB_RA:          149.0377d {+09h 56m 09.0s} (J2000),
                 149.2173d {+09h 56m 52.1s} (current),
                 148.3617d {+09h 53m 26.8s} (1950)
GRB_DEC:         +13.6654d {+13d 39' 55.4"} (J2000),
                 +13.6019d {+13d 36' 06.7"} (current),
                 +13.9033d {+13d 54' 11.8"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       48 [cnts]
IMG_START_DATE:  16400 TJD;   108 DOY;   13/04/18
IMG_START_TIME:  68583.24 SOD {19:03:03.24} UT,   129.7 [sec] since BAT Trigger Time
CENTROID_X:      288.98,  raw= 289  [pixels]
CENTROID_Y:      274.28,  raw= 274  [pixels]
ROLL:            290.48 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -55.91
GRB_POS_XRT_Z:   -34.67
IMAGE_URL:       sw00553847000msxps_rw.img
SUN_POSTN:        26.87d {+01h 47m 28s}  +11.08d {+11d 05' 01"}
SUN_DIST:        117.72 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      122.89d {+08h 11m 33s}  +14.77d {+14d 46' 29"}
MOON_DIST:        25.54 [deg]
MOON_ILLUM:      53 [%]
GAL_COORDS:      222.17, 47.03 [deg] galactic lon,lat of the burst
ECL_COORDS:      146.45,  1.03 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Apr 13 19:03:52 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     553847,   Seg_Num: 0
GRB_RA:          149.0377d {+09h 56m 09.0s} (J2000),
                 149.2173d {+09h 56m 52.1s} (current),
                 148.3617d {+09h 53m 26.8s} (1950)
GRB_DEC:         +13.6654d {+13d 39' 55.4"} (J2000),
                 +13.6019d {+13d 36' 06.7"} (current),
                 +13.9033d {+13d 54' 11.8"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       48 [cnts]
IMG_START_DATE:  16400 TJD;   108 DOY;   13/04/18
IMG_START_TIME:  68583.24 SOD {19:03:03.24} UT,   129.7 [sec] since BAT Trigger Time
CENTROID_X:      288.98,  raw= 289  [pixels]
CENTROID_Y:      274.28,  raw= 274  [pixels]
ROLL:            290.48 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -55.91
GRB_POS_XRT_Z:   -34.67
IMAGE_URL:       sw00553847000msxps_rw.img
SUN_POSTN:        26.87d {+01h 47m 28s}  +11.08d {+11d 05' 01"}
SUN_DIST:        117.72 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      122.89d {+08h 11m 33s}  +14.77d {+14d 46' 28"}
MOON_DIST:        25.54 [deg]
MOON_ILLUM:      53 [%]
GAL_COORDS:      222.17, 47.03 [deg] galactic lon,lat of the burst
ECL_COORDS:      146.45,  1.03 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Apr 13 19:05:05 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     553847,   Seg_Num: 0
GRB_RA:          149.043d {+09h 56m 10s} (J2000),
                 149.223d {+09h 56m 54s} (current),
                 148.367d {+09h 53m 28s} (1950)
GRB_DEC:         +13.649d {+13d 38' 58"} (J2000),
                 +13.586d {+13d 35' 09"} (current),
                 +13.887d {+13d 53' 15"} (1950)
GRB_DATE:        16400 TJD;   108 DOY;   13/04/18
GRB_TIME:        68453.54 SOD {19:00:53.54} UT
TRIGGER_INDEX:   20000
GRB_PHI:           8.94 [deg]
GRB_THETA:        23.43 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     64.000 [sec] 
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    9.78 [sigma]
LC_URL:          sw00553847000msb.lc
SUN_POSTN:        26.87d {+01h 47m 28s}  +11.08d {+11d 05' 02"}
SUN_DIST:        117.73 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      122.90d {+08h 11m 35s}  +14.77d {+14d 46' 19"}
MOON_DIST:        25.54 [deg]
MOON_ILLUM:      53 [%]
GAL_COORDS:      222.19, 47.03 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      146.46,  1.01 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Lightcurve.  
COMMENTS:           
COMMENTS:        The next comments were copied from the BAT_POS Notice:  
COMMENTS:        This is an image trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 78.79,-18.39 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Apr 13 19:05:59 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     553847,   Seg_Num: 0
POINT_RA:        149.042d {+09h 56m 10s} (J2000)
POINT_DEC:       +13.648d {+13d 38' 52"} (J2000)
POINT_ROLL:      290.481d
IMG_START_DATE:  16400 TJD;   108 DOY;   13/04/18
IMG_START_TIME:  68591.66 SOD {19:03:11.66} UT,   138.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.750
N_STARS:         13
X_OFFSET:        488 [pixels]
Y_OFFSET:        592 [pixels]
X_MAX:           1447 [pixels]
Y_MAX:           1551 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00553847000msufc0138.fits
SUN_POSTN:        26.87d {+01h 47m 28s}  +11.08d {+11d 05' 03"}
SUN_DIST:        117.73 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      122.90d {+08h 11m 37s}  +14.77d {+14d 46' 13"}
MOON_DIST:        25.53 [deg]
MOON_ILLUM:      53 [%]
GAL_COORDS:      222.19, 47.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      146.46,  1.01 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Apr 13 19:06:19 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     553847,   Seg_Num: 0
POINT_RA:        149.042d {+09h 56m 10s} (J2000)
POINT_DEC:       +13.648d {+13d 38' 52"} (J2000)
POINT_ROLL:      290.481d
IMG_START_DATE:  16400 TJD;   108 DOY;   13/04/18
IMG_START_TIME:  68591.66 SOD {19:03:11.66} UT,   138.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.750
N_STARS:         13
X_OFFSET:        488 [pixels]
Y_OFFSET:        592 [pixels]
X_MAX:           1447 [pixels]
Y_MAX:           1551 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00553847000msufc0138.fits
SUN_POSTN:        26.87d {+01h 47m 28s}  +11.08d {+11d 05' 03"}
SUN_DIST:        117.73 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      122.91d {+08h 11m 38s}  +14.77d {+14d 46' 10"}
MOON_DIST:        25.53 [deg]
MOON_ILLUM:      53 [%]
GAL_COORDS:      222.19, 47.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      146.46,  1.01 [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:     Thu 18 Apr 13 19:07:28 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     553847,   Seg_Num: 0
POINT_RA:        149.042d {+09h 56m 10s} (J2000)
POINT_DEC:       +13.648d {+13d 38' 52"} (J2000)
ROLL:            290.481d
IMG_START_DATE:  16400 TJD;   108 DOY;   13/04/18
IMG_START_TIME:  68591.66 SOD {19:03:11.66} UT,   138.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     388004602
X_OFFSET:        917 [pixels]
Y_OFFSET:        955 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1077
Y_GRB_POS:       1115
BINNING_INDEX:   1
IM_URL:          sw00553847000msuni0149.fits
SUN_POSTN:        26.87d {+01h 47m 28s}  +11.08d {+11d 05' 04"}
SUN_DIST:        117.73 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      122.92d {+08h 11m 40s}  +14.77d {+14d 46' 02"}
MOON_DIST:        25.52 [deg]
MOON_ILLUM:      53 [%]
GAL_COORDS:      222.19, 47.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      146.46,  1.01 [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:     Thu 18 Apr 13 19:07:47 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     553847,   Seg_Num: 0
POINT_RA:        149.042d {+09h 56m 10s} (J2000)
POINT_DEC:       +13.648d {+13d 38' 52"} (J2000)
ROLL:            290.481d
IMG_START_DATE:  16400 TJD;   108 DOY;   13/04/18
IMG_START_TIME:  68591.66 SOD {19:03:11.66} UT,   138.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     388004602
X_OFFSET:        917 [pixels]
Y_OFFSET:        955 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1077
Y_GRB_POS:       1115
BINNING_INDEX:   1
IM_URL:          sw00553847000msuni0149.fits
SUN_POSTN:        26.87d {+01h 47m 28s}  +11.08d {+11d 05' 05"}
SUN_DIST:        117.73 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      122.92d {+08h 11m 41s}  +14.77d {+14d 45' 60"}
MOON_DIST:        25.51 [deg]
MOON_ILLUM:      53 [%]
GAL_COORDS:      222.19, 47.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      146.46,  1.01 [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:     Thu 18 Apr 13 19:08:01 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     553847,   Seg_Num: 0
POINT_RA:        149.040d {+09h 56m 10s} (J2000)
POINT_DEC:       +13.646d {+13d 38' 44"} (J2000)
POINT_ROLL:      290.480d
IMG_START_DATE:  16400 TJD;   108 DOY;   13/04/18
IMG_START_TIME:  68749.55 SOD {19:05:49.55} UT,   296.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.172
N_STARS:         7
X_OFFSET:        597 [pixels]
Y_OFFSET:        635 [pixels]
X_MAX:           1556 [pixels]
Y_MAX:           1594 [pixels]
DET_THRESH:      5
PHOTO_THRESH:    2
SL_URL:          sw00553847000msufc0296.fits
SUN_POSTN:        26.87d {+01h 47m 28s}  +11.08d {+11d 05' 05"}
SUN_DIST:        117.73 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      122.92d {+08h 11m 41s}  +14.77d {+14d 45' 58"}
MOON_DIST:        25.51 [deg]
MOON_ILLUM:      53 [%]
GAL_COORDS:      222.20, 47.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      146.45,  1.01 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Apr 13 19:08:19 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     553847,   Seg_Num: 0
POINT_RA:        149.040d {+09h 56m 10s} (J2000)
POINT_DEC:       +13.646d {+13d 38' 44"} (J2000)
POINT_ROLL:      290.480d
IMG_START_DATE:  16400 TJD;   108 DOY;   13/04/18
IMG_START_TIME:  68749.55 SOD {19:05:49.55} UT,   296.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.172
N_STARS:         7
X_OFFSET:        597 [pixels]
Y_OFFSET:        635 [pixels]
X_MAX:           1556 [pixels]
Y_MAX:           1594 [pixels]
DET_THRESH:      5
PHOTO_THRESH:    2
SL_URL:          sw00553847000msufc0296.fits
SUN_POSTN:        26.87d {+01h 47m 28s}  +11.08d {+11d 05' 05"}
SUN_DIST:        117.73 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      122.92d {+08h 11m 42s}  +14.77d {+14d 45' 56"}
MOON_DIST:        25.51 [deg]
MOON_ILLUM:      53 [%]
GAL_COORDS:      222.20, 47.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      146.45,  1.01 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_srclist.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Apr 13 19:09:25 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     553847,   Seg_Num: 0
POINT_RA:        149.040d {+09h 56m 10s} (J2000)
POINT_DEC:       +13.646d {+13d 38' 44"} (J2000)
ROLL:            290.480d
IMG_START_DATE:  16400 TJD;   108 DOY;   13/04/18
IMG_START_TIME:  68749.55 SOD {19:05:49.55} UT,   296.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     388004760
X_OFFSET:        917 [pixels]
Y_OFFSET:        955 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1077
Y_GRB_POS:       1115
BINNING_INDEX:   1
IM_URL:          sw00553847000msuni0307.fits
SUN_POSTN:        26.87d {+01h 47m 28s}  +11.09d {+11d 05' 06"}
SUN_DIST:        117.73 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      122.93d {+08h 11m 44s}  +14.76d {+14d 45' 48"}
MOON_DIST:        25.50 [deg]
MOON_ILLUM:      53 [%]
GAL_COORDS:      222.20, 47.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      146.45,  1.01 [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:     Thu 18 Apr 13 19:09:40 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     553847,   Seg_Num: 0
POINT_RA:        149.040d {+09h 56m 10s} (J2000)
POINT_DEC:       +13.646d {+13d 38' 44"} (J2000)
ROLL:            290.480d
IMG_START_DATE:  16400 TJD;   108 DOY;   13/04/18
IMG_START_TIME:  68749.55 SOD {19:05:49.55} UT,   296.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     388004760
X_OFFSET:        917 [pixels]
Y_OFFSET:        955 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1077
Y_GRB_POS:       1115
BINNING_INDEX:   1
IM_URL:          sw00553847000msuni0307.fits
SUN_POSTN:        26.87d {+01h 47m 29s}  +11.09d {+11d 05' 06"}
SUN_DIST:        117.73 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      122.94d {+08h 11m 45s}  +14.76d {+14d 45' 46"}
MOON_DIST:        25.50 [deg]
MOON_ILLUM:      53 [%]
GAL_COORDS:      222.20, 47.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      146.45,  1.01 [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_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Apr 13 19:10:11 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     553847,   Seg_Num: 0
GRB_RA:          149.0371d {+09h 56m 08.90s} (J2000),
                 149.2167d {+09h 56m 52.00s} (current),
                 148.3611d {+09h 53m 26.66s} (1950)
GRB_DEC:         +13.6674d {+13d 40' 02.6"} (J2000),
                 +13.6039d {+13d 36' 13.9"} (current),
                 +13.9053d {+13d 54' 19.0"} (1950)
GRB_ERROR:       0.7 [arcsec radius, statistical only]
GRB_MAG:         14.96 +/- 0.14 [mag]
FILTER:          10, White
IMG_START_DATE:  16400 TJD;   108 DOY;   13/04/18
IMG_START_TIME:  68590.00 SOD {19:03:10.00} UT,   136.5 [sec] since BAT Trigger Time
SUN_POSTN:        26.87d {+01h 47m 29s}  +11.09d {+11d 05' 07"}
SUN_DIST:        117.72 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      122.94d {+08h 11m 46s}  +14.76d {+14d 45' 42"}
MOON_DIST:        25.49 [deg]
MOON_ILLUM:      53 [%]
GAL_COORDS:      222.17, 47.03 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      146.44,  1.03 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The UVOT position is 7.2 arcsec from the XRT position.  
COMMENTS:        Result based on Genie data.  
COMMENTS:        Notice generated automatically.

GCN Circular #14377
M. De Pasquale (UCL-MSSL), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), M. M. Chester (PSU), S. T. Holland (STScI), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (UCL-MSSL), C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC), A. Maselli (INAF-IASFPA), P. T. O'Brien (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU), E. Sonbas (NASA/GSFC/Adiyaman Univ.), M. C. Stroh (PSU), C. A. Swenson (PSU) and E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift Team:
At 19:00:53 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 130418A (trigger=553847). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 149.043, +13.649 which is
```
   RA(J2000) = 09h 56m 10s
   Dec(J2000) = +13d 38' 58"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual with image triggers, the BAT light curve shows no significant features.
The XRT began observing the field at 19:03:03.2 UT, 129.7 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 149.0377, 13.6654 which is equivalent to:
```
   RA(J2000)  = +09h 56m 9.05s
   Dec(J2000) = +13d 39' 55.4"
```
with an uncertainty of 5.3 arcseconds (radius, 90% containment). This location is 61 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy.
UVOT took a finding chart exposure of 150 seconds with the White filter starting 138 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	09:56:08.92 = 149.03718
  DEC(J2000) = +13:40:02.8  =  13.66744
```
with a 90%-confidence error radius of about 0.74 arc sec. This position is 7.6 arc sec. from the center of the XRT error circle. The estimated magnitude is 14.96 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03.
This source was detected on the first image trigger after it came within the BAT's field of view, so its start time may be significantly before the nominal trigger time. There is no significant fading in the XRT over the ~300 second XRT observation time. Thus it is likely that this is a very long duration event. The position of the source is 47 degrees from the Galactic plane, but that doesn't preclude a nearby source. Further determination of the characteristics of the source will await further data analysis.
Burst Advocate for this burst is M. De Pasquale (m.depasquale AT ucl.ac.uk). 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 #14378
J. Gorosabel (IAA/CSIC-UPV/EHU), S. Perez-hoyos (UPV/EHU), I. Mendikoa (UPV/EHU), A. Sanchez-Lavega (UPV/EHU), R. Hueso (UPV/EHU), J.F. Rojas (UPV/EHU), A. de Ugarte Postigo (IAA/CSIC-DARK), report on behalf of a larger collaboration:
We have observed the field of GRB130418A (de Pasquale et al. 2013; GCN Circ. 14377) with 1.23m CAHA telescope equipped with PLANETCAM. The observations started on 19:31 UT with the I-band filter. The optical afterglow reported by de Pasquale et al. (GCN Circ. 14377) is well detected with an approximate magnitue of I~15.6.
GCN Circular #14379
U.Quadri, L.Strabla, R.Girelli and A.Quadri report:
We imaged the field of GRB 130418A (de Pasquale et al. 2013; GCN Circ. 14377) detected by SWIFT(trigger 553847) with the robotic=20 telescope of (IAU station 565) Bassano Bresciano=20 Observatory, Italy.
The observations started 15 min. after the=20 GRB trigger,with our schmidt telescope=20 D=3D400 mm F/D=3D3.
Weather conditions were discrete for moon presence.
We co-added 14 unfiltered CCD exposures of 120s each.
We detect a new source of 16.3 Vmag in the error box given by SWIFT. We detected the candidate couterpart at the following position (+/- 2 arc= sec):
```
RA (J2000.0) =3D  09h 56m 08.90s=20
DEC(J2000.0) =3D +13=C2=B0 40' 02.8"
```
Magnitudes were estimated with the USNO-B1 cat.=20 and are not corrected for galactic dust extinction.
The message may be cited.
GCN Circular #14380
A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), C.C. Thoene (IAA-CSIC), J. Gorosabel (UPV/EHU, IAA-CSIC), R. Sanchez-Ramirez (IAA-CSIC), J. P. U. Fynbo (DARK/NBI), N. Tanvir (U. Leicester) and C.A. Alvarez Iglesias (GTC) report:
We have observed the afterglow of GRB 130418A (De Pasquale et al. GCN 14377) with the 10.4m GTC telescope starting at 21:45 UT (2.75 hr after the burst). Observations consisted of 2x600s using the R1000B grating, with a resolution of R~1000 in the range 3600 - 7900 A.
The spectrum shows a high S/N trace, with very weak MgII features at a redshift of z = 1.218, which we identify as the redshift of the GRB.
GCN Circular #14381
P. D'Avanzo, A. Melandri (INAF/OAB), Avet Harutyunyan, G. Mainella (INAF/TNG) report on behalf of the CIBO collaboration:
We observed the field of GRB 130418A (De Pasquale et al., GCN 14377) with the TNG telescope located in the Canary Islands. We obtained a set of images with the DOLORES camera in the B, V, R and I bands, starting on 2013 Apr 18 at 23:01:02 UT (4.0 hours after the GRB).
The optical afterglow (De Pasquale et al. GCN 14377; Gorosabel et al. GCN 14378; Quadri et al. 14379) is clearly detected in all bands. The measured R-band magnitude is 18.1 (at t-t0=4.06 h; calibrated against the USNOB1 catalogue).
We acknowledge support from the TNG visiting astronomer F. Borsa.
GCN Circular #14382
Klotz A. (IRAP-CNRS-OMP), Gendre B. (IRAP-CNRS-OMP), Boer M., Siellez K., Dereli H., Bardho O. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:
We imaged the field of GRB 130418A detected by SWIFT (trigger 553847) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France.
Continuous observations started 78.7 min after the GRB trigger due to the dusk. The elevation of the field decreased from 58 degrees above horizon and weather conditions were good. Four hours after the TAROT la Silla telescope (Chile) started to observe.
The afterglow mentioned by De Pasquale (GCNC 14377) appears clearly in the images.
The following magnitudes are obtained using the star NOMAD-1 1036-0179295 (ra=149.0472378 dec=+13.6557094 R=14.91) for flux calibration:
```
  Start   Stop    Rmag
  (min)   (min)
    78.7   84.7  17.34
    88.4   94.4  17.48
    98.2  110.2  17.59
   117.6  141.6  17.91
   156.6  186.6  18.11
   242.1  263.1  18.13
```
Considering a flux decay power law the corresponding exponent is alpha=0.65.
Magnitudes are not corrected for galactic dust extinction.
This message may be cited.
GCN Circular #14383
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 1098 s of XRT Photon Counting mode data and 3 UVOT images for GRB 130418A, 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 = 149.03689, +13.66721 which is equivalent to:
```
RA (J2000): 09h 56m 8.85s
Dec (J2000): +13d 40' 02.0"
```
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) and Evans et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #14384
N. P. M. Kuin and M. De_Paquale (UCL-MSSL) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 130418A 138 s after the BAT trigger (De_Paquale et al., GCN Circ. 14377). A source consistent with the XRT position (De Pasquale et al. GCN Circ. 14377) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
    RA  (J2000) =  09:56:08.88 = 149.03700 (deg.)
    Dec (J2000) = +13:40:02.7  =  13.66741 (deg.)
```
with an estimated uncertainty of 0.50 arc sec. (radius, 90% confidence).
Preliminary detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white              138          288          146         14.85 +/- 0.05

u                  296          353           56         14.71 +/- 0.04
v                 5634         5834          197         17.69 +/- 0.08
b                 3567         3766          197         17.41 +/- 0.05
w1                6044         6124           78         17.25 +/- 0.11
m2                5839         6039          197         17.61 +/- 0.11
w2                5430         5630          197         18.08 +/- 0.11
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).
Due to a Moon constraint, Swift observations will stop for now. Continuing aquisition of ground-based data, including ubv photometry will be useful at this time.
GCN Circular #14385
J.C. Tello, R. Sanchez-Ramirez (IAA-CSIC), J. Gorosabel (IAA/CSIC-UPV/EHU), F. Aceituno (OSN, IAA-CSIC) and A. Castro-Tirado (IAA-CSIC) on behalf of a larger collaboration report:
We observed the field of GRB130418A reported by De Pasquale et al. (GCNC 14377) with the 1.5 meter telescope at the Sierra Nevada Observatory using an I band filter, where we clearly detect a fading source coincident with the UVOT afterglow position.
Preliminary results of an image taken at 21h20m (2.33h after the burst) with a 300s exposure show the source presented a magnitude of I~17.13 when compared to the USNO-B1.0 catalogue. Another image taken at 22h45m (3.74h after the burst) with an exposure time of 60s shows a magnitude of I~17.51 (also preliminarily and when compared to the USNO-B1.0 catalogue).
More images were taken and will continue to be taken when the source rises again above the local horizon.
GCN Circular #14386
GRB 130418A: GROND detection of the optical-NIR afterglow
M. Nardini (UNIMIB), M. Tanga (MPE Garching), D. A. Kann (TLS Tautenburg) and J. Greiner (MPE Garching) report on behalf of the GROND team:
We observed the field GRB 130418A (Swift trigger 553847; M. De Pasquale et al., GCN 14377) simultaneously in g'r'i'z'JHKs with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla Observatory (Chile).
Observations started at 01:20:33 UT on April 19th, 6.3 hrs after the SWIFT BAT trigger. They were performed at an average seeing of 1" and at an average airmass of 1.38.
We detect the optical afterglow inside the 0.7" Swift/UVOT error circle reported by De Pasquale et al., (GCN 14377) in all 7 bands. Based on the first 4 min of total exposure we estimate preliminary magnitudes (all in AB system) of
```
g' = 18.79 +- 0.03,
r' = 18.46 +- 0.03,
i' = 18.22 +- 0.03,
z' = 17.95 +- 0.03,
J  = 17.62 +- 0.05,
H  = 17.17 +- 0.05 and
K  = 16.81 +- 0.11
```
Given magnitudes are calibrated against SDSS as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.03 mag in the direction of the burst (Schlegel et al. 1998).
GCN Circular #14387
D. A. Perley (Caltech) reports on behalf of a larger collaboration:
We observed the position of GRB 130418A (De Pasquale et al., GCN 14377) with the Combined Array for Research in Millimeter Astronomy at a frequency of 93 GHz (3mm) starting at 02:50 UT on 2013-04-19, 7.82 hours after the burst. Observations continued until 03:26 UT (midpoint t=8.12 hours.)
A source is clearly detected at a position consistent with the location of the UV, X-ray, and optical afterglow (De Pasquale et al., GCN 14377; Gorosabel et al., GCN 14378; Quardri et al., GCN 14379). The approximate flux at this time is ~3 mJy. Follow-up observations are planned.
We thank the CARMA staff for their support in executing these observations.
GCN Circular #14388
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), Willia= m H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC)= , Jos=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes=FAs Gonz=E1lez (UN= AM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley= (GSFC) report:
We observed the field of GRB 130418A (De Pasquale, et al., GCN 14377) wit= h the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacio= nal on Sierra San Pedro M=E1rtir from 2013/04 19.14 to 2013/04 19.19 UTC (8.2= 4 to 9.54 hours after the BAT trigger), obtaining a total of 1.07 hours exposu= re in the r' and i' bands and 0.45 hours exposure in the Z, Y, J, and H band= s.
For a source within the Swift-UVOT error circle (Kuin et al., GCN 14384), in comparison with SDSS DR8 and 2MASS, we obtain the following detections in the AB magnitude system:
```
 r'   18.87 +/- 0.02
 i'   18.77 +/- 0.02
 Z    18.30 +/- 0.02
 Y    18.07 +/- 0.02
 J    18.06 +/- 0.02
 H    17.53 +/- 0.02
```
These magnitudes are not corrected for Galactic extinction in the directi= on of the GRB. Relative to the GROND detections about 3 hrs earlier (Nardin= i et al., GCN 14386), the afterglow has faded by about 0.4 mag in all optical/NIR bands. Continued observations are planned.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedr= o M=E1rtir.
GCN Circular #14389
S. Covino, D. Fugazza, V. d'Elia, on behalf of the REM team report:
We imaged the field of GRB130418A (De Pasquale et al., GCN 14377) with the REM NIR camera equippe with the J, Hand Ks filters.
Observations started at 2013/04/18 23:12:37, i.e. about 4.2 hours after the prompt event. The optical counterpart detected by UVOT was well detected at H=15.7+-0.1 (preliminary calibration) at the beginning of our observations.
GCN Circular #14390
T. Kruehler, D. Xu (both DARK), R. Sanchez-Ramirez (IAA-CSIC), D. Malesani, J. Fynbo (both DARK) and H. Flores (GEPI/Obs. de Paris) report on behalf of a larger collaboration:
We observed the optical/NIR counterpart (e.g., De Pasquale et al. GCN 14377, Gorosabel et al. GCN 14378) of GRB 130418A (De Pasquale et al. GCN 14377) with the VLT/X-shooter spectrograph.
Our spectra cover the wavelength range 3000-25000 AA, and were taken starting on 2013 Apr 18, 23:35:08 UT (4.57 hr after the GRB) for a total exposure of 20 min.
We identify absorption lines of CIV, FeII and MgII at a common redshift of z = 1.217 (see also de Ugarte Postigo et al., GCN 14380). The doublet of CIV (1548, 1550) is also detected in a second absorption system at z = 1.218. No emission lines are evident in our spectrum.
We thank the VLT staff, in particular Henri Boffin, Dimitri Gadotti and Alex Correa, for the expert support in obtaining these data.
GCN Circular #14392
J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), M. De Pasquale (UCL-MSSL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU),C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (MSU) (i.e. 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 130418A (trigger #553847) (De Pasquale, et al., GCN Circ. 14377). The BAT ground-calculated position is RA, Dec = 149.045, 13.674 deg which is
```
    RA(J2000)  =  09h 56m 10.8s
    Dec(J2000) = +13d 40' 28.2"
```
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 89%.
It appears that BAT triggered on the decay phase of a burst already in progress when the source position came into the BAT field of view during a pre-planned slew. Therefore we do not know the true time of the start of the burst, but it was at least 50 seconds before T0, here defined as the trigger time. From T-50 sec, when the burst became visible, there is a steady decline punctuated by two peaks at approximately T-20 and T+50, the first being harder than the second. The decay continued to roughly T+300 sec. The burst location was no longer visible after T+450, when another slew took it out of the BAT field. T90 cannot be determined since BAT did not see the start of the burst, but T90 is at least 300 seconds.
The time-averaged spectrum from T-40.16 to T+285.59 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.07 +- 0.17. The fluence in the 15-150 keV band is 1.8 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-37.68 sec in the 15-150 keV band is 0.6 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. Note that these values are calculated only for the part of the burst detected by the BAT, so the fluence should be considered a lower limit.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/553847/BA/
GCN Circular #14393
M. Im (CEOU/SNU), H.-I. Sung(KASI), and Y. Urata (NCU) on behalf of EAFON
We observed the field of GRB 130418A (Pasquale et al., GCN 14377) in R, I, and z filters using the 1-m telescope at Mt. Lemmon observatory in Arizona, US.
The observation started at 2013-04-19 03:40 UT, or about 8.6 hours after the BAT alert, and continued for about 45 min. We clearly identify the fading afterglow in R- and I-band, at the location reported earlier (Gorosabel et al. GCN 14378; Quadri et al. GCN 14379; de Ugarte Postigo et al. GCN14380; D'Avanzo et al. GCN 14381; Klotz et al. GCN14382; Kuin et al. GCN14384; Tello et al. GCN 14385; Nardini et al. GCN 14386; Perley et al. GCN 14387; Butler et al. GCN 14388; Covino et al. GCN 14389; Kruehler et al. GCN 14390). On the other hand, the detection in z-band is marginal.
Preliminary magnitudes of the afterglow, calibrated against a USNO B-1 star at RA=140.047350 and Dec=+13.655828 are given below:
```
   T(mid, UT)         Mag
04-19 03:58:26     R=18.95 +- 0.07
04-19 04:04:16     I=18.18 +- 0.08
```
We thank the LOAO operator, Jae-Hyuk Yoon for performing the observation.

GCN Circular #14394
Veli-Pekka Hentunen, Markku Nissinen and Tuomo Salmi (Taurus Hill Observatory, Varkaus, Finland) report:
We have detected GRB 130418A optical afterglow at iTelescope observatories T18 and T21. Four unfiltered and three photometric V filter images with 300 sec exposure time were made at T18 (AstroCamp Observatory, Nerpio, Spain) 0.32-m/8.0 Astorgraph and KAF-6303E CCD. Two unfiltered and four photometric V filter images with 600 sec exposure time were made at T21 (Mayhill, New Mexico) 0.43-m/6.8 astrograph and FLI ProLine PL6303E CCD.
The afterglow was detected at following position RA 09:56:08.94 and DEC +13:40:02.9.
The following magnitudes were obtained from the observations using NOMAD1 1036-0179295 (V= 14.750, R = 14.910) as the comparison:

Tmid(sec) +T0     Filter         Exp time      Mag          Mag err. 
3119                     unfiltered     300         16.200CR     0.026
3406                     unfiltered     300         16.305CR     0.027
3758                     unfiltered     300         16.381CR     0.027
4118                     unfiltered     300         16.496CR     0.030
4835                      V               300         16.895V        0.082
5195                      V               300         16.979V        0.081
5546                      V               300         16.983V        0.085


6432                     V                 600         17.320V       0.075
7093                     V                 600         17.342V       0.077
8026                     unfiltered      600         17.328CR     0.044
8691                     unfiltered      600         17.519CR     0.053
9742                     V                 600         17.775V       0.123
11059                   V                 600         17.752V       0.193

GCN Circular #14395
Veli-Pekka Hentunen, Markku Nissinen and Tuomo Salmi (Taurus Hill Observatory, Varkaus, Finland) report:
We have detected GRB 130418A optical afterglow at iTelescope observatory T21 (Mayhill, New Mexico) 0.43-m/6.8 astrograph and FLI ProLine PL6303E CCD. One unfiltered image with 600 sec exposure time was made.
The afterglow was detected at following position RA 09:56:08.87 and DEC +13:40:02.7.
The following magnitude was obtained from the image using NOMAD1 1036-0179295 (R = 14.910) as the comparison:
```
Tmid(h) +To     Filter         Exp.time   Mag          Mag err. 
10.96               unfiltered    600          19.018       0.277
```
GCN Circular #14400
S. Martin (ESO/ALMA), A. de Ugarte Postigo (IAA-CSIC) and G. Petitpas (SMA) report on behalf of a larger collaboration:
We have observed the field of GRB 130418A (De Pasquale et al., GCN 14377) with the Submillimeter Array (SMA) at Mauna Kea (Hawai, USA) in submm wavelengths. Observations consisted of 1.25 hr on target with an average time 6.5 UT on 19 April 2013 (11.5 hr after the burst). We used 6 antennas on compact configuration, under average weather conditions, with a precipitable water vapour of 2.5 mm or an optical depth at 225 GHz of ~0.1. The central observing wavelength was 340 GHZ.
On a preliminary reduction we do not detect any source consistent with the position of the GRB down to a 3-sigma limit of 14.5 mJy (r.m.s. 4.8mJy). This limit is consistent with the 3 mm detection by CARMA (Perley, GCN 14387)
We acknowledge excellent support from the SMA staff.
GCN Circular #14401
B. E. Cobb (GWU), reports:
Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 130418A (GCN 14377, De Pasquale et al.) at two epochs (with mid-exposure times of 2013-04-19 00:03 UT & 01:24 UT). For each epoch, several dithered images were obtained with total summed exposure times of 15 min in V and I and 12 min in J and K.
The fading afterglow of GRB 130418A (e.g. GCN 14377, De Pasquale et al.; GCN 14378, Gorosabel et al.; GCN 14379, Quadri et al.) was detected with the following magnitudes:
```
mid-exposure
time
(hours)               V mag              I mag               J   mag              K mag
5.03944 hours   18.41 +/- 0.03  17.57 +/- 0.03  16.46 +/- 0.10  14.82 +/- 0.10
6.38972 hours   18.59 +/- 0.03  17.69 +/- 0.03  16.70 +/- 0.10  15.05 +/- 0.10
```
(Optical photometry is calibrated against Landolt standard stars and IR photometry is calibrated against a 2MASS star in the field.)
Between about 5 hrs and 6.4 hrs post-burst, the GRB afterglow fades with a decay rate of approximately alpha = 0.6 +/- 0.2 in the optical (where afterglow flux is proportional to t^-alpha).
GCN Circular #14403
K.L. Page (U. Leicester) and M. De Pasquale (UCL-MSSL) report on behalf of the Swift-XRT team:
We have analysed 2.7 ks of XRT data for GRB 130418A (De Pasquale et al. GCN Circ. 14377), from 119 s to 15.6 ks after the BAT trigger. The data comprise 262 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN. Circ 14383).
The light curve can be modelled with an initial power-law decay with an index of alpha=0.72 (+/-0.11), followed by a break at T+801 s to an alpha of 1.51 (+0.54, -0.30).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.24 (+/-0.06). The best-fitting absorption column is 2.9 (+7.3, -2.9) x 10^20 cm^-2, at a redshift of 1.218, in addition to the Galactic value of 2.7 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 1.70 (+0.24, -0.23) and a best-fitting absorption column of 2.6 (+3.0, -2.5) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.2 x 10^-11 (4.8 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Galactic foreground: 2.7 x 10^20 cm^-2
Intrinsic column:    2.6 (+3.0, -2.5) x 10^21 cm^-2 at z=1.218
Photon index:	     1.70 (+0.24, -0.23)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00553847.
This circular is an official product of the Swift-XRT team.
GCN Circular #14404
Subject: Subject: GRB 130418A: Continued RATIR Optical and NIR Observatio= ns
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), Willia= m H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC)= , Jos=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes=FAs Gonz=E1lez (UN= AM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley= (GSFC) report:
We re-observed the field of GRB 130418A (De Pasquale, et al., GCN 14377) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacional on Sierra San Pedro M=E1rtir from 2013/04 20.14 to 2013/04 20.26 UTC (32.30 to 35.30 hours after the BAT trigger), obtaining a total of 2.13 hours exposure in the r' and i' bands and 0.89 hours exposure in the Z, Y, J, and H bands.
Relative to our observations last night (GCN 14388), the GRB afterglow has faded significantly, by approximately 3 magnitudes in all bands. In comparison with SDSS DR8 and 2MASS, we find:
```
  r'    21.74 +/- 0.12
  i'    21.80 +/- 0.16
  Z     21.52 +/- 0.26
  Y     21.01 +/- 0.21
  J     20.65 +/- 0.17
  H     20.98 +/- 0.35
```
These magnitudes are in the AB system and not corrected for Galactic extinction in the direction of the GRB. Uncertainties are 1-sigma.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #14417
S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report:
The long GRB 130418A (Swift-BAT trigger #553847: De Pasquale et al., GCN 14377; Cummings et al., GCN 14392) was observed by Konus-Wind (K-W) in the waiting mode.
K-W light curve shows a soft pulse started ~215 s before the BAT trigger (T0(BAT)=3D19:00:53). A total duration of the pulse is ~120 s. The decay phase of the burst which had triggered Swift-BAT is virtually indistinguishable from the K-W background. Since the K-W ecliptic latitude response to the burst is consistent with the BAT localization, we suggest the pulse observed by K-W is an initial phase of GRB 130418A.
As observed by Konus-Wind, this part of the burst had a fluence of (1.57 =B1 0.25)x10^-5 erg/cm2 and a 3-s peak flux, measured from T0(BAT)-186 s, of (2.5 =B1 0.4)x10^-7 erg/cm2/s (both in the 20 - 1200 keV energy range).
Fitting the K-W 3-channel time-averaged spectrum (from T0(BAT)-215 s to T0(BAT)-95 s) by a simple power-law model yields a photon index of 2.12 =B1 0.09, which is consistent with the slope reported by BAT for the burst tail.
Assuming z=3D1.218 (de Ugarte Postigo et al., GCN 14380; Kruehler et al. GCN 14390) and a standard cosmology model with H_0 =3D 70 km/s/Mpc, Omega_M =3D 0.27, Omega_Lambda =3D 0.73, the isotropic energy release E_iso is (6.3 =B1 1.0)x10^52 erg, and the peak luminosity (L_iso)_max is (1.2 =B1 0.2)x10^51 erg/s.
All the quoted errors are estimated at the 1 sigma confidence level.
The K-W light curve of this burst is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB130418A/
GCN Circular #14434
A.J. van der Horst (University of Amsterdam) reports on behalf of a large collaboration:
"We observed the position of the GRB 130418A afterglow at 4.9 GHz with the Westerbork Synthesis Radio Telescope at April 21 13.53 UT to April 22 01.49 UT, i.e. 2.77 - 3.27 days after the burst (GCN 14377). We do not detect a radio source at the position of the optical counterpart (GCN 14384). The three-sigma rms noise in the map around that position is 69 microJy per beam. The formal flux measurement for a point source at the position of the optical counterpart is 34 +/- 23 microJy.
We would like to thank the WSRT staff for quickly scheduling and obtaining these observations."
GCN Circular #14438
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), Willia= m H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC)= , Jos=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes=FAs Gonz=E1lez (UN= AM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley= (GSFC) report:
We observed the field of GRB 130418A (de Pasquale et al., GCN 14377) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacio= nal on Sierra San Pedro M=E1rtir from 2013/04 22.14 to 2013/04 22.33 UTC (80.= 35 to 84.95 hours after the BAT trigger), obtaining a total of 2.84 hours exposure in the r' and i' bands and 1.19 hours exposure in the Z, Y, J, a= nd H bands.
At the position of the transient observed on 2013/04/19 (GCN 14388) and 2013/04/20 (GCN 14404), in comparison with SDSS DR8 and 2MASS, we obtain the following upper limits (3-sigma) in the AB magnitude system:
```
 r'> 23.12
 i'> 22.93
 Z > 22.52
 Y > 21.89
 J > 21.85
 H > 21.25
```
These magnitudes are not corrected for Galactic extinction in the directi= on of the GRB. The source is thus more than about 1 magnitude fainter than = it was observed to be two days ago.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedr= o M=E1rtir.
GCN Circular #14504
U.Quadri, L.Strabla, R.Girelli and A.Quadri report:
Photometric optical measurements of GRB 130418A detected by SWIFT trigger 553847 (de Pasquale et al. 2013; GCN Circ. 14377) have been done using the Schmidt telescope 0.32m F/3.1 and Starlight CCD camera HX-516 applied at direct focus. 120 sec. exposure time and 2x2 binning were used for all photos. All exposure were unfiltered. Flat field and dark have been captured and all images were corrected with them. Astrometrica software version 4.6.5.390 was used to perform differential photometry on the reduced images.
```
began of period: 2013/04/18.80415 -  17 min after  the burst.
end   of period: 2013/04/18.92338 - 188 min after  the burst.
```
The photometric results as follow:
```
------------------------------------
Date UTC             Mag.   1 sigma.
------------------------------------
	
2013 04 18.80485    15.68    0.08
2013 04 18.80846    16.12    0.13
2013 04 18.82000    16.44    0.10
2013 04 18.90014    17.64    0.08
2013 04 18.85910    17.21    0.13
2013 04 18.87354    17.39    0.12
2013 04 18.88799    17.53    0.09
2013 04 18.90968    17.74    0.09


------------------------------------
```
Magnitudes were estimated with the USNO-B1 cat. and are not corrected for galactic dust extinction.
Images and analisis are available at the following address:
http://www.osservatoriobassano.org/archivio/grb/GRB130418A-Trig-553847-2013-04-18.htm
This message may be cited.
GCN Circular #14537
P. D'Avanzo, M. Cecconi, C. P. Padilla-Torres (INAF/TNG) report on behalf of the CIBO collaboration:
We observed the field of GRB 130418A (De Pasquale et al., GCN 14377) with the TNG telescope located in the Canary Islands. We obtained a set of J-band images with the NICS camera on May 1.891 (mean observing time; about 13.1 days from the GRB).
No source is detected at the optical afterglow position (De Pasquale et al. GCN 14377; Gorosabel et al. GCN 14378; Quadri et al. 14379; Kuin et al., GCN 14384; Hentunen et al., GCN 14394) down to a 3sigma limiting magnitude of J~21.3 (calibrated against the 2MASS catalogue).

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Jochen Greiner, last update: 03-May-2013 [Disclaimer]