Gamma-ray Burst 170318A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 12:12:40 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     743065,   Seg_Num: 0
GRB_RA:          305.645d {+20h 22m 35s} (J2000),
                 305.823d {+20h 23m 18s} (current),
                 305.127d {+20h 20m 30s} (1950)
GRB_DEC:         +28.409d {+28d 24' 32"} (J2000),
                 +28.465d {+28d 27' 53"} (current),
                 +28.248d {+28d 14' 51"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       11319 [cnts]    Image_Peak=418 [image_cnts]
TRIGGER_DUR:     4.096 [sec] 
TRIGGER_INDEX:   307     E_range: 50-350 keV
BKG_INTEN:       89644 [cnts]
BKG_TIME:        43861.22 SOD {12:11:01.22} UT
BKG_DUR:         40 [sec]
GRB_DATE:        17830 TJD;    77 DOY;   17/03/18
GRB_TIME:        43916.52 SOD {12:11:56.52} UT
GRB_PHI:         -144.86 [deg]
GRB_THETA:        38.95 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     16.49 [sigma]
IMAGE_SIGNIF:    12.17 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +3  +1  +0  +1 -52  +0 
SUN_POSTN:       358.25d {+23h 53m 00s}   -0.76d {-00d 45' 32"}
SUN_DIST:         58.01 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      243.53d {+16h 14m 08s}  -15.88d {-15d 53' 05"}
MOON_DIST:        74.77 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:       68.45, -4.95 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      317.69, 46.12 [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 = 244.01,-5.49 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 12:14:21 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     743065,   Seg_Num: 0
GRB_RA:          305.6674d {+20h 22m 40.17s} (J2000),
                 305.8458d {+20h 23m 22.99s} (current),
                 305.1492d {+20h 20m 35.80s} (1950)
GRB_DEC:         +28.4064d {+28d 24' 23.0"} (J2000),
                 +28.4624d {+28d 27' 44.5"} (current),
                 +28.2451d {+28d 14' 42.3"} (1950)
GRB_ERROR:       6.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       6.78e-10 [erg/cm2/sec]
GRB_SIGNIF:      4.89 [sigma]
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  44024.48 SOD {12:13:44.48} UT,   108.0 [sec] since BAT Trigger Time
TAM[0-3]:        327.66 237.19 261.67 243.69
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       358.25d {+23h 53m 00s}   -0.76d {-00d 45' 30"}
SUN_DIST:         57.99 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      243.55d {+16h 14m 11s}  -15.89d {-15d 53' 14"}
MOON_DIST:        74.78 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:       68.46, -4.96 [deg] galactic lon,lat of the burst
ECL_COORDS:      317.72, 46.11 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.20 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 12:14:31 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     743065,   Seg_Num: 0
GRB_RA:          305.6674d {+20h 22m 40.1s} (J2000),
                 305.8458d {+20h 23m 22.9s} (current),
                 305.1492d {+20h 20m 35.8s} (1950)
GRB_DEC:         +28.4064d {+28d 24' 23.0"} (J2000),
                 +28.4624d {+28d 27' 44.5"} (current),
                 +28.2451d {+28d 14' 42.3"} (1950)
GRB_ERROR:       5.8 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       24 [cnts]
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  44024.48 SOD {12:13:44.48} UT,   108.0 [sec] since BAT Trigger Time
CENTROID_X:      246.18,  raw= 246  [pixels]
CENTROID_Y:      307.60,  raw= 308  [pixels]
ROLL:            110.71 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   21.71
GRB_POS_XRT_Z:   -141.94
IMAGE_URL:       sw00743065000msxps_rw.img
SUN_POSTN:       358.25d {+23h 53m 00s}   -0.76d {-00d 45' 30"}
SUN_DIST:         57.99 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      243.55d {+16h 14m 12s}  -15.89d {-15d 53' 15"}
MOON_DIST:        74.77 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:       68.46, -4.96 [deg] galactic lon,lat of the burst
ECL_COORDS:      317.72, 46.11 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 12:14:37 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     743065,   Seg_Num: 0
GRB_RA:          305.6674d {+20h 22m 40.1s} (J2000),
                 305.8458d {+20h 23m 22.9s} (current),
                 305.1492d {+20h 20m 35.8s} (1950)
GRB_DEC:         +28.4064d {+28d 24' 23.0"} (J2000),
                 +28.4624d {+28d 27' 44.5"} (current),
                 +28.2451d {+28d 14' 42.3"} (1950)
GRB_ERROR:       5.8 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       24 [cnts]
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  44024.48 SOD {12:13:44.48} UT,   108.0 [sec] since BAT Trigger Time
CENTROID_X:      246.18,  raw= 246  [pixels]
CENTROID_Y:      307.60,  raw= 308  [pixels]
ROLL:            110.71 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   21.71
GRB_POS_XRT_Z:   -141.94
IMAGE_URL:       sw00743065000msxps_rw.img
SUN_POSTN:       358.25d {+23h 53m 00s}   -0.76d {-00d 45' 30"}
SUN_DIST:         57.99 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      243.55d {+16h 14m 12s}  -15.89d {-15d 53' 15"}
MOON_DIST:        74.77 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:       68.46, -4.96 [deg] galactic lon,lat of the burst
ECL_COORDS:      317.72, 46.11 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 12:17:10 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     743065,   Seg_Num: 0
POINT_RA:        305.624d {+20h 22m 30s} (J2000)
POINT_DEC:       +28.415d {+28d 24' 54"} (J2000)
POINT_ROLL:      110.707d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  44033.09 SOD {12:13:53.09} UT,   116.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.526
N_STARS:         190
X_OFFSET:        600 [pixels]
Y_OFFSET:        464 [pixels]
X_MAX:           1559 [pixels]
Y_MAX:           1423 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00743065000msufc0116.fits
SUN_POSTN:       358.25d {+23h 53m 00s}   -0.76d {-00d 45' 27"}
SUN_DIST:         58.03 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      243.57d {+16h 14m 17s}  -15.89d {-15d 53' 29"}
MOON_DIST:        74.73 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:       68.44, -4.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      317.67, 46.13 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 12:17:38 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     743065,   Seg_Num: 0
POINT_RA:        305.624d {+20h 22m 30s} (J2000)
POINT_DEC:       +28.415d {+28d 24' 54"} (J2000)
POINT_ROLL:      110.707d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  44033.09 SOD {12:13:53.09} UT,   116.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.526
N_STARS:         190
X_OFFSET:        600 [pixels]
Y_OFFSET:        464 [pixels]
X_MAX:           1559 [pixels]
Y_MAX:           1423 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00743065000msufc0116.fits
SUN_POSTN:       358.25d {+23h 53m 00s}   -0.76d {-00d 45' 27"}
SUN_DIST:         58.03 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      243.57d {+16h 14m 18s}  -15.89d {-15d 53' 31"}
MOON_DIST:        74.73 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:       68.44, -4.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      317.67, 46.13 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 12:18:58 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     743065,   Seg_Num: 0
POINT_RA:        305.624d {+20h 22m 30s} (J2000)
POINT_DEC:       +28.415d {+28d 24' 54"} (J2000)
ROLL:            110.707d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  44033.09 SOD {12:13:53.09} UT,   116.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     511532051
X_OFFSET:        1023 [pixels]
Y_OFFSET:        687 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1183
Y_GRB_POS:       847
BINNING_INDEX:   1
IM_URL:          sw00743065000msuni0135.fits
SUN_POSTN:       358.25d {+23h 53m 01s}   -0.76d {-00d 45' 26"}
SUN_DIST:         58.04 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      243.59d {+16h 14m 21s}  -15.89d {-15d 53' 38"}
MOON_DIST:        74.72 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:       68.44, -4.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      317.67, 46.13 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 12:19:08 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     743065,   Seg_Num: 0
POINT_RA:        305.624d {+20h 22m 30s} (J2000)
POINT_DEC:       +28.415d {+28d 24' 54"} (J2000)
ROLL:            110.707d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  44033.09 SOD {12:13:53.09} UT,   116.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     511532051
X_OFFSET:        1023 [pixels]
Y_OFFSET:        687 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1183
Y_GRB_POS:       847
BINNING_INDEX:   1
IM_URL:          sw00743065000msuni0135.fits
SUN_POSTN:       358.25d {+23h 53m 01s}   -0.76d {-00d 45' 26"}
SUN_DIST:         58.04 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      243.59d {+16h 14m 21s}  -15.89d {-15d 53' 39"}
MOON_DIST:        74.72 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:       68.44, -4.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      317.67, 46.13 [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 Circular #20904
B. Sbarufatti (INAF-OAB/PSU), D. N. Burrows (PSU), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 12:11:56 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170318A (trigger=743065). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 305.645, +28.409 which is
```
   RA(J2000) = 20h 22m 35s
   Dec(J2000) = +28d 24' 32"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 30 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 12:13:44.4 UT, 108.0 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 305.66565, 28.40652 which is equivalent to:
```
   RA(J2000)  = 20h 22m 39.76s
   Dec(J2000) = +28d 24' 23.5"
```
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 65 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 4.45 x 10^21 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 6.78e-10 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 116 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the large, but uncertain extinction expected.
Burst Advocate for this burst is B. Sbarufatti (boris.sbarufatti AT brera.inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 12:31:45 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     743065,   Seg_Num: 0
GRB_RA:          305.6656d {+20h 22m 39.74s} (J2000),
                 305.8440d {+20h 23m 22.56s} (current),
                 305.1474d {+20h 20m 35.37s} (1950)
GRB_DEC:         +28.4065d {+28d 24' 23.4"} (J2000),
                 +28.4625d {+28d 27' 44.9"} (current),
                 +28.2452d {+28d 14' 42.7"} (1950)
GRB_ERROR:       3.7 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  44127.00 SOD {12:15:27.00} UT,   210.5 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       358.26d {+23h 53m 02s}   -0.75d {-00d 45' 13"}
SUN_DIST:         58.00 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      243.69d {+16h 14m 46s}  -15.91d {-15d 54' 46"}
MOON_DIST:        74.68 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:       68.46, -4.96 [deg] galactic lon,lat of the burst
ECL_COORDS:      317.72, 46.11 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 12:39:11 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     743065,   Seg_Num: 0
POINT_RA:        305.622d {+20h 22m 29s} (J2000)
POINT_DEC:       +28.413d {+28d 24' 48"} (J2000)
POINT_ROLL:      110.706d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  44245.12 SOD {12:17:25.12} UT,   328.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.946
N_STARS:         114
X_OFFSET:        703 [pixels]
Y_OFFSET:        367 [pixels]
X_MAX:           1662 [pixels]
Y_MAX:           1326 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw00743065000msufc0328.fits
SUN_POSTN:       358.26d {+23h 53m 04s}   -0.75d {-00d 45' 06"}
SUN_DIST:         58.04 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      243.76d {+16h 15m 01s}  -15.92d {-15d 55' 26"}
MOON_DIST:        74.60 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:       68.44, -4.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      317.67, 46.13 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 12:39:32 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     743065,   Seg_Num: 0
POINT_RA:        305.622d {+20h 22m 29s} (J2000)
POINT_DEC:       +28.413d {+28d 24' 48"} (J2000)
POINT_ROLL:      110.706d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  44245.12 SOD {12:17:25.12} UT,   328.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.946
N_STARS:         114
X_OFFSET:        703 [pixels]
Y_OFFSET:        367 [pixels]
X_MAX:           1662 [pixels]
Y_MAX:           1326 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw00743065000msufc0328.fits
SUN_POSTN:       358.27d {+23h 53m 04s}   -0.75d {-00d 45' 05"}
SUN_DIST:         58.04 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      243.76d {+16h 15m 02s}  -15.92d {-15d 55' 28"}
MOON_DIST:        74.60 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:       68.44, -4.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      317.67, 46.13 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 12:40:02 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     743065,   Seg_Num: 0
GRB_RA:          305.6666d {+20h 22m 39.98s} (J2000),
                 305.8450d {+20h 23m 22.80s} (current),
                 305.1484d {+20h 20m 35.61s} (1950)
GRB_DEC:         +28.4065d {+28d 24' 23.4"} (J2000),
                 +28.4625d {+28d 27' 44.9"} (current),
                 +28.2452d {+28d 14' 42.7"} (1950)
GRB_ERROR:       2.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  44127.00 SOD {12:15:27.00} UT,   210.5 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       358.27d {+23h 53m 04s}   -0.75d {-00d 45' 05"}
SUN_DIST:         58.00 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      243.76d {+16h 15m 03s}  -15.93d {-15d 55' 30"}
MOON_DIST:        74.63 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:       68.46, -4.96 [deg] galactic lon,lat of the burst
ECL_COORDS:      317.72, 46.11 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 12:40:51 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     743065,   Seg_Num: 0
POINT_RA:        305.622d {+20h 22m 29s} (J2000)
POINT_DEC:       +28.413d {+28d 24' 48"} (J2000)
ROLL:            110.706d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  44245.12 SOD {12:17:25.12} UT,   328.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     511532263
X_OFFSET:        1023 [pixels]
Y_OFFSET:        687 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1183
Y_GRB_POS:       847
BINNING_INDEX:   1
IM_URL:          sw00743065000msuni0347.fits
SUN_POSTN:       358.27d {+23h 53m 04s}   -0.75d {-00d 45' 04"}
SUN_DIST:         58.04 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      243.77d {+16h 15m 05s}  -15.93d {-15d 55' 35"}
MOON_DIST:        74.59 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:       68.44, -4.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      317.67, 46.13 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 12:41:10 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     743065,   Seg_Num: 0
POINT_RA:        305.622d {+20h 22m 29s} (J2000)
POINT_DEC:       +28.413d {+28d 24' 48"} (J2000)
ROLL:            110.706d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  44245.12 SOD {12:17:25.12} UT,   328.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     511532263
X_OFFSET:        1023 [pixels]
Y_OFFSET:        687 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1183
Y_GRB_POS:       847
BINNING_INDEX:   1
IM_URL:          sw00743065000msuni0347.fits
SUN_POSTN:       358.27d {+23h 53m 04s}   -0.75d {-00d 45' 04"}
SUN_DIST:         58.04 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      243.77d {+16h 15m 05s}  -15.93d {-15d 55' 36"}
MOON_DIST:        74.59 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:       68.44, -4.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      317.67, 46.13 [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 Circular #20905
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 170318A, we find an enhanced XRT position of the afterglow: RA, Dec: 305.6668, 28.4066 which is equivalent to:
```
   RA (J2000)  = 20 22 40.03
   Dec (J2000) = +28 24 23.7
```
with an uncertainty of 2.1 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/743065.
Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
GCN Circular #20907
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 2006 s of XRT Photon Counting mode data and 1 UVOT images for GRB 170318A, 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 = 305.66732, +28.40600 which is equivalent to:
```
RA (J2000): 20h 22m 40.16s
Dec (J2000): +28d 24' 21.6"
```
with an uncertainty of 1.9 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 #20912
J. R. Cummings (CPI),S. D. Barthelmy (GSFC), N. Gehrels (GSFC), H. A. Krimm (NSF/USRA),A. Y. Lien (GSFC/UMBC),C. B. Markwardt (GSFC), D. M. Palmer (LANL),T. Sakamoto (AGU),B. Sbarufatti (INAF-OAB/PSU), M. Stamatikos (OSU),T. N. Ukwatta (LANL)(i.e. the Swift-BAT team):
Using the data set from T-239 to T+483 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170318A (trigger #743065) (Sbarufatti, et al., GCN Circ. 20904). The BAT ground-calculated position is RA, Dec = 305.662, 28.408 deg which is
```
    RA(J2000)  =  20h 22m 38.9s
    Dec(J2000) = +28d 24' 30.5"
```
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 43%.
The mask-weighted light curve shows a single FRED-shaped pulse that starts approximately T+20 sec, peaks at T+2 sec and decays to background by T+100 sec. T90 (15-350 keV) is 133.7 +- 42.8 sec (estimated error including systematics).
The time-averaged spectrum from -21.544 to 175.788 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.35 +- 0.11. The fluence in the 15-150 keV band is 3.7 +- 0.3 x 10^-06erg/cm2. The 1-sec peak photon flux measured from T+1.87 sec in the 15-150 keV band is 1.2 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/743065/BA/
GCN Circular #20914
A. A. Breeveld (UCL-MSSL) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170318A 117 s after the BAT trigger (Sbarufatti et al., GCN Circ. 20904). No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. 20907) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           117          266          147         >20.4
u_FC               329          552          220         >19.6
white              117         6605          363         >20.8
v                 2222         2241           19         >17.0
b                 2147         6400          216         >19.8
u                  329         6195          417         >20.1
w1                5790         5990          197         >19.4
m2                5585         5784          197         >19.3
w2                2197        11766          560         >20.4
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.97 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #20915
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jes=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:
We observed the field of GRB 170318A (Sbarufatti, et al., GCN 20904) 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 2017/03 18.51 to 2017/03 18.53 UTC (3.0 to 27.6 minutes after the BAT trigger), obtaining a total of 0.24 hours exposure in the r and i bands and 0.11 hours exposure in the Z, Y, J, and H bands.
We do not detect a source within the Swift-XRT error circle (Evans, et al., GCN 20907). In comparison with the USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma):
```
 r > 23.39
 i > 22.82
 Z > 21.72
 Y > 21.56
 J > 21.12
 H > 20.73
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. We note that this field suffers large Galactic extinction (A_V~3).
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #20917
S. J. LaPorte (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU) and report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team:
We have analysed 7.0 ks of XRT data for GRB 170318A, from 98 s to 41.1 ks after the BAT trigger. The data comprise 94 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode.
The light curve can be modelled with an initial power-law decay with an index of alpha=1.09 (+0.51, -0.29), followed by a break at T+208 s to an alpha of 2.74 (+0.76, -0.17).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 0.84 (+0.20, -0.19). The best-fitting absorption column is 6.3 (+2.7, -1.9) x 10^21 cm^-2, consistent with the Galactic value of 4.4 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 0.92 (+0.35, -0.30) and a best-fitting absorption column of 6.4 (+4.6, -1.9) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 8.3 x 10^-11 (9.3 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     6.4 (+4.6, -1.9) x 10^21 cm^-2
Galactic foreground: 4.4 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     0.92 (+0.35, -0.30)
```
If the light curve continues to decay with a power-law decay index of 2.74, the count rate at T+24 hours will be 4.0 x 10^-7 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.4 x 10^-17 (3.8 x 10^-17) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00743065.
This circular is an official product of the Swift-XRT team.
GCN Circular #20925
Max Genecov, WeiKang Zhang, and Alex Filippenko (UC Berkeley) report on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, responded to Swift GRB 170318A (Sbarufatti, et al., GCN 20904) starting at 12:33:14 UT, ~23 minutes after the burst. The target was at low elevation but rising. Observations were performed with an automatic sequence in the clear (roughly R) and I filters, and the exposure time was 20 s per image. We do not detect any optical source within the XRT error circle (Evans, et al., GCN 20907). The limiting magnitude of the co-added clear band image is ~17.6 at a mid-time of 39.7 minutes after the burst.
GCN Circular #20956
K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender (Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)
The AMI Large Array robotically triggered on the Swift alert for GRB 170318A (Sbarufatti et al., GCN 20904) as part of the 4pisky program, and subsequent follow up observations were obtained up to 10 days post-burst. Our observations at 15 GHz on 2016 Mar 18.55 and Mar 21.50 (UT) do not reveal any radio source at the XRT location (Evans et al., GCN 20907), with 3sigma upper limits of 159 uJy and 93 uJy respectively.
We thank the AMI staff for scheduling these observations. The AMI-GRB database is a log of all GRB follow up observations with the AMI, and is available at http://4pisky.org/ami-grb/.

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Jochen Greiner, last update: 31-Mar-2017 [Disclaimer]