Gamma-ray Burst 170317A

(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:     Fri 17 Mar 17 09:50:19 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     742866,   Seg_Num: 0
GRB_RA:           93.088d {+06h 12m 21s} (J2000),
                  93.424d {+06h 13m 42s} (current),
                  92.110d {+06h 08m 26s} (1950)
GRB_DEC:         +50.520d {+50d 31' 13"} (J2000),
                 +50.515d {+50d 30' 53"} (current),
                 +50.533d {+50d 31' 59"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       3118 [cnts]    Image_Peak=150 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   149     E_range: 25-100 keV
BKG_INTEN:       20132 [cnts]
BKG_TIME:        35141.23 SOD {09:45:41.23} UT
BKG_DUR:         8 [sec]
GRB_DATE:        17829 TJD;    76 DOY;   17/03/17
GRB_TIME:        35159.08 SOD {09:45:59.08} UT
GRB_PHI:          23.67 [deg]
GRB_THETA:        37.63 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.53 [sigma]
IMAGE_SIGNIF:    7.39 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  -3  +0  +0  +8  +0 
SUN_POSTN:       357.24d {+23h 48m 59s}   -1.19d {-01d 11' 36"}
SUN_DIST:         94.85 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.38d {+15h 21m 31s}  -13.15d {-13d 08' 55"}
MOON_DIST:       128.91 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.34, 14.83 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       92.20, 27.10 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This Notice was delayed by more than 60 sec past the end of the trigger integration interval;  
COMMENTS:        probably due to it occurring during a Malindi downlink session.  
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 = 17.91,-20.37 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 17 Mar 17 09:50:45 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     742866,   Seg_Num: 0
POINT_RA:         93.051d {+06h 12m 12s} (J2000)
POINT_DEC:       +50.529d {+50d 31' 44"} (J2000)
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  35242.35 SOD {09:47:22.35} UT,   83.3 [sec] since BAT Trigger Time
COUNTS:          10    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 17 Mar 17 09:51:51 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     742866,   Seg_Num: 0
GRB_RA:           93.088d {+06h 12m 21s} (J2000),
                  93.424d {+06h 13m 42s} (current),
                  92.110d {+06h 08m 26s} (1950)
GRB_DEC:         +50.520d {+50d 31' 13"} (J2000),
                 +50.515d {+50d 30' 53"} (current),
                 +50.533d {+50d 31' 59"} (1950)
GRB_DATE:        17829 TJD;    76 DOY;   17/03/17
GRB_TIME:        35159.08 SOD {09:45:59.08} UT
TRIGGER_INDEX:   149
GRB_PHI:          23.67 [deg]
GRB_THETA:        37.63 [deg]
DELTA_TIME:      -24.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.53 [sigma]
IMAGE_SIGNIF:    7.39 [sigma]
LC_URL:          sw00742866000msb.lc
SUN_POSTN:       357.25d {+23h 48m 59s}   -1.19d {-01d 11' 35"}
SUN_DIST:         94.85 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.39d {+15h 21m 34s}  -13.15d {-13d 09' 06"}
MOON_DIST:       128.92 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.34, 14.83 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       92.20, 27.10 [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 = 17.91,-20.37 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 17 Mar 17 09:53:35 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     742866,   Seg_Num: 0
POINT_RA:         93.050d {+06h 12m 12s} (J2000)
POINT_DEC:       +50.529d {+50d 31' 44"} (J2000)
POINT_ROLL:      273.744d
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  35245.65 SOD {09:47:25.65} UT,   86.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.491
N_STARS:         85
X_OFFSET:        298 [pixels]
Y_OFFSET:        614 [pixels]
X_MAX:           1257 [pixels]
Y_MAX:           1573 [pixels]
DET_THRESH:      20
PHOTO_THRESH:    12
SL_URL:          sw00742866000msufc0086.fits
SUN_POSTN:       357.25d {+23h 48m 59s}   -1.19d {-01d 11' 33"}
SUN_DIST:         94.82 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.41d {+15h 21m 38s}  -13.16d {-13d 09' 18"}
MOON_DIST:       128.95 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.32, 14.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       92.18, 27.11 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 17 Mar 17 09:54:13 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     742866,   Seg_Num: 0
POINT_RA:         93.050d {+06h 12m 12s} (J2000)
POINT_DEC:       +50.529d {+50d 31' 44"} (J2000)
POINT_ROLL:      273.744d
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  35245.65 SOD {09:47:25.65} UT,   86.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.491
N_STARS:         85
X_OFFSET:        298 [pixels]
Y_OFFSET:        614 [pixels]
X_MAX:           1257 [pixels]
Y_MAX:           1573 [pixels]
DET_THRESH:      20
PHOTO_THRESH:    12
SL_URL:          sw00742866000msufc0086.fits
SUN_POSTN:       357.25d {+23h 48m 59s}   -1.19d {-01d 11' 32"}
SUN_DIST:         94.82 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.41d {+15h 21m 39s}  -13.16d {-13d 09' 23"}
MOON_DIST:       128.95 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.32, 14.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       92.18, 27.11 [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 17 Mar 17 09:55:03 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     742866,   Seg_Num: 0
POINT_RA:         93.050d {+06h 12m 12s} (J2000)
POINT_DEC:       +50.529d {+50d 31' 44"} (J2000)
ROLL:            273.744d
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  35245.65 SOD {09:47:25.65} UT,   86.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     511436864
X_OFFSET:        617 [pixels]
Y_OFFSET:        933 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       777
Y_GRB_POS:       1093
BINNING_INDEX:   1
IM_URL:          sw00742866000msuni0105.fits
SUN_POSTN:       357.25d {+23h 48m 59s}   -1.19d {-01d 11' 32"}
SUN_DIST:         94.82 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.42d {+15h 21m 40s}  -13.16d {-13d 09' 29"}
MOON_DIST:       128.95 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.32, 14.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       92.18, 27.11 [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 17 Mar 17 09:55:11 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     742866,   Seg_Num: 0
GRB_RA:           93.0629d {+06h 12m 15.09s} (J2000),
                  93.3994d {+06h 13m 35.84s} (current),
                  92.0850d {+06h 08m 20.39s} (1950)
GRB_DEC:         +50.4943d {+50d 29' 39.4"} (J2000),
                 +50.4889d {+50d 29' 20.0"} (current),
                 +50.5068d {+50d 30' 24.4"} (1950)
GRB_ERROR:       3.6 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  35251.00 SOD {09:47:31.00} UT,   91.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       357.25d {+23h 48m 59s}   -1.19d {-01d 11' 31"}
SUN_DIST:         94.83 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.42d {+15h 21m 41s}  -13.16d {-13d 09' 30"}
MOON_DIST:       128.97 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.35, 14.80 [deg] galactic lon,lat of the burst
ECL_COORDS:       92.19, 27.08 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
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 1.1% < P(seren) < 2.8%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 17 Mar 17 09:55:25 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     742866,   Seg_Num: 0
POINT_RA:         93.050d {+06h 12m 12s} (J2000)
POINT_DEC:       +50.529d {+50d 31' 44"} (J2000)
ROLL:            273.744d
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  35245.65 SOD {09:47:25.65} UT,   86.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     511436864
X_OFFSET:        617 [pixels]
Y_OFFSET:        933 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       777
Y_GRB_POS:       1093
BINNING_INDEX:   1
IM_URL:          sw00742866000msuni0105.fits
SUN_POSTN:       357.25d {+23h 48m 59s}   -1.19d {-01d 11' 31"}
SUN_DIST:         94.82 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.42d {+15h 21m 41s}  -13.16d {-13d 09' 31"}
MOON_DIST:       128.96 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.32, 14.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       92.18, 27.11 [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 17 Mar 17 09:57:55 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     742866,   Seg_Num: 0
GRB_RA:           93.0615d {+06h 12m 14.75s} (J2000),
                  93.3980d {+06h 13m 35.51s} (current),
                  92.0836d {+06h 08m 20.06s} (1950)
GRB_DEC:         +50.4930d {+50d 29' 34.8"} (J2000),
                 +50.4876d {+50d 29' 15.3"} (current),
                 +50.5055d {+50d 30' 19.7"} (1950)
GRB_ERROR:       1.1 [arcsec radius, statistical only]
GRB_MAG:         18.04 +/- 0.40 [mag]
FILTER:          10, White
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  35242.00 SOD {09:47:22.00} UT,   82.9 [sec] since BAT Trigger Time
SUN_POSTN:       357.25d {+23h 49m 00s}   -1.19d {-01d 11' 29"}
SUN_DIST:         94.83 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.44d {+15h 21m 46s}  -13.16d {-13d 09' 49"}
MOON_DIST:       128.98 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.35, 14.80 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       92.19, 27.08 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        Result based on srclist data.  
COMMENTS:        Notice generated automatically.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 17 Mar 17 10:01:57 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     742866,   Seg_Num: 0
POINT_RA:         93.049d {+06h 12m 12s} (J2000)
POINT_DEC:       +50.527d {+50d 31' 36"} (J2000)
POINT_ROLL:      273.744d
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  35457.73 SOD {09:50:57.73} UT,   298.7 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.357
N_STARS:         175
X_OFFSET:        58 [pixels]
Y_OFFSET:        374 [pixels]
X_MAX:           1497 [pixels]
Y_MAX:           1813 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00742866000msufc0298.fits
SUN_POSTN:       357.25d {+23h 49m 00s}   -1.19d {-01d 11' 25"}
SUN_DIST:         94.82 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.48d {+15h 21m 54s}  -13.17d {-13d 10' 17"}
MOON_DIST:       129.00 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.32, 14.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       92.18, 27.11 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 17 Mar 17 10:02:17 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     742866,   Seg_Num: 0
POINT_RA:         93.049d {+06h 12m 12s} (J2000)
POINT_DEC:       +50.527d {+50d 31' 36"} (J2000)
POINT_ROLL:      273.744d
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  35457.73 SOD {09:50:57.73} UT,   298.7 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.357
N_STARS:         175
X_OFFSET:        58 [pixels]
Y_OFFSET:        374 [pixels]
X_MAX:           1497 [pixels]
Y_MAX:           1813 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00742866000msufc0298.fits
SUN_POSTN:       357.25d {+23h 49m 01s}   -1.19d {-01d 11' 24"}
SUN_DIST:         94.82 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.48d {+15h 21m 55s}  -13.17d {-13d 10' 20"}
MOON_DIST:       129.00 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.32, 14.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       92.18, 27.11 [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:     Fri 17 Mar 17 10:02:45 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     742866,   Seg_Num: 0
GRB_RA:           93.0611d {+06h 12m 14.66s} (J2000),
                  93.3976d {+06h 13m 35.41s} (current),
                  92.0832d {+06h 08m 19.96s} (1950)
GRB_DEC:         +50.4926d {+50d 29' 33.3"} (J2000),
                 +50.4872d {+50d 29' 13.9"} (current),
                 +50.5051d {+50d 30' 18.3"} (1950)
GRB_ERROR:       2.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  35251.00 SOD {09:47:31.00} UT,   91.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       357.25d {+23h 49m 01s}   -1.19d {-01d 11' 24"}
SUN_DIST:         94.83 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.48d {+15h 21m 56s}  -13.17d {-13d 10' 23"}
MOON_DIST:       129.01 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.35, 14.80 [deg] galactic lon,lat of the burst
ECL_COORDS:       92.19, 27.08 [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 1.1% < P(seren) < 2.8%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 17 Mar 17 10:03:26 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     742866,   Seg_Num: 0
POINT_RA:         93.049d {+06h 12m 12s} (J2000)
POINT_DEC:       +50.527d {+50d 31' 36"} (J2000)
ROLL:            273.744d
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  35457.73 SOD {09:50:57.73} UT,   298.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     511437076
X_OFFSET:        617 [pixels]
Y_OFFSET:        933 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       777
Y_GRB_POS:       1093
BINNING_INDEX:   1
IM_URL:          sw00742866000msuni0317.fits
SUN_POSTN:       357.25d {+23h 49m 01s}   -1.19d {-01d 11' 23"}
SUN_DIST:         94.81 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.49d {+15h 21m 57s}  -13.17d {-13d 10' 28"}
MOON_DIST:       129.01 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.32, 14.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       92.18, 27.11 [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 17 Mar 17 10:03:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     742866,   Seg_Num: 0
POINT_RA:         93.049d {+06h 12m 12s} (J2000)
POINT_DEC:       +50.527d {+50d 31' 36"} (J2000)
ROLL:            273.744d
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  35457.73 SOD {09:50:57.73} UT,   298.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     511437076
X_OFFSET:        617 [pixels]
Y_OFFSET:        933 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       777
Y_GRB_POS:       1093
BINNING_INDEX:   1
IM_URL:          sw00742866000msuni0317.fits
SUN_POSTN:       357.25d {+23h 49m 01s}   -1.19d {-01d 11' 23"}
SUN_DIST:         94.81 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.49d {+15h 21m 58s}  -13.18d {-13d 10' 31"}
MOON_DIST:       129.01 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.32, 14.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       92.18, 27.11 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN Circular #20885
S. J. LaPorte (PSU), A. P. Beardmore (U Leicester), B. Mingo (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 09:45:59 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170317A (trigger=742866). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 93.088, +50.520 which is
```
   RA(J2000) = 06h 12m 21s
   Dec(J2000) = +50d 31' 13"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a FRED structure with a duration of about 10 sec. The peak count rate was ~3000 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 09:47:22.4 UT, 83.3 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 93.06317, 50.49431 which is equivalent to:
```
   RA(J2000)  = 06h 12m 15.16s
   Dec(J2000) = +50d 29' 39.5"
```
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 109 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 2.53 x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 86 seconds after the BAT trigger. There is a candidate afterglow in the list of sources generated on-board at
```
  RA(J2000)  =	06:12:14.78 =  93.06160
  DEC(J2000) = +50:29:34.8  =  50.49300
```
with a 90%-confidence error radius of about 1.10 arc sec. This position is 5.7 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.05. No correction has been made for the expected extinction corresponding to E(B-V) of 0.19.
Burst Advocate for this burst is S. J. LaPorte (extragsam AT gmail.com). 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:     Fri 17 Mar 17 10:09:08 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     742866,   Seg_Num: 0
POINT_RA:         93.048d {+06h 12m 12s} (J2000)
POINT_DEC:       +50.526d {+50d 31' 35"} (J2000)
POINT_ROLL:      273.743d
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  36036.00 SOD {10:00:36.00} UT,   876.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.587
N_STARS:         190
X_OFFSET:        58 [pixels]
Y_OFFSET:        374 [pixels]
X_MAX:           1497 [pixels]
Y_MAX:           1813 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00742866000msufc0876.fits
SUN_POSTN:       357.26d {+23h 49m 02s}   -1.19d {-01d 11' 18"}
SUN_DIST:         94.81 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.53d {+15h 22m 08s}  -13.19d {-13d 11' 08"}
MOON_DIST:       129.04 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.32, 14.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       92.18, 27.11 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 17 Mar 17 10:09:27 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     742866,   Seg_Num: 0
POINT_RA:         93.048d {+06h 12m 12s} (J2000)
POINT_DEC:       +50.526d {+50d 31' 35"} (J2000)
POINT_ROLL:      273.743d
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  36036.00 SOD {10:00:36.00} UT,   876.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.587
N_STARS:         190
X_OFFSET:        58 [pixels]
Y_OFFSET:        374 [pixels]
X_MAX:           1497 [pixels]
Y_MAX:           1813 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00742866000msufc0876.fits
SUN_POSTN:       357.26d {+23h 49m 02s}   -1.19d {-01d 11' 17"}
SUN_DIST:         94.81 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.54d {+15h 22m 09s}  -13.19d {-13d 11' 10"}
MOON_DIST:       129.05 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.32, 14.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       92.18, 27.11 [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 17 Mar 17 10:10:52 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     742866,   Seg_Num: 0
POINT_RA:         93.048d {+06h 12m 12s} (J2000)
POINT_DEC:       +50.526d {+50d 31' 35"} (J2000)
ROLL:            273.743d
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  36036.00 SOD {10:00:36.00} UT,   876.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     511437654
X_OFFSET:        617 [pixels]
Y_OFFSET:        933 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       777
Y_GRB_POS:       1093
BINNING_INDEX:   1
IM_URL:          sw00742866000msuni0895.fits
SUN_POSTN:       357.26d {+23h 49m 02s}   -1.19d {-01d 11' 16"}
SUN_DIST:         94.81 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.55d {+15h 22m 12s}  -13.19d {-13d 11' 20"}
MOON_DIST:       129.05 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.32, 14.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       92.18, 27.11 [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 17 Mar 17 10:11:10 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     742866,   Seg_Num: 0
POINT_RA:         93.048d {+06h 12m 12s} (J2000)
POINT_DEC:       +50.526d {+50d 31' 35"} (J2000)
ROLL:            273.743d
IMG_START_DATE:  17829 TJD;    76 DOY;   17/03/17
IMG_START_TIME:  36036.00 SOD {10:00:36.00} UT,   876.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     511437654
X_OFFSET:        617 [pixels]
Y_OFFSET:        933 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       777
Y_GRB_POS:       1093
BINNING_INDEX:   1
IM_URL:          sw00742866000msuni0895.fits
SUN_POSTN:       357.26d {+23h 49m 02s}   -1.19d {-01d 11' 16"}
SUN_DIST:         94.81 [deg]   Sun_angle= -6.4 [hr] (East of Sun)
MOON_POSTN:      230.55d {+15h 22m 12s}  -13.19d {-13d 11' 22"}
MOON_DIST:       129.06 [deg]
MOON_ILLUM:      79 [%]
GAL_COORDS:      163.32, 14.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       92.18, 27.11 [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 #20886
E. Mazaeva (IKI), A. Pozanenko (IKI), A. Kochergin (UAFO), A. Volnova (IKI), E. Chornaya (UAFO), A. Matkin (UAFO, ISON), I. Molotov (KIAM) report on behalf of larger GRB follow-up collaboration:
We observed the field of the GRB 170317A (LaPorte et al., GCN 20885) with SANTEL-650 (0.65m) telescope of UAFO/ISON-Ussuriysk observatory starting on March, 17 (UT) 10:20:37. We obtained series of unfiltered images of 60 s exposure. In a first combined images we detected optical afterglow (LaPorte et al., GCN 20885). Preliminary photometry of some initial combined image is following
```
Date       UT start  t-T0   Filter  Exp.  OT     err  UL (3sigma)
                      (mid, days)    (s)

2017-03-17 10:20:37  0.0321 none   20*60  18.95  0.08 21.5
```
In comparison with early reported photometry (LaPorte et al., GCN 20885) the OT is faded, and we confirm the afterglow of the GRB 170317A.
Photometry is based on nearby USNO-B1.0 stars
```
USNO_B1_id   R2
1405-0167482 15.08
1405-0167474 15.43
1405-0167493 16.10
1405-0167484 16.14
1404-0169177 15.93
1405-0167639 15.62
1405-0167631 15.69
```
GCN Circular #20887
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 2369 s of XRT Photon Counting mode data and 2 UVOT images for GRB 170317A, 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 = 93.06206, +50.49305 which is equivalent to:
```
RA (J2000): 06h 12m 14.89s
Dec (J2000): +50d 29' 35.0"
```
with an uncertainty of 1.7 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 #20888
L. P. Xin, T. M. Zhang, J. Y. Wei, Y. L. Qiu, J. S. Deng,=20 J. Wang, X. H. Han=EF=BC=8CC. Wu and E. W. Liang reports: =20 We began to observe GRB 170317A (LaPorte et al., GCN 20885) =20 with Xinglong 0.8-m TNT telescope at 2017-03-17,11:39:17 (UT),=20 about 1.9 hours after the Swift trigger time.=20 =20 The optical afterglow reported ( LaPorte et al., GCN 20885;=20 Mazaeva et al., GCN 20886) was clearly detected in the=20 stacked 11*300 sec R-band image. =20 Preliminary analysis shows that the brightness of the optical afterglow in R band is about 19.8+/-0.1 mag, calibrated by nearby USNO B1.0 objects at the mid time of 2.3 hours after the burst.
This message could be cited.
We thank the excellent support of the Xinglong 80cm TNT staff, particularly S. Liu
GCN Circular #20889
J. Mao, Y. Xin and J.-M. Bai (YNAO) report:
We observed the field of GRB 170317A (LaPorte et al., GCN 20885) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG) station of Yunnan Observatories. Observations began from 13:58:18 UT, about 4.2 hours after the trigger. We detected the afterglow with R~19.96+/-0.10 mag, calibrated by a nearby USNO-B1.0 star.
GCN Circular #20891
A. Cholden-Brown (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Mingo (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC) and report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team:
We have analysed 6.9 ks of XRT data for GRB 170317A, from 68 s to 13.5 ks after the BAT trigger. The data comprise 8 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode.
The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=3.8 (+4.2, -1.4). At T+105 s the decay flattens to an alpha of 0.58 (+0.07, -0.09) before breaking again at T+3006 s to a final decay with index alpha=1.4 (+0.4, -0.3).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.05 (+0.10, -0.07). The best-fitting absorption column is consistent with the Galactic value of 2.5 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     2.5 (+/-0.3) x 10^21 cm^-2
Galactic foreground: 2.5 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     2.05 (+0.10, -0.07)
```
If the light curve continues to decay with a power-law decay index of 1.4, the count rate at T+24 hours will be 2.2 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.9 x 10^-14 (1.1 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00742866.
This circular is an official product of the Swift-XRT team.
GCN Circular #20892
K. Yanagisawa, D. Kuroda, Y. Shimizu, H. Izumiura (OAO/NAOJ), M. Yoshida (Hiroshima), K. Ohta(Kyoto) and N. Kawai (Tokyo Tech.) report on behalf of the MITSuME collaboration:
We observed the field of GRB 170317A (LaPorte et al., GCN 20885) in Ks-band with a wide-field near infrared imager at Okayama Astrophysical Observatory (Japan). The imager has effective aperture of 0.91 m.
Observations started from 09:54 UT on 17th March, 8 min after the BAT trigger, to 10:38 UT. The total exposure of 17.0 min was successfully obtained.
In our co-add image, we did not find any new point source within the XRT error circle (Beardmore et al., GCN 20887) down to the limiting magnitude of Ks=16.1 (Vega, S/N=5). The photometric calibration was made against 2MASS field stars.
```
T0+[sec]    MID-UT     T-EXP[sec]      Ks
---------------------------------------------------
   +1,819    10:16      1020.0          >16.1
---------------------------------------------------
T0+ : Elapsed time after the burt [sec]
T-EXP: Total Exposure time [sec]
```
GCN Circular #20893
E. Mazaeva (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 170317A (LaPorte et al., GCN 20885) with AZT-33IK telescope of Sayan observatory (Mondy) starting on March, 17 (UT) 13:56:13. We obtained 60 of 60 s exposure images in R-filter. The optical afterglow (LaPorte et al., GCN 20885; Mazaeva et al., GCN 20886; Xin et al., GCN 20888; Mao et al., GCN 20889) is clearly visible in stacked images. Preliminary photometry of the afterglow is following
```
Date       UT start   t-T0    Filter  Exp.     OT     Err.  UL
                      (mid, days)      (s)

2017-03-17 13:56:13  0.18073  R      20*60    20.94  0.10  22.5
```
The photometry is based on nearby USNO-B.10 stars Ref.stars
```
USNO_B1_id   R2
1405-0167493 16.10
1405-0167631 15.69
1404-0169027 16.03
1405-0167512 16.85
1404-0169128 16.25
```
GCN Circular #20894
N. P. M. Kuin (UCL-MSSL) and S. J. LaPorte (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170317A 87 s after the BAT trigger (LaPorte et al., GCN Circ.20885). A fading source consistent with the XRT position (Beardmore et al. GCN Circ. 20887) is detected in the initial UVOT exposures. The GRB afterglow was also observed by Mazaeva et al. (GCN Circ. 20886) and Mao et al. (GCN. Circ. 20889) in the R band.
The preliminary UVOT position is:
```
    RA  (J2000) =  06:12:14.82 =  93.06173 (deg.)
    Dec (J2000) = +50:29:35.2  =  50.49310 (deg.)
```
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits 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               87          237          147         17.53 +/- 0.04
v                  629         1597          117         18.36 +/- 0.19
b                  554         1349           78         19.12 +/- 0.19
u                  299          549          246         17.75 +/- 0.07
w1                 678         7320          588         20.20 +/- 0.29
m2                 653         7115          398        >19.8
w2                 604         8141          607        >20.2
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.19 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #20896
S. D. Barthelmy (GSFC), J. R. Cummings (CPI), N. Gehrels (GSFC), H. A. Krimm (NSF/USRA), S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170317A (trigger #742866) (LaPorte et al., GCN Circ. 20885). The BAT ground-calculated position is RA, Dec = 93.087, 50.500 deg which is
```
  RA(J2000)  =  06h 12m 21.0s
  Dec(J2000) = +50d 30' 00.5"
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 46%.
The mask-weighted light curve shows a FRED-like pulse that starts at ~T-2 s, peaks at ~ T+2 s, and ends at ~T+18 s. T90 (15-350 keV) is 11.94 +- 4.87 sec (estimated error including systematics).
The time-averaged spectrum from T-0.29 to T+18.29 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.80 +- 0.49, and Epeak of 58.8 +- 10.5 keV (chi squared 75.18 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.3 +- 0.1 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+1.28 sec in the 15-150 keV band is 3.5 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.78 +- 0.10 (chi squared 89.59 for 57 d.o.f.). 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/742866/BA/
GCN Circular #20899
D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME and OISTER collaboration:
We observed the field of GRB 170317A (LaPorte et al., GCNC 20885) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.
The observation started on 2017-03-17 10:14:19 UT (~28 min after the burst). We detected the previously reported afterglow (LaPorte et al., GCNC 20885; Mazaeva et al., GCNC 20886) in Rc and Ic bands.
Three sigma upper limit and photometric results of the OT are listed below. We used GSC2.3 catalog for flux calibration.
```
#T0+[day]  MID-UT    T-EXP[sec]   g'     Rc   Rc_err  Ic   Ic_err
------------------------------------------------------------------
0.06138    11:14:22    6120.0     >20.5  19.3 0.2     19.2 0.3"
------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #20901
C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc (U. Nova Gorica), C.G. Mundell (U. Bath) on behalf of a large collaboration report:
We observed Swift GRB 170317A (LaPorte et al. GCN 20885) on March 18, 06:01 UT (0.84 days since the GRB) with the 2-m LCO Faulkes Telescope North with SDSS r and i filters. We marginally detect the optical afterglow (LaPorte et al.; Mazaeva et al. GCN 20886, 20893; Xin et al. GCN 20888; Mao et al. GCN 20889, 20890; Kuin et al. GCN 20894) in the r filter with the following values:
```
Mid Time      Exposure       Filter       Magnitude (AB)
(days)           (s)
-------------------------------------------------------
0.87          10x120          SDSS-R        22.9 +- 0.3
0.88          10x120          SDSS-I        > 22.0
-------------------------------------------------------
```
as calibrated against nearby PanSTARRS-1 DR1 objects.
GCN Circular #20911
Alan M. Watson (UNAM), Nat Butler (ASU), 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 170317A (LaPorte et al., GCN 20885) 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 18.13 to 2017/03 18.30 UTC (17.37 to 21.38 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, and H bands.
For a source within the enhanced Swift-XRT error circle (Beardmore et al., GCN 20887), in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections and 3-sigma upper limits:
```
  r     22.85 +/- 0.05
  i     22.86 +/- 0.09
  Z     22.92 +/- 0.30
  Y     22.34 +/- 0.26
  J     22.41 +/- 0.35
  H     > 21.95
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #20920
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 170317A (LaPorte et al., GCN 20885) 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 19.13 to 2017/03 19.30 UTC (41.26 to 45.37 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, and H bands.
For a source within the enhanced Swift-XRT error circle (Beardmore et al., GCN 20887), in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections and 3-sigma upper limits:
```
 r	23.70 +/- 0.10
 i	23.93 +/- 0.26
 Z	> 23.07
 Y	> 22.51
 J	> 22.27
 H	> 21.75
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
The source has faded by about a magnitude in r and i since our earlier observations (Watson et al., GCN 20911).
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #20922
H.L. Xiao (PSI), W. Hajdas (PSI) and R. Marcinkowski (PSI) report on beh= alf of the POLAR collaboration:
At 2017-03-17 09:45:56.0 UT(T0), during a routine on-ground search of dat= a, POLAR detected GRB 170317A (Swift BAT (trigger # 742866); LaPorte et al., GCN 20885).
The POLAR light curve consists of one peak with duration (T90) of 6.00 =EF= =BF=BD 1.00 s measured from T0. The 1.00 s peak flux at T0 + 5.50 s is equal to 370 =EF=BF=BD 50 counts/= sec. POLAR recorded 1500 events from the burst. Above measurements are in the energy range of about 15 - 300 keV.
LC_URL: http://polar.psi.ch/triggers/GRB_170317A.png
Using the best location from Swift-BAT, which is (J2000):
```
RA : 93.087 [deg]
Dec: 50.500 [deg]
```
the incident angle in the POLAR coordinate at T0 is:
```
Theta: 81.38 [deg]
Phi: 4.61 [deg]
```
The analysis results presented above are preliminary. POLAR is a dedicate= d Gamma-Ray Burst polarimeter which was launched on-board the Chinese spa= ce laboratory Tiangong-2 (TG-2) on Sep 15, 2016. The energy detection range = of POLAR is ~ 50-500 keV. More information about POLAR can be found at http://polar.psi.ch/pub , http://polar.ihep.ac.cn/en/ and http://isdc.unige.ch/polar/ .
This message is quotable in publications.
GCN Circular #20924
E. Mazaeva (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 170317A (LaPorte et al., GCN 20885) with AZT-33IK telescope of Sayan observatory (Mondy) starting on March, 18 (UT) 14:57:48. We several images in R-filter. The optical afterglow (LaPorte et al., GCN 20885; Mazaeva et al., GCN 20886; Xin et al., GCN 20888; Mao et al., GCN 20889) is visible in stacked images. Preliminary photometry of the afterglow is following
```
Date       UT start   t-T0    Filter  Exp.     OT     Err.  UL
                      (mid, days)      (s)

2017-03-18 14:57:48  1.23738  R       30*120   23.25  0.22  23.6
```
The photometry is based on nearby USNO-B.10 stars Ref.stars
```
USNO_B1_id   R2

1405-0167631 15.69
1404-0169027 16.03
1405-0167512 16.85
1404-0169128 16.25
```
GCN Circular #20955
K. P. Mooley, 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 170317A (LaPorte et al., GCN 20885) 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 17.59, Mar 18.78, Mar 20.79 and Mar 22.78 (UT) do not reveal any radio source at the XRT location (Beardmore et al., GCN 20887), with 3sigma upper limits of 126 uJy, 246 uJy, 84 uJy and 111 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/.
GCN Circular #20966
Changsu Choi(CEOU/SNU), Tae-Woo Kim(DOAO/NYSC), Myungshin Im(CEOU/SNU), on behalf of a larger collaboration
We observed the field of GRB 170317A (LaPorte et al., GCN 20885) with 1m telescope of Deokheung Optical Astronomy Observatory (DOAO) in Korea, starting from 2017/3/17 10:41:47 to 11:59:41.5 UT which is 0.042 days to 0.093 days after BAT trigger. .
We obtained V, R, I images and clearly detected afterglow on the stacked images (LaPorte et al., GCN 20885; Mazaeva et al., GCN20886; Xin et al., GCN 20888; Mao et al., GCN 20889; Kuroda et al., GCN20899).
The photometric calibration is based on in APASS catalog in the observed field. No galactic extinction correction is applied.
```
Date            UT start         t-T0       Filter     Exp.      Mag
Err.

                            (mid, days)           (s)

2017-03-17 10:41:47        0.042     I           180*3    18.86     0.10

2017-03-17 10:51:01        0.049     R          300*3    19.66     0.07

2017-03-17 11:06:18        0.057     I           300*5    20.29     0.26

2017-03-17 11:31:41        0.079     V          300*3    20.38     0.15

2017-03-17 11:46:59        0.086     R          300*2    19.98     0.15

2017-03-17 11:57:10        0.093     V          300*2    20.77     0.23
```
GCN Circular #21001
A. Moskvitin (SAO RAS), E. Mazaeva (IKI), A. Pozanenko (IKI), A. Volnova (IKI), on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 170317A (LaPorte et al. GCN 20885) with the SAO RAS telescope Zeiss-1000 + CCD photometer on March, 17 (18:12:00--19:58:03 UT). We obtained several images in Rc band. The optical afterglow (LaPorte et al., GCN 20885; Mazaeva et al., GCN 20886; Xin et al., GCN 20888; Mao et al., GCN 20889; Kuroda et al., GCN 20899) is detected in a stacked frame. Preliminary photometry is following
```
Date       UT start   t-T0        Filter  Exp.   OT     Err. UL
                      (mid, days)         (s)

2017-03-17 18:12:00   0.38823     Rc     15*300  22.3   0.3  22.6
```
Photometry is based on nearby USNO-B1.0 stars previously used in GCN 20886.

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Jochen Greiner, last update: 07-Apr-2017 [Disclaimer]