Gamma-ray Burst 170903A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 03 Sep 17 12:49:21 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     770528,   Seg_Num: 0
GRB_RA:          254.512d {+16h 58m 03s} (J2000),
                 254.672d {+16h 58m 41s} (current),
                 254.059d {+16h 56m 14s} (1950)
GRB_DEC:         +34.983d {+34d 59' 01"} (J2000),
                 +34.957d {+34d 57' 26"} (current),
                 +35.059d {+35d 03' 32"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       3271 [cnts]    Image_Peak=184 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   153     E_range: 25-100 keV
BKG_INTEN:       19663 [cnts]
BKG_TIME:        46132.37 SOD {12:48:52.37} UT
BKG_DUR:         8 [sec]
GRB_DATE:        17999 TJD;   246 DOY;   17/09/03
GRB_TIME:        46147.21 SOD {12:49:07.21} UT
GRB_PHI:         -29.27 [deg]
GRB_THETA:        46.71 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     17.77 [sigma]
IMAGE_SIGNIF:    9.84 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  +0  +0  +0  -4  +0 
SUN_POSTN:       162.67d {+10h 50m 40s}   +7.36d {+07d 21' 33"}
SUN_DIST:         87.42 [deg]   Sun_angle= -6.1 [hr] (East of Sun)
MOON_POSTN:      310.64d {+20h 42m 33s}  -16.65d {-16d 38' 49"}
MOON_DIST:        74.02 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:       57.71, 37.42 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      246.21, 57.15 [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 = 183.84,16.39 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(0.0<100sec) coincident with the FERMI_GBM event (trignum=526135752).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 03 Sep 17 12:49:41 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      57
TRIGGER_NUM:     526135752
GRB_RA:          251.983d {+16h 47m 56s} (J2000),
                 252.150d {+16h 48m 36s} (current),
                 251.512d {+16h 46m 03s} (1950)
GRB_DEC:         +32.600d {+32d 36' 00"} (J2000),
                 +32.570d {+32d 34' 11"} (current),
                 +32.687d {+32d 41' 14"} (1950)
GRB_ERROR:       13.13 [deg radius, statistical plus systematic]
GRB_INTEN:       144 [cnts/sec]
DATA_SIGNIF:     10.90 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        17999 TJD;   246 DOY;   17/09/03
GRB_TIME:        46147.79 SOD {12:49:07.79} UT
GRB_PHI:         275.00 [deg]
GRB_THETA:        90.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.80
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      81%  GRB
2nd_MOST_LIKELY:  13%  Generic SGR
DETECTORS:       0,0,0, 0,1,0, 0,0,1, 0,0,0, 0,0,
SUN_POSTN:       162.67d {+10h 50m 40s}   +7.36d {+07d 21' 33"}
SUN_DIST:         85.61 [deg]   Sun_angle= -6.0 [hr] (East of Sun)
MOON_POSTN:      310.64d {+20h 42m 34s}  -16.65d {-16d 38' 47"}
MOON_DIST:        74.47 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:       54.26, 39.08 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      243.42, 54.39 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2017/bn170903534/quicklook/glg_lc_medres34_bn170903534.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 3.35,-5.48 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=770528).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 03 Sep 17 12:49:45 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      56
TRIGGER_NUM:     526135752
GRB_RA:          255.600d {+17h 02m 24s} (J2000),
                 255.746d {+17h 02m 59s} (current),
                 255.187d {+17h 00m 45s} (1950)
GRB_DEC:         +40.130d {+40d 07' 48"} (J2000),
                 +40.106d {+40d 06' 20"} (current),
                 +40.200d {+40d 12' 01"} (1950)
GRB_ERROR:       9.75 [deg radius, statistical only]
DATA_SIGNIF:     12.80 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        17999 TJD;   246 DOY;   17/09/03
GRB_TIME:        46147.79 SOD {12:49:07.79} UT
GRB_PHI:         276.00 [deg]
GRB_THETA:        98.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4153 (Gnd S/W Version number)
SUN_POSTN:       162.67d {+10h 50m 40s}   +7.36d {+07d 21' 33"}
SUN_DIST:         87.61 [deg]   Sun_angle= -6.2 [hr] (East of Sun)
MOON_POSTN:      310.64d {+20h 42m 34s}  -16.65d {-16d 38' 46"}
MOON_DIST:        76.30 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:       64.27, 37.27 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      245.80, 62.36 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2017/bn170903534/quicklook/glg_lc_medres34_bn170903534.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_526135752.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=770528).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 03 Sep 17 12:49:32 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      46
TRIGGER_NUM:     526135752
GRB_RA:          246.567d {+16h 26m 16s} (J2000),
                 246.731d {+16h 26m 55s} (current),
                 246.103d {+16h 24m 25s} (1950)
GRB_DEC:         +34.633d {+34d 37' 60"} (J2000),
                 +34.594d {+34d 35' 39"} (current),
                 +34.745d {+34d 44' 42"} (1950)
GRB_ERROR:       12.52 [deg radius, statistical plus systematic]
GRB_INTEN:       154 [cnts/sec]
DATA_SIGNIF:     7.50 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        17999 TJD;   246 DOY;   17/09/03
GRB_TIME:        46147.79 SOD {12:49:07.79} UT
GRB_PHI:         280.00 [deg]
GRB_THETA:        90.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.63
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      82%  GRB
2nd_MOST_LIKELY:  13%  Generic SGR
DETECTORS:       0,0,0, 0,1,0, 0,0,1, 0,0,0, 0,0,
SUN_POSTN:       162.67d {+10h 50m 40s}   +7.36d {+07d 21' 33"}
SUN_DIST:         80.96 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      310.64d {+20h 42m 33s}  -16.65d {-16d 38' 48"}
MOON_DIST:        79.38 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:       56.09, 43.84 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      234.96, 55.26 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2017/bn170903534/quicklook/glg_lc_medres34_bn170903534.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 3.35,-5.48 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=770528).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 03 Sep 17 12:52:57 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     770528,   Seg_Num: 0
GRB_RA:          254.512d {+16h 58m 03s} (J2000),
                 254.672d {+16h 58m 41s} (current),
                 254.059d {+16h 56m 14s} (1950)
GRB_DEC:         +34.983d {+34d 59' 01"} (J2000),
                 +34.957d {+34d 57' 26"} (current),
                 +35.059d {+35d 03' 32"} (1950)
GRB_DATE:        17999 TJD;   246 DOY;   17/09/03
GRB_TIME:        46147.21 SOD {12:49:07.21} UT
TRIGGER_INDEX:   153
GRB_PHI:         -29.27 [deg]
GRB_THETA:        46.71 [deg]
DELTA_TIME:      -43.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     17.77 [sigma]
IMAGE_SIGNIF:    9.84 [sigma]
LC_URL:          sw00770528000msb.lc
SUN_POSTN:       162.67d {+10h 50m 40s}   +7.36d {+07d 21' 30"}
SUN_DIST:         87.42 [deg]   Sun_angle= -6.1 [hr] (East of Sun)
MOON_POSTN:      310.67d {+20h 42m 41s}  -16.64d {-16d 38' 29"}
MOON_DIST:        74.04 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:       57.71, 37.42 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      246.21, 57.15 [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 = 183.84,16.39 [deg].

GCN Circular #21793
C. B. Markwardt (NASA/GSFC), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), J. A. Kennea (PSU), K. L. Page (U Leicester), J. L. Racusin (NASA/GSFC) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 12:49:07 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170903A (trigger=770528). Swift did not slew due to an observing constraint. The BAT on-board calculated location is RA, Dec 254.512, +34.983, which is
```
   RA(J2000)  =  16h 58m 03s
   Dec(J2000) = +34d 59' 01"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a few peaks with a total duration of about 30 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~4 sec after the trigger.
Due to an observing constraint, Swift will not slew until T0+49.5 minutes. There will be no XRT or UVOT data until this time.
Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt AT nasa.gov). 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:     Sun 03 Sep 17 13:41:12 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     770528,   Seg_Num: 0
POINT_RA:        254.488d {+16h 57m 57s} (J2000)
POINT_DEC:       +34.994d {+34d 59' 37"} (J2000)
IMG_START_DATE:  17999 TJD;   246 DOY;   17/09/03
IMG_START_TIME:  49264.68 SOD {13:41:04.68} UT,   3117.5 [sec] since BAT Trigger Time
COUNTS:          1    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        0    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:     Sun 03 Sep 17 13:49:45 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     770528,   Seg_Num: 0
GRB_RA:          254.5271d {+16h 58m 06.50s} (J2000),
                 254.6872d {+16h 58m 44.92s} (current),
                 254.0744d {+16h 56m 17.84s} (1950)
GRB_DEC:         +34.9789d {+34d 58' 44.0"} (J2000),
                 +34.9528d {+34d 57' 10.0"} (current),
                 +35.0542d {+35d 03' 15.2"} (1950)
GRB_ERROR:       4.6 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17999 TJD;   246 DOY;   17/09/03
IMG_START_TIME:  49606.00 SOD {13:46:46.00} UT,   3458.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       162.70d {+10h 50m 49s}   +7.34d {+07d 20' 37"}
SUN_DIST:         87.42 [deg]   Sun_angle= -6.1 [hr] (East of Sun)
MOON_POSTN:      311.17d {+20h 44m 42s}  -16.56d {-16d 33' 19"}
MOON_DIST:        74.30 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:       57.71, 37.41 [deg] galactic lon,lat of the burst
ECL_COORDS:      246.24, 57.15 [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 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 03 Sep 17 13:50:07 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     770528,   Seg_Num: 0
POINT_RA:        254.487d {+16h 57m 57s} (J2000)
POINT_DEC:       +34.992d {+34d 59' 30"} (J2000)
POINT_ROLL:      277.118d
IMG_START_DATE:  17999 TJD;   246 DOY;   17/09/03
IMG_START_TIME:  49630.98 SOD {13:47:10.98} UT,   3483.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.158
N_STARS:         45
X_OFFSET:        321 [pixels]
Y_OFFSET:        594 [pixels]
X_MAX:           1280 [pixels]
Y_MAX:           1553 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00770528000msufc3483.fits
SUN_POSTN:       162.70d {+10h 50m 49s}   +7.34d {+07d 20' 37"}
SUN_DIST:         87.38 [deg]   Sun_angle= -6.1 [hr] (East of Sun)
MOON_POSTN:      311.18d {+20h 44m 43s}  -16.55d {-16d 33' 16"}
MOON_DIST:        74.34 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:       57.72, 37.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      246.17, 57.15 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 03 Sep 17 13:50:21 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     770528,   Seg_Num: 0
POINT_RA:        254.487d {+16h 57m 57s} (J2000)
POINT_DEC:       +34.992d {+34d 59' 30"} (J2000)
POINT_ROLL:      277.118d
IMG_START_DATE:  17999 TJD;   246 DOY;   17/09/03
IMG_START_TIME:  49630.98 SOD {13:47:10.98} UT,   3483.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.158
N_STARS:         45
X_OFFSET:        321 [pixels]
Y_OFFSET:        594 [pixels]
X_MAX:           1280 [pixels]
Y_MAX:           1553 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00770528000msufc3483.fits
SUN_POSTN:       162.70d {+10h 50m 49s}   +7.34d {+07d 20' 37"}
SUN_DIST:         87.38 [deg]   Sun_angle= -6.1 [hr] (East of Sun)
MOON_POSTN:      311.18d {+20h 44m 43s}  -16.55d {-16d 33' 15"}
MOON_DIST:        74.34 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:       57.72, 37.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      246.17, 57.15 [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:     Sun 03 Sep 17 13:50:42 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     770528,   Seg_Num: 0
GRB_RA:          254.5251d {+16h 58m 06.02s} (J2000),
                 254.6852d {+16h 58m 44.44s} (current),
                 254.0724d {+16h 56m 17.36s} (1950)
GRB_DEC:         +34.9793d {+34d 58' 45.4"} (J2000),
                 +34.9532d {+34d 57' 11.4"} (current),
                 +35.0546d {+35d 03' 16.7"} (1950)
GRB_ERROR:       3.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17999 TJD;   246 DOY;   17/09/03
IMG_START_TIME:  49606.00 SOD {13:46:46.00} UT,   3458.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       162.70d {+10h 50m 49s}   +7.34d {+07d 20' 37"}
SUN_DIST:         87.41 [deg]   Sun_angle= -6.1 [hr] (East of Sun)
MOON_POSTN:      311.18d {+20h 44m 44s}  -16.55d {-16d 33' 13"}
MOON_DIST:        74.31 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:       57.71, 37.41 [deg] galactic lon,lat of the burst
ECL_COORDS:      246.23, 57.15 [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 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 03 Sep 17 13:51:31 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     770528,   Seg_Num: 0
POINT_RA:        254.487d {+16h 57m 57s} (J2000)
POINT_DEC:       +34.992d {+34d 59' 30"} (J2000)
ROLL:            277.118d
IMG_START_DATE:  17999 TJD;   246 DOY;   17/09/03
IMG_START_TIME:  49630.98 SOD {13:47:10.98} UT,   3483.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     526139250
X_OFFSET:        640 [pixels]
Y_OFFSET:        913 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       800
Y_GRB_POS:       1073
BINNING_INDEX:   1
IM_URL:          sw00770528000msuni3503.fits
SUN_POSTN:       162.70d {+10h 50m 49s}   +7.34d {+07d 20' 36"}
SUN_DIST:         87.38 [deg]   Sun_angle= -6.1 [hr] (East of Sun)
MOON_POSTN:      311.19d {+20h 44m 46s}  -16.55d {-16d 33' 09"}
MOON_DIST:        74.35 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:       57.72, 37.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      246.17, 57.15 [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:     Sun 03 Sep 17 13:51:38 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     770528,   Seg_Num: 0
POINT_RA:        254.487d {+16h 57m 57s} (J2000)
POINT_DEC:       +34.992d {+34d 59' 30"} (J2000)
ROLL:            277.118d
IMG_START_DATE:  17999 TJD;   246 DOY;   17/09/03
IMG_START_TIME:  49630.98 SOD {13:47:10.98} UT,   3483.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     526139250
X_OFFSET:        640 [pixels]
Y_OFFSET:        913 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       800
Y_GRB_POS:       1073
BINNING_INDEX:   1
IM_URL:          sw00770528000msuni3503.fits
SUN_POSTN:       162.70d {+10h 50m 49s}   +7.34d {+07d 20' 36"}
SUN_DIST:         87.38 [deg]   Sun_angle= -6.1 [hr] (East of Sun)
MOON_POSTN:      311.19d {+20h 44m 46s}  -16.55d {-16d 33' 08"}
MOON_DIST:        74.35 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:       57.72, 37.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      246.17, 57.15 [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 #21794
S. Campana (INAF-OAB), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU) and G. Tagliaferri (INAF-OAB) report on behalf of the Swift-XRT team:
The XRT began observing the field of GRB 170903A at 13:41:04.6 UT, 3117.5 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 254.5260, 34.9796 which is equivalent to:
```
   RA(J2000)  = 16h 58m 06.23s
   Dec(J2000) = +34d 58' 46.6"
```
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This location is 43 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 in excess of the Galactic value (1.74 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 6.3 (+3.39/-2.89) x 10^21 cm^-2 (90% confidence).
GCN Circular #21795
H.X. Feng, D. Xu, Z.P. Zhu (NAOC), S.G. Ma, T.Z. Yang, J.H. Liu, P. Zong, H.B. Niu, J.Z. Liu, A. Esamdin, L. Ma (all XAO), Y.D. Hu (IAA-CSIC), Y. Qing (Geneva Observatory) report:
We observed the field of GRB 170903A (Markwardt et al., GCN 21793) using the 1m telescope located at Nanshan, Xinjiang, China. We obtained 3x180s R-band frames, starting at 14:08:09 UT on 2017-09-03, i.e., 1.317 hr after the burst.
No optical source is detected at the XRT position (Campana et al., GCN 21794) in the stacked image, down to a limiting magnitude of m(R)~21.3, calibrated with the nearby SDSS field.
GCN Circular #21796
S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), 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-61 to T+242 sec from recent telemetry downlinks, we report further analysis of BAT GRB 170903A (trigger #770528) (Markwardt, et al., GCN Circ. 21793). The BAT ground-calculated position is RA, Dec = 254.532, 34.985 deg, which is
```
   RA(J2000)  =  16h 58m 07.7s 
   Dec(J2000) = +34d 59' 07.5" 
```
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 30%.
The mask-weighted light curve shows two slightly overlapping peaks starting at ~T-5 sec, with a maximum at ~T+1 sec, and returning to baseline at ~T+70 sec. T90 (15-350 keV) is 29.2 +- 4.4 sec (estimated error including systematics).
The time-averaged spectrum from T-10.00 to T+25.70 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.94 +- 0.12. The fluence in the 15-150 keV band is 2.4 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.58 sec in the 15-150 keV band is 3.9 +- 0.5 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/770528/BA/
GCN Circular #21797
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 1379 s of XRT Photon Counting mode data and 2 UVOT images for GRB 170903A, 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 = 254.52613, +34.97887 which is equivalent to:
```
RA (J2000): 16h 58m 6.27s
Dec (J2000): +34d 58' 43.9"
```
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 #21799
A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), L. Izzo (HETH/IAA-CSIC) C.C. Thoene (HETH/IAA-CSIC), D.A. Kann (HETH/IAA-CSIC), K.E. Heintz (DARK/NBI), N. Castro-Rodriguez (GRANTECAN, IAC, ULL), A. Marante (GRANTECAN) report on behalf of a larger collaboration:
We have observed the field of GRB 170903A (Markwardt et al., GCN 21793) with OSIRIS at the 10.4m GTC telescope. Observations started at 20:49 UT (8.0 hrs after the burst). Observations consisted of an acquisition image in i-band and 3x900s spectra with the R1000B grism, which covers the range between 3700 and 7880 AA.
The acquisition image shows a single source within the refined XRT error box (Goad et al., GCN 21797), with an i-band magnitude (AB) of 23.17 +/- 0.15. The object appears unresolved at a seeing of 0.6=E2=80=9D. Spectroscopy of it shows a weak trace covering the complete range above 4000 AA and a single, very prominent emission feature. Due to the strength of this feature and the non-detection of any other features in the spectral range, we identify it as the unresolved [OII] 3727/3729 doublet at a redshift of 0.886, which we propose as the redshift of the host galaxy and hence of the GRB.
GCN Circular #21800
P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and C.B. Markwardt report on behalf of the Swift-XRT team:
We have analysed 7.0 ks of XRT data for GRB 170903A (Markwardt et al. GCN Circ. 21793), from 3.4 ks to 32.1 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 21797).
The light curve can be modelled with a power-law decay with a decay index of alpha=0.41 (+/-0.08).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.22 (+0.19, -0.18). The best-fitting absorption column is 5.6 (+1.1, -1.0) x 10^21 cm^-2, in excess of the Galactic value of 1.7 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.7 x 10^-11 (7.2 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     5.6 (+1.1, -1.0) x 10^21 cm^-2
Galactic foreground: 1.7 x 10^20 cm^-2
Excess significance: 9.3 sigma
Photon index:	     2.22 (+0.19, -0.18)
```
If the light curve continues to decay with a power-law decay index of 0.41, the count rate at T+24 hours will be 0.048 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x 10^-12 (3.5 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00770528.
This circular is an official product of the Swift-XRT team.
GCN Circular #21801
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 MITSuME and OISTER collaboration:
We observed the field of GRB 170903A (Markwardt et al., GCNC 21793) 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 2017-09-03 12:49:43 UT (~35 sec after the burst). We did not find any new point source within the enhanced XRT error circle (Goad et al., GCNC 21797) in all the three bands.
Three sigma upper limits of the OT are listed below. We used SDSS-DR8 catalog for flux calibration.
```
#T0+[day]  MID-UT    T-EXP[sec]   g'    Rc     Ic
-----------------------------------------------------
0.03712    13:42:34    5280.0   >19.4  >19.5  >18.7
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #21805
E. Mazaeva (IKI), E. Chornaya (UAFO), A. Pozanenko (IKI), A. Volnova (IKI), A. Matkin (UAFO), I. Molotov (KIAM) report on behalf of larger GRB follow-up collaboration:
We observed the field of Swift GRB 170903A (Markwardt et al., GCN 21793) with SANTEL-650 (0.65m) telescope of UAFO/ISON-Ussuriysk observatory. We obtained several unfiltered images starting on Sep. 03 (UT) 13:20:15. Within enhanced XRT position (Goad et al., GCN 21797) we do not detect any source. Preliminary photometry of a combined image is following
```
Date       UT start  t-T0     Filter  Exp.      OT   Err.  UL
                     (mid, days)       (s)

2017-09-03 13:20:15  0.04847  CR      120*30    n/d  n/d   20.4
```
Photometry is based on nearby SDSS DR9 stars
```
SDSS_DR9_id         R(Lupton)
J165744.06+345751.4 16.01
J165803.01+345725.1 16.56
J165808.53+350159.7 15.58
J165749.08+345655.1 16.66
J165805.88+345230.1 16.24
```
GCN Circular #21806
A. A. Breeveld (UCL-MSSL) and C. B. Markwardt (NASA/GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170903A 3484 s after the BAT trigger (Markwardt et al., GCN Circ. 21793). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 21797) 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          3484         3634          147         >20.7
white             3484         4865          344         >21.6
v                 3640         5275          393         >19.7
b                 4460         4660          197         >20.5
u                 4255         4455          197         >21.0
w1                4050         9664          362         >20.7
m2                3845         5482          393         >20.4
w2                4871         5071          197         >21.8
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #21812
F. Berlato (MPE) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 12:49:07.79 UT on 3 September 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 170903A (trigger 526135752 / 170903534), which was also detected by the Swift/BAT (Markwardt et al., GCN 21793).
The GBM on-ground localization is consistent with the Swift location.
The angle from the Fermi LAT boresight at the GBM trigger time is 93 degrees.
The GBM light curve shows two pulses with a duration (T90) of about 25 s (50-300 keV). The time-averaged spectrum from T0-1.5 s to T0+25.5 s is adequately fit by a Comptonized model, with index -1.56 +/- 0.10 and Epeak 124 +/- 33 keV . The event fluence (10-1000 keV) in the time interval is (4.34 +/- 0.54)E-06 erg/cm^2. The 1-sec peak photon flux (10-1000 keV) measured starting from T0-1.5 s is (5.80 +/- 0.36) ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #21813
F Berlato (MPE) and C Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 12:49:07.79 UT on 3 September 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 170903A (trigger 526135752 / 170903534), which was also detected by the Swift/BAT (Markwardt et al., GCN 21793).
The Swift localization, consistent with the GBM one, is RA = 254.532 deg, DEC = 34.985 deg (J2000, equivalent to 16h 58m 7.7s, +34d 59' 7.5"), with an uncertainty of 1.3 arcmin (radius, sys+stat, 90% containment).
The angle from the Fermi LAT boresight at the GBM trigger time is 93 deg.
The GBM light curve shows two pulses with a duration (T90) of about 25 s (50-300 keV). The time-averaged spectrum from T0-1.5 s to T0+25.5 s is adequately fit by a Comptonized model, with index -1.56 +/- 0.10 and Epeak 124 +/- 33 keV . The event fluence (10-1000 keV) in the time interval is (4.34 +/- 0.54)E-06 erg/cm^2. The 1-sec peak photon flux (10-1000 keV) measured starting from T0-1.5 s is (5.80 +/- 0.36) ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #21950
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 170903A (Markwardt et al., GCN 21793) 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 2017 Sep 03.57, Sep 04.79, Sep 06.82, Sep 12.66 (UT) do not reveal any radio source at the XRT location (Goad et al., GCN 21797), with 3sigma upper limits of 225 uJy, 120 uJy, 126 uJy, 99 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: 01-Oct-2017 [Disclaimer]