Gamma-ray Burst 230903A

(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:     Sun 03 Sep 23 17:23:27 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1189514,   Seg_Num: 0
GRB_RA:            9.926d {+00h 39m 42s} (J2000),
                  10.209d {+00h 40m 50s} (current),
                   9.326d {+00h 37m 18s} (1950)
GRB_DEC:         -40.924d {-40d 55' 25"} (J2000),
                 -40.794d {-40d 47' 38"} (current),
                 -41.198d {-41d 11' 53"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       4940 [cnts]    Image_Peak=172 [image_cnts]
TRIGGER_DUR:     2.048 [sec] 
TRIGGER_INDEX:   444     E_range: 15-50 keV
BKG_INTEN:       51703 [cnts]
BKG_TIME:        62544.05 SOD {17:22:24.05} UT
BKG_DUR:         24 [sec]
GRB_DATE:        20190 TJD;   246 DOY;   23/09/03
GRB_TIME:        62576.24 SOD {17:22:56.24} UT
GRB_PHI:          93.76 [deg]
GRB_THETA:        28.63 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     11.66 [sigma]
IMAGE_SIGNIF:    7.63 [sigma]
MERIT_PARAMS:     +1  +0  +0  +1  +1  -2  +0  +0 +75  +0 
SUN_POSTN:       162.43d {+10h 49m 43s}   +7.45d {+07d 27' 17"}
SUN_DIST:        138.50 [deg]   Sun_angle= 10.1 [hr] (West of Sun)
MOON_POSTN:       29.01d {+01h 56m 03s}  +12.30d {+12d 17' 49"}
MOON_DIST:        55.87 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      312.12,-75.99 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      349.27,-40.75 [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 = 145.87,-13.02 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(2.0<100sec) coincident with the FERMI_GBM event (trignum=715454583).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 03 Sep 23 17:23:28 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      46
TRIGGER_NUM:     715454583
GRB_RA:            5.617d {+00h 22m 28s} (J2000),
                   5.914d {+00h 23m 39s} (current),
                   4.987d {+00h 19m 57s} (1950)
GRB_DEC:         -22.900d {-22d 53' 59"} (J2000),
                 -22.769d {-22d 46' 07"} (current),
                 -23.177d {-23d 10' 37"} (1950)
GRB_ERROR:       34.38 [deg radius, statistical plus systematic]
GRB_INTEN:       60 [cnts/sec]
DATA_SIGNIF:     4.90 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        20190 TJD;   246 DOY;   23/09/03
GRB_TIME:        62578.81 SOD {17:22:58.81} UT
GRB_PHI:         206.00 [deg]
GRB_THETA:        80.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.81
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      82%  GRB
2nd_MOST_LIKELY:  13%  Generic SGR
DETECTORS:       0,0,0, 0,0,0, 0,1,0, 0,0,1, 0,0,
SUN_POSTN:       162.43d {+10h 49m 43s}   +7.45d {+07d 27' 17"}
SUN_DIST:        152.72 [deg]   Sun_angle= 10.4 [hr] (West of Sun)
MOON_POSTN:       29.01d {+01h 56m 03s}  +12.30d {+12d 17' 49"}
MOON_DIST:        41.73 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:       64.15,-82.20 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      355.51,-23.13 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230903724/quicklook/glg_lc_medres34_bn230903724.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 164.78,12.78 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the SWIFT_BAT event (trignum=1189514).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 03 Sep 23 17:23:45 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     715454583
GRB_RA:            6.480d {+00h 25m 55s} (J2000),
                   6.776d {+00h 27m 06s} (current),
                   5.854d {+00h 23m 25s} (1950)
GRB_DEC:         -25.000d {-25d 00' 00"} (J2000),
                 -24.869d {-24d 52' 08"} (current),
                 -25.277d {-25d 16' 35"} (1950)
GRB_ERROR:       18.59 [deg radius, statistical only]
DATA_SIGNIF:     5.80 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        20190 TJD;   246 DOY;   23/09/03
GRB_TIME:        62578.81 SOD {17:22:58.81} UT
GRB_PHI:         207.00 [deg]
GRB_THETA:        82.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       162.43d {+10h 49m 43s}   +7.45d {+07d 27' 17"}
SUN_DIST:        150.95 [deg]   Sun_angle= 10.4 [hr] (West of Sun)
MOON_POSTN:       29.01d {+01h 56m 03s}  +12.30d {+12d 17' 54"}
MOON_DIST:        43.03 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:       51.88,-83.89 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      355.29,-25.37 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230903724/quicklook/glg_lc_medres34_bn230903724.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_715454583.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(2.0<100sec) coincident with the SWIFT_BAT event (trignum=1189514).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 03 Sep 23 17:32:20 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     715454583
GRB_RA:           13.440d {+00h 53m 46s} (J2000),
                  13.736d {+00h 54m 57s} (current),
                  12.815d {+00h 51m 16s} (1950)
GRB_DEC:         -13.460d {-13d 27' 35"} (J2000),
                 -13.332d {-13d 19' 54"} (current),
                 -13.731d {-13d 43' 51"} (1950)
GRB_ERROR:       16.63 [deg radius, statistical only]
GRB_DATE:        20190 TJD;   246 DOY;   23/09/03
GRB_TIME:        62578.81 SOD {17:22:58.81} UT
GRB_PHI:         213.00 [deg]
GRB_THETA:        70.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       162.43d {+10h 49m 44s}   +7.45d {+07d 27' 09"}
SUN_DIST:        148.68 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:       29.09d {+01h 56m 22s}  +12.33d {+12d 20' 04"}
MOON_DIST:        29.84 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      125.32,-76.32 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        6.92,-17.67 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230903724/quicklook/glg_lc_medres34_bn230903724.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230903724/quicklook/glg_locplot_all_bn230903724.png
COMMENTS:        Fermi-GBM Final Position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file should be available by the time this FINAL notice is produced.  
COMMENTS:        This notice was generated completely by automated pipeline processing.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the SWIFT_BAT event (trignum=1189514).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 03 Sep 23 17:24:56 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1189514,   Seg_Num: 0
POINT_RA:          9.928d {+00h 39m 43s} (J2000)
POINT_DEC:       -40.953d {-40d 57' 09"} (J2000)
IMG_START_DATE:  20190 TJD;   246 DOY;   23/09/03
IMG_START_TIME:  62687.98 SOD {17:24:47.98} UT,   111.7 [sec] since BAT Trigger Time
COUNTS:          4    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:     Sun 03 Sep 23 17:26:43 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1189514,   Seg_Num: 0
GRB_RA:            9.926d {+00h 39m 42s} (J2000),
                  10.209d {+00h 40m 50s} (current),
                   9.326d {+00h 37m 18s} (1950)
GRB_DEC:         -40.924d {-40d 55' 25"} (J2000),
                 -40.794d {-40d 47' 38"} (current),
                 -41.198d {-41d 11' 53"} (1950)
GRB_DATE:        20190 TJD;   246 DOY;   23/09/03
GRB_TIME:        62576.24 SOD {17:22:56.24} UT
TRIGGER_INDEX:   444
GRB_PHI:          93.76 [deg]
GRB_THETA:        28.63 [deg]
DELTA_TIME:      -18.00 [sec]
TRIGGER_DUR:     2.048 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     11.66 [sigma]
IMAGE_SIGNIF:    7.63 [sigma]
LC_URL:          sw01189514000msb.lc
SUN_POSTN:       162.43d {+10h 49m 43s}   +7.45d {+07d 27' 14"}
SUN_DIST:        138.50 [deg]   Sun_angle= 10.1 [hr] (West of Sun)
MOON_POSTN:       29.04d {+01h 56m 10s}  +12.31d {+12d 18' 39"}
MOON_DIST:        55.89 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      312.12,-75.99 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      349.27,-40.75 [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 = 145.87,-13.02 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 03 Sep 23 17:28:52 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1189514,   Seg_Num: 0
GRB_RA:            9.9109d {+00h 39m 38.61s} (J2000),
                  10.1943d {+00h 40m 46.63s} (current),
                   9.3109d {+00h 37m 14.61s} (1950)
GRB_DEC:         -40.9493d {-40d 56' 57.4"} (J2000),
                 -40.8195d {-40d 49' 10.3"} (current),
                 -41.2238d {-41d 13' 25.6"} (1950)
GRB_ERROR:       3.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  20190 TJD;   246 DOY;   23/09/03
IMG_START_TIME:  62701.00 SOD {17:25:01.00} UT,   124.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       162.43d {+10h 49m 44s}   +7.45d {+07d 27' 12"}
SUN_DIST:        138.49 [deg]   Sun_angle= 10.1 [hr] (West of Sun)
MOON_POSTN:       29.06d {+01h 56m 15s}  +12.32d {+12d 19' 11"}
MOON_DIST:        55.93 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      312.15,-75.97 [deg] galactic lon,lat of the burst
ECL_COORDS:      349.24,-40.77 [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 Circular #34608
The Fermi GBM team reports the detection of a likely LONG GRB
At 17:22:58 UT on 3 Sep 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230903A (trigger 715454583.81493 / 230903724).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 13.4, Dec = -13.5 (J2000 degrees, equivalent to J2000 00h 53m, -13d 30'), with a statistical uncertainty of 16.6 degrees.
The angle from the Fermi LAT boresight is 70.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230903724/quicklook/glg_skymap_all_bn230903724.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230903724/quicklook/glg_healpix_all_bn230903724.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230903724/quicklook/glg_lc_medres34_bn230903724.gif

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 03 Sep 23 17:36:07 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1189514,   Seg_Num: 0
POINT_RA:          9.929d {+00h 39m 43s} (J2000)
POINT_DEC:       -40.955d {-40d 57' 16"} (J2000)
POINT_ROLL:      136.267d
IMG_START_DATE:  20190 TJD;   246 DOY;   23/09/03
IMG_START_TIME:  62848.53 SOD {17:27:28.53} UT,   272.3 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.512
N_STARS:         68
X_OFFSET:        17 [pixels]
Y_OFFSET:        272 [pixels]
X_MAX:           1456 [pixels]
Y_MAX:           1711 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw01189514000msufc0272.fits
SUN_POSTN:       162.44d {+10h 49m 45s}   +7.45d {+07d 27' 06"}
SUN_DIST:        138.47 [deg]   Sun_angle= 10.1 [hr] (West of Sun)
MOON_POSTN:       29.13d {+01h 56m 30s}  +12.35d {+12d 21' 02"}
MOON_DIST:        55.98 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      312.09,-75.96 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      349.25,-40.78 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 03 Sep 23 17:36:15 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1189514,   Seg_Num: 0
POINT_RA:          9.929d {+00h 39m 43s} (J2000)
POINT_DEC:       -40.955d {-40d 57' 16"} (J2000)
POINT_ROLL:      136.267d
IMG_START_DATE:  20190 TJD;   246 DOY;   23/09/03
IMG_START_TIME:  62848.53 SOD {17:27:28.53} UT,   272.3 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.512
N_STARS:         68
X_OFFSET:        17 [pixels]
Y_OFFSET:        272 [pixels]
X_MAX:           1456 [pixels]
Y_MAX:           1711 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw01189514000msufc0272.fits
SUN_POSTN:       162.44d {+10h 49m 45s}   +7.45d {+07d 27' 05"}
SUN_DIST:        138.47 [deg]   Sun_angle= 10.1 [hr] (West of Sun)
MOON_POSTN:       29.13d {+01h 56m 31s}  +12.35d {+12d 21' 04"}
MOON_DIST:        55.98 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      312.09,-75.96 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      349.25,-40.78 [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 Circular #34609
V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko, G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij (Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gress, N.M. Budnev, O.Ershova (Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich (Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB230903.72 (trigger No 1189514,00h 39m 42.24s , -40d 55m 26.4s, R=0.05) errorbox 65 sec after notice time and 100 sec after trigger time at 2023-09-03 17:24:36 UT, with upper limit up to 16.0 mag. Observations started at twilight. The observations began at zenith distance = 80 deg. The sun altitude is -13.8 deg.
The galactic latitude b = -76 deg., longitude l = 310 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2264930
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

     110 |         MASTER-SAAO |  P/ |    20 | 14.9 |        
     268 |         MASTER-SAAO |  P/ |    50 | 16.0 |        
     335 |         MASTER-SAAO |  P/ |    60 | 15.8 |        
     426 |         MASTER-SAAO |  P/ |    60 | 15.9 |        
     506 |         MASTER-SAAO |  P/ |    60 | 16.0 |        
```
The observation and reduction will continue. The message may be cited.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 03 Sep 23 17:37:29 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1189514,   Seg_Num: 0
POINT_RA:          9.929d {+00h 39m 43s} (J2000)
POINT_DEC:       -40.955d {-40d 57' 16"} (J2000)
ROLL:            136.267d
IMG_START_DATE:  20190 TJD;   246 DOY;   23/09/03
IMG_START_TIME:  62848.53 SOD {17:27:28.53} UT,   272.3 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     715454880
X_OFFSET:        576 [pixels]
Y_OFFSET:        831 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       736
Y_GRB_POS:       991
BINNING_INDEX:   1
IM_URL:          sw01189514000msuni0304.fits
SUN_POSTN:       162.44d {+10h 49m 45s}   +7.45d {+07d 27' 04"}
SUN_DIST:        138.47 [deg]   Sun_angle= 10.1 [hr] (West of Sun)
MOON_POSTN:       29.14d {+01h 56m 33s}  +12.36d {+12d 21' 22"}
MOON_DIST:        55.99 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      312.09,-75.96 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      349.25,-40.78 [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 23 17:43:11 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1189514,   Seg_Num: 0
POINT_RA:          9.929d {+00h 39m 43s} (J2000)
POINT_DEC:       -40.955d {-40d 57' 15"} (J2000)
POINT_ROLL:      136.267d
IMG_START_DATE:  20190 TJD;   246 DOY;   23/09/03
IMG_START_TIME:  63449.57 SOD {17:37:29.57} UT,   873.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.081
N_STARS:         71
X_OFFSET:        17 [pixels]
Y_OFFSET:        272 [pixels]
X_MAX:           1456 [pixels]
Y_MAX:           1711 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw01189514000msufc0873.fits
SUN_POSTN:       162.44d {+10h 49m 46s}   +7.45d {+07d 26' 59"}
SUN_DIST:        138.47 [deg]   Sun_angle= 10.1 [hr] (West of Sun)
MOON_POSTN:       29.19d {+01h 56m 46s}  +12.38d {+12d 22' 49"}
MOON_DIST:        56.03 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      312.09,-75.96 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      349.25,-40.78 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 03 Sep 23 17:43:25 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1189514,   Seg_Num: 0
POINT_RA:          9.929d {+00h 39m 43s} (J2000)
POINT_DEC:       -40.955d {-40d 57' 15"} (J2000)
POINT_ROLL:      136.267d
IMG_START_DATE:  20190 TJD;   246 DOY;   23/09/03
IMG_START_TIME:  63449.57 SOD {17:37:29.57} UT,   873.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.081
N_STARS:         71
X_OFFSET:        17 [pixels]
Y_OFFSET:        272 [pixels]
X_MAX:           1456 [pixels]
Y_MAX:           1711 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw01189514000msufc0873.fits
SUN_POSTN:       162.44d {+10h 49m 46s}   +7.45d {+07d 26' 59"}
SUN_DIST:        138.48 [deg]   Sun_angle= 10.1 [hr] (West of Sun)
MOON_POSTN:       29.19d {+01h 56m 46s}  +12.38d {+12d 22' 53"}
MOON_DIST:        56.03 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      312.09,-75.96 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      349.25,-40.78 [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:     Sun 03 Sep 23 17:44:30 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1189514,   Seg_Num: 0
POINT_RA:          9.929d {+00h 39m 43s} (J2000)
POINT_DEC:       -40.955d {-40d 57' 15"} (J2000)
ROLL:            136.267d
IMG_START_DATE:  20190 TJD;   246 DOY;   23/09/03
IMG_START_TIME:  63449.57 SOD {17:37:29.57} UT,   873.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     715455481
X_OFFSET:        576 [pixels]
Y_OFFSET:        831 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       736
Y_GRB_POS:       991
BINNING_INDEX:   1
IM_URL:          sw01189514000msuni0905.fits
SUN_POSTN:       162.44d {+10h 49m 46s}   +7.45d {+07d 26' 58"}
SUN_DIST:        138.48 [deg]   Sun_angle= 10.1 [hr] (West of Sun)
MOON_POSTN:       29.20d {+01h 56m 49s}  +12.39d {+12d 23' 09"}
MOON_DIST:        56.04 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      312.09,-75.96 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      349.25,-40.78 [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 23 17:44:43 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1189514,   Seg_Num: 0
POINT_RA:          9.929d {+00h 39m 43s} (J2000)
POINT_DEC:       -40.955d {-40d 57' 15"} (J2000)
ROLL:            136.267d
IMG_START_DATE:  20190 TJD;   246 DOY;   23/09/03
IMG_START_TIME:  63449.57 SOD {17:37:29.57} UT,   873.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     715455481
X_OFFSET:        576 [pixels]
Y_OFFSET:        831 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       736
Y_GRB_POS:       991
BINNING_INDEX:   1
IM_URL:          sw01189514000msuni0905.fits
SUN_POSTN:       162.44d {+10h 49m 46s}   +7.45d {+07d 26' 58"}
SUN_DIST:        138.48 [deg]   Sun_angle= 10.1 [hr] (West of Sun)
MOON_POSTN:       29.20d {+01h 56m 49s}  +12.39d {+12d 23' 12"}
MOON_DIST:        56.04 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      312.09,-75.96 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      349.25,-40.78 [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 #34610
A. D'Ai (INAF-IASFPA), E. Ambrosi (INAF-IASFPA), J.D. Gropp (PSU), J. A. Kennea (PSU), A. Y. Lien (U Tampa), A. Melandri (INAF-OAR), M. J. Moss (GWU), D. M. Palmer (LANL) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 17:22:56 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 230903A (trigger=1189514). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 9.926, -40.924 which is
```
   RA(J2000) = 00h 39m 42s
   Dec(J2000) = -40d 55' 25"
```
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 10 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 17:24:47.9 UT, 111.7 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 9.91169, -40.94930 which is equivalent to:
```
   RA(J2000)  = 00h 39m 38.81s
   Dec(J2000) = -40d 56' 57.5"
```
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 99 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 https://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 (2.68 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 2.6 (+2.17/-1.93) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 250 seconds with the U filter starting 117 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 19.2 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 18.0 mag.
Burst Advocate for this burst is A. D'Ai (antonino.dai AT 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/)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 03 Sep 23 17:37:43 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1189514,   Seg_Num: 0
POINT_RA:          9.929d {+00h 39m 43s} (J2000)
POINT_DEC:       -40.955d {-40d 57' 16"} (J2000)
ROLL:            136.267d
IMG_START_DATE:  20190 TJD;   246 DOY;   23/09/03
IMG_START_TIME:  62848.53 SOD {17:27:28.53} UT,   272.3 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     715454880
X_OFFSET:        576 [pixels]
Y_OFFSET:        831 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       736
Y_GRB_POS:       991
BINNING_INDEX:   1
IM_URL:          sw01189514000msuni0304.fits
SUN_POSTN:       162.44d {+10h 49m 45s}   +7.45d {+07d 27' 04"}
SUN_DIST:        138.47 [deg]   Sun_angle= 10.1 [hr] (West of Sun)
MOON_POSTN:       29.14d {+01h 56m 34s}  +12.36d {+12d 21' 26"}
MOON_DIST:        55.99 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      312.09,-75.96 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      349.25,-40.78 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 03 Sep 23 17:37:20 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1189514,   Seg_Num: 0
GRB_RA:            9.9113d {+00h 39m 38.71s} (J2000),
                  10.1947d {+00h 40m 46.72s} (current),
                   9.3113d {+00h 37m 14.71s} (1950)
GRB_DEC:         -40.9491d {-40d 56' 56.7"} (J2000),
                 -40.8193d {-40d 49' 09.6"} (current),
                 -41.2236d {-41d 13' 24.9"} (1950)
GRB_ERROR:       1.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  20190 TJD;   246 DOY;   23/09/03
IMG_START_TIME:  62701.00 SOD {17:25:01.00} UT,   124.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       162.44d {+10h 49m 45s}   +7.45d {+07d 27' 04"}
SUN_DIST:        138.49 [deg]   Sun_angle= 10.1 [hr] (West of Sun)
MOON_POSTN:       29.14d {+01h 56m 33s}  +12.36d {+12d 21' 20"}
MOON_DIST:        55.99 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      312.15,-75.97 [deg] galactic lon,lat of the burst
ECL_COORDS:      349.24,-40.77 [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 Circular #34611
R. Strausbaugh (Eastern Illinois University), A. Cucchiara (NASA) report on behalf of a larger collaboration:
We observed the Swift GRB 230903A (D'ai et al., GCN 34610) field with the LCOGT 1-meter Sinistro instrument at the South African Astronomical Observatory site, on September 3, from 20:08 to 20:41 UT (corresponding to 2.77 to 3.32 hours from the GRB trigger time) with the Bessel R and I filters.
We performed a series of 3x300s exposures in each band. We do not detect a source within the Swift-XRT error region (D'Ai et al., GCN 34610) in either band.
The following upper limits are calculated using the USNO-B1.0 catalog as reference:
```
R > 20.5
I > 19.0
```
These magnitudes are not corrected for galactic extinction.
GCN Circular #34618
O.J. Roberts (USRA), B. Mailyan (Florida Tech) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 17:22:58.81 UT on the 3rd September 2023 , the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 230903A (trigger 715454583 / 230903724) which was also detected by the Swift/BAT (A. D'ai et al. 2023, GCN 34610). The Fermi GBM Final Real-time Localization (GCN 34608) is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 98 degrees.
The GBM light curve consists of one pulse with a duration (T90) of about 3 s (50-300 keV). The time-averaged spectrum from T0-4.0 s to T0+1.0 s is best fit by a simple power law function with index -1.78 +/- 0.09.
A power law function with an exponential high-energy cutoff fits the spectrum equally well. The power law index is -1.27 +/- 0.33 and the cutoff energy, parameterized as Epeak, is 95 +/- 31 keV.
The event fluence (10-1000 keV) in this time interval is (5.87 +/- 0.85)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0-1s in the 10-1000 keV band is 2.0 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN Circular #34619
V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko, G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij (Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gress, N.M. Budnev, O.Ershova (Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich (Blagoveschensk Educational State University)
MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 230903A ( Fermi GBM team, GCN 34608) errorbox 49439 sec after notice time and 49475 sec after trigger time at 2023-09-04 07:07:34 UT, with upper limit up to 18.3 mag. The observations began at zenith distance = 24 deg. The sun altitude is -47.1 deg.
MASTER-Amur robotic telescope located in Russia (Blagoveshchensk State Pedagogical University) started inspect of the Fermi GRB 230903A errorbox 83217 sec after notice time and 83253 sec after trigger time at 2023-09-04 16:30:32 UT, with upper limit up to 16.5 mag. The observations began at zenith distance = 50 deg. The sun altitude is -31.3 deg.
The galactic latitude b = -76 deg., longitude l = 128 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2264968
We obtain a following upper limits.
```
Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   49505 | 2023-09-04 07:07:34 |         MASTER-OAFA | (23h 45m 07.73s , -21d 40m 56.2s) |   C |    60 | 18.3 |        
   50337 | 2023-09-04 07:21:25 |         MASTER-OAFA | (23h 45m 12.23s , -21d 40m 04.4s) |   C |    60 | 18.3 |        
   83283 | 2023-09-04 16:30:32 |         MASTER-Amur | (00h 45m 02.38s , +01d 03m 22.9s) |   C |    60 | 16.4 |        
   83363 | 2023-09-04 16:31:51 |         MASTER-Amur | (00h 52m 59.10s , +01d 05m 05.8s) |   C |    60 | 16.5 |        
   83442 | 2023-09-04 16:33:11 |         MASTER-Amur | (00h 44m 55.77s , +02d 58m 32.3s) |   C |    60 | 16.5 |        
   83522 | 2023-09-04 16:34:30 |         MASTER-Amur | (00h 52m 50.71s , +02d 58m 14.6s) |   C |    60 | 16.2 |        
   83941 | 2023-09-04 16:41:29 |         MASTER-Amur | (00h 44m 58.62s , +01d 04m 26.3s) |   C |    60 | 16.2 |        
   84021 | 2023-09-04 16:42:49 |         MASTER-Amur | (00h 52m 58.54s , +01d 03m 22.6s) |   C |    60 | 16.2 |        
   84100 | 2023-09-04 16:44:08 |         MASTER-Amur | (00h 44m 54.16s , +02d 58m 06.4s) |   C |    60 | 16.2 |        
   84180 | 2023-09-04 16:45:28 |         MASTER-Amur | (00h 52m 50.10s , +02d 57m 42.0s) |   C |    60 | 15.9 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #34623
M. J. Moss (GSFC), S. D. Barthelmy (GSFC), A. D'Ai (INAF-IASFPA), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 230903A (trigger #1189514) (D'Ai, et al., GCN Circ. 34610). The BAT ground-calculated position is RA, Dec = 9.898, -40.910 deg which is
```
   RA(J2000)  =  00h 39m 35.5s 
   Dec(J2000) = -40d 54' 34.5" 
```
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 40%.
The mask weighted light curve shows a single short pulse. T90 (15-350 keV) is 2.54 +- 0.27 sec (estimated error including systematics). The T90 and the spectral hardness of this burst places it on the border of the long-soft and hard-short burst classifications.
The time-averaged spectrum from T+0.20 to T+2.93 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index -0.66 +- 1.49, and Epeak of 63.4 +- 17.8 keV (chi squared 44.41 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 2.2 +- 0.4 x 10^-07 erg/cm2 and the 1-sec peak flux measured from T+0.50 sec in the 15-150 keV band is 1.3 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.40 +- 0.21 (chi squared 54.66 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/1189514/BA/
GCN Circular #34624
D. Pieterse (Radboud University), D. B. Malesani (Radboud and DAWN/NBI), E. Le Floc=E2=80=99h (CEA-Saclay), A. Saccardi (GEPI, Obs. de Paris) and N. R. Tanvir (Univ. of Leicester) report on behalf of the Stargate collaboration :
We observed the field of GRB230903A (Fermi GBM team, GCN 34608 ; D=E2=80=99Ai et al., GCN 34610) using the ESO VLT UT3 (Melipal) equipped with the X-shooter instrument. Three 60s exposures were obtained in the r-band on 2023 September 4.097 UT (T-To ~8.95h). The observations were performed under poor weather conditions, with a seeing of 3.2 arcsec measured in the data. We do not detect any source coinciding with the location of the X-ray afterglow detected by Swift/XRT (D=E2=80=99Ai et al., GCN 34610). We obtain the following upper limit, calibrated using a faint, nearby object from the Legacy Survey (Dey et al. 2019, ApJ, 257, 29).
r > 22.7 mag (AB)
This estimate is not corrected for Galactic extinction and is consistent with the non-detection reported earlier by LCOGT (Strausbaugh et al., GCN 34611).
We acknowledge excellent support from the ESO observing staff in Paranal, in particular Claudia Paladini and Jonathan Smoker.
GCN Circular #34625
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 832 s of XRT Photon Counting mode data and 2 UVOT images for GRB 230903A, 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 = 9.91061, -40.95001 which is equivalent to:
```
RA (J2000): 00h 39m 38.55s
Dec (J2000): -40d 57' 00.0"
```
with an uncertainty of 2.2 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 #34626
K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), S. Dichiara (PSU) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 2.3 ks of XRT data for GRB 230903A, from 97 s to 29.3 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 power-law decay with a decay index of alpha=1.17 (+/-0.09).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.00 (+0.24, -0.22). The best-fitting absorption column is 8.2 (+5.9, -5.0) x 10^20 cm^-2, in excess of the Galactic value of 2.7 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 3.3 x 10^-11 (3.9 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     8.2 (+5.9, -5.0) x 10^20 cm^-2
Galactic foreground: 2.7 x 10^20 cm^-2
Excess significance: 1.8 sigma
Photon index:	     2.00 (+0.24, -0.22)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01189514.
This circular is an official product of the Swift-XRT team.
GCN Circular #34650
R. Jayaraman (MIT), M.M. Fausnaugh (TTU/MIT), R. Vanderspek (MIT), and G.R. Ricker (MIT) report:
The Transiting Exoplanet Survey Satellite (TESS; Ricker et al. JATIS 2015) observed the location of the gamma-ray burst GRB230903A (GCN 34608, Fermi GBM Team et al.; GCN 34610, D=E2=80=99Ai et al.) at a 200 second cadence continuously from 2.8 days before the trigger to 3.75 days after the trigger. The GRB occurred during TESS observational Sector 69, in the field of view of Camera 2, CCD 3.
We extracted a light curve from the calibrated TESS Full-Frame Images (FFIs) produced by TICA (Fausnaugh et al. RNAAS 2020), using difference imaging and forced photometry at the enhanced location provided by Swift-XRT in GCN 34625 (Beardmore et al.). Our analysis procedure is described in Fausnaugh et al. 2023 (arXiv:2307.11815).
TESS observations show a flux excess of 5.1-sigma above the background in the 200s FFI exposure that encompasses the Fermi trigger time, corresponding to an apparent magnitude of 17.20 =C2=B1 0.05 in the TESS band (600 nm=E2==80=931000 nm). Further analysis is ongoing.
The TICA data are publicly available on the MAST archive at https://archive.stsci.edu/hlsp/tica.

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Jochen Greiner, last update: 10-Sep-2023 [Disclaimer]