Gamma-ray Burst 230723B

(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 23 Jul 23 11:42:45 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1180410,   Seg_Num: 0
GRB_RA:          250.379d {+16h 41m 31s} (J2000),
                 250.692d {+16h 42m 46s} (current),
                 249.714d {+16h 38m 51s} (1950)
GRB_DEC:          -5.327d {-05d 19' 37"} (J2000),
                  -5.371d {-05d 22' 14"} (current),
                  -5.232d {-05d 13' 55"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1208 [cnts]    Image_Peak=93 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   42     E_range: 25-100 keV
BKG_INTEN:       12682 [cnts]
BKG_TIME:        42136.30 SOD {11:42:16.30} UT
BKG_DUR:         8 [sec]
GRB_DATE:        20148 TJD;   204 DOY;   23/07/23
GRB_TIME:        42152.88 SOD {11:42:32.88} UT
GRB_PHI:         -21.37 [deg]
GRB_THETA:        44.67 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     14.24 [sigma]
IMAGE_SIGNIF:    8.27 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +2  -1  +0  +0 +60  +0 
SUN_POSTN:       122.59d {+08h 10m 21s}  +20.06d {+20d 03' 51"}
SUN_DIST:        127.53 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:      183.54d {+12h 14m 09s}   +0.85d {+00d 50' 60"}
MOON_DIST:        67.35 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:       11.69, 25.69 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      249.57, 16.73 [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 = 213.84,-12.40 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(1.0<100sec) coincident with the FERMI_GBM event (trignum=711805358).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 23 Jul 23 11:43:02 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     711805358
GRB_RA:          249.883d {+16h 39m 32s} (J2000),
                 250.179d {+16h 40m 43s} (current),
                 249.257d {+16h 37m 02s} (1950)
GRB_DEC:          +3.017d {+03d 01' 00"} (J2000),
                  +2.972d {+02d 58' 19"} (current),
                  +3.114d {+03d 06' 50"} (1950)
GRB_ERROR:       9.23 [deg radius, statistical plus systematic]
GRB_INTEN:       184 [cnts/sec]
DATA_SIGNIF:     13.30 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        20148 TJD;   204 DOY;   23/07/23
GRB_TIME:        42153.03 SOD {11:42:33.03} UT
GRB_PHI:         124.00 [deg]
GRB_THETA:        70.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.17
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      95%  GRB
2nd_MOST_LIKELY:   2%  SGR_1806n20
DETECTORS:       0,0,0, 0,0,0, 0,0,0, 1,1,0, 0,0,
SUN_POSTN:       122.59d {+08h 10m 21s}  +20.06d {+20d 03' 51"}
SUN_DIST:        123.67 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:      183.54d {+12h 14m 09s}   +0.85d {+00d 50' 56"}
MOON_DIST:        66.63 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:       19.44, 30.51 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      247.75, 24.92 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230723488/quicklook/glg_lc_medres34_bn230723488.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 225.78,14.77 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=1180410).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 23 Jul 23 11:43:11 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      58
TRIGGER_NUM:     711805358
GRB_RA:          249.283d {+16h 37m 08s} (J2000),
                 249.589d {+16h 38m 21s} (current),
                 248.634d {+16h 34m 32s} (1950)
GRB_DEC:          -1.917d {-01d 55' 00"} (J2000),
                  -1.963d {-01d 57' 45"} (current),
                  -1.817d {-01d 49' 00"} (1950)
GRB_ERROR:       6.95 [deg radius, statistical plus systematic]
GRB_INTEN:       212 [cnts/sec]
DATA_SIGNIF:     21.70 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        20148 TJD;   204 DOY;   23/07/23
GRB_TIME:        42153.03 SOD {11:42:33.03} UT
GRB_PHI:         125.00 [deg]
GRB_THETA:        75.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.90
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      67%  GRB
2nd_MOST_LIKELY:  19%  SGR_1806n20
DETECTORS:       0,0,0, 0,0,0, 0,0,0, 1,1,0, 0,0,
SUN_POSTN:       122.59d {+08h 10m 21s}  +20.06d {+20d 03' 51"}
SUN_DIST:        125.22 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:      183.54d {+12h 14m 09s}   +0.85d {+00d 50' 54"}
MOON_DIST:        66.10 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:       14.23, 28.47 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      247.91, 19.95 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230723488/quicklook/glg_lc_medres34_bn230723488.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 225.78,14.77 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=1180410).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 23 Jul 23 11:43:20 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     711805358
GRB_RA:          249.360d {+16h 37m 26s} (J2000),
                 249.680d {+16h 38m 43s} (current),
                 248.682d {+16h 34m 44s} (1950)
GRB_DEC:          -8.240d {-08d 14' 23"} (J2000),
                  -8.286d {-08d 17' 08"} (current),
                  -8.140d {-08d 08' 24"} (1950)
GRB_ERROR:       3.11 [deg radius, statistical only]
DATA_SIGNIF:     23.40 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        20148 TJD;   204 DOY;   23/07/23
GRB_TIME:        42153.03 SOD {11:42:33.03} UT
GRB_PHI:         127.00 [deg]
GRB_THETA:        81.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       122.59d {+08h 10m 21s}  +20.06d {+20d 03' 51"}
SUN_DIST:        127.59 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:      183.54d {+12h 14m 10s}   +0.85d {+00d 50' 52"}
MOON_DIST:        66.54 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:        8.40, 24.88 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      248.96, 13.70 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230723488/quicklook/glg_lc_medres34_bn230723488.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_711805358.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(1.0<100sec) coincident with the SWIFT_BAT event (trignum=1180410).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 23 Jul 23 11:51:56 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     711805358
GRB_RA:          249.340d {+16h 37m 22s} (J2000),
                 249.660d {+16h 38m 38s} (current),
                 248.662d {+16h 34m 39s} (1950)
GRB_DEC:          -8.340d {-08d 20' 23"} (J2000),
                  -8.386d {-08d 23' 08"} (current),
                  -8.240d {-08d 14' 24"} (1950)
GRB_ERROR:       3.59 [deg radius, statistical only]
GRB_DATE:        20148 TJD;   204 DOY;   23/07/23
GRB_TIME:        42153.03 SOD {11:42:33.03} UT
GRB_PHI:         127.00 [deg]
GRB_THETA:        81.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       122.59d {+08h 10m 22s}  +20.06d {+20d 03' 46"}
SUN_DIST:        127.60 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:      183.60d {+12h 14m 25s}   +0.81d {+00d 48' 51"}
MOON_DIST:        66.46 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:        8.30, 24.84 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      248.95, 13.60 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230723488/quicklook/glg_lc_medres34_bn230723488.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230723488/quicklook/glg_locplot_all_bn230723488.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(1.0<100sec) coincident with the SWIFT_BAT event (trignum=1180410).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Jul 23 11:46:27 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1180410,   Seg_Num: 0
GRB_RA:          250.379d {+16h 41m 31s} (J2000),
                 250.692d {+16h 42m 46s} (current),
                 249.714d {+16h 38m 51s} (1950)
GRB_DEC:          -5.327d {-05d 19' 37"} (J2000),
                  -5.371d {-05d 22' 14"} (current),
                  -5.232d {-05d 13' 55"} (1950)
GRB_DATE:        20148 TJD;   204 DOY;   23/07/23
GRB_TIME:        42152.88 SOD {11:42:32.88} UT
TRIGGER_INDEX:   42
GRB_PHI:         -21.37 [deg]
GRB_THETA:        44.67 [deg]
DELTA_TIME:      -56.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     14.24 [sigma]
IMAGE_SIGNIF:    8.27 [sigma]
LC_URL:          sw01180410000msb.lc
SUN_POSTN:       122.59d {+08h 10m 21s}  +20.06d {+20d 03' 49"}
SUN_DIST:        127.53 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:      183.56d {+12h 14m 15s}   +0.84d {+00d 50' 08"}
MOON_DIST:        67.32 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:       11.69, 25.69 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      249.57, 16.73 [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 = 213.84,-12.40 [deg].

GCN Circular #34234
K. L. Page (U Leicester), J.D. Gropp (PSU), H. A. Krimm (NSF), T. M. Parsotan (GSFC/UMBC/CRESSTII) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 11:42:32 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 230723B (trigger=1180410). The BAT on-board calculated location is RA, Dec 250.379, -5.327 which is
```
   RA(J2000) = 16h 41m 31s
   Dec(J2000) = -05d 19' 37"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 10 sec. The peak count rate was ~2200 counts/sec (15-350 keV), at ~1 sec after the trigger.
Due to an observing constraint, Swift will not slew until T0+50.2 minutes. There will be no XRT or UVOT data until this time.
Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Jul 23 12:48:17 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1180410,   Seg_Num: 0
POINT_RA:        250.351d {+16h 41m 24s} (J2000)
POINT_DEC:        -5.347d {-05d 20' 47"} (J2000)
IMG_START_DATE:  20148 TJD;   204 DOY;   23/07/23
IMG_START_TIME:  45447.61 SOD {12:37:27.61} UT,   3294.7 [sec] since BAT Trigger Time
COUNTS:          35    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        4    Max_iter_allowed= 4
ERROR_CODE:      2
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        Algorithm did not converge; too many iterations.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Jul 23 12:50:29 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1180410,   Seg_Num: 0
POINT_RA:        250.351d {+16h 41m 24s} (J2000)
POINT_DEC:        -5.347d {-05d 20' 47"} (J2000)
POINT_ROLL:      291.249d
IMG_START_DATE:  20148 TJD;   204 DOY;   23/07/23
IMG_START_TIME:  45451.23 SOD {12:37:31.23} UT,   3298.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.625
N_STARS:         38
X_OFFSET:        456 [pixels]
Y_OFFSET:        807 [pixels]
X_MAX:           1415 [pixels]
Y_MAX:           1766 [pixels]
DET_THRESH:      20
PHOTO_THRESH:    12
SL_URL:          sw01180410000msufc3298.fits
SUN_POSTN:       122.63d {+08h 10m 32s}  +20.05d {+20d 03' 16"}
SUN_DIST:        127.47 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:      184.03d {+12h 16m 08s}   +0.59d {+00d 35' 08"}
MOON_DIST:        66.80 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:       11.66, 25.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      249.54, 16.71 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Jul 23 12:50:46 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1180410,   Seg_Num: 0
POINT_RA:        250.351d {+16h 41m 24s} (J2000)
POINT_DEC:        -5.347d {-05d 20' 47"} (J2000)
POINT_ROLL:      291.249d
IMG_START_DATE:  20148 TJD;   204 DOY;   23/07/23
IMG_START_TIME:  45451.23 SOD {12:37:31.23} UT,   3298.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.625
N_STARS:         38
X_OFFSET:        456 [pixels]
Y_OFFSET:        807 [pixels]
X_MAX:           1415 [pixels]
Y_MAX:           1766 [pixels]
DET_THRESH:      20
PHOTO_THRESH:    12
SL_URL:          sw01180410000msufc3298.fits
SUN_POSTN:       122.63d {+08h 10m 32s}  +20.05d {+20d 03' 16"}
SUN_DIST:        127.47 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:      184.04d {+12h 16m 09s}   +0.58d {+00d 35' 04"}
MOON_DIST:        66.80 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:       11.66, 25.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      249.54, 16.71 [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 23 Jul 23 12:51:58 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1180410,   Seg_Num: 0
POINT_RA:        250.351d {+16h 41m 24s} (J2000)
POINT_DEC:        -5.347d {-05d 20' 47"} (J2000)
ROLL:            291.249d
IMG_START_DATE:  20148 TJD;   204 DOY;   23/07/23
IMG_START_TIME:  45451.23 SOD {12:37:31.23} UT,   3298.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     711808682
X_OFFSET:        775 [pixels]
Y_OFFSET:        1126 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       935
Y_GRB_POS:       1286
BINNING_INDEX:   1
IM_URL:          sw01180410000msuni3330.fits
SUN_POSTN:       122.63d {+08h 10m 32s}  +20.05d {+20d 03' 16"}
SUN_DIST:        127.47 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:      184.04d {+12h 16m 11s}   +0.58d {+00d 34' 47"}
MOON_DIST:        66.79 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:       11.66, 25.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      249.54, 16.71 [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 23 Jul 23 12:52:13 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1180410,   Seg_Num: 0
POINT_RA:        250.351d {+16h 41m 24s} (J2000)
POINT_DEC:        -5.347d {-05d 20' 47"} (J2000)
ROLL:            291.249d
IMG_START_DATE:  20148 TJD;   204 DOY;   23/07/23
IMG_START_TIME:  45451.23 SOD {12:37:31.23} UT,   3298.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     711808682
X_OFFSET:        775 [pixels]
Y_OFFSET:        1126 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       935
Y_GRB_POS:       1286
BINNING_INDEX:   1
IM_URL:          sw01180410000msuni3330.fits
SUN_POSTN:       122.63d {+08h 10m 32s}  +20.05d {+20d 03' 15"}
SUN_DIST:        127.47 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:      184.05d {+12h 16m 11s}   +0.58d {+00d 34' 44"}
MOON_DIST:        66.79 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:       11.66, 25.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      249.54, 16.71 [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 #34236
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 230723B at 12:37:27.6 UT, 3294.7 seconds after the BAT trigger. No source was detected in 807 s of promptly downlinked data, which covered 88% of the BAT error circle. We are waiting for the full dataset to detect and localise the XRT counterpart.
GCN Circular #34238
K.L. Page and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
We have analysed 1.0 ks of XRT data for GRB 230723B, from 3.3 ks to 4.4 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The refined XRT position is RA, Dec = 250.3798, -5.3348 which is equivalent to:
```
RA (J2000): 16 41 31.15
Dec(J2000): -05 20 05.2
```
with an uncertainty of 4.1 arcsec (radius, 90% confidence).
This circular is an official product of the Swift-XRT team.
GCN Circular #34239
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (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. Gres, N.M. Budnev (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),
A. Gabovich, V.Yurkov (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 GRB 230723B ( K. L. Page et al., GCN 34234) errorbox 18882 sec after notice time and 18900 sec after trigger time at 2023-07-23 16:57:33 UT, with upper limit up to 19.3 mag. Observations started at twilight. The observations began at zenith distance = 42 deg. The sun altitude is -13.0 deg.
The galactic latitude b = 25 deg., longitude l = 12 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2243736
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   18990 |         MASTER-SAAO |   C |   180 | 18.1 |        
   18990 |         MASTER-SAAO |   C |   180 | 19.1 |        
   19201 |         MASTER-SAAO |   C |   180 | 18.4 |        
   19201 |         MASTER-SAAO |   C |   180 | 19.3 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #34240
M. H. Siegle (PSU) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 230723B 3298 s after the BAT trigger (Page et al., GCN Circ. 34234). No optical afterglow consistent with the XRT position (Page and Evans, GCN Circ. 34238) 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          3298         3448          147         >20.6
white             3298         4680          344         >20.9
v                 3456         3655          197         >19.1
b                 4276         4475          197         >20.1
u                 4070         4270          197         >20.0
w1                3866         4065          197         >19.3
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.411 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #34241
J.F. Agui Fernandez (IAA-CSIC), A. de Ugarte Postigo (OCA/CNRS), C.C. Thoene (ASU-CAS), M. Blazek (CAHA) report:
We observed the field of GRB 230723B (Page et al. GCN 34234) with CAFOS at the 2.2m CAHA telescope, at Calar Alto Observatory, in Almeria (Spain). The observation consisted of 9x360s exposures in i-band, starting at 20:34 UT and with mean epoch on 0.389 days after the burst. We do not see any new source within the XRT error box (Page & Evans, GCN 34238) down to a 3-sigma limit of 23.0 mag. We do notice that there is a faint object at the Eastern edge of the XRT error box with a magnitude of 22.4 mag, with coordinates (J2000): 16:41:31.43, -5:20:05.7, but that seems to be also there, at a similar magnitude, in the PanSTARRS images. It is not possible at this time to determine if this object could be the host galaxy of GRB 230723B.
GCN Circular #34247
C. Adami (LAM), J.-C. Cuillandre (CEA Paris-Saclay), M. Ollivier, H. Dole (= IAS, Universit=C3=A9 Paris-Saclay), T. Adami (ENS Paris-Saclay), A. de Ugar= te Postigo (OCA/CNRS), E. Le Floc=E2=80=99h, D. G=C3=B6tz (CEA Paris-Saclay= ), A.Saccardi, S.Vergani (GEPI, Obs. de Paris), S. Basa (LAM), report on be= half of a larger collaboration :
We observed the field of GRB 230723B (Page et al. GCN 34234) using the T193= cm and T120cm telescopes at Observatoire de Haute-Provence (France). We obt= ained 26 exposures in the r=E2=80=99-band (4x30sec + 22x150sec) with MISTRA= L on the T193cm for a total exposure time of 57min, starting at 20:54 UT wi= th a mean epoch at ~0.42days after trigger. At the same time we also obtain= ed 10 exposures of 6min in the I-band at T120cm (total time of 1h). In the = r=E2=80=99-band and I-band combined frames, we do not detect any new source= within the XRT error box (Page & Evans, GCN 34238). Our photometric calibr= ation was performed using nearby stars from the PanSTARRS catalog, leading = to the following lower limits :
```
r=E2=80=99 > 21 mag (AB, 3 sigma)
I > 19.25 mag (AB, 3 sigma)
```
These non-detections are consistent with the CAHA deeper observations in th= e i-band reported earlier by Agui Fernandez et al. (GCN 34241).
We acknowledge the excellent support from Observatoire de Haute-Provence, i= n particular Yoann Degot-Longhi, and we also thank Alice Morel.
GCN Circular #34248
J.P. Osborne (U. Leicester), K.L. Page (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 6.5 ks of XRT data for GRB 230723B, from 3.3 ks to 28.6 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. Using 1149 s of PC mode data and 3 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 250.37810, -5.33463 which is equivalent to:
```
RA (J2000): 16h 41m 30.74s
Dec(J2000): -05d 20' 04.7"
```
with an uncertainty of 2.4 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.6 (+0.6, -0.4).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.4 (+0.6, -0.5). The best-fitting absorption column is 6.8 (+4.5, -3.3) x 10^21 cm^-2, in excess of the Galactic value of 2.2 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 4.0 x 10^-11 (9.4 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     6.8 (+4.5, -3.3) x 10^21 cm^-2
Galactic foreground: 2.2 x 10^21 cm^-2
Excess significance: 2.3 sigma
Photon index:	     2.4 (+0.6, -0.5)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01180410.
This circular is an official product of the Swift-XRT team.
GCN Circular #34249
J.Mangan (CNRS/IJCLab) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
At 11:42:33.03 UT on 23 July 2023, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 230723B (trigger 711805358 / 230723488), which was also detected by Swift BAT (K. L. Page et al. 2023, GCN 34234). The Fermi GBM on-ground location is consistent with the Swift BAT position.
The angle from the Fermi LAT boresight at the GBM trigger time is 78 degrees.
The GBM light curve consists of a single peak with a duration (T90) of about 10 s (50-300 keV). The time-averaged spectrum from T0-2 s to T0+9 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.9 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 59.1 +/- 2.7 keV.
The event fluence (10-1000 keV) in this time interval is (3.8 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.2 s in the 10-1000 keV band is 7.8 +/- 0.4 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 #34250
U.Quadri and L.Strabla (Bassano Bresciano Astronomical Observatory), in a large collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy), B. De Simone (Universita' degli Studi Di Salerno) report:
We imaged the field of GRB 230723B detected by SWIFT(trigger 1180410) with the robotic telescope of (IAU station 565) Bassano Bresciano Observatory, Italy. Member of: AAVSO - American Association of Variable Star Observers. UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili. GAC - Gruppo Astrofili Cremonesi.
The observations started 518 min after the GRB trigger, at the end of twilight, with our Newton telescope D=250 mm F/D=4.8.
Weather conditions were medium.
We co-added 70 exposures of 120 sec each.
```
Start T0+      End T0+       R lim
518.43 min   598.40 min      19
```
We did not found any optical counterpart in the error box of the XRTcandidate. Page et al. GCN 34234
Magnitudes were estimated with the Gaia DR2 cat. and are not corrected for galactic dust extinction.
Reference: http://www.osservatoriobassano.org/GRB.asp
The message may be cited.
GCN Circular #34251
J.F. Agui Fernandez (IAA-CSIC), A. de Ugarte Postigo (OCA/CNRS), C.C. Thoene (ASU-CAS), M. Blazek and Ana Guijarro Roman (CAHA) report:
After XRT delivered its refined analysis and updated GRB localisation (Osborne et al. GCN 34248) we noticed that the new localisation has very little overlap with the fist one. The revised localisation is no longer consistent with the object mentioned in our previous GCN (Agui Fernandez et al. GCN 34241). However, within the new localisation circle and outside the original one, we detect an object at coordinates (J2000): 16:41:30.65 -5:20:04.5 with an AB magnitude of i = 22.4+/-0.2 mag as compared to PanSTARRS field objects. No object is detected in PanSTARRS at this position. Further observations will be needed to confirm the object variability and its possible identification as the optical counterpart of GRB 230723A.
GCN Circular #34252
S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez and L. Bellizzi (Montarrenti Observatory, Siena, Italy) report:
We observed the field of the GRB 230723B (Trigger 1180410, K.L. Page et al., GCN 34234, V. Lipunov, GCN 34239; J.F. Agui Fernandez, GCN 34241; C. Adami, GCN 34247; U. Quadri, GCN 34250; J.F. Agui Fernandez, GCN 34251) with the automatic 0.53m Ritchey-Chretien telescope + U47 detector at Montarrenti Observatory (Siena, Italy, IAU code C88).
The observations were started under good weather conditions at 2023-07-23 21:13:37 UT (approximately 9.5 hours after notice) stacking 30x30s clear filter CCD exposures.
We have not found optical transient within the error-box of the Neil Gehrels Swift Observatory position (RA 16h 41m 30.74s, Dec. -05d 20m 04.7s - J2000). Mag. upper limit R = 20.83 +/-0.14
Magnitudes were obtained from USNO-B1 catalogue and are not corrected for galactic extinction.
GCN Circular #34253
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy in a large collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy), B. De Simone (Universita' degli Studi Di Salerno) report:
We image the field of GRB 230723B detected by SWIFT(trigger 1180410) with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy. Member of: AAVSO - American Association of Variable Star Observers. UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili. AstroCampania Associazione
The observations started at 19:19 UT of 2023/07/23, after 7,40 hours after the GRB trigger, at the end of twilight with principal telescope SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME I took 32 image of 60 sec each. All images are unfiltered, calibrated with masterdark and masterflat,stacked with Tycho Tracker software We have not detected any clearly visible sources, up to 20th magnitude with clear skies.
```
   Start T0+                  End T0+        Rlim
19:19:39 UT            19:54:47 UT      20
```
We did not found any optical counterpart in the error box of the XRTcandidate. Page et al. GCN 34234
Magnitudes were estimated with the Gaia DR2 cat. and are not corrected for galactic dust extinction.
The message may be cited.
GCN Circular #34254
E. Pavoni and L. Moretti (Leavitt Observatory), in a large collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy), B. De Simone (Universita' degli Studi Di Salerno) report:
We imaged the field of GRB 230723B detected by SWIFT(trigger 1180410) with telescope of Leavitt Observatory, Italy. Member of: UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili. ATA - Associazione Tuscolana di Astronomia.
The observations began at 21:31 UT on 2023/07/23, 577 min after the GRB trigger, with our RC telescope D=250 mm F/D=8.
Weather conditions were medium.
We took 30 images of 120 sec each. All images are unfiltered, calibrated with master dark and master flat, stacked with ASTAP software.
We have not detected any clearly visible sources, up to 19.9th magnitude with clear sky at
```
RA(J2000)  = 16h 41m 43.83s
Dec(J2000) = -05d 17' 16.04"
```
on a field of view 31.1 x 26.8 arcmin
```
Start                End              Rlim
577 min         637 min      19.9
```
Magnitudes were estimated with the Gaia DR3 cat. and are not corrected for galactic dust extinction.
The message may be cited.
GCN Circular #34259
Claudio Lopresti (Gruppo Astronomia Digitale - GAD Observatory, La Spezia, = Italy) in a large collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan),=20 Y. Niino (Tokyo University, Institute of Astronomy),=20 K. Kalinowski (Aarhus University, Department of Physics and Astronomy), B. De Simone (Universita' degli Studi Di Salerno) Unione Astrofili Italiani (UAI) report:
We imaged the field of GRB 230723B detected by SWIFT(trigger 1180410) with the telescope LX200 12=E2=80=9D of GAD Observatory, La Spezia, Italy Member of: UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili, GRB section. GAD - Gruppo Astronomia Digitale.
Start T0+ End T0+ R lim 557 min 641 min 19 We did not found any optical counterpart in the error box of the XRT candidate. Page et al. GCN 34234 Magnitudes were estimated with the Gaia EDR3 cat. and are not corrected for galactic dust extinction. Reference: https://www.parcodellestelle.com/ The message may be cited.
GCN Circular #34267
G. E. Anderson (Curtin), A. Gulati (USyd), J. K. Leung (USyd), A. J. van de= r Horst (GWU), L. Rhodes (Oxford), S. Chastain (UNM) on behalf of the PanRa= dio GRB collaboration
The Australia Telescope Compact Array (ATCA) performed rapid-response follo= w-up observations of the long GRB 230723B (Page et al. GCN 34234) at 5.5, 9= , 16.7, and 21.2 GHz as part of the Large ATCA =E2=80=9CPanRadio GRB=E2=80= =9D follow-up programme C3542 (PI. Anderson). ATCA was on target observing = at 2023-07-23 11:51 UT, just 9 minutes post-burst and observed for 4 hrs.= There is no radio source coincident with the enhanced XRT position (Page e= t al. GCN 34238) with 3 sigma upper limits of 150, 90, 90 and 150 microJy/b= eam at 5.5, 9.0, 16.7 and 21.2 GHz, respectively. Further observations are = planned.
We thank the CSIRO Space and Astronomy staff for supporting these observati= ons and maintaining the ATCA rapid-response observing mode.
We acknowledge the Gomeroi people as the traditional owners of the Observat= ory site. The Australia Telescope Compact Array is part of the Australia Te= lescope National Facility (https://ror.org/05qajvd42) which is funded by th= e Australian Government for operation as a National Facility managed by CSI= RO.
GCN Circular #34268
M. Sasada, I. Takahashi, M. Niwano, S. Sato, S. Hayatsu, N. Higuchi, H. Tak= ei, H. Seki, Y. Yatsu (Tokyo Tech), K. L. Murata (Kyoto U) and N. Kawai (Ri= ken) report on behalf of the MITSuME collaboration:
We observed the field of GRB 230723B (Page et al. GCN Circular #34234, Camp= ana et al. #34236, Page et al. #34238, Lipunov et al. #34239, Siegle et al.= #34240, Agui Fernandez et al. #34241, Adami et al. #34247, Osborne et al. = #34248, Mangan et al. #34249, Quadri et al. #34250, Agui Fernandez et al. #= 34251, Leonini et al. #34252, Ruocco et al. #34253, Pavoni et al. #34254, L= opresti et al. #34259, Anderson et al. #34267) with the optical three color= (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope Akeno= .
The observation with a series of 10 sec exposures started at 2023-07-23 11:= 43:20 UT (48 seconds after the Swift/BAT detection). We stacked the images = with good conditions. In the stacked image at 454 seconds after the burst, = we detected an object of Ic=3D17.1+/-0.2 at the coordinate reported by Agui= Fernandez et al. #34251. We also report the g=E2=80=99-, Rc- and Ic-band 3= -sigma upper limits of the stacked images.
```
T0+[sec] |MID-UT | T-EXP[sec] | 3-sigma limits
---------------------------------------------------------------------------=
---------------------
454  | 2023-07-23 11:50:06 | 220 | g=E2=80=99>18.0, Rc>17.8, Ic>17.6
1419 | 2023-07-23 12:06:11 | 1020 | g=E2=80=99>18.6, Rc>18.5, Ic>18.2
 3763 | 2023-07-23 12:45:15 | 1890 | g'>19.0, Rc>18.5, Ic>18.0
---------------------------------------------------------------------------=
---------------------
```
T0+ : Elapsed time after the burst T-EXP: Total Exposure time
We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 r and i bands were converted to our Rc- and Ic-band magnitudes following Tonry et al. (2012), Table 6. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).
GCN Circular #34271
J.F. Agui Fernandez (IAA-CSIC), A. de Ugarte Postigo (OCA/CNRS), C.C. Thoene (ASU-CAS), J. Flores and Ana Guijarro Roman (CAHA) report:
We have performed follow-up observations on the GRB 230723B field (Page et al. GCN 34324, Osborne et al. GCN 34248) with CAFOS in the 2.2m telescope at the Calar Alto Observatory in Almeria, Spain. Observations consisted of 9x360s in i-band, starting at 2023-07-25T20:46:11 UT with a mean epoch 2.393 days after the burst. We detect the object reported in Agui Fernandez et al. (GCN 34251) at a magnitude consistent with our previous observation. The early optical detection of the transient at a consistent location by Sasada et al. (GCN 34268) indicates that the detection in the first Calar Alto observation was already dominated by the host galaxy contribution. The interpolation from the observation of Sasada et al. (GCN 34251) to the one of Agui Fernandez et al. (GCN 34251) indicates a decay rate of at least alpha=1.1 (where F_nu ~ t^-alpha). Extrapolating this, the GRB afterglow should be dimmer than 24 mag at the time of our follow-up observations. We do note, that the host galaxy should be in the range for emission line spectroscopy with 8-10m telescopes.
GCN Circular #34295
N. H. Hayatsu, H. Hanayama (NAOJ), M. Sasada, I. Takahashi, M. Niwano, S. Sato, S. Hayatsu, N. Higuchi, H. Takei, H. Seki, Y. Yatsu (Tokyo Tech), K. L. Murata (Kyoto U) and N. Kawai (Riken) report on behalf of the MITSuME collaboration:
report:
We observed the field of GRB 230723B (Page et al. GCN Circular #34234, Campana et al. #34236, Page et al. #34238, Lipunov et al. #34239, Siegle et al. #34240, Agui Fernandez et al. #34241, Adami et al. #34247, Osborne et al. #34248, Mangan et al. #34249, Quadri et al. #34250, Agui Fernandez et al. #34251, Leonini et al. #34252, Ruocco et al. #34253, Pavoni et al. #34254, Lopresti et al. #34259, Anderson et al. #34267, Sanada et al. #34268, and Agui Fernandez et al. #34271) with the optical three color (g', Rc, and Ic) CCD cameras attached to the 105 cm Murikabushi telescope of Ishigakijima Astronomical Observatory, Okinawa, Japan.=20
The observation with a series of 60 sec exposures started at 2023-07-23 12:21:20.29 UT (2328 seconds after the Swift/BAT detection). In the stacked image at 3193 seconds after the burst, we detected an object of g'=3D20.5+/-0.2, Rc=3D19.4+/-0.1, and Ic=3D19.6+/-0.1 at the coordinate reported by Agui Fernandez et al. #34251. We also report the g=E2=80=99-, Rc- and Ic-band 5-sigma upper limits of the stacked images.
```
TT0+[sec] | MID-UT | T-EXP[sec] | candidate magnitudes | 5-sigma limits
------------------------------------------------------------------------------------------------
3193 | 2023-07-23 12:35:45 | 1080 | g'=3D20.5+/-0.2, Rc=3D19.4+/-0.1, Ic=3D=19.6+/-0.1 | g'>20.6, Rc>21.2, Ic>20.1
------------------------------------------------------------------------------------------------
```
T0+ : Elapsed time after the burst T-EXP: Total Exposure time
We used PS1 catalog for flux calibration. The conversion from PS1 r and i band to our Rc and Ic band is by the equation of Tonry et al. (2012), Table. 6. The magnitudes are expressed in the AB system. The images were processed through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).
GCN Circular #34297
T. Sakamoto (AGU), S. D. Barthelmy (GSFC), 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), M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+60 sec from the recent telemetry downlink, we report further analysis of BAT GRB 230723B (trigger #1180410) (Page, et al., GCN Circ. 34234). The BAT ground-calculated position is RA, Dec = 250.391, -5.319 deg which is
```
   RA(J2000)  =  16h 41m 33.8s 
   Dec(J2000) = -05d 19' 08.1" 
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 39%.
The light curve shows a fast rise exponential decay type profile. T90 (15-350 keV) is 6.64 +- 0.81 sec (estimated error including systematics).
The time-averaged spectrum from T-0.22 to T+7.94 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.09 +- 0.38, and Epeak of 65.9 +- 15.8 keV (chi squared 41.57 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.7 +- 0.1 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T+1.64 sec in the 15-150 keV band is 5.1 +- 0.5 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.77 +- 0.08 (chi squared 52.21 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/1180410/BA/

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