Gamma-ray Burst 240523A

(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:     Thu 23 May 24 14:43:50 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1230423,   Seg_Num: 0
GRB_RA:           33.567d {+02h 14m 16s} (J2000),
                  33.849d {+02h 15m 24s} (current),
                  32.989d {+02h 11m 57s} (1950)
GRB_DEC:         -22.020d {-22d 01' 12"} (J2000),
                 -21.907d {-21d 54' 26"} (current),
                 -22.253d {-22d 15' 10"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       10596 [cnts]    Image_Peak=281 [image_cnts]
TRIGGER_DUR:     4.096 [sec] 
TRIGGER_INDEX:   292     E_range: 15-50 keV
BKG_INTEN:       92122 [cnts]
BKG_TIME:        52934.50 SOD {14:42:14.50} UT
BKG_DUR:         40 [sec]
GRB_DATE:        20453 TJD;   144 DOY;   24/05/23
GRB_TIME:        52991.90 SOD {14:43:11.90} UT
GRB_PHI:          -5.33 [deg]
GRB_THETA:        42.59 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     8.54 [sigma]
IMAGE_SIGNIF:    8.50 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +1  -1  +0  +0 -63  +0 
SUN_POSTN:        60.91d {+04h 03m 39s}  +20.75d {+20d 44' 47"}
SUN_DIST:         50.17 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.66d {+16h 02m 38s}  -24.57d {-24d 33' 58"}
MOON_DIST:       126.73 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.27,-70.51 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       22.57,-33.22 [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 = 279.27,8.90 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 May 24 14:45:46 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1230423,   Seg_Num: 0
POINT_RA:         33.559d {+02h 14m 14s} (J2000)
POINT_DEC:       -22.027d {-22d 01' 38"} (J2000)
IMG_START_DATE:  20453 TJD;   144 DOY;   24/05/23
IMG_START_TIME:  53139.62 SOD {14:45:39.62} UT,   147.7 [sec] since BAT Trigger Time
COUNTS:          10    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 May 24 14:47:38 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1230423,   Seg_Num: 0
GRB_RA:           33.567d {+02h 14m 16s} (J2000),
                  33.849d {+02h 15m 24s} (current),
                  32.989d {+02h 11m 57s} (1950)
GRB_DEC:         -22.020d {-22d 01' 12"} (J2000),
                 -21.907d {-21d 54' 26"} (current),
                 -22.253d {-22d 15' 10"} (1950)
GRB_DATE:        20453 TJD;   144 DOY;   24/05/23
GRB_TIME:        52991.90 SOD {14:43:11.90} UT
TRIGGER_INDEX:   292
GRB_PHI:          -5.33 [deg]
GRB_THETA:        42.59 [deg]
DELTA_TIME:      19.00 [sec]
TRIGGER_DUR:     4.096 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     8.54 [sigma]
IMAGE_SIGNIF:    8.50 [sigma]
LC_URL:          sw01230423000msb.lc
SUN_POSTN:        60.91d {+04h 03m 39s}  +20.75d {+20d 44' 49"}
SUN_DIST:         50.17 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.70d {+16h 02m 47s}  -24.58d {-24d 34' 29"}
MOON_DIST:       126.70 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.27,-70.51 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       22.57,-33.22 [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 = 279.27,8.90 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 May 24 14:48:31 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1230423,   Seg_Num: 0
POINT_RA:         33.559d {+02h 14m 14s} (J2000)
POINT_DEC:       -22.027d {-22d 01' 35"} (J2000)
POINT_ROLL:      33.877d
IMG_START_DATE:  20453 TJD;   144 DOY;   24/05/23
IMG_START_TIME:  53143.04 SOD {14:45:43.04} UT,   151.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.061
N_STARS:         13
X_OFFSET:        551 [pixels]
Y_OFFSET:        542 [pixels]
X_MAX:           1510 [pixels]
Y_MAX:           1501 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    9
SL_URL:          sw01230423000msufc0151.fits
SUN_POSTN:        60.91d {+04h 03m 39s}  +20.75d {+20d 44' 49"}
SUN_DIST:         50.18 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.70d {+16h 02m 49s}  -24.58d {-24d 34' 37"}
MOON_DIST:       126.69 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.28,-70.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       22.56,-33.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 May 24 14:48:39 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1230423,   Seg_Num: 0
POINT_RA:         33.559d {+02h 14m 14s} (J2000)
POINT_DEC:       -22.027d {-22d 01' 35"} (J2000)
POINT_ROLL:      33.877d
IMG_START_DATE:  20453 TJD;   144 DOY;   24/05/23
IMG_START_TIME:  53143.04 SOD {14:45:43.04} UT,   151.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.061
N_STARS:         13
X_OFFSET:        551 [pixels]
Y_OFFSET:        542 [pixels]
X_MAX:           1510 [pixels]
Y_MAX:           1501 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    9
SL_URL:          sw01230423000msufc0151.fits
SUN_POSTN:        60.91d {+04h 03m 39s}  +20.75d {+20d 44' 49"}
SUN_DIST:         50.18 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.71d {+16h 02m 49s}  -24.58d {-24d 34' 38"}
MOON_DIST:       126.68 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.28,-70.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       22.56,-33.23 [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:     Thu 23 May 24 14:49:54 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1230423,   Seg_Num: 0
POINT_RA:         33.559d {+02h 14m 14s} (J2000)
POINT_DEC:       -22.027d {-22d 01' 35"} (J2000)
ROLL:            33.877d
IMG_START_DATE:  20453 TJD;   144 DOY;   24/05/23
IMG_START_TIME:  53143.04 SOD {14:45:43.04} UT,   151.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     738168376
X_OFFSET:        870 [pixels]
Y_OFFSET:        861 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1030
Y_GRB_POS:       1021
BINNING_INDEX:   1
IM_URL:          sw01230423000msuni0185.fits
SUN_POSTN:        60.91d {+04h 03m 40s}  +20.75d {+20d 44' 50"}
SUN_DIST:         50.19 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.72d {+16h 02m 52s}  -24.58d {-24d 34' 48"}
MOON_DIST:       126.68 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.28,-70.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       22.56,-33.23 [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:     Thu 23 May 24 14:50:08 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1230423,   Seg_Num: 0
POINT_RA:         33.559d {+02h 14m 14s} (J2000)
POINT_DEC:       -22.027d {-22d 01' 35"} (J2000)
ROLL:            33.877d
IMG_START_DATE:  20453 TJD;   144 DOY;   24/05/23
IMG_START_TIME:  53143.04 SOD {14:45:43.04} UT,   151.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     738168376
X_OFFSET:        870 [pixels]
Y_OFFSET:        861 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1030
Y_GRB_POS:       1021
BINNING_INDEX:   1
IM_URL:          sw01230423000msuni0185.fits
SUN_POSTN:        60.92d {+04h 03m 40s}  +20.75d {+20d 44' 50"}
SUN_DIST:         50.19 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.72d {+16h 02m 53s}  -24.58d {-24d 34' 50"}
MOON_DIST:       126.68 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.28,-70.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       22.56,-33.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 May 24 14:54:45 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1230423,   Seg_Num: 0
POINT_RA:         33.558d {+02h 14m 14s} (J2000)
POINT_DEC:       -22.027d {-22d 01' 35"} (J2000)
POINT_ROLL:      33.878d
IMG_START_DATE:  20453 TJD;   144 DOY;   24/05/23
IMG_START_TIME:  53301.57 SOD {14:48:21.57} UT,   309.7 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.328
N_STARS:         18
X_OFFSET:        311 [pixels]
Y_OFFSET:        302 [pixels]
X_MAX:           1750 [pixels]
Y_MAX:           1741 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw01230423000msufc0309.fits
SUN_POSTN:        60.92d {+04h 03m 40s}  +20.75d {+20d 44' 52"}
SUN_DIST:         50.19 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.76d {+16h 03m 03s}  -24.59d {-24d 35' 27"}
MOON_DIST:       126.65 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.28,-70.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       22.56,-33.22 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 May 24 14:54:55 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1230423,   Seg_Num: 0
POINT_RA:         33.558d {+02h 14m 14s} (J2000)
POINT_DEC:       -22.027d {-22d 01' 35"} (J2000)
POINT_ROLL:      33.878d
IMG_START_DATE:  20453 TJD;   144 DOY;   24/05/23
IMG_START_TIME:  53301.57 SOD {14:48:21.57} UT,   309.7 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.328
N_STARS:         18
X_OFFSET:        311 [pixels]
Y_OFFSET:        302 [pixels]
X_MAX:           1750 [pixels]
Y_MAX:           1741 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw01230423000msufc0309.fits
SUN_POSTN:        60.92d {+04h 03m 40s}  +20.75d {+20d 44' 52"}
SUN_DIST:         50.19 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.77d {+16h 03m 04s}  -24.59d {-24d 35' 29"}
MOON_DIST:       126.64 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.28,-70.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       22.56,-33.22 [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:     Thu 23 May 24 14:56:07 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1230423,   Seg_Num: 0
POINT_RA:         33.558d {+02h 14m 14s} (J2000)
POINT_DEC:       -22.027d {-22d 01' 35"} (J2000)
ROLL:            33.878d
IMG_START_DATE:  20453 TJD;   144 DOY;   24/05/23
IMG_START_TIME:  53301.57 SOD {14:48:21.57} UT,   309.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     738168535
X_OFFSET:        870 [pixels]
Y_OFFSET:        861 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1030
Y_GRB_POS:       1021
BINNING_INDEX:   1
IM_URL:          sw01230423000msuni0343.fits
SUN_POSTN:        60.92d {+04h 03m 41s}  +20.75d {+20d 44' 53"}
SUN_DIST:         50.19 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.78d {+16h 03m 06s}  -24.59d {-24d 35' 39"}
MOON_DIST:       126.64 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.28,-70.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       22.56,-33.22 [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:     Thu 23 May 24 14:56:23 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1230423,   Seg_Num: 0
POINT_RA:         33.558d {+02h 14m 14s} (J2000)
POINT_DEC:       -22.027d {-22d 01' 35"} (J2000)
ROLL:            33.878d
IMG_START_DATE:  20453 TJD;   144 DOY;   24/05/23
IMG_START_TIME:  53301.57 SOD {14:48:21.57} UT,   309.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     738168535
X_OFFSET:        870 [pixels]
Y_OFFSET:        861 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1030
Y_GRB_POS:       1021
BINNING_INDEX:   1
IM_URL:          sw01230423000msuni0343.fits
SUN_POSTN:        60.92d {+04h 03m 41s}  +20.75d {+20d 44' 53"}
SUN_DIST:         50.19 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.78d {+16h 03m 07s}  -24.59d {-24d 35' 41"}
MOON_DIST:       126.63 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.28,-70.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       22.56,-33.22 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 May 24 15:00:15 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1230423,   Seg_Num: 0
GRB_RA:           33.5681d {+02h 14m 16.34s} (J2000),
                  33.8502d {+02h 15m 24.05s} (current),
                  32.9898d {+02h 11m 57.54s} (1950)
GRB_DEC:         -22.0332d {-22d 01' 59.5"} (J2000),
                 -21.9202d {-21d 55' 12.8"} (current),
                 -22.2659d {-22d 15' 57.4"} (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:  20453 TJD;   144 DOY;   24/05/23
IMG_START_TIME:  53147.00 SOD {14:45:47.00} UT,   155.1 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        60.92d {+04h 03m 41s}  +20.75d {+20d 44' 55"}
SUN_DIST:         50.19 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.82d {+16h 03m 16s}  -24.60d {-24d 36' 12"}
MOON_DIST:       126.61 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.31,-70.52 [deg] galactic lon,lat of the burst
ECL_COORDS:       22.57,-33.23 [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:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 1.1% < P(seren) < 2.8%.

GCN Circular #36536
M. H. Siegel (PSU), J.D. Gropp (PSU), R. Gupta (NASA/GSFC), J. A. Kennea (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII), H. A. Krimm (NSF), K. L. Page (U Leicester), D. M. Palmer (LANL) and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 14:43:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 240523A (trigger=1230423). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 33.567, -22.020 which is
```
   RA(J2000) = 02h 14m 16s
   Dec(J2000) = -22d 01' 12"
```
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 40 sec. The peak count rate was ~800 counts/sec (15-350 keV), at ~-1 sec after the trigger.
The XRT began observing the field at 14:45:39.6 UT, 147.7 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 33.56813, -22.03320 which is equivalent to:
```
   RA(J2000)  = 02h 14m 16.35s
   Dec(J2000) = -22d 01' 59.5"
```
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 47 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. No spectrum from the promptly downlinked event data is yet available to determine the column density.
UVOT took a finding chart exposure of 150 seconds with the White filter starting 151 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 25% of the BAT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the BAT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.015.
Burst Advocate for this burst is M. H. Siegel (siegel AT swift.psu.edu). 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:     Thu 23 May 24 15:05:01 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1230423,   Seg_Num: 0
POINT_RA:         33.558d {+02h 14m 14s} (J2000)
POINT_DEC:       -22.027d {-22d 01' 36"} (J2000)
POINT_ROLL:      33.878d
IMG_START_DATE:  20453 TJD;   144 DOY;   24/05/23
IMG_START_TIME:  53855.79 SOD {14:57:35.79} UT,   863.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.250
N_STARS:         27
X_OFFSET:        311 [pixels]
Y_OFFSET:        302 [pixels]
X_MAX:           1750 [pixels]
Y_MAX:           1741 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    13
SL_URL:          sw01230423000msufc0863.fits
SUN_POSTN:        60.93d {+04h 03m 42s}  +20.75d {+20d 44' 57"}
SUN_DIST:         50.19 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.86d {+16h 03m 27s}  -24.61d {-24d 36' 51"}
MOON_DIST:       126.58 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.28,-70.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       22.56,-33.22 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 May 24 15:05:18 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1230423,   Seg_Num: 0
POINT_RA:         33.558d {+02h 14m 14s} (J2000)
POINT_DEC:       -22.027d {-22d 01' 36"} (J2000)
POINT_ROLL:      33.878d
IMG_START_DATE:  20453 TJD;   144 DOY;   24/05/23
IMG_START_TIME:  53855.79 SOD {14:57:35.79} UT,   863.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.250
N_STARS:         27
X_OFFSET:        311 [pixels]
Y_OFFSET:        302 [pixels]
X_MAX:           1750 [pixels]
Y_MAX:           1741 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    13
SL_URL:          sw01230423000msufc0863.fits
SUN_POSTN:        60.93d {+04h 03m 42s}  +20.75d {+20d 44' 57"}
SUN_DIST:         50.19 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.86d {+16h 03m 27s}  -24.62d {-24d 36' 53"}
MOON_DIST:       126.58 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.28,-70.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       22.56,-33.22 [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:     Thu 23 May 24 15:07:16 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1230423,   Seg_Num: 0
POINT_RA:         33.558d {+02h 14m 14s} (J2000)
POINT_DEC:       -22.027d {-22d 01' 36"} (J2000)
ROLL:            33.878d
IMG_START_DATE:  20453 TJD;   144 DOY;   24/05/23
IMG_START_TIME:  53855.79 SOD {14:57:35.79} UT,   863.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     738169089
X_OFFSET:        870 [pixels]
Y_OFFSET:        861 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1030
Y_GRB_POS:       1021
BINNING_INDEX:   1
IM_URL:          sw01230423000msuni0897.fits
SUN_POSTN:        60.93d {+04h 03m 42s}  +20.75d {+20d 44' 58"}
SUN_DIST:         50.19 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.88d {+16h 03m 32s}  -24.62d {-24d 37' 09"}
MOON_DIST:       126.56 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.28,-70.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       22.56,-33.22 [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:     Thu 23 May 24 15:07:33 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1230423,   Seg_Num: 0
POINT_RA:         33.558d {+02h 14m 14s} (J2000)
POINT_DEC:       -22.027d {-22d 01' 36"} (J2000)
ROLL:            33.878d
IMG_START_DATE:  20453 TJD;   144 DOY;   24/05/23
IMG_START_TIME:  53855.79 SOD {14:57:35.79} UT,   863.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     738169089
X_OFFSET:        870 [pixels]
Y_OFFSET:        861 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1030
Y_GRB_POS:       1021
BINNING_INDEX:   1
IM_URL:          sw01230423000msuni0897.fits
SUN_POSTN:        60.93d {+04h 03m 43s}  +20.75d {+20d 44' 58"}
SUN_DIST:         50.19 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      240.88d {+16h 03m 32s}  -24.62d {-24d 37' 12"}
MOON_DIST:       126.56 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      202.28,-70.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       22.56,-33.22 [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 #36537
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 3015 s of XRT Photon Counting mode data and 7 UVOT images for GRB 240523A, 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 = 33.56798, -22.03336 which is equivalent to:
```
RA (J2000): 02h 14m 16.31s
Dec (J2000): -22d 02' 00.1"
```
with an uncertainty of 2.1 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 #36538
R. Brivio (INAF-OAB), D.N. Burrows (PSU), J. D. Gropp (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 6.5 ks of XRT data for GRB 240523A, from 132 s to 27.6 ks after the BAT trigger. The data comprise 8 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode.
The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=2.8 (+0.6, -0.4). At T+400 s the decay flattens to an alpha of -0.4 (+0.3, -0.5) before breaking again at T+2137 s to a final decay with index alpha=1.41 (+0.26, -0.24).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.06 (+0.24, -0.22). The best-fitting absorption column is 1.1 (+0.6, -0.5) x 10^21 cm^-2, in excess of the Galactic value of 1.6 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 (4.2 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.1 (+0.6, -0.5) x 10^21 cm^-2
Galactic foreground: 1.6 x 10^20 cm^-2
Excess significance: 2.9 sigma
Photon index:	     2.06 (+0.24, -0.22)
```
If the light curve continues to decay with a power-law decay index of 1.41, the count rate at T+24 hours will be 2.0 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.5 x 10^-14 (8.2 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01230423.
This circular is an official product of the Swift-XRT team.
GCN Circular #36543
A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU), M. H. Siegel (PSU) (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 240523A (trigger #1230423) (Siegel et al., GCN Circ. 36536). The BAT ground-calculated position is RA, Dec = 33.537, -22.053 deg which is
```
   RA(J2000)  =  02h 14m 08.9s
   Dec(J2000) = -22d 03' 10.6"
```
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 47%.
The mask-weighted light curve shows a multi-peaked structure that starts at ~T-6 s and ends at ~T+46 s. The main peak occurs at ~T+1 s. T90 (15-350 keV) is 41.93 +- 8.66 sec (estimated error including systematics).
The time-averaged spectrum from T-6.37 to T+46.30 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.07 +- 0.20. The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.18 sec in the 15-150 keV band is 1.0 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1230423

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Jochen Greiner, last update: 26-May-2024 [Disclaimer]