Gamma-ray Burst 240809A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:30:42 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1247745,   Seg_Num: 0
GRB_RA:          237.551d {+15h 50m 12s} (J2000),
                 237.871d {+15h 51m 29s} (current),
                 236.901d {+15h 47m 36s} (1950)
GRB_DEC:          -2.321d {-02d 19' 15"} (J2000),
                  -2.394d {-02d 23' 38"} (current),
                  -2.170d {-02d 10' 12"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       3713 [cnts]    Image_Peak=294 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   127     E_range: 50-350 keV
BKG_INTEN:       14170 [cnts]
BKG_TIME:        30614.04 SOD {08:30:14.04} UT
BKG_DUR:         8 [sec]
GRB_DATE:        20531 TJD;   222 DOY;   24/08/09
GRB_TIME:        30629.59 SOD {08:30:29.59} UT
GRB_PHI:         162.16 [deg]
GRB_THETA:        28.33 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     90.07 [sigma]
IMAGE_SIGNIF:    12.85 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +3  +2  +0  +0 +13  +0 
SUN_POSTN:       139.70d {+09h 18m 48s}  +15.66d {+15d 39' 44"}
SUN_DIST:         98.51 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.26d {+12h 41m 01s}   -4.85d {-04d 51' 04"}
MOON_DIST:        47.57 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      235.83, 17.35 [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 = 143.36,19.41 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:32:32 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     1247745,   Seg_Num: 0
GRB_RA:          237.5464d {+15h 50m 11.1s} (J2000),
                 237.8664d {+15h 51m 27.9s} (current),
                 236.8967d {+15h 47m 35.2s} (1950)
GRB_DEC:          -2.3178d {-02d 19' 04.0"} (J2000),
                  -2.3910d {-02d 23' 27.5"} (current),
                  -2.1671d {-02d 10' 01.4"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       158 [cnts]
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  30717.90 SOD {08:31:57.90} UT,   88.3 [sec] since BAT Trigger Time
CENTROID_X:      306.16,  raw= 306  [pixels]
CENTROID_Y:      296.75,  raw= 297  [pixels]
ROLL:            285.48 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -3.16
GRB_POS_XRT_Z:   -2.90
IMAGE_URL:       sw01247745000msxps_rw.img
SUN_POSTN:       139.70d {+09h 18m 48s}  +15.66d {+15d 39' 43"}
SUN_DIST:         98.51 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.27d {+12h 41m 04s}   -4.86d {-04d 51' 30"}
MOON_DIST:        47.56 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the burst
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:32:34 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     1247745,   Seg_Num: 0
GRB_RA:          237.5464d {+15h 50m 11.1s} (J2000),
                 237.8664d {+15h 51m 27.9s} (current),
                 236.8967d {+15h 47m 35.2s} (1950)
GRB_DEC:          -2.3178d {-02d 19' 04.0"} (J2000),
                  -2.3910d {-02d 23' 27.5"} (current),
                  -2.1671d {-02d 10' 01.4"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       158 [cnts]
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  30717.90 SOD {08:31:57.90} UT,   88.3 [sec] since BAT Trigger Time
CENTROID_X:      306.16,  raw= 306  [pixels]
CENTROID_Y:      296.75,  raw= 297  [pixels]
ROLL:            285.48 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -3.16
GRB_POS_XRT_Z:   -2.90
IMAGE_URL:       sw01247745000msxps_rw.img
SUN_POSTN:       139.70d {+09h 18m 48s}  +15.66d {+15d 39' 43"}
SUN_DIST:         98.51 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.27d {+12h 41m 04s}   -4.86d {-04d 51' 30"}
MOON_DIST:        47.56 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the burst
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:32:22 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1247745,   Seg_Num: 0
GRB_RA:          237.5464d {+15h 50m 11.13s} (J2000),
                 237.8664d {+15h 51m 27.94s} (current),
                 236.8967d {+15h 47m 35.21s} (1950)
GRB_DEC:          -2.3178d {-02d 19' 04.0"} (J2000),
                  -2.3910d {-02d 23' 27.5"} (current),
                  -2.1671d {-02d 10' 01.4"} (1950)
GRB_ERROR:       4.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       4.67e-09 [erg/cm2/sec]
GRB_SIGNIF:      12.56 [sigma]
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  30717.90 SOD {08:31:57.90} UT,   88.3 [sec] since BAT Trigger Time
TAM[0-3]:        327.65 237.16 261.60 243.72
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       139.70d {+09h 18m 48s}  +15.66d {+15d 39' 43"}
SUN_DIST:         98.51 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.27d {+12h 41m 04s}   -4.86d {-04d 51' 28"}
MOON_DIST:        47.56 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the burst
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.35 arcmin from the BAT position.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:34:19 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1247745,   Seg_Num: 0
GRB_RA:          237.551d {+15h 50m 12s} (J2000),
                 237.871d {+15h 51m 29s} (current),
                 236.901d {+15h 47m 36s} (1950)
GRB_DEC:          -2.321d {-02d 19' 15"} (J2000),
                  -2.394d {-02d 23' 38"} (current),
                  -2.170d {-02d 10' 12"} (1950)
GRB_DATE:        20531 TJD;   222 DOY;   24/08/09
GRB_TIME:        30629.59 SOD {08:30:29.59} UT
TRIGGER_INDEX:   127
GRB_PHI:         162.16 [deg]
GRB_THETA:        28.33 [deg]
DELTA_TIME:      45.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     90.07 [sigma]
IMAGE_SIGNIF:    12.85 [sigma]
LC_URL:          sw01247745000msb.lc
SUN_POSTN:       139.70d {+09h 18m 48s}  +15.66d {+15d 39' 41"}
SUN_DIST:         98.51 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.28d {+12h 41m 08s}   -4.87d {-04d 51' 55"}
MOON_DIST:        47.55 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      235.83, 17.35 [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 = 143.36,19.41 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:34:59 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1247745,   Seg_Num: 0
POINT_RA:        237.547d {+15h 50m 11s} (J2000)
POINT_DEC:        -2.318d {-02d 19' 06"} (J2000)
POINT_ROLL:      285.481d
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  30727.59 SOD {08:32:07.59} UT,   98.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.806
N_STARS:         94
X_OFFSET:        440 [pixels]
Y_OFFSET:        552 [pixels]
X_MAX:           1399 [pixels]
Y_MAX:           1511 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw01247745000msufc0097.fits
SUN_POSTN:       139.70d {+09h 18m 49s}  +15.66d {+15d 39' 41"}
SUN_DIST:         98.50 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.29d {+12h 41m 09s}   -4.87d {-04d 52' 04"}
MOON_DIST:        47.54 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:35:11 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1247745,   Seg_Num: 0
POINT_RA:        237.547d {+15h 50m 11s} (J2000)
POINT_DEC:        -2.318d {-02d 19' 06"} (J2000)
POINT_ROLL:      285.481d
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  30727.59 SOD {08:32:07.59} UT,   98.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.806
N_STARS:         94
X_OFFSET:        440 [pixels]
Y_OFFSET:        552 [pixels]
X_MAX:           1399 [pixels]
Y_MAX:           1511 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw01247745000msufc0097.fits
SUN_POSTN:       139.70d {+09h 18m 49s}  +15.66d {+15d 39' 41"}
SUN_DIST:         98.50 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.29d {+12h 41m 09s}   -4.87d {-04d 52' 07"}
MOON_DIST:        47.54 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:36:28 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1247745,   Seg_Num: 0
POINT_RA:        237.547d {+15h 50m 11s} (J2000)
POINT_DEC:        -2.318d {-02d 19' 06"} (J2000)
ROLL:            285.481d
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  30727.59 SOD {08:32:07.59} UT,   98.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     744885161
X_OFFSET:        798 [pixels]
Y_OFFSET:        872 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       958
Y_GRB_POS:       1032
BINNING_INDEX:   1
IM_URL:          sw01247745000msuni0131.fits
SUN_POSTN:       139.70d {+09h 18m 49s}  +15.66d {+15d 39' 40"}
SUN_DIST:         98.50 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.30d {+12h 41m 11s}   -4.87d {-04d 52' 25"}
MOON_DIST:        47.53 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:36:38 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1247745,   Seg_Num: 0
POINT_RA:        237.547d {+15h 50m 11s} (J2000)
POINT_DEC:        -2.318d {-02d 19' 06"} (J2000)
ROLL:            285.481d
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  30727.59 SOD {08:32:07.59} UT,   98.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     744885161
X_OFFSET:        798 [pixels]
Y_OFFSET:        872 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       958
Y_GRB_POS:       1032
BINNING_INDEX:   1
IM_URL:          sw01247745000msuni0131.fits
SUN_POSTN:       139.70d {+09h 18m 49s}  +15.66d {+15d 39' 40"}
SUN_DIST:         98.50 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.30d {+12h 41m 12s}   -4.87d {-04d 52' 27"}
MOON_DIST:        47.53 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:37:21 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     1247745,   Seg_Num: 0
GRB_RA:          237.5438d {+15h 50m 10.51s} (J2000),
                 237.8638d {+15h 51m 27.31s} (current),
                 236.8941d {+15h 47m 34.58s} (1950)
GRB_DEC:          -2.3175d {-02d 19' 02.9"} (J2000),
                  -2.3907d {-02d 23' 26.4"} (current),
                  -2.1668d {-02d 10' 00.3"} (1950)
GRB_ERROR:       0.6 [arcsec radius, statistical only]
GRB_MAG:         14.47 +/- 0.14 [mag]
FILTER:          10, White
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  30724.00 SOD {08:32:04.00} UT,   94.4 [sec] since BAT Trigger Time
SUN_POSTN:       139.70d {+09h 18m 49s}  +15.66d {+15d 39' 39"}
SUN_DIST:         98.50 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.30d {+12h 41m 13s}   -4.88d {-04d 52' 37"}
MOON_DIST:        47.52 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.87 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The UVOT position is 9.4 arcsec from the XRT position.  
COMMENTS:        Result based on Genie data.  
COMMENTS:        Notice generated automatically.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:41:38 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1247745,   Seg_Num: 0
POINT_RA:        237.547d {+15h 50m 11s} (J2000)
POINT_DEC:        -2.318d {-02d 19' 03"} (J2000)
POINT_ROLL:      285.481d
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  30939.43 SOD {08:35:39.43} UT,   309.8 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.708
N_STARS:         52
X_OFFSET:        478 [pixels]
Y_OFFSET:        552 [pixels]
X_MAX:           1437 [pixels]
Y_MAX:           1511 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw01247745000msufc0309.fits
SUN_POSTN:       139.71d {+09h 18m 50s}  +15.66d {+15d 39' 36"}
SUN_DIST:         98.50 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.33d {+12h 41m 20s}   -4.89d {-04d 53' 37"}
MOON_DIST:        47.49 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:41:47 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1247745,   Seg_Num: 0
POINT_RA:        237.547d {+15h 50m 11s} (J2000)
POINT_DEC:        -2.318d {-02d 19' 03"} (J2000)
POINT_ROLL:      285.481d
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  30939.43 SOD {08:35:39.43} UT,   309.8 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.708
N_STARS:         52
X_OFFSET:        478 [pixels]
Y_OFFSET:        552 [pixels]
X_MAX:           1437 [pixels]
Y_MAX:           1511 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw01247745000msufc0309.fits
SUN_POSTN:       139.71d {+09h 18m 50s}  +15.66d {+15d 39' 36"}
SUN_DIST:         98.50 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.34d {+12h 41m 21s}   -4.89d {-04d 53' 39"}
MOON_DIST:        47.49 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN Circular #37110
P. A. Evans (U Leicester), R. A. J. Eyles-Ferris (U Leicester), K. L. Page (U Leicester) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 08:30:29 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 240809A (trigger=1247745). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 237.551, -2.321 which is
```
   RA(J2000) = 15h 50m 12s
   Dec(J2000) = -02d 19' 15"
```
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 30 sec. The peak count rate was ~22500 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 08:31:57.9 UT, 88.3 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 237.5464, -2.3178 which is equivalent to:
```
   RA(J2000)  = 15h 50m 11.14s
   Dec(J2000) = -02d 19' 04.1"
```
with an uncertainty of 12 arcseconds (radius, 90% containment). This location is 20 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy.
UVOT took a finding chart exposure of 150 seconds with the White filter starting 98 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	15:50:10.51 = 237.54381
  DEC(J2000) = -02:19:03.2  =  -2.31756
```
with a 90%-confidence error radius of about 0.61 arc sec. This position is 9.4 arc sec. from the center of the XRT error circle. The estimated magnitude is 14.47 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.249.
Burst Advocate for this burst is P. A. Evans (pae9 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:     Fri 09 Aug 24 08:48:04 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1247745,   Seg_Num: 0
POINT_RA:        237.547d {+15h 50m 11s} (J2000)
POINT_DEC:        -2.318d {-02d 19' 02"} (J2000)
POINT_ROLL:      285.482d
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  31494.16 SOD {08:44:54.16} UT,   864.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.547
N_STARS:         190
X_OFFSET:        238 [pixels]
Y_OFFSET:        312 [pixels]
X_MAX:           1677 [pixels]
Y_MAX:           1751 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw01247745000msufc0864.fits
SUN_POSTN:       139.71d {+09h 18m 51s}  +15.66d {+15d 39' 31"}
SUN_DIST:         98.50 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.38d {+12h 41m 31s}   -4.92d {-04d 55' 06"}
MOON_DIST:        47.45 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:49:18 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1247745,   Seg_Num: 0
POINT_RA:        237.547d {+15h 50m 11s} (J2000)
POINT_DEC:        -2.318d {-02d 19' 02"} (J2000)
ROLL:            285.482d
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  31494.16 SOD {08:44:54.16} UT,   864.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     744885928
X_OFFSET:        797 [pixels]
Y_OFFSET:        871 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       957
Y_GRB_POS:       1031
BINNING_INDEX:   1
IM_URL:          sw01247745000msuni0898.fits
SUN_POSTN:       139.71d {+09h 18m 51s}  +15.66d {+15d 39' 30"}
SUN_DIST:         98.50 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.39d {+12h 41m 34s}   -4.92d {-04d 55' 23"}
MOON_DIST:        47.44 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:49:31 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1247745,   Seg_Num: 0
POINT_RA:        237.547d {+15h 50m 11s} (J2000)
POINT_DEC:        -2.318d {-02d 19' 02"} (J2000)
ROLL:            285.482d
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  31494.16 SOD {08:44:54.16} UT,   864.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     744885928
X_OFFSET:        797 [pixels]
Y_OFFSET:        871 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       957
Y_GRB_POS:       1031
BINNING_INDEX:   1
IM_URL:          sw01247745000msuni0898.fits
SUN_POSTN:       139.71d {+09h 18m 51s}  +15.66d {+15d 39' 30"}
SUN_DIST:         98.50 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.39d {+12h 41m 34s}   -4.92d {-04d 55' 26"}
MOON_DIST:        47.44 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:47:50 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1247745,   Seg_Num: 0
POINT_RA:        237.547d {+15h 50m 11s} (J2000)
POINT_DEC:        -2.318d {-02d 19' 02"} (J2000)
POINT_ROLL:      285.482d
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  31494.16 SOD {08:44:54.16} UT,   864.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.547
N_STARS:         190
X_OFFSET:        238 [pixels]
Y_OFFSET:        312 [pixels]
X_MAX:           1677 [pixels]
Y_MAX:           1751 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw01247745000msufc0864.fits
SUN_POSTN:       139.71d {+09h 18m 51s}  +15.66d {+15d 39' 31"}
SUN_DIST:         98.50 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.38d {+12h 41m 31s}   -4.92d {-04d 55' 03"}
MOON_DIST:        47.45 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:43:03 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1247745,   Seg_Num: 0
POINT_RA:        237.547d {+15h 50m 11s} (J2000)
POINT_DEC:        -2.318d {-02d 19' 03"} (J2000)
ROLL:            285.481d
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  30939.43 SOD {08:35:39.43} UT,   309.8 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     744885373
X_OFFSET:        798 [pixels]
Y_OFFSET:        872 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       958
Y_GRB_POS:       1032
BINNING_INDEX:   1
IM_URL:          sw01247745000msuni0343.fits
SUN_POSTN:       139.71d {+09h 18m 50s}  +15.66d {+15d 39' 35"}
SUN_DIST:         98.50 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.34d {+12h 41m 23s}   -4.90d {-04d 53' 56"}
MOON_DIST:        47.48 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 09 Aug 24 08:43:17 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1247745,   Seg_Num: 0
POINT_RA:        237.547d {+15h 50m 11s} (J2000)
POINT_DEC:        -2.318d {-02d 19' 03"} (J2000)
ROLL:            285.481d
IMG_START_DATE:  20531 TJD;   222 DOY;   24/08/09
IMG_START_TIME:  30939.43 SOD {08:35:39.43} UT,   309.8 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     744885373
X_OFFSET:        798 [pixels]
Y_OFFSET:        872 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       958
Y_GRB_POS:       1032
BINNING_INDEX:   1
IM_URL:          sw01247745000msuni0343.fits
SUN_POSTN:       139.71d {+09h 18m 50s}  +15.66d {+15d 39' 35"}
SUN_DIST:         98.50 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.35d {+12h 41m 23s}   -4.90d {-04d 54' 00"}
MOON_DIST:        47.48 [deg]
MOON_ILLUM:      21 [%]
GAL_COORDS:        5.81, 37.86 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      235.82, 17.35 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN Circular #37113
SVOM/GRM team: Chen-Wei Wang, Yue Huang, Yong-Wei Dong, Jiang-Tao Liu, Shi-= Jie Zheng, Jian-Chao Sun, Wen-Jun Tan, Jiang He, Min Gao, Hao-Xuan Guo, Lu = Li, Yong-Ye Li, Hong-Wei Liu, Xin Liu, Hao-Li Shi, Li-Ming Song, You-Li Tuo= , Hao-Xi Wang, Jin Wang, Jin-Zhou Wang, Ping Wang, Rui-Jie Wang, Yu-Xi Wang= , Bo-Bing Wu, Shao-Lin Xiong, Jian-Ying Ye, Yi-Tao Yin, Wen-Hui Yu, Fan Zha= ng, Li Zhang, Peng Zhang, Shuang-Nan Zhang, Wen-Long Zhang, Yan-Ting Zhang,= Shu-Min Zhao, Xiao-Yun Zhao, Chao Zheng (IHEP), Maria-Grazia Bernardini (L= UPM/INAF-OAB), Laurent Bouchet (IRAP), David Corre (CEA), Tais Maiolino (LU= PM), Fr=C3=A9d=C3=A9ric Piron (LUPM) , St=C3=A9phane Schanne (CEA), Jingwei= Wang (IAP)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (I= HEP), St=C3=A9phane Basa (LAM), JeanLuc Att=C3=A9ia (IRAP), Arnaud Claret (= CEA), Zi-Gao Dai (USTC), Fr=C3=A9d=C3=A9ric Daigne (IAP), Jin-Song Deng (NA= OC), Andrea Goldwurm (APC), Diego G=C3=B6tz (CEA), Xu-Hui Han (NAOC), Cyril= Lachaud (APC), En-Wei Liang (GXU), Yu-Lei Qiu (NAOC), Susanna Vergani (Obs= .Paris), Jing Wang (NAOC), Chao Wu (NAOC), Li-Ping Xin (NAOC), Bing Zhang (= UNLV)
report on behalf of the SVOM team:
During the commissioning phase, the SVOM/GRM was triggered in-flight by a l= ong GRB 240809A at 2024-08-09T08:30:28 UT (T0), which also triggered Swift/= BAT (GCN 37110).
The real-time alert data and light curves of SVOM/GRM were downlinked to th= e ground through the VHF system with low latency. The light curves show tha= t this burst consists of a single pulse with a T90 of 13.0+1.1 s.
The GRM light curve can be found here: https://www.bursthub.cn/admin/static/svgrb240809A.png
The Space Variable Objects Monitor (SVOM) is a China-France joint mission l= ed by the Chinese National Space Administration (CNSA, China), National Cen= ter for Space Studies (CNES, France) and the Chinese Academy of Sciences (C= AS, China), which is dedicated to observing gamma-ray bursts and other tran= sient phenomena in the energetic universe. GRM is developed by the Institut= e of High Energy Physics (IHEP) of CAS.
The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang@ih= ep.ac.cn)
GCN Circular #37114
Megan Dubay, Dylan Dutton, Donovan Schlekat, Daniel Reichart, Joshua Haislip, Vladimir Kouprianov, Ruide Fu, Arie Verveer, Daryl Janzen, John Kennewall, Colin Armstrong, Ken Stranger (Skynet Robotic Telescope Network at the University of North Carolina at Chapel Hill); Michael Fitzgerald, Wayne Rosing, Andrew Yen (Photon Ranch/Las Cumbres Observatory).
We observed the field of GRB 240809A with one of the Photon Ranch=E2=80=99s 0.4m telescopes at Eltham College Observatory (ECO1) beginning at ~540s post-trigger by the Swift-BAT instrument. Continuing observations on both the ECO1 telescope and Skynet=E2=80=99s PROMPT telescopes at both Meckering Observatory and Perth Observatory are underway. Our first detection occurred at 09:42 UTC on August 9, 2024, approximately 40 minutes after the optical counterpart discovery by Swift (Evans et al., GCN 37110).
We detect the optical afterglow at coordinates consistent with the reported coordinates from the Swift-UVOT observation.
The coordinates are:
```
R.A. (J2000): 15:50:10.47
Dec. (J2000): -02:19:02.89
```
We report the most recent photometry below. Additional measurements are underway.
```
ExpLen  | Telescope   | Filter | Mag    | Mag Error | MJD        
——————————————————————————————————————————————————————————————————
155     | PROMPT-MO-1 | I      | 17.798 | 0.101     | 60531.4581
186     | PROMPT-MO-1 | R      | 18.125 | 0.069     | 60531.4561
254     | R-COP       | R      | 18.634 | 0.253     | 60531.4669
```
Our images have been calibrated using stars from the APASS catalog.
GCN Circular #37115
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 1278 s of XRT Photon Counting mode data and 3 UVOT images for GRB 240809A, 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 = 237.54399, -2.31789 which is equivalent to:
```
RA (J2000): 15h 50m 10.56s
Dec (J2000): -02d 19' 04.4"
```
with an uncertainty of 2.0 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 #37116
S.Q. Jiang, Z.P. Zhu, S.Y. Fu, X. Liu, J. An, D. Xu (NAOC), J.Z. Liu (XAO) report on behalf of a large collaboration:
We observed the field of GRB 240809A detected by Swift (Evans et al. GCN 37110) using the 100C telescope of the JinShan project located at Altay, Xinjiang, China. A series of 200 s and 300 s frames were obtained in the Sloan g-, r-, i- and z- bands, starting at 15:08:20.24 UT on 2024-08-09, i.e., 6.63 hr after the Swift/BAT trigger.
The optical afterglow (Evans et al. GCN 37110; Dubay et al. GCN 37114) of the burst is clearly detected in our stacked images. Preliminary photometric results are as follows:
```
-----------------------------------------------------------------
Tmid-T0(hr)  Exp(s)   Filter      Mag+/-MagErr
-----------------------------------------------------------------
7.404        3x200      g        20.05 +/- 0.05
7.578        3x200      r        19.86 +/- 0.09
6.758        3x300      i        19.49 +/- 0.04
7.100        5x300      z        19.47 +/- 0.08
-----------------------------------------------------------------
```
calibrated with nearby PanSTARRS stars and not corrected for Galactic extinction.
We acknowledge the excellent support from S.W Luo, M.M. Yang, Z. K. Feng, Q. C. Zhao and L.F. Huo for enabling these observations.
GCN Circular #37117
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 GRB 240809A ( P. A. Evans et al., GCN 37110) errorbox 32075 sec after notice time and 32089 sec after trigger time at 2024-08-09 17:25:19 UT, with upper limit up to 16.4 mag. Observations started at twilight. The observations began at zenith distance = 30 deg. The sun altitude is -16.8 deg.
The galactic latitude b = 37 deg., longitude l = 6 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2556110
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   32180 |         MASTER-SAAO |   C |   180 | 16.4 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #37121
A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), J. D. Gropp (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 6.8 ks of XRT data for GRB 240809A, from 77 s to 45.8 ks after the BAT trigger. The data comprise 1.3 ks in Windowed Timing (WT) mode (the first 9 s were 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=1.02 (+0.06, -0.05). At T+257 s the decay flattens to an alpha of 0.825 (+/-0.028) before breaking again at T+2884 s to a final decay with index alpha=1.57 (+/-0.06).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.706 (+/-0.030). The best-fitting absorption column is 1.94 (+0.13, -0.12) x 10^21 cm^-2, in excess of the Galactic value of 1.5 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.66 (+/-0.10) and a best-fitting absorption column of 1.9 (+/-0.4) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.4 x 10^-11 (5.3 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.9 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 1.5 x 10^21 cm^-2
Excess significance: 1.8 sigma
Photon index:	     1.66 (+/-0.10)
```
If the light curve continues to decay with a power-law decay index of 1.57, the count rate at T+24 hours will be 0.050 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.2 x 10^-12 (2.6 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01247745.
This circular is an official product of the Swift-XRT team.
GCN Circular #37122
Rashmi Gottumukkala (DAWN/NBI), Chandana Chandrasherkhar Hegde (DAWN/DTU), Jens Reersted Larsen (IFA), Ulrika Woulhoj Jakobsen (DTU), Rasmus Damgaard Nielsen (DAWN/NBI), Nikolaj Bjerregaard Sillassen (DAWN/DTU), Albert Bjerregard Sneppen (DAWN/NBI), Johan P. U. Fynbo (DAWN/NBI), Antonio de Ugarte Postigo (CNRS), Daniele B. Malesani (DAWN/NBI and Radboud Univ.) and Nial R. Tanvir (U. Leicester) report:
We observed the afterglow of GRB 240809A (Evans et al. GCN 37110; Want et al. GCN37113; Dubai et al. GCN37114; Jiang et al. GCN 37116) with ALFOSC on the 2.5 m Nordic Optical Telescope (La Palma, Spain). The observation consisted of 300 s imaging in r-band followed by 4x1200 s spectroscopy covering the range between 3500 and 9500 AA. The observation started at 2024 Aug 9.87846 UT, 12.575 hr after the burst.
The afterglow is well detected in imaging at r ~ 20.3 mag. The spectrum shows continuum emission over the complete spectral range. We identify marginal spectral features which seem to match Mg II, Mg I and Fe II at a common redshift of 1.495, which we propose as the most likely redshift of this GRB.
Further observations to confirm this measurement are encouraged.
GCN Circular #37123
S.P.R. Shilling (Lancaster U.) and P. A. Evans (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 240809A 98 s after the BAT trigger (Evans et al., GCN Circ. 37110). A source consistent with the enhanced XRT position (Osborne et al., GCN Circ. 37115) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
    RA  (J2000) =  15:50:10.52 = 237.54385 (deg.)
    Dec (J2000) = -02:19:03.0  =  -2.31751 (deg.)
```
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).
Preliminary detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white               98          248          147         14.42 +/- 0.02
v                  640          660           19         16.11 +/- 0.14
b                  565          585           19         16.28 +/- 0.09
u                  310          560          246         15.13 +/- 0.03
w1                 689          709           19         16.19 +/- 0.17
m2                 665         1263           78         17.31 +/- 0.18
w2                 616         1387           97         18.33 +/- 0.24
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.249 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #37125
T. Mohan, A. Mehla, R. Kumar, V. Swain, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:
We observed the field of GRB 240809A detected by Swift (Evans et al., GCN 37110; optical follow-up Dubay et al GCN 37114; Jiang et al GCN 37116; Lipunov et al GCN 37117; Gottumukkala et al GCN 37122) with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2024-08-09 17:15:14 UT, i.e., 8.75 hours after the Swift trigger. We obtained one exposure of 300 seconds in the r' filter. In our image, we clearly detected the afterglow at the coordinates reported by Swift/UVOT Detection (Evans et al., GCN 37110). The photometry results follow as:
```
--------------------------------------------------------------------------------------------------
| JD (mid)          | t-t0 (hours) | Filter | Total Exposure (s) | Magnitude (AB) | Limiting mag |
| ----------------- | ------------ |------- | ------------------ | -------------- | ------------ |
| 2460532.218912037 |     8.75     |   r'   |       300          | 19.8 +/- 0.2   |    20.26     |
--------------------------------------------------------------------------------------------------
```
Our observations are consistent with those reported by Dubay et al. in GCN 37114 and Jiang et al. in GCN 37116. The magnitude is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.
GCN Circular #37127
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to GRB 240809A detected by Swift
(Evans et al., GCN 37110) starting about 0.86 days after the bust.
Observations were performed in the clear (roughly R) filter, and
the exposure time was 60s per image. A total of 30 images were
obtained. We detected the optical afterglow (Evans et al.,
GCN 37110; Dubay et al., GCN 37114; Jiang et al., GCN 37116;
Gottumukkala et al., GCN 37122; Mohan et al., GCN 37125) in our
coadd image in clear band. We measured its brightness of 21.0 +/-
0.2 mag at a mid time of ~0.86 days after the burst, calibrated to
the Pan-STARRS1 catalog.
GCN Circular #37129
B. Schneider (MIT), D. B. Malesani (DAWN/NBI and Radboud Univ.), A. de Ugarte Postigo (CNRS), J. P. U. Fynbo (DAWN/NBI), R. Gottumukkala (DAWN/NBI), L. Izzo (INAF/OACn and DARK/NBI), N. R. Tanvir (Univ. Leicester), D. Xu (NAOC), report on behalf of the Stargate collaboration:
We observed the afterglow of GRB 240809A (Evans et al., GCN 37110; Wang et al., GCN 37113; Dubay et al., GCN 37114; Jiang et al., GCN 37116; Gottumukkala et al., GCN 37122; Shilling & Evans, GCN 37123; Mohan et al., GCN 37125; Zheng & Filippenko, GCN 37127) using the X-shooter spectrograph mounted on the ESO VLT UT3 (Melipal). The observation mid time was 2024 Aug 10.056 UT (16.84 hr after the GRB), consisted of 6 exposures of 600 s each and covered the wavelength range 3000-21000 AA.
In images taken with the acquisition camera, we clearly detect the optical afterglow. In the r band, we measure an AB magnitude of r ~ 20.9, calibrated against the Pan-STARRS catalog.
In a preliminary reduction, we clearly detect continuum over the entire wavelength range. From detection of multiple absorption features, which we interpret as due to Fe II, Mg II, C IV, Al lI and Si II, we infer a common redshift of z = 1.494. No emission lines from the underlying host galaxy are detected in a preliminary analysis. This redshift is perfectly consistent with the value by Gottumukkala et al. (GCN 37122). We thus confirm that z = 1.494 is the redshift of GRB 240809A. We also note the presence of additional absorption features, likely due to an intervening system at z = 0.844.
We acknowledge expert support from the ESO staff in Paranal, in particular Maria Jose Rain, Rob van Holstein, and Boris Haeussler.
GCN Circular #37131
U.Quadri, L.Strabla and P.Madurini (Bassano Bresciano Astronomical Observatory),
Members of: AAVSO - American Association of Variable Star Observers. UAI/SSV - Unione Astrofili Italiani/SSV-GRB section. GAC - Gruppo Astrofili Cremonesi.
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 240809A detected by SWIFT(trigger 1247745) with the robotic telescope of (IAU station 565) Bassano Bresciano Observatory, Italy. The observations started 11.38 hours after the GRB trigger, At the end of twilight with our Newton telescope D=450 mm F/D=4.5.
We co-added 150 exposures of 20 sec each (total 50 min).
```
  Start T0+      End T0+          CR lim
  11.38 hour    12.29 hour         20.6
```
We detected a (fading) afterglow in the error box of the XRTcandidate (Evans et al., GCN 37110; Wang et al., GCN 37113; Dubay et al., GCN 37114; Jiang et al., GCN 37116; V. Lipunov et al., GCN 37117; Gottumukkala et al., GCN 37122; Shilling & Evans, GCN 37123; Mohan et al., GCN 37125; Zheng & Filippenko, GCN 37127; B. Schneider et al., GCN 37129) at the following position (+/- 3 arcsec):
```
RA (J2000.0) =   15 50 10.46
DEC(J2000.0) =  -02 19 04.6
```
The results of our photometry are:
```
---------------------------------------------
    Date UT          Exp        Afterglow
    Middle          (Min)        CR-mag
---------------------------------------------
2024 08 09.84773      50       19.7 +/- 0.2
---------------------------------------------
```
CR magnitude is unfiltered with R zero point.
Comparison stars used:
```
------------------------------
Pan-STARRS obj ID        R-Mag
------------------------------
105212375756448208      16.639
105202375684658035      17.916
105202375288851708      17.912
105192375172794156      17.312
105182375066235940      17.998
------------------------------
```
Magnitudes were estimated with the pan-STARRS cat and are derived using Lupton (2005) equations and are not corrected for galactic dust extinction.
Reference: http://www.osservatoriobassano.org/grb.asp
The message may be cited.
GCN Circular #37132
R. Brivio, Y.-D. Hu, S. Covino, P. D=E2=80=99Avanzo, D. Fugazza (INAF-OAB) = report on behalf of the REM team:
We observed the field of GRB 240809A (Evans et al., GCN 37110; Want et al.,= GCN 37113; Dubai et al., GCN 37114; Jiang et al., GCN 37116) with the REM = 60cm robotic telescope located at the ESO observatory of La Silla (Chile). = The observations were carried in the g, r, i, z, J, H, K bands, starting on= 2024 August 09 at 23:07:36 UT (i.e. 14.6 hours after the burst), and lasti= ng for about 1 hour. From preliminary photometry, we detect the optical afterglow at a position= consistent with the UVOT detection (Schilling&Evans, GCN 37123), at the fo= llowing AB magnitude in the r band:
r =3D 20.75 +- 0.20 (calibrated against PanSTARRS catalogue) at a mid-time of t-t0 ~ 15.1 hours after the GRB trigger.
GCN Circular #37134
A. Bochenek and D. A. Perley (LJMU) report:
We observed the Gamma-Ray Burst GRB240809A (Evans et al. GCN 37110 ; Want e= t al. GCN37113) using the IO:O optical camera on the 2m robotic Liverpool T= elescope. We obtained 5x120s exposures with the SDSS-R and SDSS-I filters s= tarting at 2024-08-09 21:48:46 UT, approximately 13.3 hours after the trigg= er.
The afterglow is detected in every exposure at a position consistent with p= revious detections reported by Dubay et al. (GCN 37114) and Jiang et al. (G= CN 37116). The obtained results are given below:
```
MJD (mid)          T_mid - T_0       Filter      Mag. (AB)
60531.91279        13.40 h             r          20.54 =C2=B1 0.05
60531.18419        13.60 h             i          20.43 =C2=B1 0.05
```
The photometry was obtained using nearby PanSTARRS secondary standards and = was not corrected for extinction.
GCN Circular #37139
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
The long-duration GRB 240809A (Swift-BAT detection: Evans et al., GCN 37110; SVOM-GRM detection: Wang et al., GCN 37113) triggered Konus-Wind at T0=30629.035 s UT (08:30:29.035).
The burst light curve shows a multipeaked structure which starts at ~T0-4.7 s and has a total duration of ~36.9 s. The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB240809_T30629/
As observed by Konus-Wind, the burst had a fluence of 1.30(-0.09,+0.09)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+5.488 s, of 3.14(-0.45,+0.44)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+32.768 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.84(-0.07,+0.07), the high energy photon index beta = -2.54(-0.62,+0.28), the peak energy Ep = 1097(-146,+164) keV (chi2 = 118/97 dof).
The spectrum near the maximum count rate (measured from T0+0.256 to T0+6.144 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.59(-0.07,+0.08), the high energy photon index beta = -2.50(-0.32,+0.21), the peak energy Ep = 1240(-146,+160) keV (chi2 = 111/82 dof).
Assuming the redshift z=1.494 (Schneider et al., GCN 37129) and a standard cosmology model with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is 7.8(-0.5,+0.5)x10^53 erg, the peak luminosity L_iso is 4.7(-0.7,+0.7)x10^53 erg/s, the rest-frame peak energy of the time-integrated spectrum Ep,i,z is 2736(-364,+409) keV, and the rest-frame peak energy at the peak of the emission Ep,p,z is 3093(-364,+399) keV. With the obtained estimates, GRB 240809A is inside 90% prediction bands for both 'Amati' and 'Yonetoku' relations derived for the sample of >300 long KW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021), see http://www.ioffe.ru/LEA/GRBs/GRB240809_T30629/GRB240809A_rest_frame.pdf
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN Circular #37154
S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 240809A (trigger #1247745) (Evans, et al., GCN Circ. 37110). The BAT ground-calculated position is RA, Dec = 237.545, -2.331 deg which is
```
   RA(J2000)  =  15h 50m 10.8s
   Dec(J2000) = -02d 19' 51.1"
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 72%.
The mask-weighted light curve shows a single peaked fast rise exponential decay structure with a tail that lasts until ~100 seconds after the trigger time. T90 (15-350 keV) is 72.86 +- 19.39 sec (estimated error including systematics).
The time-averaged spectrum from -10.876 to 180.52 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.17 +- 0.05. The fluence in the 15-150 keV band is 9.7 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+2.68 sec in the 15-150 keV band is 12.8 +- 0.4 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/1247745
GCN Circular #37157
T. Laskar (University of Utah), C. Christy (University of Arizona), K. D. Alexander (University of Arizona), G. Schroeder (Northwestern University), C. Pe=C3=B1a (University of Utah), E. Berger (Harvard University), R. Chornock (UC Berkeley), W. Fong (Northwestern University), R. Margutti (UC Berkeley), and P. Schady (University of Bath) report on behalf of a larger collaboration:
"We observed GRB 240809A (Evans et al., GCN 37110) with the Atacama Large Millimeter/Submillimeter Array (ALMA) at 97.5 GHz over two epochs, beginning on 2024 August 09 19:30 UT and 2024 August 10 23:28 UT, at 11 h and 39 h after the burst, respectively. Preliminary analysis reveals a fading mm source, with flux density of ~ 0.1 mJy in the first epoch, which we identify as the radio counterpart of GRB 240809A. Further observations are planned.
We thank the JAO staff, AoD, P2G, and the entire ALMA team for their help with these observations."
GCN Circular #37158
C. Christy (University of Arizona), T. Laskar (University of Utah), K. D. Alexander (University of Arizona), G. Schroeder (Northwestern University), C. Pe=C3=B1a (University of Utah), E. Berger (Harvard University), R. Chorn= ock (UC Berkeley), W. Fong (Northwestern University), R. Margutti (UC Berkeley), and P. Schady (University of Bath) report on behalf of a larger collaboration:
"We observed GRB 240809A (Evans et al., GCN 37110) with the Karl G. Jansky Very Large Array (VLA) beginning on 2024 August 10 02:25 UTC (17.9 h after the burst) at multiple frequencies. In preliminary analysis, we detect the radio counterpart (Laskar et al., GCN 37157) with a flux density of ~ 0.2 mJy at 15 GHz, and position:
```
RA (J2000)  =3D  15h 50m 10.5s
Dec (J2000) =3D -02d 19' 5.1"
```
with a (statistical) uncertainty of 0.2" in each coordinate. This position is consistent with the X-ray and optical position (Evans et al., GCN 37110). Further observations are planned.
We thank the VLA staff for scheduling and executing these observations"
GCN Circular #37159
Thierry Midavaine on behalf of the RAPAS network reports (#1) :
P. Martinez and C. Latg=C3=A9 [1], M. Serrau [2] and A. Leroy [3] observed the Gamma-Ray Burst GRB240809A (Evans et al. GCN 37110 ; Want et al.GCN 37113) using [1] ADAGIO N 820mm telescope at Belesta Observatory (IAU A05) equiped with a Moravian CMOS camera, [2] SC 300mm telescope at Vidauban [A77] equiped with a QHYCCD CMOS camera and [3] SC 350mm telescope at Madagascar equiped with a ZWO ASI CMOS camera. [1] and [2] are equiped with the set of 3 RAPAS filters meeting the Gaia G, Gbp and Grp photometric bands. The FITS files are reduced with the Gaia photometric catalog in respective spectral bands.
The afterglow is detected RA(J2000) =3D 5h 50m 10.55s ; Dec(J2000) =3D -02d= 19' 03.3" [1]
```
MJD (mid)          Gaia filter band      mag.(Gaia)    RAPAS station

60531.66128        G                     19.75 =C2=B1 0.14  [3]
60531.86667        Grp                   20.48 =C2=B1 0.60  [1]
60531.86736        G                     20.52 =C2=B1 0.47  [2]
60531.87778        Gbp                   20.10 =C2=B1 0.32  [1]
60531.89444        G                     20.58 =C2=B1 0.19  [1]
```
RAPAS ( https://proam-gemini.fr/rapas/ ) is a new ProAm collaboration funde= d by Paris Observatory, delivering to a network of french amateur observato= ries a set of 3 filters meeting the Gaia spectral bands. This network is de= dicated to deliver data in the Gaia photometric system on selected astrophy= sical alerts by Astro-COLIBRI ( https://astro-colibri.com/ ) or from Gaia alerts.
GCN Circular #37162
C. Christy (University of Arizona), W. Farah (SETI Institute), T. Laskar (University of Utah), K. D. Alexander (University of Arizona), G. Schroeder (Northwestern University), C. Pe=C3=B1a (University of Utah), A. Pollak (SE= TI Institute), A. Siemion (SETI Institute), E. Berger (Harvard University), R. Chornock (UC Berkeley), W. Fong (Northwestern University), R. Margutti (UC Berkeley), and P. Schady (University of Bath) report on behalf of a larger collaboration:
"We observed GRB 240809A (Evans et al., GCN 37110) with the Allen Telescope Array (ATA) beginning on 2024 August 09 23:25 UTC (14.9 h after the burst) at 5GHz and 8GHz. In our preliminary analysis, we do not detect any radio emission at or near the X-ray and optical position (Evans et al., GCN 37110) or radio position (Christy et al., GCN 37158) to a 3-sigma limit of ~0.9mJy at 5GHz and ~2.0mJy at 8GHz.
We thank the ATA staff for quickly scheduling these observations"
GCN Circular #37167
C. Christy (University of Arizona), T. Laskar (University of Utah), K. D. Alexander (University of Arizona), G. Schroeder (Northwestern University), C. Pe=C3=B1a (University of Utah), E. Berger (Harvard University), R. Chornock (UC Berkeley), W. Fong (Northwestern University), R. Margutti (UC Berkeley), and P. Schady (University of Bath) report on behalf of a larger collaboration:
"The declination of the VLA radio counterpart of GRB 240809A given in GCN 37158 is incorrect. The correct source position is:
```
RA (J2000)  =3D  15h 50m 10.5s
Dec (J2000) =3D -02d 19' 3.4"
```
with a (statistical) uncertainty of 0.2" in each coordinate. We apologize for any confusion caused."
GCN Circular #37194
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: Following the Swift trigger no. 1247745 (GCN 37110 P. A. Evans (U Leicester), R. A. J. Eyles-Ferris (U Leicester),K. L. Page (U Leicester) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team) from the Swift Burst Alert Telescope (BAT), we pointed at the coordinates RA(J2000)=15h 50m 12s: Dec(J2000)=-02d 19' 15" and started our observations 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.
The observations started at 19:25 UT of 2023/08/09, after about 11 hours after the GRB trigger, with clear sky, with principal telescope SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME I took 48 unfiltered images of 60 sec .
```
   Start                 End               Rlim
19:25:37 UT            20:35:28 UT         20.5
```
All images, calibrated with masterdark and masterflat have been measured with Thycho Tracker software We have detected a faint source at the enhanced position reported by Swift-XRT teamat following position
```
RA (J2000.0)   15 50 10.54
Dec (J2000.0) -02 19 05.3  
```
with the following photometry and astrometry:
GRB 240809A 15 50 10.54 -02 19 05.3 20.0 C82
Magnitudes were estimated with the GAIA DR2 cat. and are not corrected for galactic dust extinction.
The message may be cited.
GCN Circular #37244
S. Belkin (HSE, IKI), N. Pankov (HSE, IKI), E. Klunko (ISTP), R. Ya. Inasaridze (AbAO), A. Pozanenko (IKI) report on behalf of GRB-IKI-FuN:
We observed the field of GRB 240809A, detected by Swift (Evans et al., GCN 37110) and SVOM (Wang et al., GCN 37113), using the AZT-33IK 1.5-meter telescope at the Sayan Observatory (Mondy) and the AS-32 0.7-meter telescope at the Abastumani Observatory (AbAO). The observations began on 2024-08-09 at 13:54:52 (UT) and 17:27:38 (UT), respectively, i.e., about 0.2 and 7 hours after the Swift trigger. The preliminary photometry of the optical counterpart (Evans et al., GCN 37110; Dubay et al., GCN 37114; Jiang et al., GCN 37116; Gottumukkala et al., GCN 37122; Shilling et al., GCN 37123; Mohan et al., GCN 37125; Zheng & Filippenko, GCN 37127; Schneider et al., GCN 37129; Quadri et al., GCN 37131; Brivio et al., GCN 37132; Midavaine et al., GCN 37159; Ruocco et al., GCN 37194) is provided below:
```
Date UT Start t-T0 Exp. Filter OT Err. UL Telescope
(mid, days) (s) (3sigma)
2024-08-09 13:54:52 0.24228 49*60 R 19.45 0.05 22.3 AZT-33IK
2024-08-09 17:27:38 0.37302 44*60 R n/d n/d 20.0 AS-32
```
The magnitudes were calibrated using nearby comparison stars from the USNO-B1.0 catalog (R2 magnitudes). No correction was made for the Galactic extinction toward the GRB, corresponding to E(B-V) = 0.213 (S&F 2011). The optical light curve is well fitted by a power-law model with an index of -1.3, which is typical for GRBs.

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Jochen Greiner, last update: 23-Aug-2024 [Disclaimer]