Gamma-ray Burst 210824A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 24 Aug 21 04:10:39 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1070157,   Seg_Num: 0
GRB_RA:          232.132d {+15h 28m 32s} (J2000),
                 232.391d {+15h 29m 34s} (current),
                 231.535d {+15h 26m 08s} (1950)
GRB_DEC:         +11.135d {+11d 08' 07"} (J2000),
                 +11.061d {+11d 03' 41"} (current),
                 +11.307d {+11d 18' 26"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       11096 [cnts]    Image_Peak=447 [image_cnts]
TRIGGER_DUR:     4.096 [sec] 
TRIGGER_INDEX:   298     E_range: 25-100 keV
BKG_INTEN:       86828 [cnts]
BKG_TIME:        14948.39 SOD {04:09:08.39} UT
BKG_DUR:         40 [sec]
GRB_DATE:        19450 TJD;   236 DOY;   21/08/24
GRB_TIME:        15001.64 SOD {04:10:01.64} UT
GRB_PHI:          81.27 [deg]
GRB_THETA:        22.55 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     14.03 [sigma]
IMAGE_SIGNIF:    11.96 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +2  +1  +0  +0 -22  +0 
SUN_POSTN:       153.27d {+10h 13m 04s}  +11.03d {+11d 02' 04"}
SUN_DIST:         77.38 [deg]   Sun_angle= -5.3 [hr] (East of Sun)
MOON_POSTN:      354.50d {+23h 37m 59s}   -7.60d {-07d 35' 52"}
MOON_DIST:       122.85 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       17.24, 49.82 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      226.46, 29.03 [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 = 236.75,12.88 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(2.0<100sec) coincident with the FERMI_GBM event (trignum=651471008).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 24 Aug 21 04:10:26 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     651471008
GRB_RA:          231.533d {+15h 26m 08s} (J2000),
                 231.805d {+15h 27m 13s} (current),
                 230.907d {+15h 23m 38s} (1950)
GRB_DEC:          +3.567d {+03d 34' 00"} (J2000),
                  +3.492d {+03d 29' 31"} (current),
                  +3.741d {+03d 44' 28"} (1950)
GRB_ERROR:       17.88 [deg radius, statistical plus systematic]
GRB_INTEN:       112 [cnts/sec]
DATA_SIGNIF:     7.40 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        19450 TJD;   236 DOY;   21/08/24
GRB_TIME:        15003.06 SOD {04:10:03.06} UT
GRB_PHI:         269.00 [deg]
GRB_THETA:        70.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      0.58
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      95%  GRB
2nd_MOST_LIKELY:   4%  Generic Transient
DETECTORS:       0,0,0, 1,1,0, 0,1,0, 0,0,0, 0,0,
SUN_POSTN:       153.26d {+10h 13m 04s}  +11.03d {+11d 02' 04"}
SUN_DIST:         78.09 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      354.50d {+23h 37m 59s}   -7.60d {-07d 35' 55"}
MOON_DIST:       122.85 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:        7.25, 46.21 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      228.11, 21.59 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210824174/quicklook/glg_lc_medres34_bn210824174.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 155.87,10.17 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 24 Aug 21 04:10:48 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     651471008
GRB_RA:          240.940d {+16h 03m 46s} (J2000),
                 241.196d {+16h 04m 47s} (current),
                 240.348d {+16h 01m 24s} (1950)
GRB_DEC:         +11.250d {+11d 15' 00"} (J2000),
                 +11.192d {+11d 11' 30"} (current),
                 +11.386d {+11d 23' 11"} (1950)
GRB_ERROR:       5.85 [deg radius, statistical only]
DATA_SIGNIF:     9.40 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        19450 TJD;   236 DOY;   21/08/24
GRB_TIME:        15003.06 SOD {04:10:03.06} UT
GRB_PHI:         269.00 [deg]
GRB_THETA:        82.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       153.27d {+10h 13m 04s}  +11.03d {+11d 02' 04"}
SUN_DIST:         85.88 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
MOON_POSTN:      354.50d {+23h 38m 00s}   -7.60d {-07d 35' 49"}
MOON_DIST:       114.22 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       23.20, 42.23 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      236.10, 31.33 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210824174/quicklook/glg_lc_medres34_bn210824174.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_651471008.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the SWIFT_BAT event (trignum=1070157).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 24 Aug 21 04:11:58 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      1
TRIGGER_NUM:     651471008
GRB_RA:          242.080d {+16h 08m 19s} (J2000),
                 242.329d {+16h 09m 19s} (current),
                 241.504d {+16h 06m 01s} (1950)
GRB_DEC:         +14.730d {+14d 43' 48"} (J2000),
                 +14.674d {+14d 40' 26"} (current),
                 +14.862d {+14d 51' 42"} (1950)
GRB_ERROR:       4.64 [deg radius, statistical only]
DATA_SIGNIF:     12.80 [sigma]
DATA_INTERVAL:   15.360 [sec]
GRB_DATE:        19450 TJD;   236 DOY;   21/08/24
GRB_TIME:        15003.06 SOD {04:10:03.06} UT
GRB_PHI:         271.00 [deg]
GRB_THETA:        85.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       153.27d {+10h 13m 04s}  +11.03d {+11d 02' 03"}
SUN_DIST:         86.33 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
MOON_POSTN:      354.51d {+23h 38m 02s}   -7.59d {-07d 35' 33"}
MOON_DIST:       113.29 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       28.11, 42.70 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      236.45, 34.97 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210824174/quicklook/glg_lc_medres34_bn210824174.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_651471008.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the SWIFT_BAT event (trignum=1070157).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 24 Aug 21 04:19:28 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     651471008
GRB_RA:          235.130d {+15h 40m 31s} (J2000),
                 235.389d {+15h 41m 33s} (current),
                 234.532d {+15h 38m 08s} (1950)
GRB_DEC:         +10.430d {+10d 25' 48"} (J2000),
                 +10.361d {+10d 21' 41"} (current),
                 +10.590d {+10d 35' 25"} (1950)
GRB_ERROR:       5.34 [deg radius, statistical only]
GRB_DATE:        19450 TJD;   236 DOY;   21/08/24
GRB_TIME:        15003.06 SOD {04:10:03.06} UT
GRB_PHI:         272.00 [deg]
GRB_THETA:        77.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       153.27d {+10h 13m 05s}  +11.03d {+11d 01' 57"}
SUN_DIST:         80.40 [deg]   Sun_angle= -5.5 [hr] (East of Sun)
MOON_POSTN:      354.57d {+23h 38m 17s}   -7.56d {-07d 33' 50"}
MOON_DIST:       119.94 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       18.46, 46.91 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      229.92, 29.15 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210824174/quicklook/glg_lc_medres34_bn210824174.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210824174/quicklook/glg_locplot_all_bn210824174.png
COMMENTS:        Fermi-GBM Final Position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file should be available by the time this FINAL notice is produced.  
COMMENTS:        This notice was generated completely by automated pipeline processing.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the SWIFT_BAT event (trignum=1070157).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 24 Aug 21 04:14:07 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1070157,   Seg_Num: 0
GRB_RA:          232.132d {+15h 28m 32s} (J2000),
                 232.391d {+15h 29m 34s} (current),
                 231.535d {+15h 26m 08s} (1950)
GRB_DEC:         +11.135d {+11d 08' 07"} (J2000),
                 +11.061d {+11d 03' 41"} (current),
                 +11.307d {+11d 18' 26"} (1950)
GRB_DATE:        19450 TJD;   236 DOY;   21/08/24
GRB_TIME:        15001.64 SOD {04:10:01.64} UT
TRIGGER_INDEX:   298
GRB_PHI:          81.27 [deg]
GRB_THETA:        22.55 [deg]
DELTA_TIME:      -44.00 [sec]
TRIGGER_DUR:     4.096 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     14.03 [sigma]
IMAGE_SIGNIF:    11.96 [sigma]
LC_URL:          sw01070157000msb.lc
SUN_POSTN:       153.27d {+10h 13m 04s}  +11.03d {+11d 02' 01"}
SUN_DIST:         77.38 [deg]   Sun_angle= -5.3 [hr] (East of Sun)
MOON_POSTN:      354.53d {+23h 38m 06s}   -7.58d {-07d 35' 04"}
MOON_DIST:       122.87 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       17.24, 49.82 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      226.46, 29.03 [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 = 236.75,12.88 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 24 Aug 21 04:15:14 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1070157,   Seg_Num: 0
POINT_RA:        232.142d {+15h 28m 34s} (J2000)
POINT_DEC:       +11.144d {+11d 08' 38"} (J2000)
IMG_START_DATE:  19450 TJD;   236 DOY;   21/08/24
IMG_START_TIME:  15308.47 SOD {04:15:08.47} UT,   306.8 [sec] since BAT Trigger Time
COUNTS:          4    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 24 Aug 21 04:18:57 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1070157,   Seg_Num: 0
GRB_RA:          232.1051d {+15h 28m 25.22s} (J2000),
                 232.3637d {+15h 29m 27.29s} (current),
                 231.5081d {+15h 26m 01.93s} (1950)
GRB_DEC:         +11.1516d {+11d 09' 05.7"} (J2000),
                 +11.0778d {+11d 04' 40.0"} (current),
                 +11.3237d {+11d 19' 25.4"} (1950)
GRB_ERROR:       7.4 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19450 TJD;   236 DOY;   21/08/24
IMG_START_TIME:  15322.00 SOD {04:15:22.00} UT,   320.4 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       153.27d {+10h 13m 05s}  +11.03d {+11d 01' 57"}
SUN_DIST:         77.35 [deg]   Sun_angle= -5.3 [hr] (East of Sun)
MOON_POSTN:      354.57d {+23h 38m 16s}   -7.57d {-07d 33' 57"}
MOON_DIST:       122.94 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       17.24, 49.86 [deg] galactic lon,lat of the burst
ECL_COORDS:      226.43, 29.04 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN Circular #30699
The Fermi GBM team reports the detection of a likely LONG GRB
At 04:10:03 UT on 24 Aug 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210824A (trigger 651471008.06188 / 210824174).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 235.1, Dec = 10.4 (J2000 degrees, equivalent to J2000 15h 40m, 10d 24'), with a statistical uncertainty of 5.3 degrees.
The angle from the Fermi LAT boresight is 77.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210824174/quicklook/glg_skymap_all_bn210824174.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210824174/quicklook/glg_healpix_all_bn210824174.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210824174/quicklook/glg_lc_medres34_bn210824174.gif

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 24 Aug 21 04:30:27 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1070157,   Seg_Num: 0
POINT_RA:        232.142d {+15h 28m 34s} (J2000)
POINT_DEC:       +11.144d {+11d 08' 39"} (J2000)
POINT_ROLL:      278.925d
IMG_START_DATE:  19450 TJD;   236 DOY;   21/08/24
IMG_START_TIME:  15312.44 SOD {04:15:12.44} UT,   310.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.041
N_STARS:         33
X_OFFSET:        484 [pixels]
Y_OFFSET:        444 [pixels]
X_MAX:           1443 [pixels]
Y_MAX:           1403 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw01070157000msufc0310.fits
SUN_POSTN:       153.28d {+10h 13m 07s}  +11.03d {+11d 01' 47"}
SUN_DIST:         77.38 [deg]   Sun_angle= -5.3 [hr] (East of Sun)
MOON_POSTN:      354.66d {+23h 38m 39s}   -7.52d {-07d 31' 19"}
MOON_DIST:       122.99 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       17.26, 49.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      226.47, 29.04 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 24 Aug 21 04:30:43 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1070157,   Seg_Num: 0
POINT_RA:        232.142d {+15h 28m 34s} (J2000)
POINT_DEC:       +11.144d {+11d 08' 39"} (J2000)
POINT_ROLL:      278.925d
IMG_START_DATE:  19450 TJD;   236 DOY;   21/08/24
IMG_START_TIME:  15312.44 SOD {04:15:12.44} UT,   310.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.041
N_STARS:         33
X_OFFSET:        484 [pixels]
Y_OFFSET:        444 [pixels]
X_MAX:           1443 [pixels]
Y_MAX:           1403 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw01070157000msufc0310.fits
SUN_POSTN:       153.28d {+10h 13m 07s}  +11.03d {+11d 01' 47"}
SUN_DIST:         77.38 [deg]   Sun_angle= -5.3 [hr] (East of Sun)
MOON_POSTN:      354.66d {+23h 38m 40s}   -7.52d {-07d 31' 16"}
MOON_DIST:       122.99 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       17.26, 49.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      226.47, 29.04 [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:     Tue 24 Aug 21 04:31:50 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1070157,   Seg_Num: 0
POINT_RA:        232.142d {+15h 28m 34s} (J2000)
POINT_DEC:       +11.144d {+11d 08' 39"} (J2000)
ROLL:            278.925d
IMG_START_DATE:  19450 TJD;   236 DOY;   21/08/24
IMG_START_TIME:  15312.44 SOD {04:15:12.44} UT,   310.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     651471340
X_OFFSET:        803 [pixels]
Y_OFFSET:        763 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       963
Y_GRB_POS:       923
BINNING_INDEX:   1
IM_URL:          sw01070157000msuni0338.fits
SUN_POSTN:       153.28d {+10h 13m 07s}  +11.03d {+11d 01' 46"}
SUN_DIST:         77.38 [deg]   Sun_angle= -5.3 [hr] (East of Sun)
MOON_POSTN:      354.67d {+23h 38m 42s}   -7.52d {-07d 31' 00"}
MOON_DIST:       123.00 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       17.26, 49.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      226.47, 29.04 [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:     Tue 24 Aug 21 04:32:00 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1070157,   Seg_Num: 0
POINT_RA:        232.142d {+15h 28m 34s} (J2000)
POINT_DEC:       +11.144d {+11d 08' 39"} (J2000)
ROLL:            278.925d
IMG_START_DATE:  19450 TJD;   236 DOY;   21/08/24
IMG_START_TIME:  15312.44 SOD {04:15:12.44} UT,   310.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     651471340
X_OFFSET:        803 [pixels]
Y_OFFSET:        763 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       963
Y_GRB_POS:       923
BINNING_INDEX:   1
IM_URL:          sw01070157000msuni0338.fits
SUN_POSTN:       153.28d {+10h 13m 07s}  +11.03d {+11d 01' 46"}
SUN_DIST:         77.38 [deg]   Sun_angle= -5.3 [hr] (East of Sun)
MOON_POSTN:      354.68d {+23h 38m 42s}   -7.52d {-07d 30' 58"}
MOON_DIST:       123.00 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       17.26, 49.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      226.47, 29.04 [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 #30700
K. L. Page (U Leicester), N. J. Klingler (GSFC/UMBC/CRESSTII), H. A. Krimm (NSF), A. Y. Lien (U Tampa), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 04:10:01 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210824A (trigger=1070157). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 232.132, +11.135 which is
```
   RA(J2000) = 15h 28m 32s
   Dec(J2000) = +11d 08' 07"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 50 sec. The peak count rate was ~1600 counts/sec (15-350 keV), at ~3 sec after the trigger.
The XRT began observing the field at 04:15:08.4 UT, 306.9 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 232.10513, 11.15208 which is equivalent to: RA(J2000) = 15h 28m 25.23s Dec(J2000) = +11d 09' 07.5" with an uncertainty of 7.2 arcseconds (radius, 90% containment). This location is 113 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (3.31 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 8.5 (+5.30/-4.44) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 310 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 none of the XRT error circle. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.036.
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 Circular #30702
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 1505 s of XRT Photon Counting mode data and 3 UVOT images for GRB 210824A, 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 = 232.10583, +11.15351 which is equivalent to:
```
RA (J2000): 15h 28m 25.40s
Dec (J2000): +11d 09' 12.6"
```
with an uncertainty of 2.4 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 #30704
V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), B. Sbarufatti (PSU), D.N. Burrows (PSU), J. D. Gropp (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), A. Melandri (INAF-OAB) and K.L. Page report on behalf of the Swift-XRT team:
We have analysed 6.6 ks of XRT data for GRB 210824A (Page et al. GCN Circ. 30700), from 320 s to 28.9 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 30702).
The late-time light curve (from T0+3.9 ks) can be modelled with a power-law decay with a decay index of alpha=0.94 (+0.25, -0.23).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.4 (+/-0.4). The best-fitting absorption column is 6.8 (+3.1, -2.3) x 10^21 cm^-2, in excess of the Galactic value of 3.3 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 3.6 x 10^-11 (8.4 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     6.8 (+3.1, -2.3) x 10^21 cm^-2
Galactic foreground: 3.3 x 10^20 cm^-2
Excess significance: 4.6 sigma
Photon index:	     2.4 (+/-0.4)
```
If the light curve continues to decay with a power-law decay index of 0.94, the count rate at T+24 hours will be 2.4 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.5 x 10^-14 (2.0 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01070157.
This circular is an official product of the Swift-XRT team.
GCN Circular #30705
X. Liu, S.Y. Fu (NAOC), Z.P. Zhu (NAOC,HUST), D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of Swift GRB 210824A (Page et al. GCN Circ. 30700) using the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. We obtained 10x200 s frames in the Sloan r-band, starting at 14:54:25 UT on 2021-08-24, i.e., 10.74 hr after the BAT trigger.
No optical source is detected in our stacked image at the enhanced Swift/XRT position (Goad et al., GCN 30702), down to a limiting magnitude of r~21.1, calibrated with the nearby PanSTARRS field.
GCN Circular #30706
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (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, O.Ershova (Irkutsk State University, API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko (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) started inspect of the Fermi GRB 210824A ( Fermi GBM team, GCN 30699) errorbox 45625 sec after notice time and 45651 sec after trigger time at 2021-08-24 16:50:54 UT, with upper limit up to 17.2 mag. Observations started at twilight. The observations began at zenith distance = 46 deg. The sun altitude is -7.8 deg.
The galactic latitude b = 46 deg., longitude l = 19 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1698440
We obtain a following upper limits.
```
Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   45682 | 2021-08-24 16:50:54 |         MASTER-SAAO | (15h 30m 37.82s , +12d 36m 58.0s) |   C |    60 | 16.0 |        
   45762 | 2021-08-24 16:52:14 |         MASTER-SAAO | (15h 38m 47.90s , +12d 35m 22.7s) |   C |    60 | 16.6 |        
   45841 | 2021-08-24 16:53:34 |         MASTER-SAAO | (15h 24m 16.66s , +10d 42m 42.8s) |   C |    60 | 17.0 |        
   45921 | 2021-08-24 16:54:54 |         MASTER-SAAO | (15h 32m 23.86s , +10d 43m 21.8s) |   C |    60 | 17.2 |  
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #30707
S. Lesage (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 04:10:03 UT on 24 August 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210824A (trigger 651471008/210824174) which was also detected by Swift BAT (K. L. Page et al. 2021, GCN 30700). The Fermi GBM Final Real-time Localization (GCN 30699) is consistent with the Swift BAT position.
The angle from the Fermi LAT boresight is 75 degrees.
The GBM light curve consists of a single emission episode with a duration (T90) of about 33 s (10-1000 keV). The time-averaged spectrum from T0-0.6 to T0+28 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.2 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 552 +/- 286 keV.
The event fluence (10-1000 keV) in this time interval is (5.3 +/- 0.6)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+4.1 s in the 10-1000 keV band is 2.2 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog:https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN Circular #30708
Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado and M.D. Caballero-Garcia (IAA-CSIC), D. Hiriart, W. H. Lee (UNAM), C. J. Perez del Pulgar and I. Carrasco (UMA), I. H. Park (SKKU) on behalf of a larger collaboration, report:
The 60cm BOOTES-5/JGT robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically responded in 54 s to the Swift trigger of GRB 210824A (Page et al., GCNC 30700) , a burst which was also detected by Fermi (Fermi GBM team, GCNC 30699). In the co-added clear image (10 x 10 s), no optical afterglow is detected within the X-ray afterglow position (Page et al., GCNC 30700; Goad et al., GCNC 30702) down to 19.9 mag.
We thank the staff at Observatorio Astronomico Nacional in San Pedro Martir for its excellent support.

GCN Circular #30709
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (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, O.Ershova (Irkutsk State University, API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko (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 210824A ( K. L. Page et al., GCN 30700) errorbox 45612 sec after notice time and 45332 sec after trigger time at 2021-08-24 16:50:54 UT, with upper limit up to 19.4 mag. Observations started at twilight. The observations began at zenith distance = 46 deg. The sun altitude is -7.8 deg.
MASTER-Tavrida robotic telescope located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 210824A errorbox 48172 sec after notice time and 47892 sec after trigger time at 2021-08-24 17:33:34 UT, with upper limit up to 19.1 mag. Observations started at twilight. The observations began at zenith distance = 47 deg. The sun altitude is -10.9 deg.
MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 210824A errorbox 50320 sec after notice time and 50041 sec after trigger time at 2021-08-24 18:09:23 UT, with upper limit up to 17.4 mag. The observations began at zenith distance = 56 deg. The sun altitude is -21.7 deg.
The galactic latitude b = 49 deg., longitude l = 17 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1698433
We obtain a following upper limits.

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   45363 |         MASTER-SAAO |   C |    60 | 16.0 |        
   45522 |         MASTER-SAAO |   C |    60 | 17.0 |        
   45602 |         MASTER-SAAO |   C |    60 | 17.2 |        
   46324 |         MASTER-SAAO |   C |    60 | 18.5 |        
   46483 |         MASTER-SAAO |   C |    60 | 18.7 |        
   46563 |         MASTER-SAAO |   C |    60 | 18.8 |        
   47281 |         MASTER-SAAO |   C |    60 | 19.4 |        
   47440 |         MASTER-SAAO |   C |    60 | 19.3 |        
   47520 |         MASTER-SAAO |   C |    60 | 19.4 |        
   47983 |      MASTER-Tavrida |   C |   180 | 17.8 |        
   49103 |      MASTER-Tavrida |   C |   180 | 19.1 |        
   49875 |      MASTER-Tavrida |   C |    60 | 18.7 |        
   50071 |   MASTER-Kislovodsk |   C |    60 | 15.8 |        
   50252 |      MASTER-Tavrida |   C |   180 | 19.0 |        
   50310 |   MASTER-Kislovodsk |   C |   180 | 15.1 |        
   50310 |   MASTER-Kislovodsk |   C |   180 | 15.3 |        
   51024 |      MASTER-Tavrida |   C |    60 | 18.4 |        
   51479 |      MASTER-Tavrida |   C |    60 | 18.4 |        
   51558 |      MASTER-Tavrida |   C |    60 | 18.4 |        
   52080 |   MASTER-Kislovodsk |   C |    60 | 16.6 |        
   52268 |         MASTER-SAAO |   C |    60 | 18.8 |        
   52527 |      MASTER-Tavrida |   C |    60 | 18.1 |        
   52605 |      MASTER-Tavrida |   C |    60 | 18.1 |        
   53102 |   MASTER-Kislovodsk |   C |   180 | 17.1 |        
   53102 |   MASTER-Kislovodsk |   C |   180 | 17.4 |        
   53227 |         MASTER-SAAO |   C |    60 | 18.6 |        
   53242 |   MASTER-Kislovodsk |   C |    60 | 17.0 |        
   53476 |      MASTER-Tavrida |   C |    60 | 17.9 |        
   53555 |      MASTER-Tavrida |   C |    60 | 17.9 |        
   54344 |   MASTER-Kislovodsk |   C |   180 | 17.0 |        
   54344 |   MASTER-Kislovodsk |   C |   180 | 17.1 |        
   54478 |      MASTER-Tavrida |   C |   180 | 18.0 |        
   54482 |         MASTER-SAAO |   C |   180 | 18.5 |        
   54617 |      MASTER-Tavrida |   C |    60 | 17.6 |        
   55565 |         MASTER-SAAO |   C |   180 | 17.0 |        
   55613 |      MASTER-Tavrida |   C |   180 | 17.8 |        
   55831 |      MASTER-Tavrida |   C |    60 | 17.5 |        
   56489 |   MASTER-Kislovodsk |   C |    60 | 12.8 |        
   56489 |   MASTER-Kislovodsk |   C |    60 | 14.0 |        
   56723 |         MASTER-SAAO |   C |   180 | 15.9 |

Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.

GCN Circular #30718
M. Niwano, K. L. Murata, R. Hosokawa, N. Ito, Y. Imai, H. Takamatsu, R. Noto, S. Sato, M. Takaku, R. Yamaguchi, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 210824A (Fermi GBM team, GCN Circular #30699, K. L. Page et al. GCN Circular #30700, M.R. Goad et al. GCN Circular #30702, V. D'Elia et al. GCN Circular #30704, X. Liu et al. GCN Circular #30705, V. Lipunov et al. GCN Circular #30706, S. Lesage et al. GCN Circular #30707, Y.-D. Hu et al. GCN Circular #30708, V. Lipunov et al. GCN Circular #30709) 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 60 sec exposures started at 2021-08-25 10:20:44 UT (30.1 hours after Fermi trigger). We stacked the images with good conditions. We did not detect any uncatalogued sources within the XRT error region (V. D'Elia et al. GCN Circular #30706). We obtained the 5-sigma limits of the stacked images as follows.
```
T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------ 

31.3 2021-08-25 12:29:20.71 4740 g'>18.6, Rc>19.0, Ic>18.3
------------------------------------------------------------------------------------------------ 

T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
```
We used PS1 catalog for flux calibration. 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 #30722
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), K. L. Page (U Leicester), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210824A (trigger #1070157) (Page, et al., GCN Circ. 30700). The BAT ground-calculated position is RA, Dec = 232.115, 11.169 deg which is
```
 RA(J2000)  =  15h 28m 27.5s 
 Dec(J2000) = +11d 10' 09.9" 
```
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 60%.
The mask-weighted light curve shows a single broad pulse with some sub-structure. It begins around T-15 sec, peaks at the trigger time and decays to background by T+40 sec. We note that the light curve has a gap from T+110 sec to T+240 sec due to the burst going out of the field of view (for a pre-planned slew that started before the trigger had been fully processed) and then coming back into FOV when the pre-planned slew ended and the automated target slew had started. The burst appears to be over before this time. T90 (15-350 keV) is 37.55 +- 4.79 sec (estimated error including systematics).
The time-averaged spectrum from T-13.70 to T+30.94 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.18 +- 0.11. The fluence in the 15-150 keV band is 1.7 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+1.02 sec in the 15-150 keV band is 1.3 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1070157/BA/
GCN Circular #30730
GRB 210824A: Swift/UVOT Upper Limits
S. J. LaPorte (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 210824A 311 s after the BAT trigger (Page et al., GCN Circ. 30700). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 30702) 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           311          461          147         >20.8
white              311         4350          364         >20.9
v                  467         4760          236         >19.4
b                  565         4145          235         >20.1
u                  541         5220           83         >19.6
w1                 516         5170          236         >20.4
m2                4765         4965          197         >20.3
w2                4356         4555          197         >19.9
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.037 in the direction of the burst (Schlegel et al. 1998).

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Jochen Greiner, last update: 27-Aug-2021 [Disclaimer]