Gamma-ray Burst 210524A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 24 May 21 05:00:33 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      58
TRIGGER_NUM:     643525204
GRB_RA:          352.133d {+23h 28m 32s} (J2000),
                 352.425d {+23h 29m 42s} (current),
                 351.448d {+23h 25m 47s} (1950)
GRB_DEC:         -48.433d {-48d 25' 59"} (J2000),
                 -48.315d {-48d 18' 54"} (current),
                 -48.709d {-48d 42' 31"} (1950)
GRB_ERROR:       12.28 [deg radius, statistical plus systematic]
GRB_INTEN:       152 [cnts/sec]
DATA_SIGNIF:     9.90 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        19358 TJD;   144 DOY;   21/05/24
GRB_TIME:        17999.09 SOD {04:59:59.09} UT
GRB_PHI:         130.00 [deg]
GRB_THETA:        55.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      2.41
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      75%  GRB
2nd_MOST_LIKELY:  22%  Generic SGR
SUN_POSTN:        61.23d {+04h 04m 56s}  +20.81d {+20d 48' 22"}
SUN_DIST:         92.32 [deg]   Sun_angle= 4.6 [hr] (West of Sun)
MOON_POSTN:      210.36d {+14h 01m 27s}   -8.91d {-08d 54' 25"}
MOON_DIST:       113.74 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:      334.45,-63.31 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      329.90,-40.57 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210524208/quicklook/glg_lc_medres34_bn210524208.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(5.0<100sec) coincident with the CALET_GBM event (trignum=1305867469).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 24 May 21 05:00:42 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     643525204
GRB_RA:          351.130d {+23h 24m 31s} (J2000),
                 351.419d {+23h 25m 41s} (current),
                 350.451d {+23h 21m 48s} (1950)
GRB_DEC:         -40.400d {-40d 23' 59"} (J2000),
                 -40.282d {-40d 16' 55"} (current),
                 -40.675d {-40d 40' 28"} (1950)
GRB_ERROR:       9.76 [deg radius, statistical only]
DATA_SIGNIF:     8.10 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        19358 TJD;   144 DOY;   21/05/24
GRB_TIME:        17999.09 SOD {04:59:59.09} UT
GRB_PHI:         121.00 [deg]
GRB_THETA:        57.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:        61.23d {+04h 04m 56s}  +20.81d {+20d 48' 22"}
SUN_DIST:         89.06 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      210.36d {+14h 01m 27s}   -8.91d {-08d 54' 27"}
MOON_DIST:       119.08 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:      350.89,-67.69 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      334.09,-33.23 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210524208/quicklook/glg_lc_medres34_bn210524208.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_643525204.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
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(5.0<100sec) coincident with the CALET_GBM event (trignum=1305867469).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 24 May 21 05:01:29 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      0
TRIGGER_NUM:     643525204
GRB_RA:          348.330d {+23h 13m 19s} (J2000),
                 348.628d {+23h 14m 31s} (current),
                 347.631d {+23h 10m 31s} (1950)
GRB_DEC:         -45.190d {-45d 11' 23"} (J2000),
                 -45.073d {-45d 04' 23"} (current),
                 -45.462d {-45d 27' 43"} (1950)
GRB_ERROR:       4.75 [deg radius, statistical only]
DATA_SIGNIF:     14.10 [sigma]
DATA_INTERVAL:   10.240 [sec]
GRB_DATE:        19358 TJD;   144 DOY;   21/05/24
GRB_TIME:        17999.09 SOD {04:59:59.09} UT
GRB_PHI:         127.00 [deg]
GRB_THETA:        58.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:        61.23d {+04h 04m 56s}  +20.81d {+20d 48' 22"}
SUN_DIST:         93.10 [deg]   Sun_angle= 4.8 [hr] (West of Sun)
MOON_POSTN:      210.37d {+14h 01m 29s}   -8.91d {-08d 54' 39"}
MOON_DIST:       114.26 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:      343.73,-63.39 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      329.10,-36.46 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210524208/quicklook/glg_lc_medres34_bn210524208.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_643525204.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
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(5.0<100sec) coincident with the CALET_GBM event (trignum=1305867469).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 24 May 21 05:01:39 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      1
TRIGGER_NUM:     643525204
GRB_RA:          342.210d {+22h 48m 50s} (J2000),
                 342.521d {+22h 50m 05s} (current),
                 341.479d {+22h 45m 55s} (1950)
GRB_DEC:         -45.980d {-45d 58' 47"} (J2000),
                 -45.866d {-45d 51' 58"} (current),
                 -46.245d {-46d 14' 39"} (1950)
GRB_ERROR:       3.32 [deg radius, statistical only]
DATA_SIGNIF:     20.40 [sigma]
DATA_INTERVAL:   12.288 [sec]
GRB_DATE:        19358 TJD;   144 DOY;   21/05/24
GRB_TIME:        17999.09 SOD {04:59:59.09} UT
GRB_PHI:         129.00 [deg]
GRB_THETA:        62.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:        61.23d {+04h 04m 56s}  +20.81d {+20d 48' 22"}
SUN_DIST:         97.33 [deg]   Sun_angle= 5.2 [hr] (West of Sun)
MOON_POSTN:      210.37d {+14h 01m 29s}   -8.91d {-08d 54' 41"}
MOON_DIST:       110.52 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:      346.89,-59.31 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      323.99,-35.12 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210524208/quicklook/glg_lc_medres34_bn210524208.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_643525204.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(5.0<100sec) coincident with the CALET_GBM event (trignum=1305867469).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 24 May 21 05:00:43 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      69
TRIGGER_NUM:     643525204
GRB_RA:          353.350d {+23h 33m 24s} (J2000),
                 353.637d {+23h 34m 33s} (current),
                 352.677d {+23h 30m 42s} (1950)
GRB_DEC:         -43.867d {-43d 52' 00"} (J2000),
                 -43.748d {-43d 44' 53"} (current),
                 -44.143d {-44d 08' 34"} (1950)
GRB_ERROR:       4.37 [deg radius, statistical plus systematic]
GRB_INTEN:       913 [cnts/sec]
DATA_SIGNIF:     60.30 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        19358 TJD;   144 DOY;   21/05/24
GRB_TIME:        17999.09 SOD {04:59:59.09} UT
GRB_PHI:         124.00 [deg]
GRB_THETA:        55.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.74
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      84%  GRB
2nd_MOST_LIKELY:  13%  Generic SGR
SUN_POSTN:        61.23d {+04h 04m 56s}  +20.81d {+20d 48' 22"}
SUN_DIST:         89.33 [deg]   Sun_angle= 4.5 [hr] (West of Sun)
MOON_POSTN:      210.36d {+14h 01m 27s}   -8.91d {-08d 54' 27"}
MOON_DIST:       117.71 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:      341.05,-67.04 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      333.81,-37.06 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210524208/quicklook/glg_lc_medres34_bn210524208.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(5.0<100sec) coincident with the CALET_GBM event (trignum=1305867469).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 24 May 21 05:01:50 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      3
TRIGGER_NUM:     643525204
GRB_RA:          340.500d {+22h 42m 00s} (J2000),
                 340.816d {+22h 43m 16s} (current),
                 339.759d {+22h 39m 02s} (1950)
GRB_DEC:         -46.710d {-46d 42' 35"} (J2000),
                 -46.598d {-46d 35' 50"} (current),
                 -46.972d {-46d 58' 18"} (1950)
GRB_ERROR:       2.02 [deg radius, statistical only]
DATA_SIGNIF:     50.90 [sigma]
DATA_INTERVAL:   16.384 [sec]
GRB_DATE:        19358 TJD;   144 DOY;   21/05/24
GRB_TIME:        17999.09 SOD {04:59:59.09} UT
GRB_PHI:         130.00 [deg]
GRB_THETA:        63.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:        61.23d {+04h 04m 56s}  +20.81d {+20d 48' 22"}
SUN_DIST:         98.69 [deg]   Sun_angle= 5.4 [hr] (West of Sun)
MOON_POSTN:      210.37d {+14h 01m 30s}   -8.91d {-08d 54' 44"}
MOON_DIST:       109.13 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:      346.66,-57.93 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      322.30,-35.22 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210524208/quicklook/glg_lc_medres34_bn210524208.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_643525204.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(5.0<100sec) coincident with the CALET_GBM event (trignum=1305867469).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 24 May 21 05:01:59 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      4
TRIGGER_NUM:     643525204
GRB_RA:          339.120d {+22h 36m 29s} (J2000),
                 339.438d {+22h 37m 45s} (current),
                 338.373d {+22h 33m 29s} (1950)
GRB_DEC:         -46.520d {-46d 31' 11"} (J2000),
                 -46.409d {-46d 24' 30"} (current),
                 -46.779d {-46d 46' 45"} (1950)
GRB_ERROR:       1.17 [deg radius, statistical only]
DATA_SIGNIF:     56.90 [sigma]
DATA_INTERVAL:   20.480 [sec]
GRB_DATE:        19358 TJD;   144 DOY;   21/05/24
GRB_TIME:        17999.09 SOD {04:59:59.09} UT
GRB_PHI:         130.00 [deg]
GRB_THETA:        64.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:        61.23d {+04h 04m 56s}  +20.81d {+20d 48' 22"}
SUN_DIST:         99.51 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      210.38d {+14h 01m 30s}   -8.91d {-08d 54' 46"}
MOON_DIST:       108.48 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:      347.73,-57.15 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      321.38,-34.62 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210524208/quicklook/glg_lc_medres34_bn210524208.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_643525204.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(5.0<100sec) coincident with the CALET_GBM event (trignum=1305867469).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 24 May 21 05:09:24 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     643525204
GRB_RA:          337.320d {+22h 29m 17s} (J2000),
                 337.643d {+22h 30m 34s} (current),
                 336.562d {+22h 26m 15s} (1950)
GRB_DEC:         -47.050d {-47d 02' 59"} (J2000),
                 -46.940d {-46d 56' 23"} (current),
                 -47.306d {-47d 18' 21"} (1950)
GRB_ERROR:       1.53 [deg radius, statistical only]
GRB_DATE:        19358 TJD;   144 DOY;   21/05/24
GRB_TIME:        17999.09 SOD {04:59:59.09} UT
GRB_PHI:         131.00 [deg]
GRB_THETA:        65.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:        61.24d {+04h 04m 58s}  +20.81d {+20d 48' 26"}
SUN_DIST:        100.86 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:      210.45d {+14h 01m 47s}   -8.94d {-08d 56' 40"}
MOON_DIST:       107.11 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:      347.75,-55.81 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      319.75,-34.54 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210524208/quicklook/glg_lc_medres34_bn210524208.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210524208/quicklook/glg_locplot_all_bn210524208.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(5.0<100sec) coincident with the CALET_GBM event (trignum=1305867469).

GCN Circular #30071
The Fermi GBM team reports the detection of a likely LONG GRB
At 04:59:59 UT on 24 May 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210524A (trigger 643525204.091768 / 210524208).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 337.3, Dec = -47.0 (J2000 degrees, equivalent to J2000 22h 29m, -47d 00'), with a statistical uncertainty of 1.5 degrees.
The angle from the Fermi LAT boresight is 65.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210524208/quicklook/glg_skymap_all_bn210524208.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/bn210524208/quicklook/glg_healpix_all_bn210524208.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210524208/quicklook/glg_lc_medres34_bn210524208.gif
GCN Circular #30072
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-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 210524A ( Fermi GBM team, GCN 30071) errorbox 559 sec after notice time and 597 sec after trigger time at 2021-05-24 05:09:56 UT, with upper limit up to 17.0 mag. Observations started at twilight. The observations began at zenith distance = 81 deg. The sun altitude is -12.3 deg.
The galactic latitude b = -56 deg., longitude l = 348 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1620119
We obtain a following upper limits.
```
Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

     657 | 2021-05-24 05:09:56 |          MASTER-IAC | (22h 28m 27.06s , -47d 09m 06.7s) |  P| |   120 | 16.8 |        
     657 | 2021-05-24 05:09:56 |          MASTER-IAC | (22h 27m 16.27s , -47d 03m 27.4s) |  P- |   120 | 16.4 |        
     812 | 2021-05-24 05:12:16 |          MASTER-IAC | (22h 28m 21.78s , -47d 10m 15.3s) |  P| |   150 | 17.0 |        
     812 | 2021-05-24 05:12:16 |          MASTER-IAC | (22h 27m 11.27s , -47d 04m 34.4s) |  P- |   150 | 16.6 |        
     997 | 2021-05-24 05:15:06 |          MASTER-IAC | (22h 28m 27.57s , -47d 09m 54.6s) |  P| |   180 | 16.9 |        
     997 | 2021-05-24 05:15:06 |          MASTER-IAC | (22h 27m 17.33s , -47d 04m 12.7s) |  P- |   180 | 16.5 |        
    1197 | 2021-05-24 05:18:26 |          MASTER-IAC | (22h 28m 24.64s , -47d 08m 43.0s) |  P| |   180 | 16.7 |        
    1197 | 2021-05-24 05:18:26 |          MASTER-IAC | (22h 27m 14.65s , -47d 03m 01.0s) |  P- |   180 | 16.2 |        
    1397 | 2021-05-24 05:21:45 |          MASTER-IAC | (22h 28m 24.73s , -47d 10m 02.6s) |  P| |   180 | 16.4 |        
    1397 | 2021-05-24 05:21:45 |          MASTER-IAC | (22h 27m 14.82s , -47d 04m 19.1s) |  P- |   180 | 15.9 |        
```
The observation and reduction will continue. The message may be cited.
GCN Circular #30073
B. Biltzinger, F. Kunzweiler, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 643525204 at 04:59:59 on 24 May 2021 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60).
The best-fit position (1 sigma statistical errors) is:
```
RA(2000.0) = 343.2+/-0.7 deg
Decl.(2000.0) = -47.2+/-0.4 deg
```
We estimate an additional systematic error of 2 deg.
Further details are available at: https://grb.mpe.mpg.de/grb/GRB210524208/
The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB210524208/healpix
The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB210524208/json
GCN Circular #30076
K. Hurley, on behalf of the IPN,
I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,
D. Svinkin, S. Golenetskii, D. Frederiks, A. Ridnaia, A. Lysenko, and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, and C. Wilson-Hodge on behalf of the Fermi GBM team,
A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team, and
W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report:
The intense, long-duration GRB 210524A (Fermi-GBM detection: The Fermi GBM team, GCN Circ. 30071; BALROG localization: Biltzinger et al., GCN Circ. 30073) was detected by Fermi (GBM trigger 643525204), Konus-Wind, Mars-Odyssey (HEND), INTEGRAL (SPI-ACS), and Swift-BAT at about 17999 s UT (04:59:59). The burst was outside the coded field of view of the BAT.
We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:
```
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   343.564 (22h 54m 15s) -46.672 (-46d 40' 19")
  Corners:
   342.645 (22h 50m 35s) -49.867 (-49d 52' 00")
   344.262 (22h 57m 03s) -43.354 (-43d 21' 13")
   344.203 (22h 56m 49s) -43.132 (-43d 07' 56")
   342.607 (22h 50m 26s) -49.680 (-49d 40' 48")
  ---------------------------------------------
```
The error box area is 1584 sq. arcmin, and its maximum dimension is 6.8 deg (the minimum one is 4 arcmin). The Sun distance was 95 deg.
This box may be improved.
The IPN localization is consistent with, but reduces the area of, the Fermi RoboBA and BALROG localizations (GCN Circ. 30071 and 30073).
A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB210524_T18010/IPN/
The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.
GCN Circular #30077
D. Svinkin, S. Golenetskii, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 210524A (Fermi-GBM detection: The Fermi GBM team, GCN Circ. 30071; IPN triangulation: Hurley et al., GCN Circ. 30076) triggered Konus-Wind at T0=18010.925 s UT (05:00:10.925).
The burst light curve shows a multi-peaked structure which starts at ~T0-3.5 s and has a total duration of ~11.5 s. The emission is seen up to ~1 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB210524_T18010/
As observed by Konus-Wind, the burst had a fluence of 8.64(-0.52,+0.56)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0+2.752 s, of 3.76(-1.00,+1.00)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 2 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.33(-0.19,+0.20) and Ep = 99(-10,+11) keV (chi2 = 45/56 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.7 (chi2 = 45/55 dof).
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.

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Jochen Greiner, last update: 25-May-2021 [Disclaimer]