Gamma-ray Burst 190531B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 31 May 19 20:10:36 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      50
TRIGGER_NUM:     581026217
GRB_RA:           21.883d {+01h 27m 32s} (J2000),
                  22.092d {+01h 28m 22s} (current),
                  21.345d {+01h 25m 23s} (1950)
GRB_DEC:         -44.717d {-44d 43' 00"} (J2000),
                 -44.616d {-44d 36' 58"} (current),
                 -44.976d {-44d 58' 31"} (1950)
GRB_ERROR:       8.02 [deg radius, statistical plus systematic]
GRB_INTEN:       194 [cnts/sec]
DATA_SIGNIF:     11.10 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        18634 TJD;   151 DOY;   19/05/31
GRB_TIME:        72612.14 SOD {20:10:12.14} UT
GRB_PHI:         300.00 [deg]
GRB_THETA:        25.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      0.52
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      95%  GRB
2nd_MOST_LIKELY:   4%  Generic Transient
DETECTORS:       1,0,0, 1,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        68.46d {+04h 33m 51s}  +21.96d {+21d 57' 37"}
SUN_DIST:         78.88 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       37.44d {+02h 29m 46s}   +9.64d {+09d 38' 38"}
MOON_DIST:        56.01 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      282.93,-70.98 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      356.80,-48.67 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_lc_medres34_bn190531840.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 178.08,-2.12 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 31 May 19 20:10:48 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      60
TRIGGER_NUM:     581026217
GRB_RA:           24.090d {+01h 36m 22s} (J2000),
                  24.308d {+01h 37m 14s} (current),
                  23.528d {+01h 34m 07s} (1950)
GRB_DEC:         -34.980d {-34d 58' 47"} (J2000),
                 -34.881d {-34d 52' 52"} (current),
                 -35.235d {-35d 14' 04"} (1950)
GRB_ERROR:       3.89 [deg radius, statistical only]
DATA_SIGNIF:     13.70 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        18634 TJD;   151 DOY;   19/05/31
GRB_TIME:        72612.14 SOD {20:10:12.14} UT
GRB_PHI:         323.00 [deg]
GRB_THETA:        26.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4153 (Gnd S/W Version number)
SUN_POSTN:        68.46d {+04h 33m 51s}  +21.96d {+21d 57' 37"}
SUN_DIST:         70.61 [deg]   Sun_angle= 2.9 [hr] (West of Sun)
MOON_POSTN:       37.44d {+02h 29m 46s}   +9.64d {+09d 38' 41"}
MOON_DIST:        46.23 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      254.95,-77.60 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        6.01,-41.22 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_lc_medres34_bn190531840.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_581026217.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.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 31 May 19 20:10:45 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      61
TRIGGER_NUM:     581026217
GRB_RA:           22.300d {+01h 29m 12s} (J2000),
                  22.508d {+01h 30m 02s} (current),
                  21.764d {+01h 27m 03s} (1950)
GRB_DEC:         -44.983d {-44d 58' 59"} (J2000),
                 -44.883d {-44d 53' 00"} (current),
                 -45.241d {-45d 14' 28"} (1950)
GRB_ERROR:       6.23 [deg radius, statistical plus systematic]
GRB_INTEN:       499 [cnts/sec]
DATA_SIGNIF:     19.70 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        18634 TJD;   151 DOY;   19/05/31
GRB_TIME:        72612.14 SOD {20:10:12.14} UT
GRB_PHI:         300.00 [deg]
GRB_THETA:        25.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.52
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      95%  GRB
2nd_MOST_LIKELY:   4%  Generic Transient
DETECTORS:       1,0,0, 1,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        68.46d {+04h 33m 51s}  +21.96d {+21d 57' 37"}
SUN_DIST:         78.87 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       37.44d {+02h 29m 46s}   +9.64d {+09d 38' 40"}
MOON_DIST:        56.17 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      282.47,-70.61 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      356.94,-49.05 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_lc_medres34_bn190531840.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 178.08,-2.12 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 31 May 19 20:10:52 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      72
TRIGGER_NUM:     581026217
GRB_RA:           22.617d {+01h 30m 28s} (J2000),
                  22.824d {+01h 31m 18s} (current),
                  22.083d {+01h 28m 20s} (1950)
GRB_DEC:         -45.167d {-45d 10' 00"} (J2000),
                 -45.067d {-45d 04' 00"} (current),
                 -45.424d {-45d 25' 26"} (1950)
GRB_ERROR:       4.95 [deg radius, statistical plus systematic]
GRB_INTEN:       1005 [cnts/sec]
DATA_SIGNIF:     30.10 [sigma]
INTEG_TIME:      0.512 [sec]
GRB_DATE:        18634 TJD;   151 DOY;   19/05/31
GRB_TIME:        72612.14 SOD {20:10:12.14} UT
GRB_PHI:         300.00 [deg]
GRB_THETA:        25.00 [deg]
DATA_TIME_SCALE: 0.5120 [sec]
HARD_RATIO:      0.33
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      96%  GRB
2nd_MOST_LIKELY:   3%  Generic Transient
DETECTORS:       1,0,0, 1,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        68.46d {+04h 33m 51s}  +21.96d {+21d 57' 37"}
SUN_DIST:         78.86 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:       37.44d {+02h 29m 46s}   +9.64d {+09d 38' 41"}
MOON_DIST:        56.28 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      282.12,-70.35 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      357.07,-49.33 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_lc_medres34_bn190531840.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 178.08,-2.12 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 31 May 19 20:11:07 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      96
TRIGGER_NUM:     581026217
GRB_RA:           23.300d {+01h 33m 12s} (J2000),
                  23.505d {+01h 34m 01s} (current),
                  22.771d {+01h 31m 05s} (1950)
GRB_DEC:         -45.533d {-45d 31' 59"} (J2000),
                 -45.434d {-45d 26' 02"} (current),
                 -45.790d {-45d 47' 21"} (1950)
GRB_ERROR:       3.83 [deg radius, statistical plus systematic]
GRB_INTEN:       1813 [cnts/sec]
DATA_SIGNIF:     107.70 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        18634 TJD;   151 DOY;   19/05/31
GRB_TIME:        72612.14 SOD {20:10:12.14} UT
GRB_PHI:         300.00 [deg]
GRB_THETA:        25.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      0.42
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      95%  GRB
2nd_MOST_LIKELY:   4%  Generic Transient
DETECTORS:       1,0,0, 1,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        68.46d {+04h 33m 51s}  +21.96d {+21d 57' 37"}
SUN_DIST:         78.81 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:       37.44d {+02h 29m 47s}   +9.65d {+09d 38' 44"}
MOON_DIST:        56.49 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      281.36,-69.81 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      357.36,-49.91 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_lc_medres34_bn190531840.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 178.08,-2.12 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 31 May 19 20:11:01 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      75
TRIGGER_NUM:     581026217
GRB_RA:           16.233d {+01h 04m 56s} (J2000),
                  16.453d {+01h 05m 49s} (current),
                  15.667d {+01h 02m 40s} (1950)
GRB_DEC:         -43.917d {-43d 55' 00"} (J2000),
                 -43.813d {-43d 48' 46"} (current),
                 -44.184d {-44d 11' 03"} (1950)
GRB_ERROR:       4.13 [deg radius, statistical plus systematic]
GRB_INTEN:       1164 [cnts/sec]
DATA_SIGNIF:     69.90 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        18634 TJD;   151 DOY;   19/05/31
GRB_TIME:        72612.14 SOD {20:10:12.14} UT
GRB_PHI:         300.00 [deg]
GRB_THETA:        20.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      0.49
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      95%  GRB
2nd_MOST_LIKELY:   4%  Generic Transient
DETECTORS:       1,0,0, 1,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        68.46d {+04h 33m 51s}  +21.96d {+21d 57' 37"}
SUN_DIST:         81.20 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:       37.44d {+02h 29m 46s}   +9.65d {+09d 38' 43"}
MOON_DIST:        56.76 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      294.60,-72.99 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      352.49,-45.76 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_lc_medres34_bn190531840.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 178.08,-2.12 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 31 May 19 20:12:03 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      3
TRIGGER_NUM:     581026217
GRB_RA:           20.560d {+01h 22m 14s} (J2000),
                  20.776d {+01h 23m 06s} (current),
                  20.004d {+01h 20m 01s} (1950)
GRB_DEC:         -40.970d {-40d 58' 11"} (J2000),
                 -40.869d {-40d 52' 07"} (current),
                 -41.231d {-41d 13' 51"} (1950)
GRB_ERROR:       1.30 [deg radius, statistical only]
DATA_SIGNIF:     46.30 [sigma]
DATA_INTERVAL:   14.336 [sec]
GRB_DATE:        18634 TJD;   151 DOY;   19/05/31
GRB_TIME:        72612.14 SOD {20:10:12.14} UT
GRB_PHI:         309.00 [deg]
GRB_THETA:        23.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41531 (Gnd S/W Version number)
SUN_POSTN:        68.46d {+04h 33m 52s}  +21.96d {+21d 57' 38"}
SUN_DIST:         76.86 [deg]   Sun_angle= 3.2 [hr] (West of Sun)
MOON_POSTN:       37.45d {+02h 29m 49s}   +9.65d {+09d 38' 55"}
MOON_DIST:        52.81 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      280.27,-74.77 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      358.58,-44.99 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_lc_medres34_bn190531840.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_581026217.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.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 31 May 19 20:12:13 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      5
TRIGGER_NUM:     581026217
GRB_RA:           19.100d {+01h 16m 24s} (J2000),
                  19.317d {+01h 17m 16s} (current),
                  18.541d {+01h 14m 10s} (1950)
GRB_DEC:         -42.010d {-42d 00' 35"} (J2000),
                 -41.908d {-41d 54' 28"} (current),
                 -42.274d {-42d 16' 24"} (1950)
GRB_ERROR:       1.09 [deg radius, statistical only]
DATA_SIGNIF:     68.10 [sigma]
DATA_INTERVAL:   18.432 [sec]
GRB_DATE:        18634 TJD;   151 DOY;   19/05/31
GRB_TIME:        72612.14 SOD {20:10:12.14} UT
GRB_PHI:         306.00 [deg]
GRB_THETA:        22.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41531 (Gnd S/W Version number)
SUN_POSTN:        68.46d {+04h 33m 52s}  +21.96d {+21d 57' 38"}
SUN_DIST:         78.36 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:       37.45d {+02h 29m 49s}   +9.65d {+09d 38' 56"}
MOON_DIST:        54.18 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      285.60,-74.27 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      356.48,-45.30 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_lc_medres34_bn190531840.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_581026217.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        Bright hard burst in the GBM.  
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.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 31 May 19 20:11:50 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      2
TRIGGER_NUM:     581026217
GRB_RA:           21.650d {+01h 26m 36s} (J2000),
                  21.863d {+01h 27m 27s} (current),
                  21.099d {+01h 24m 24s} (1950)
GRB_DEC:         -41.400d {-41d 23' 59"} (J2000),
                 -41.300d {-41d 17' 58"} (current),
                 -41.659d {-41d 39' 32"} (1950)
GRB_ERROR:       1.81 [deg radius, statistical only]
DATA_SIGNIF:     29.40 [sigma]
DATA_INTERVAL:   9.216 [sec]
GRB_DATE:        18634 TJD;   151 DOY;   19/05/31
GRB_TIME:        72612.14 SOD {20:10:12.14} UT
GRB_PHI:         308.00 [deg]
GRB_THETA:        24.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41531 (Gnd S/W Version number)
SUN_POSTN:        68.46d {+04h 33m 52s}  +21.96d {+21d 57' 38"}
SUN_DIST:         76.59 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       37.45d {+02h 29m 48s}   +9.65d {+09d 38' 52"}
MOON_DIST:        52.93 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      278.35,-74.01 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      359.25,-45.79 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_lc_medres34_bn190531840.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_581026217.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.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 31 May 19 20:11:44 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      1
TRIGGER_NUM:     581026217
GRB_RA:           20.480d {+01h 21m 55s} (J2000),
                  20.697d {+01h 22m 47s} (current),
                  19.921d {+01h 19m 41s} (1950)
GRB_DEC:         -40.050d {-40d 02' 59"} (J2000),
                 -39.949d {-39d 56' 55"} (current),
                 -40.311d {-40d 18' 40"} (1950)
GRB_ERROR:       2.76 [deg radius, statistical only]
DATA_SIGNIF:     18.30 [sigma]
DATA_INTERVAL:   7.168 [sec]
GRB_DATE:        18634 TJD;   151 DOY;   19/05/31
GRB_TIME:        72612.14 SOD {20:10:12.14} UT
GRB_PHI:         311.00 [deg]
GRB_THETA:        23.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41531 (Gnd S/W Version number)
SUN_POSTN:        68.46d {+04h 33m 52s}  +21.96d {+21d 57' 38"}
SUN_DIST:         76.25 [deg]   Sun_angle= 3.2 [hr] (West of Sun)
MOON_POSTN:       37.45d {+02h 29m 48s}   +9.65d {+09d 38' 51"}
MOON_DIST:        51.97 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      278.81,-75.62 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      359.18,-44.18 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_lc_medres34_bn190531840.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_581026217.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.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 31 May 19 20:19:34 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     581026217
GRB_RA:           20.160d {+01h 20m 38s} (J2000),
                  20.378d {+01h 21m 31s} (current),
                  19.598d {+01h 18m 23s} (1950)
GRB_DEC:         -39.400d {-39d 23' 59"} (J2000),
                 -39.299d {-39d 17' 54"} (current),
                 -39.662d {-39d 39' 42"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
GRB_DATE:        18634 TJD;   151 DOY;   19/05/31
GRB_TIME:        72612.14 SOD {20:10:12.14} UT
GRB_PHI:         314.00 [deg]
GRB_THETA:        22.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41531 (Gnd S/W Version number)
SUN_POSTN:        68.47d {+04h 33m 53s}  +21.96d {+21d 57' 40"}
SUN_DIST:         75.96 [deg]   Sun_angle= 3.2 [hr] (West of Sun)
MOON_POSTN:       37.52d {+02h 30m 04s}   +9.67d {+09d 40' 18"}
MOON_DIST:        51.50 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      278.43,-76.31 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      359.36,-43.49 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_lc_medres34_bn190531840.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_locplot_all_bn190531840.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:        In the LAT Field-of-view.  
COMMENTS:        Bright hard burst in the GBM.  
COMMENTS:        This is likely a Long GRB.

GCN Circular #24695
The Fermi GBM team reports the detection of a likely LONG GRB
At 20:10:12 UT on 31 May 2019, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 190531B (trigger 581026217.141598 / 190531840).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 20.2, Dec = -39.4 (J2000 degrees, equivalent to J2000 01h 20m, -39d 23'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 22.0 degrees.
The skymap can be found here: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_skymap_all_bn190531840.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_healpix_all_bn190531840.fit
The GBM light curve can be found here: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_lc_medres34_bn190531840.gif
GCN Circular #24696
F. Kunzweiler, B. Biltzinger, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 581026217 at 20:10:12 on 31 May 2019 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) = 27.9+/-0.8 deg Decl.(2000.0) = -40.8+/-0.6 deg We estimate an additional systematic error of 2 deg.
Further details are available at: https://grb.mpe.mpg.de/grb/GRB190531840/
The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB190531840/healpix
The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB190531840/json
GCN Circular #24699
F. Kunzweiler & J. Greiner (both MPE Garching)
GCN 24696 wrongly named Fermi trigger 581026217 / GRB 190531840 as GRB 190531A, but it should be GRB 190531B.
We apologize for any confusion this might have caused.

GCN Notice

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 01 Jun 19 00:26:37 UT
NOTICE_TYPE:     Fermi-LAT Offline Position
TRIGGER_NUM:     581026217 
GRB_RA:           24.370d {+01h 37m 29s} (J2000),
                  24.579d {+01h 38m 19s} (current),
                  23.832d {+01h 35m 20s} (1950)
GRB_DEC:         -41.970d {-41d 58' 11"} (J2000),
                 -41.872d {-41d 52' 17"} (current),
                 -42.224d {-42d 13' 26"} (1950)
GRB_ERROR:       6.60 [arcmin radius, 90% containment, statistical only]
GRB_DATE:        18634 TJD;   151 DOY;   19/05/31
GRB_TIME:        72612.14 SOD {20:10:12.14} UT
TRIGGER_ID:      0x0
MISC:            0x40000000
SUN_POSTN:        68.65d {+04h 34m 35s}  +21.99d {+21d 59' 06"}
SUN_DIST:         75.74 [deg]   Sun_angle= 2.9 [hr] (West of Sun)
MOON_POSTN:       39.64d {+02h 38m 33s}  +10.43d {+10d 25' 51"}  
MOON_DIST:        54.10 [deg] 
MOON_ILLUM:      7 [%]
GAL_COORDS:      273.50,-72.43 [deg] galactic lon,lat of the burst (or transient)      
ECL_COORDS:        1.31,-47.36 [deg] ecliptic lon,lat of the burst (or
transient)
COMMENTS:        Fermi LAT Offline position.
COMMENTS:        This Notice was ground-generated -- not flight-generated.
COMMENTS:        It is the result of human-in-the-loop processing.
COMMENTS:        This is a human generated position of a LAT ground detection.
COMMENTS:        This source corresponds to GBM trigger 581026217 / 190531840.

GCN Circular #24701
M. Axelsson (KTH and Stockholm Univ.), M. Arimoto (Kanazawa Univ.), D. Kocevski (NASA/MSFC) and F. Longo (Univ. and INFN Trieste) report on behalf of the Fermi-LAT team:
On May 31, 2019, Fermi-LAT detected high-energy emission from GRB 190531B, which was also detected by Fermi-GBM (trigger 581026217 / 190531840; GCN 24695).
The best LAT on-ground location is found to be
RA, Dec 24.37, -41.97 (degrees, J2000)
with an error radius of 0.11 deg (90% containment, statistical error only). This was 25 deg from the LAT boresight at the time of the GBM trigger:
T0 = 20:10:12.14 UT.
The data from the Fermi-LAT show a significant increase in the event rate after the GBM trigger that is spatially and temporally correlated with the GBM emission with high significance.
The photon flux above 100 MeV in the time interval 0-700 s after the GBM trigger is 8.9e-6 ph/cm2/s. The highest-energy photon in this interval is a 7.0 GeV event observed at T0+325s.
The estimated photon index above 100 MeV is -2.1 +/- 0.2.
The Fermi-LAT point of contact for this burst is Francesco Longo (Francesco.Longo@ts.infn.it).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
GCN Circular #24702
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the Fermi/LAT GRB 190531B. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/ToO_GRBs/00020895
Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Fermi/LAT event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular #24705
P. Veres and C. Meegan (both UAH) report on behalf of the Fermi GBM Team:
"At 20:10:12.14 UT on 31 May 2019, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 190531B (trigger 581026217 / 190531840, GCN #24695), which was also detected by Fermi-LAT (GCN # 24701).
The GBM light curve consists of multiple peaks with a duration (T90) of about 38.4 s (50-300 keV).
The time-averaged spectrum from T0 to T0+44.4 s is best fit by a Band function with Epeak = 473 +/- 14 keV, alpha = -0.79 +/- 0.01, and beta = -2.33 +/- 0.06.
The event fluence (10-1000 keV) in this time interval is (9.91 +/- 0.08)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+31.2 s in the 10-1000 keV band is 27.7 +/- 0.4 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN Circular #24706
P. D'Avanzo (INAF-OAB), S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernadini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , A. Tohuvavohu (PSU) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 190531B (Axelsson et al. GCN Circ. 24701), collecting 5.0 ks of Photon Counting (PC) mode data between T0+18.2 ks and T0+29.7 ks.
Eleven uncatalogued X-ray sources are detected, of which one ("Source 8") is above the RASS limit, and is therefore likely the GRB afterglow. Using 1291 s of PC mode data and 1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 24.29620, -41.95841 which is equivalent to:
```
RA (J2000): 01h 37m 11.09s
Dec(J2000): -41d 57' 30.3"
```
with an uncertainty of 1.6 arcsec (radius, 90% confidence). This position is 3.4 arcmin from the Fermi/LAT position.
The light curve can be modelled with a power-law decay with a decay index of alpha=1.0 (+/-0.3).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.20 (+0.15, -0.14). The best-fitting absorption column is 9.1 (+1.2, -1.1) x 10^21 cm^-2, in excess of the Galactic value of 1.8 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 4.2 x 10^-11 (9.0 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     9.1 (+1.2, -1.1) x 10^21 cm^-2
Galactic foreground: 1.8 x 10^20 cm^-2
Excess significance: 12.8 sigma
Photon index:	     2.20 (+0.15, -0.14)
```
If the light curve continues to decay with a power-law decay index of 1.0, the count rate at T+24 hours will be 0.14 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.9 x 10^-12 (1.3 x 10^-11) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis of the likely afterglow are at http://www.swift.ac.uk/ToO_GRBs/00020895/Source8.php. The results of the full analysis of the XRT observations are available at http://www.swift.ac.uk/ToO_GRBs/00020895.
This circular is an official product of the Swift-XRT team.
GCN Circular #24707
V. Lipunov, V.Kornilov, E.Gorbovskoy, N.Tiurina, A.Kuznetsov, I.Gorbunov, V.Vladimirov, P.Balanutsa, D.Vlasenko, D.Zimnukhov, F.Balakin,A. Chasovnikov, V.Topolev, V.Senik, D.Kuvshinov(Lomonosov Moscow State University, SAI, Physics Department),
D. Buckley (South African Astronomical Observatory),
R. Podesta, C. Lopez, C.Francile, F. Podesta (Observatorio Astronomico Felix Aguilar OAFA, San Juan National University),
H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE, SJNU)
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias),
O. Gress, N.M. Budnev, O.Ershova, S.Yazev (Applied Physics Institute, Irkutsk State University),
V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk Educational State University),
A. Tlatov, D.Dormidontov, A.V. Parhomenko (Kislovodsk Solar Station of the Pulkovo Observatory),
MASTER Global Robotic Net (Lipunov et al., 2010, Advances in Astronomy,vol.2010, 30L (http://observ.pereplet.ru) observed Fermi GRB 190531B (Ttrig=2019-05-31 20:10:12UT, GBM team GCN24695, Veres et al. GCN 24705; BALROG localization RA,Dec(2000) = 27.9(+/-0.8d) -40.8(+/-0.6) Kunzweiler et al. GCN 24696, GCN 24699, LAT localization RA,Dec= 24.37, -41.97 +-0.11d(90%) Axelsson et al. GCN24701, Swift XRT afterglow 01h 37m 11.09s -41d 57' 30.3" +-1.6 arcsec(90%) D'Avanzo et al. GCN24706, Evans et al. 24702 )
At alert time
```
MASTER-SAAO:   Error-Box_altitude=-15d, Sun_alt=-57d.
MASTER-OAFA:   Error-Box_altitude=+15d, Sun_alt=+15d
```
MASTER-SAAO robotic telescope (located in South African Astronomical Observatory) was pointed to the GRB190531A 4934 sec after notice time and 20321 sec after trigger time at 2019-06-01 01:48:53 UT . Error-box_alt=21deg, sun_alt=-47deg. There is no OT at Swift XRT position with unfiltered mlim=20.6m
MASTER-OAFA robotic telescope (located in Argentina) was pointed to the GRB190531A at 2019-06-01 08:55:19UT Error-box_alt=34deg, sun_alt=-32deg. There is no OT at Swift XRT position with unfiltered mlim=20.0m
Reduction will be continued. The message may be cited.
GCN Circular #24711
J. Japelj (U. Amsterdam), A. Rossi (INAF-OAS), D. B. Malesani (DTU Space), K. E. Heintz (Univ. Iceland), G. Pugliese, L. Kaper (U. Amsterdam) report on behalf of the Stargate collaboration:
We observed the field of GRB 190531B (Fermi GBM team, GCN 24695; Kunzweiler et al., GCN 24696; Axelsson et al., GCN 24701) with the ESO VLT UT2 (Kueyen), using the X-shooter acquisition camera. A 3x30 s exposure with the SDSS r filter was taken at approximate time 2019 June 1.39 UT (0.55 days after GRB).
We do not detect any new object within the error region of the detected X-ray afterglow (D'Avanzo et al., GCN 24706), down to a 3-sigma limiting magnitude r > 23 AB (calibrated against nearby star at position RA=01:37:12.696, Dec=-41:57:36.702). The closest source to the XRT error circle is at RA=01:37:11.37, Dec=-41:57:30.73, which is 3.1 arcsec away from the XRT location, and is thus unlikely to be related to the GRB.
We acknowledge excellent support from the observing team in Paranal, in particular Alex Correa, Florian Rodler and Pascale Hibon.
GCN Circular #24713
Q. B. Yi, S. Xiao, Q. Luo, C. Cai, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, X. F. Lu, A. M. Zhang, Y. F. Zhang, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team:
At 2019-05-31T20:10:12.00 (T0), Insight-HXMT/HE detected GRB 190531B (trigger ID: HEB190531840) in a routine search of the data, which was also triggered by Fermi/GBM (GCN #24695) and Fermi/LAT (GCN #24701).
The Insight-HXMT/HE light curve mainly consists of multiple pulses with a duration (T90) of 27.82 s measured from T0+7.93 s. The 1-ms peak rate, measured from T0+31.40 s, is 13079 cnts/sec. The total counts from this burst is 91598 counts. URL_LC: http://www.hxmt.org/images/GRB/HEB190531840_lc.jpg
All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 80-800 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope.
Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org.
GCN Circular #24730
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 190531B (Fermi-GBM detection: The Fermi GBM team, GCN Circ. 24695; Fermi-GBM observations: Veres and Meegan, GCN Circ. 24705; Fermi-LAT detection: Axelsson et al., GCN Circ. 24701; Insight-HXMT/HE detection: Yi et al., GCN Circ. 24713) triggered Konus-Wind at T0=72616.175 s UT (20:10:16.175).
The burst light curve shows a multipeaked structure which starts at ~T0-38 s and has a total duration of ~110 s. The emission is seen up to ~5 MeV.
As observed by Konus-Wind, the burst had a fluence of 1.51(-0.15,+0.16)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+17.648 s, of 1.96(-0.30,+0.30)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+83.712 s) is best fit in the 20 keV - 5 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.73(-0.08,+0.08), the high energy photon index beta = -2.25(-0.21,+0.14), the peak energy Ep = 364(-34,+40) keV (chi2 = 63/72 dof).
The spectrum near the maximum count rate (measured from T0+15.616 to T0+19.456 s) is best fit in the 20 keV - 7 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.60(-0.08,+0.09), the high energy photon index beta = -2.64(-0.46,+0.26), the peak energy Ep = 520(-53,+55) keV (chi2 = 87/77 dof).
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB190531_T72616/
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN Circular #24731
GRB 190531B: Swift/UVOT Upper Limits
K. K. Simpson (PSU) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 190531B 18175 s after the LAT trigger (Axelsson et al., GCN Circ. 24701). No optical afterglow consistent with the XRT position (D'Avanzo et al., GCN Circ. 24706) 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 initial exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

b                18661        24137          365         >20.5
u                18497        29702          551         >21.1
w1               18175        29509         1132         >20.7
m2               19630        25766          972         >20.9
w2               18826        24990         1459         >21.3
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #24738
Y. Shimizu (Kanagawa U), A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena), and the CALET collaboration:
The long GRB 190531B (Fermi-LAT detection: Axelsson et al.,GCN Circ. 24701; Fermi-GBM observations: Veres and Meegan, GCN Circ. 24705; Insight-HXMT/HE detection: Yi et al., GCN Circ. 24713; Konus-Wind observation: Svinkin et al., GCN Circ. 24730) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 20:10:20.034 UTC on 31 May 2019. The burst signal was seen by all CGBM detectors. No real-time CGBM GCN notice was distributed about this trigger because the real-time communication from the ISS was off (loss of signal).
The burst light curve shows a multi-peaked emission episode which starts at T-9.7 sec, peaks at 14.5 sec and ends at T+74.5 sec. The T90 and T50 durations measured by the SGM data are 36.8 +- 20.0 sec and 13.5 +- 0.9 sec (40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1243368627/
The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.

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Jochen Greiner, last update: 04-Jun-2019 [Disclaimer]