Gamma-ray Burst 200826B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Wed 26 Aug 20 22:10:07 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     620172587
GRB_RA:          296.300d {+19h 45m 12s} (J2000),
                 296.250d {+19h 45m 00s} (current),
                 296.416d {+19h 45m 40s} (1950)
GRB_DEC:         +71.817d {+71d 49' 00"} (J2000),
                 +71.868d {+71d 52' 03"} (current),
                 +71.693d {+71d 41' 35"} (1950)
GRB_ERROR:       5.50 [deg radius, statistical plus systematic]
GRB_INTEN:       1078 [cnts/sec]
DATA_SIGNIF:     22.80 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        19087 TJD;   239 DOY;   20/08/26
GRB_TIME:        79782.72 SOD {22:09:42.72} UT
GRB_PHI:          20.00 [deg]
GRB_THETA:       150.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.54
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      93%  GRB
2nd_MOST_LIKELY:   4%  Generic Transient
DETECTORS:       0,0,0, 0,1,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       156.00d {+10h 24m 01s}  +10.00d {+09d 59' 51"}
SUN_DIST:         94.05 [deg]   Sun_angle= -9.3 [hr] (East of Sun)
MOON_POSTN:      258.31d {+17h 13m 14s}  -22.27d {-22d 15' 56"}
MOON_DIST:        97.64 [deg]
MOON_ILLUM:      63 [%]
GAL_COORDS:      103.87, 21.63 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       41.25, 79.40 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200826923/quicklook/glg_lc_medres34_bn200826923.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 209.65,1.28 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Wed 26 Aug 20 22:10:18 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      59
TRIGGER_NUM:     620172587
GRB_RA:          306.183d {+20h 24m 44s} (J2000),
                 306.221d {+20h 24m 53s} (current),
                 306.090d {+20h 24m 22s} (1950)
GRB_DEC:         +67.733d {+67d 43' 60"} (J2000),
                 +67.801d {+67d 48' 04"} (current),
                 +67.569d {+67d 34' 09"} (1950)
GRB_ERROR:       3.28 [deg radius, statistical plus systematic]
GRB_INTEN:       15138 [cnts/sec]
DATA_SIGNIF:     519.60 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        19087 TJD;   239 DOY;   20/08/26
GRB_TIME:        79782.72 SOD {22:09:42.72} UT
GRB_PHI:          24.00 [deg]
GRB_THETA:       155.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.49
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      93%  GRB
2nd_MOST_LIKELY:   4%  Generic Transient
DETECTORS:       0,0,0, 0,1,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       156.00d {+10h 24m 01s}  +10.00d {+09d 59' 51"}
SUN_DIST:         99.33 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      258.31d {+17h 13m 15s}  -22.27d {-22d 15' 57"}
MOON_DIST:        96.69 [deg]
MOON_ILLUM:      63 [%]
GAL_COORDS:      101.62, 16.77 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       21.37, 76.10 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200826923/quicklook/glg_lc_medres34_bn200826923.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 209.65,1.28 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Wed 26 Aug 20 22:10:27 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     620172587
GRB_RA:          162.690d {+10h 50m 46s} (J2000),
                 163.000d {+10h 52m 00s} (current),
                 161.934d {+10h 47m 44s} (1950)
GRB_DEC:         +53.550d {+53d 32' 60"} (J2000),
                 +53.440d {+53d 26' 24"} (current),
                 +53.815d {+53d 48' 55"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
DATA_SIGNIF:     151.60 [sigma]
DATA_INTERVAL:   1.024 [sec]
GRB_DATE:        19087 TJD;   239 DOY;   20/08/26
GRB_TIME:        79782.72 SOD {22:09:42.72} UT
GRB_PHI:          11.00 [deg]
GRB_THETA:       100.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       156.00d {+10h 24m 01s}  +10.00d {+09d 59' 51"}
SUN_DIST:         43.81 [deg]   Sun_angle= -0.5 [hr] (East of Sun)
MOON_POSTN:      258.31d {+17h 13m 15s}  -22.27d {-22d 15' 58"}
MOON_DIST:       110.82 [deg]
MOON_ILLUM:      63 [%]
GAL_COORDS:      154.73, 55.48 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      139.63, 41.89 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200826923/quicklook/glg_lc_medres34_bn200826923.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_620172587.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        Bright hard burst in the GBM.  
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:     Wed 26 Aug 20 22:11:25 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      5
TRIGGER_NUM:     620172587
GRB_RA:          161.890d {+10h 47m 34s} (J2000),
                 162.205d {+10h 48m 49s} (current),
                 161.123d {+10h 44m 30s} (1950)
GRB_DEC:         +54.850d {+54d 51' 00"} (J2000),
                 +54.741d {+54d 44' 26"} (current),
                 +55.114d {+55d 06' 51"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
DATA_SIGNIF:     369.20 [sigma]
DATA_INTERVAL:   9.216 [sec]
GRB_DATE:        19087 TJD;   239 DOY;   20/08/26
GRB_TIME:        79782.72 SOD {22:09:42.72} UT
GRB_PHI:          12.00 [deg]
GRB_THETA:       101.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       156.00d {+10h 24m 01s}  +10.00d {+09d 59' 50"}
SUN_DIST:         45.01 [deg]   Sun_angle= -0.4 [hr] (East of Sun)
MOON_POSTN:      258.32d {+17h 13m 18s}  -22.27d {-22d 16' 04"}
MOON_DIST:       111.49 [deg]
MOON_ILLUM:      63 [%]
GAL_COORDS:      153.45, 54.31 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      138.19, 42.76 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200826923/quicklook/glg_lc_medres34_bn200826923.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_620172587.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
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:     Wed 26 Aug 20 22:18:52 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     620172587
GRB_RA:          151.280d {+10h 05m 07s} (J2000),
                 151.614d {+10h 06m 27s} (current),
                 150.467d {+10h 01m 52s} (1950)
GRB_DEC:         +51.650d {+51d 38' 60"} (J2000),
                 +51.549d {+51d 32' 56"} (current),
                 +51.893d {+51d 53' 36"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
GRB_DATE:        19087 TJD;   239 DOY;   20/08/26
GRB_TIME:        79782.72 SOD {22:09:42.72} UT
GRB_PHI:          17.00 [deg]
GRB_THETA:        96.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       156.01d {+10h 24m 02s}  +10.00d {+09d 59' 43"}
SUN_DIST:         41.71 [deg]   Sun_angle= 0.3 [hr] (West of Sun)
MOON_POSTN:      258.40d {+17h 13m 36s}  -22.28d {-22d 16' 47"}
MOON_DIST:       117.59 [deg]
MOON_ILLUM:      63 [%]
GAL_COORDS:      163.19, 50.41 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      132.90, 36.94 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200826923/quicklook/glg_lc_medres34_bn200826923.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200826923/quicklook/glg_locplot_all_bn200826923.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.

GCN Circular #28292
The Fermi GBM team reports the detection of a likely LONG GRB
At 22:09:42 UT on 26 Aug 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 200826B (trigger 620172587.721156 / 200826923).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 151.3, Dec = 51.7 (J2000 degrees, equivalent to J2000 10h 05m, 51d 42'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 96.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200826923/quicklook/glg_skymap_all_bn200826923.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200826923/quicklook/glg_healpix_all_bn200826923.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200826923/quicklook/glg_lc_medres34_bn200826923.gif
GCN Circular #28298
C. Malacaria (NASA-MSFC/USRA) and C.Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 22:09:42.72 UT on 26 August 2020, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 200826B (trigger 620172587 / 200826923).
The on-ground calculated location, using the GBM trigger data, was reported in GCN 28292.
The GBM light curve shows an exceptionally bright long GRB with a duration (T90) of about 7.4 s (50-300 keV). The time-averaged spectrum from T0-0.003 s to T0+ 12.544 s is best fit by a Band function with Epeak = 410.3 +/- 5.6 keV, alpha = -0.64 +/- 0.01, and beta = -2.52 +/- 0.04 The event fluence (10-1000 keV) in this time interval is (1.414 +/- 0.006)E-04 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+5.1 s in the 10-1000 keV band is 110.1 +/- 0.7 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 #28303
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, R. Aptekar, D. Frederiks, A. Ridnaia, 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,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report:
The long-duration GRB 200826B (Fermi-GBM detection: The Fermi GBM Team, GCN Circ. 28292; Malacaria and Meegan, GCN Circ. 28298) has been detected by Fermi (GBM trigger 620172587), Konus-Wind, INTEGRAL (SPI-ACS), and Mars-Odyssey (HEND), so far, at about 79779 s UT (22:09:39).
We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:
```
   ---------------------------------------------
    RA(2000), deg          Dec(2000), deg
   ---------------------------------------------
   Center:
    153.175 (10h 12m 42s) +57.580 (+57d 34' 48")
   Corners:
    154.647 (10h 18m 35s) +58.181 (+58d 10' 52")
    153.503 (10h 14m 01s) +58.301 (+58d 18' 03")
    151.749 (10h 07m 00s) +56.954 (+56d 57' 14")
    152.864 (10h 11m 27s) +56.858 (+56d 51' 28")
   ---------------------------------------------
```
The error box area is 3280 sq. arcmin, and its maximum dimension is 2.0 deg (the minimum one is 33.4 arcmin). The Sun distance was 47 deg.
This box may be improved.
The IPN localization is consistent with, but reduces the area of, the Fermi RoboBA localization (GCN Circ. 28292).
A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB200826_T79779/IPN
The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.
GCN Circular #28304
A. Ridnaia, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration, very bright GRB 200826B (Fermi-GBM detection: The Fermi GBM Team, GCN Circ. 28292; Malacaria & Meegan, GCN Circ. 28298; IPN triangulation: Hurley et al., GCN Circ. 28303) triggered Konus-Wind at T0=79779.087 s UT (22:09:39.087).
The burst light curve shows a bright, multi-peaked pulse which started at ~T0-3 s and had a total duration of ~23 s. A weak post-burst emission is visible in the 18-70 keV band up to the end of the KW trigger record at ~T0+250 s. The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB200826_T79779/
As observed by Konus-Wind, the burst had a fluence of (2.0 ą 0.1)x10^-4 erg/cm^2 and a 64-ms peak energy flux, measured from T0+4.922, of (4.8 ą 0.4)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum of the burst (measured from T0 to T0+17.408 s) can be described, in the 20 keV - 15 MeV range, by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.54 (-0.04,+0.04), the high energy photon index beta = -2.38 (-0.07,+0.06), the peak energy Ep = 337 (-14,+15) keV, chi2 = 169/96 dof.
The spectrum near the peak count rate (measured from T0+4.864 to T0+5.120 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.18 (-0.18,+0.22), the high energy photon index beta = -2.42 (-0.23,+0.17), the peak energy Ep = 320 (-45,+48) keV, chi2 = 58/48 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: 26-Sep-2020 [Disclaimer]