Gamma-ray Burst 181120A

(All information courtesy of the instrument teams.)

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Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 20 Nov 18 06:21:57 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      59
TRIGGER_NUM:     564387684
GRB_RA:           33.510d {+02h 14m 02s} (J2000),
                  33.756d {+02h 15m 02s} (current),
                  32.858d {+02h 11m 26s} (1950)
GRB_DEC:          +4.270d {+04d 16' 12"} (J2000),
                  +4.358d {+04d 21' 27"} (current),
                  +4.037d {+04d 02' 13"} (1950)
GRB_ERROR:       2.49 [deg radius, statistical only]
DATA_SIGNIF:     31.30 [sigma]
DATA_INTERVAL:   1.024 [sec]
GRB_DATE:        18442 TJD;   324 DOY;   18/11/20
GRB_TIME:        22879.08 SOD {06:21:19.08} UT
GRB_PHI:         159.00 [deg]
GRB_THETA:        67.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4153 (Gnd S/W Version number)
SUN_POSTN:       235.61d {+15h 42m 27s}  -19.68d {-19d 41' 00"}
SUN_DIST:        153.76 [deg]   Sun_angle= -10.5 [hr] (East of Sun)
MOON_POSTN:       20.71d {+01h 22m 52s}   +3.33d {+03d 19' 31"}
MOON_DIST:        13.05 [deg]
MOON_ILLUM:      90 [%]
GAL_COORDS:      158.50,-52.80 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       32.75, -8.67 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn181120265/quicklook/glg_lc_medres34_bn181120265.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_564387684.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.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 20 Nov 18 06:21:43 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      47
TRIGGER_NUM:     564387684
GRB_RA:           28.867d {+01h 55m 28s} (J2000),
                  29.121d {+01h 56m 29s} (current),
                  28.195d {+01h 52m 47s} (1950)
GRB_DEC:         +13.150d {+13d 09' 00"} (J2000),
                 +13.242d {+13d 14' 31"} (current),
                 +12.905d {+12d 54' 19"} (1950)
GRB_ERROR:       6.57 [deg radius, statistical plus systematic]
GRB_INTEN:       569 [cnts/sec]
DATA_SIGNIF:     28.60 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        18442 TJD;   324 DOY;   18/11/20
GRB_TIME:        22879.08 SOD {06:21:19.08} UT
GRB_PHI:         151.00 [deg]
GRB_THETA:        60.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.90
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      96%  GRB
2nd_MOST_LIKELY:   1%  Generic Transient
SUN_POSTN:       235.61d {+15h 42m 27s}  -19.68d {-19d 41' 00"}
SUN_DIST:        153.83 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:       20.71d {+01h 22m 51s}   +3.32d {+03d 19' 28"}
MOON_DIST:        12.94 [deg]
MOON_ILLUM:      90 [%]
GAL_COORDS:      146.04,-46.83 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       31.46,  1.24 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn181120265/quicklook/glg_lc_medres34_bn181120265.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 20 Nov 18 06:22:25 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      0
TRIGGER_NUM:     564387684
GRB_RA:           34.970d {+02h 19m 53s} (J2000),
                  35.218d {+02h 20m 52s} (current),
                  34.313d {+02h 17m 15s} (1950)
GRB_DEC:          +5.920d {+05d 55' 12"} (J2000),
                  +6.006d {+06d 00' 22"} (current),
                  +5.691d {+05d 41' 27"} (1950)
GRB_ERROR:       1.94 [deg radius, statistical only]
DATA_SIGNIF:     27.20 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        18442 TJD;   324 DOY;   18/11/20
GRB_TIME:        22879.08 SOD {06:21:19.08} UT
GRB_PHI:         160.00 [deg]
GRB_THETA:        65.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41531 (Gnd S/W Version number)
SUN_POSTN:       235.61d {+15h 42m 27s}  -19.68d {-19d 41' 00"}
SUN_DIST:        155.92 [deg]   Sun_angle= -10.6 [hr] (East of Sun)
MOON_POSTN:       20.72d {+01h 22m 53s}   +3.33d {+03d 19' 36"}
MOON_DIST:        14.70 [deg]
MOON_ILLUM:      90 [%]
GAL_COORDS:      159.11,-50.63 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       34.69, -7.59 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn181120265/quicklook/glg_lc_medres34_bn181120265.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_564387684.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(1.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=8162).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 20 Nov 18 06:30:36 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     564387684
GRB_RA:           36.990d {+02h 27m 58s} (J2000),
                  37.239d {+02h 28m 57s} (current),
                  36.331d {+02h 25m 19s} (1950)
GRB_DEC:          +6.560d {+06d 33' 36"} (J2000),
                  +6.644d {+06d 38' 38"} (current),
                  +6.337d {+06d 20' 12"} (1950)
GRB_ERROR:       2.69 [deg radius, statistical only]
GRB_DATE:        18442 TJD;   324 DOY;   18/11/20
GRB_TIME:        22879.08 SOD {06:21:19.08} UT
GRB_PHI:         162.00 [deg]
GRB_THETA:        64.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41531 (Gnd S/W Version number)
SUN_POSTN:       235.62d {+15h 42m 28s}  -19.69d {-19d 41' 05"}
SUN_DIST:        157.90 [deg]   Sun_angle= -10.8 [hr] (East of Sun)
MOON_POSTN:       20.79d {+01h 23m 09s}   +3.35d {+03d 21' 13"}
MOON_DIST:        16.71 [deg]
MOON_ILLUM:      90 [%]
GAL_COORDS:      161.19,-49.01 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       36.81, -7.64 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn181120265/quicklook/glg_lc_medres34_bn181120265.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn181120265/quicklook/glg_locplot_all_bn181120265.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(1.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=8162).

GCN NOTICE

 
TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 20 Nov 18 14:16:43 UT
NOTICE_TYPE:     Fermi-LAT Offline Position
TRIGGER_NUM:     564387684 
GRB_RA:           20.384d {+01h 21m 32s} (J2000),
                  20.629d {+01h 22m 31s} (current),
                  19.737d {+01h 18m 57s} (1950)
GRB_DEC:          +4.173d {+04d 10' 23"} (J2000),
                  +4.271d {+04d 16' 17"} (current),
                  +3.911d {+03d 54' 41"} (1950)
GRB_ERROR:       59.51 [arcmin radius, 90% containment, statistical only]
GRB_DATE:        18442 TJD;   324 DOY;   18/11/20
GRB_TIME:        22879.07 SOD {06:21:19.07} UT
TRIGGER_ID:      0x20000000
MISC:            0x40008000
SUN_POSTN:       235.96d {+15h 43m 50s}  -19.76d {-19d 45' 28"}
SUN_DIST:        142.27 [deg]   Sun_angle= -9.6 [hr] (East of Sun)
MOON_POSTN:       24.75d {+01h 38m 59s}   +4.87d {+04d 52' 21"}
MOON_DIST:         4.15 [deg]
MOON_ILLUM:      92 [%] 
GAL_COORDS:      137.15,-57.87 [deg] galactic lon,lat of the burst (or transient)      
ECL_COORDS:       20.40, -4.10 [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.

GCN Circular #23427
E. Bissaldi (Politecnico & INFN Bari), M. Axelsson (KTH ans Stockholm Univ.), G. Vianello (Stanford Univ.), F. Longo (Univ. & INFN Trieste), and D. Kocevski (NASA/MSFC) report on behalf of the Fermi-LAT team:
On November 20, 2018, Fermi-LAT detected high-energy emission from GRB 181120A, which was also detected by Fermi-GBM (trigger 181120265 / 564387684). The best LAT on-ground location is found to be
RA, Dec: 20.38, 4.17 (degrees, J2000)
with an error radius of 1 deg (90% containment, statistical error only). This was 71 deg from the LAT boresight at the time of the GBM trigger: T0 = 06:21:19.08 UT.
The data from the Fermi-LAT show a significant (~5 sigma) increase in the event rate in the time interval 3000-6000 s after the GBM emission. We note that the LAT location is 16 degrees from the GBM one. Based on our analysis, we rule out contamination from the Earth limb, and the nearest known point source is ~2 degrees away.
The photon flux above 100 MeV in the time interval 3000-6000 s after the GBM trigger is (2.2 +/- 0.7)E-06 ph/cm2/s. The estimated photon index above 100 MeV is 4.0 +/- 0.9. We note that the spectrum is softer than the one typically seen from GRBs. The highest-energy photon is a 410 MeV event which is observed 5530 seconds after the GBM trigger.
A Swift ToO has been requested for this burst.
The Fermi-LAT point of contact for this burst is Elisabetta Bissaldi (elisabetta.bissaldi@ba.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 #23428
C. Fletcher (USRA) and E. Bissaldi (Politecnico & INFN Bari) report on behalf of the Fermi GBM Team:
"At 06:21:19.08 UT on 20 November 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 181120A (trigger 564387684 / 181120265), which was also detected by the LAT (Bissaldi et al. 2018, GCN 23427) The GBM on-ground location is consistent with the LAT position.
The angle from the Fermi LAT boresight at the GBM trigger time is 71 degrees.
The GBM light curve shows a single bright pulse followed by extended emission with a duration (T90) of about 17 s (50-300 keV). The time-averaged spectrum from T0-0.5 s to T0+16.9 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.95 +/- 0.08 and the cutoff energy, parameterized as Epeak, is 158 +/- 14 keV
The event fluence (10-1000 keV) in this time interval is (4.60 +/- 0.191)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.1 s in the 10-1000 keV band is 11.5 +/- 0.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."

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Jochen Greiner, last update: 21-Nov-2018 [Disclaimer]