Gamma-ray Burst 181125A

(All information courtesy of the instrument teams.)

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 25 Nov 18 08:54:59 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     873433,   Seg_Num: 0
GRB_RA:          268.413d {+17h 53m 39s} (J2000),
                 268.660d {+17h 54m 38s} (current),
                 267.760d {+17h 51m 02s} (1950)
GRB_DEC:          -2.613d {-02d 36' 47"} (J2000),
                  -2.616d {-02d 36' 56"} (current),
                  -2.604d {-02d 36' 13"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       2455 [cnts]    Image_Peak=150 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   146     E_range: 25-100 keV
BKG_INTEN:       14730 [cnts]
BKG_TIME:        32066.02 SOD {08:54:26.02} UT
BKG_DUR:         8 [sec]
GRB_DATE:        18447 TJD;   329 DOY;   18/11/25
GRB_TIME:        32079.91 SOD {08:54:39.91} UT
GRB_PHI:         -63.04 [deg]
GRB_THETA:        23.91 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     12.28 [sigma]
IMAGE_SIGNIF:    8.18 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  -2 -100  +0 -84  +0 
SUN_POSTN:       240.99d {+16h 03m 58s}  -20.76d {-20d 45' 41"}
SUN_DIST:         32.49 [deg]   Sun_angle= -1.8 [hr] (East of Sun)
MOON_POSTN:       91.22d {+06h 04m 54s}  +21.02d {+21d 01' 26"}
MOON_DIST:       161.42 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:       23.87, 11.60 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      268.30, 20.82 [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 = 79.97,-14.49 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(2.0<100sec) coincident with the FERMI_GBM event (trignum=564828886).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 25 Nov 18 08:55:05 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      44
TRIGGER_NUM:     564828886
GRB_RA:          248.800d {+16h 35m 12s} (J2000),
                 249.055d {+16h 36m 13s} (current),
                 248.125d {+16h 32m 30s} (1950)
GRB_DEC:          -7.717d {-07d 43' 00"} (J2000),
                  -7.755d {-07d 45' 15"} (current),
                  -7.614d {-07d 36' 51"} (1950)
GRB_ERROR:       32.33 [deg radius, statistical plus systematic]
GRB_INTEN:       73 [cnts/sec]
DATA_SIGNIF:     4.70 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        18447 TJD;   329 DOY;   18/11/25
GRB_TIME:        32081.73 SOD {08:54:41.73} UT
GRB_PHI:          12.00 [deg]
GRB_THETA:        60.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.43
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      84%  GRB
2nd_MOST_LIKELY:  12%  Solar Flare
DETECTORS:       0,1,0, 0,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       240.99d {+16h 03m 58s}  -20.76d {-20d 45' 41"}
SUN_DIST:         15.16 [deg]   Sun_angle= -0.5 [hr] (East of Sun)
MOON_POSTN:       91.23d {+06h 04m 54s}  +21.02d {+21d 01' 26"}
MOON_DIST:       154.81 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:        8.52, 25.64 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      248.31, 14.14 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn181125371/quicklook/glg_lc_medres34_bn181125371.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 354.98,4.33 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the SWIFT_BAT event (trignum=873433).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 25 Nov 18 08:55:19 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     564828886
GRB_RA:          250.810d {+16h 43m 14s} (J2000),
                 251.066d {+16h 44m 16s} (current),
                 250.133d {+16h 40m 32s} (1950)
GRB_DEC:          -8.040d {-08d 02' 23"} (J2000),
                  -8.074d {-08d 04' 27"} (current),
                  -7.947d {-07d 56' 48"} (1950)
GRB_ERROR:       19.49 [deg radius, statistical only]
DATA_SIGNIF:     5.30 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        18447 TJD;   329 DOY;   18/11/25
GRB_TIME:        32081.73 SOD {08:54:41.73} UT
GRB_PHI:          14.00 [deg]
GRB_THETA:        61.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4153 (Gnd S/W Version number)
SUN_POSTN:       240.99d {+16h 03m 58s}  -20.76d {-20d 45' 41"}
SUN_DIST:         15.99 [deg]   Sun_angle= -0.7 [hr] (East of Sun)
MOON_POSTN:       91.23d {+06h 04m 55s}  +21.02d {+21d 01' 27"}
MOON_DIST:       156.63 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:        9.48, 23.82 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      250.39, 14.10 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn181125371/quicklook/glg_lc_medres34_bn181125371.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_564828886.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=873433).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 25 Nov 18 08:59:04 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     873433,   Seg_Num: 0
GRB_RA:          268.413d {+17h 53m 39s} (J2000),
                 268.660d {+17h 54m 38s} (current),
                 267.760d {+17h 51m 02s} (1950)
GRB_DEC:          -2.613d {-02d 36' 47"} (J2000),
                  -2.616d {-02d 36' 56"} (current),
                  -2.604d {-02d 36' 13"} (1950)
GRB_DATE:        18447 TJD;   329 DOY;   18/11/25
GRB_TIME:        32079.91 SOD {08:54:39.91} UT
TRIGGER_INDEX:   146
GRB_PHI:         -63.04 [deg]
GRB_THETA:        23.91 [deg]
DELTA_TIME:      52.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.28 [sigma]
IMAGE_SIGNIF:    8.18 [sigma]
LC_URL:          sw00873433000msb.lc
SUN_POSTN:       240.99d {+16h 03m 58s}  -20.76d {-20d 45' 43"}
SUN_DIST:         32.49 [deg]   Sun_angle= -1.8 [hr] (East of Sun)
MOON_POSTN:       91.27d {+06h 05m 04s}  +21.03d {+21d 01' 36"}
MOON_DIST:       161.41 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:       23.87, 11.60 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      268.30, 20.82 [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 = 79.97,-14.49 [deg].

GCN Circular #23448
E. Sonbas (Adiyaman Univ.), S. D. Barthelmy (GSFC), P. D'Avanzo (INAF-OAB), A. Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB) and K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift Observatory Team:
At 08:54:39 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 181125A (trigger=873433). Swift did not slew due to an observing constraint. The BAT on-board calculated location is RA, Dec 268.413, -2.613, which is
```
   RA(J2000)  =  17h 53m 39s
   Dec(J2000) = -02d 36' 47"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak with a duration of about 10 sec. The peak count rate was ~1400 counts/sec (15-350 keV), at ~1 sec after the trigger.
Due to a Sun observing constraint, Swift cannot slew to the BAT position until 15:18 UT on 2019 January 31. There will thus be no XRT or UVOT data for this trigger before this time.
Burst Advocate for this burst is E. Sonbas (edasonbas AT yahoo.com). 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/too.html.)
GCN Circular #23450
T. Sakamoto (AGU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), E. Sonbas (Adiyaman Univ.), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-142 s to T+641 s (when the burst was in the BAT FOV) from the recent telemetry downlink, we report further analysis of BAT GRB 181125A (trigger #873433) (Sonbas et al., GCN Circ. 23448). The BAT ground-calculated position is RA, Dec = 268.391, -2.634 deg which is
```
  RA(J2000)  =  17h 53m 33.8s
  Dec(J2000) = -02d 38' 01.2"
```
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 69%.
The mask-weighted light curve shows a single-peaked structure that starts and peaks at ~T0, and ends at ~T+11 s. T90 (15-350 keV) is 10.5 +- 5.0 sec (estimated error including systematics).
The time-averaged spectrum from T-0.18 to T+11.24 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.57 +- 0.31. The fluence in the 15-150 keV band is 3.3 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.24 sec in the 15-150 keV band is 1.5 +- 0.3 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/873433/BA/
GCN Circular #23451
E. Bissaldi (Politecnico & INFN Bari) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 08:54:41.73 UT on 25 November 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 181125A (trigger 564828886 / 181125371), which was also detected by the Swift-BAT (Sonbas et al. 2018, GCN 23448). The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 64 degrees.
The GBM light curve shows a structured emission with a duration (T90) of about 4 s (50-300 keV). The time-averaged spectrum from T0-1.8 s to T0+2 s is adequately fit by a simple power law function with index -1.8 +/- 0.1.
The event fluence (10-1000 keV) in this time interval is (4.3 +/- 0.10)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0-1.15 s in the 10-1000 keV band is 2.0 +/- 0.2 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: 25-Nov-2018 [Disclaimer]