Gamma-ray Burst 210306B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Mar 21 09:32:45 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1036024,   Seg_Num: 0
GRB_RA:          331.848d {+22h 07m 23s} (J2000),
                 332.109d {+22h 08m 26s} (current),
                 331.230d {+22h 04m 55s} (1950)
GRB_DEC:         +10.175d {+10d 10' 30"} (J2000),
                 +10.279d {+10d 16' 44"} (current),
                  +9.930d {+09d 55' 49"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       6666 [cnts]    Image_Peak=185 [image_cnts]
TRIGGER_DUR:     2.048 [sec] 
TRIGGER_INDEX:   264     E_range: 25-100 keV
BKG_INTEN:       69735 [cnts]
BKG_TIME:        34301.38 SOD {09:31:41.38} UT
BKG_DUR:         24 [sec]
GRB_DATE:        19279 TJD;    65 DOY;   21/03/06
GRB_TIME:        34334.27 SOD {09:32:14.27} UT
GRB_PHI:         -72.69 [deg]
GRB_THETA:        37.79 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     10.04 [sigma]
IMAGE_SIGNIF:    8.40 [sigma]
MERIT_PARAMS:     +1  +0  +0  +1  +2  -1 -100  +0 -92  +0 
SUN_POSTN:       347.15d {+23h 08m 35s}   -5.51d {-05d 30' 28"}
SUN_DIST:         21.76 [deg]   Sun_angle= 1.0 [hr] (West of Sun)
MOON_POSTN:      259.33d {+17h 17m 18s}  -23.45d {-23d 26' 52"}
MOON_DIST:        78.69 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:       70.45,-35.48 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      337.71, 20.29 [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 = 19.73,-8.56 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(0.0<100sec) coincident with the FERMI_GBM event (trignum=636715939).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 06 Mar 21 09:32:17 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      49
TRIGGER_NUM:     636715939
GRB_RA:          339.767d {+22h 39m 04s} (J2000),
                 340.011d {+22h 40m 03s} (current),
                 339.192d {+22h 36m 46s} (1950)
GRB_DEC:         +33.933d {+33d 55' 60"} (J2000),
                 +34.044d {+34d 02' 38"} (current),
                 +33.673d {+33d 40' 21"} (1950)
GRB_ERROR:       14.12 [deg radius, statistical plus systematic]
GRB_INTEN:       71 [cnts/sec]
DATA_SIGNIF:     6.20 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        19279 TJD;    65 DOY;   21/03/06
GRB_TIME:        34334.42 SOD {09:32:14.42} UT
GRB_PHI:         300.00 [deg]
GRB_THETA:        15.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.41
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      84%  GRB
2nd_MOST_LIKELY:   7%  Solar Flare
DETECTORS:       0,1,0, 1,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       347.15d {+23h 08m 35s}   -5.51d {-05d 30' 28"}
SUN_DIST:         40.12 [deg]   Sun_angle= 0.5 [hr] (West of Sun)
MOON_POSTN:      259.32d {+17h 17m 17s}  -23.45d {-23d 26' 49"}
MOON_DIST:        95.73 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:       93.83,-21.35 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      356.97, 38.78 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210306397/quicklook/glg_lc_medres34_bn210306397.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 27.17,-16.68 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 06 Mar 21 09:32:25 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      60
TRIGGER_NUM:     636715939
GRB_RA:          343.333d {+22h 53m 20s} (J2000),
                 343.585d {+22h 54m 21s} (current),
                 342.739d {+22h 50m 57s} (1950)
GRB_DEC:         +29.733d {+29d 43' 60"} (J2000),
                 +29.846d {+29d 50' 47"} (current),
                 +29.467d {+29d 28' 01"} (1950)
GRB_ERROR:       14.32 [deg radius, statistical plus systematic]
GRB_INTEN:       98 [cnts/sec]
DATA_SIGNIF:     9.30 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        19279 TJD;    65 DOY;   21/03/06
GRB_TIME:        34334.42 SOD {09:32:14.42} UT
GRB_PHI:         320.00 [deg]
GRB_THETA:        15.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.91
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      91%  GRB
2nd_MOST_LIKELY:   3%  Distant Particles
DETECTORS:       0,1,0, 1,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       347.15d {+23h 08m 35s}   -5.51d {-05d 30' 28"}
SUN_DIST:         35.52 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:      259.32d {+17h 17m 17s}  -23.45d {-23d 26' 50"}
MOON_DIST:        96.81 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:       94.36,-26.51 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      357.85, 33.65 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210306397/quicklook/glg_lc_medres34_bn210306397.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 27.17,-16.68 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 06 Mar 21 09:32:34 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      59
TRIGGER_NUM:     636715939
GRB_RA:          337.910d {+22h 31m 38s} (J2000),
                 338.170d {+22h 32m 41s} (current),
                 337.297d {+22h 29m 11s} (1950)
GRB_DEC:         +14.720d {+14d 43' 12"} (J2000),
                 +14.829d {+14d 49' 46"} (current),
                 +14.463d {+14d 27' 45"} (1950)
GRB_ERROR:       6.46 [deg radius, statistical only]
DATA_SIGNIF:     9.80 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        19279 TJD;    65 DOY;   21/03/06
GRB_TIME:        34334.42 SOD {09:32:14.42} UT
GRB_PHI:         334.00 [deg]
GRB_THETA:        30.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       347.15d {+23h 08m 35s}   -5.51d {-05d 30' 28"}
SUN_DIST:         22.20 [deg]   Sun_angle= 0.6 [hr] (West of Sun)
MOON_POSTN:      259.32d {+17h 17m 18s}  -23.45d {-23d 26' 50"}
MOON_DIST:        86.00 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:       79.62,-36.13 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      345.45, 22.20 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210306397/quicklook/glg_lc_medres34_bn210306397.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_636715939.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/SWIFT NOTICE
NOTICE_DATE:     Sat 06 Mar 21 09:37:40 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     86200,   Seg_Num: 2
GRB_RA:          331.848d {+22h 07m 23s} (J2000),
                 332.109d {+22h 08m 26s} (current),
                 331.230d {+22h 04m 55s} (1950)
GRB_DEC:         +10.175d {+10d 10' 30"} (J2000),
                 +10.279d {+10d 16' 44"} (current),
                  +9.930d {+09d 55' 49"} (1950)
GRB_DATE:        19279 TJD;    65 DOY;   21/03/06
GRB_TIME:        34334.27 SOD {09:32:14.27} UT
TRIGGER_INDEX:   264
GRB_PHI:         -72.69 [deg]
GRB_THETA:        37.79 [deg]
DELTA_TIME:      17156.00 [sec]
TRIGGER_DUR:     2.048 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    0.00 [sigma]
LC_URL:          sw01036024000msb.lc
SUN_POSTN:       347.15d {+23h 08m 36s}   -5.51d {-05d 30' 23"}
SUN_DIST:         21.76 [deg]   Sun_angle= 1.0 [hr] (West of Sun)
MOON_POSTN:      259.38d {+17h 17m 30s}  -23.46d {-23d 27' 20"}
MOON_DIST:        78.64 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:       70.45,-35.48 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      337.71, 20.29 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Lightcurve.  
COMMENTS:           
COMMENTS:        WARNING: No BAT_Position TDRSS message was received for this trigger_number!  
COMMENTS:           
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 = 19.73,-8.56 [deg].  
COMMENTS:        The 3rd packet (of 3) was missing in the lightcurve data stream.

GCN Circular #29601
E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC), K. L. Page (U Leicester) and T. Sakamoto (AGU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 09:32:14 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210306B (trigger=1036024). Swift did not slew to the burst because of Sun constraint. The BAT on-board calculated location is RA, Dec 331.848, +10.175 which is
```
   RA(J2000)  = 22h 07m 23s
   Dec(J2000) = +10d 10' 30"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a few peaks structure with a duration of at least 15 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger.
Due to an observing constraint, Swift will not slew to this target. There will be no XRT or UVOT data.
Burst Advocate for this burst is E. Ambrosi (elena.ambrosi AT inaf.it). 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/)
GCN Circular #29612
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), A. D'Ai (INAF-IASFPA), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210306B (trigger #1036024) (D'Ai, et al., GCN Circ. 29601). The BAT ground-calculated position is RA, Dec = 331.813, 10.152 deg which is
```
    RA(J2000)  =  22h 07m 15.1s
    Dec(J2000) = +10d 09' 06.8"
```
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 21%.
The BAT light curve showed a multi-peaked structure that starts at T-2 s and ends at ~T+25 s. T90 (15-350 keV) is 24.32 +- 2.45 sec (estimated error including systematics).
The time-averaged spectrum from T-2.42 to T+24.63 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.38 +- 0.20. The fluence in the 15-150 keV band is 1.7 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+1.04 sec in the 15-150 keV band is 2.4 +- 0.5 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/1036024/BA/
GCN Circular #29637
S. Lesage (UAH), A. von Kienlin (MPE), and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 09:32:14.42 UT on 06 March 2021, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 210306B (trigger 636715939 / 210306397) which was also detected by the Swift/BAT (Ambrosi et al. 2021, GCN 29601). The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 37 degrees.
The GBM light curve shows a single-peaked structure with a duration (T90) of about 15 s (50-300 keV). The time-averaged spectrum from T0-1.3 s to T0+14.1 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.0 +/- 0.2 and the cutoff energy, parameterized as Epeak, is 73 +/- 8 keV.
The event fluence (10-1000 keV) in this time interval is (1.3 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.0 s in the 10-1000 keV band is 2.7 +/- 0.2 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/"

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Jochen Greiner, last update: 09-Mar-2021 [Disclaimer]