Gamma-ray Burst 210102C

(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 02 Jan 21 20:38:29 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1015728,   Seg_Num: 0
GRB_RA:          235.737d {+15h 42m 57s} (J2000),
                 236.079d {+15h 44m 19s} (current),
                 234.923d {+15h 39m 41s} (1950)
GRB_DEC:         -37.222d {-37d 13' 19"} (J2000),
                 -37.288d {-37d 17' 15"} (current),
                 -37.064d {-37d 03' 48"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       3313 [cnts]    Image_Peak=179 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   137     E_range: 15-50 keV
BKG_INTEN:       20385 [cnts]
BKG_TIME:        74277.73 SOD {20:37:57.73} UT
BKG_DUR:         8 [sec]
GRB_DATE:        19216 TJD;     2 DOY;   21/01/02
GRB_TIME:        74291.37 SOD {20:38:11.37} UT
GRB_PHI:         -151.62 [deg]
GRB_THETA:        30.15 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.96 [sigma]
IMAGE_SIGNIF:    8.14 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +1  -2 -100  +0 -72  +0 
SUN_POSTN:       283.78d {+18h 55m 07s}  -22.83d {-22d 49' 52"}
SUN_DIST:         43.23 [deg]   Sun_angle= 3.2 [hr] (West of Sun)
MOON_POSTN:      151.34d {+10h 05m 22s}  +16.93d {+16d 55' 31"}
MOON_DIST:        96.12 [deg]
MOON_ILLUM:      86 [%]
GAL_COORDS:      336.89, 14.09 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      242.04,-17.05 [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 = 243.73,-15.49 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 02 Jan 21 20:41:52 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1015728,   Seg_Num: 0
GRB_RA:          235.737d {+15h 42m 57s} (J2000),
                 236.079d {+15h 44m 19s} (current),
                 234.923d {+15h 39m 41s} (1950)
GRB_DEC:         -37.222d {-37d 13' 19"} (J2000),
                 -37.288d {-37d 17' 15"} (current),
                 -37.064d {-37d 03' 48"} (1950)
GRB_DATE:        19216 TJD;     2 DOY;   21/01/02
GRB_TIME:        74291.37 SOD {20:38:11.37} UT
TRIGGER_INDEX:   137
GRB_PHI:         -151.62 [deg]
GRB_THETA:        30.15 [deg]
DELTA_TIME:      77.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.96 [sigma]
IMAGE_SIGNIF:    8.14 [sigma]
LC_URL:          sw01015728000msb.lc
SUN_POSTN:       283.78d {+18h 55m 08s}  -22.83d {-22d 49' 51"}
SUN_DIST:         43.24 [deg]   Sun_angle= 3.2 [hr] (West of Sun)
MOON_POSTN:      151.37d {+10h 05m 29s}  +16.92d {+16d 54' 56"}
MOON_DIST:        96.09 [deg]
MOON_ILLUM:      86 [%]
GAL_COORDS:      336.89, 14.09 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      242.04,-17.05 [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 = 243.73,-15.49 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 02 Jan 21 20:39:38 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     631312759
GRB_RA:          226.800d {+15h 07m 12s} (J2000),
                 227.150d {+15h 08m 36s} (current),
                 225.969d {+15h 03m 53s} (1950)
GRB_DEC:         -43.500d {-43d 30' 00"} (J2000),
                 -43.580d {-43d 34' 46"} (current),
                 -43.308d {-43d 18' 28"} (1950)
GRB_ERROR:       16.80 [deg radius, statistical plus systematic]
GRB_INTEN:       96 [cnts/sec]
DATA_SIGNIF:     4.60 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        19216 TJD;     2 DOY;   21/01/02
GRB_TIME:        74354.40 SOD {20:39:14.40} UT
GRB_PHI:         337.00 [deg]
GRB_THETA:       140.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.72
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      73%  GRB
2nd_MOST_LIKELY:  24%  Distant Particles
DETECTORS:       0,0,0, 0,1,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       283.78d {+18h 55m 07s}  -22.83d {-22d 49' 52"}
SUN_DIST:         50.60 [deg]   Sun_angle= 3.8 [hr] (West of Sun)
MOON_POSTN:      151.35d {+10h 05m 24s}  +16.92d {+16d 55' 19"}
MOON_DIST:        91.76 [deg]
MOON_ILLUM:      86 [%]
GAL_COORDS:      327.47, 12.81 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      236.80,-24.91 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210102861/quicklook/glg_lc_medres34_bn210102861.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 272.12,16.12 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(63.0<100sec) coincident with the SWIFT_BAT event (trignum=1015728).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 02 Jan 21 20:39:47 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      59
TRIGGER_NUM:     631312759
GRB_RA:          232.683d {+15h 30m 44s} (J2000),
                 233.033d {+15h 32m 08s} (current),
                 231.853d {+15h 27m 25s} (1950)
GRB_DEC:         -40.883d {-40d 52' 59"} (J2000),
                 -40.954d {-40d 57' 13"} (current),
                 -40.713d {-40d 42' 46"} (1950)
GRB_ERROR:       8.32 [deg radius, statistical plus systematic]
GRB_INTEN:       237 [cnts/sec]
DATA_SIGNIF:     10.20 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        19216 TJD;     2 DOY;   21/01/02
GRB_TIME:        74354.40 SOD {20:39:14.40} UT
GRB_PHI:         338.00 [deg]
GRB_THETA:       135.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.26
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      52%  GRB
2nd_MOST_LIKELY:  44%  Distant Particles
DETECTORS:       0,0,0, 0,1,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       283.78d {+18h 55m 07s}  -22.83d {-22d 49' 52"}
SUN_DIST:         45.99 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      151.35d {+10h 05m 25s}  +16.92d {+16d 55' 18"}
MOON_DIST:        94.95 [deg]
MOON_ILLUM:      86 [%]
GAL_COORDS:      332.68, 12.61 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      240.56,-21.18 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210102861/quicklook/glg_lc_medres34_bn210102861.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 272.12,16.12 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(63.0<100sec) coincident with the SWIFT_BAT event (trignum=1015728).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 02 Jan 21 20:39:56 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     631312759
GRB_RA:          237.170d {+15h 48m 41s} (J2000),
                 237.484d {+15h 49m 56s} (current),
                 236.424d {+15h 45m 42s} (1950)
GRB_DEC:         -24.500d {-24d 30' 00"} (J2000),
                 -24.563d {-24d 33' 46"} (current),
                 -24.348d {-24d 20' 50"} (1950)
GRB_ERROR:       6.63 [deg radius, statistical only]
DATA_SIGNIF:     10.80 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        19216 TJD;     2 DOY;   21/01/02
GRB_TIME:        74354.40 SOD {20:39:14.40} UT
GRB_PHI:         326.00 [deg]
GRB_THETA:       121.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       283.78d {+18h 55m 07s}  -22.83d {-22d 49' 52"}
SUN_DIST:         42.23 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:      151.35d {+10h 05m 25s}  +16.92d {+16d 55' 16"}
MOON_DIST:        93.57 [deg]
MOON_ILLUM:      86 [%]
GAL_COORDS:      346.60, 22.98 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      240.34, -4.38 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210102861/quicklook/glg_lc_medres34_bn210102861.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_631312759.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(63.0<100sec) coincident with the SWIFT_BAT event (trignum=1015728).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 02 Jan 21 20:40:42 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      0
TRIGGER_NUM:     631312759
GRB_RA:          234.030d {+15h 36m 07s} (J2000),
                 234.351d {+15h 37m 24s} (current),
                 233.267d {+15h 33m 04s} (1950)
GRB_DEC:         -28.740d {-28d 44' 23"} (J2000),
                 -28.808d {-28d 48' 29"} (current),
                 -28.575d {-28d 34' 29"} (1950)
GRB_ERROR:       6.34 [deg radius, statistical only]
DATA_SIGNIF:     19.30 [sigma]
DATA_INTERVAL:   10.240 [sec]
GRB_DATE:        19216 TJD;     2 DOY;   21/01/02
GRB_TIME:        74354.40 SOD {20:39:14.40} UT
GRB_PHI:         327.00 [deg]
GRB_THETA:       126.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       283.78d {+18h 55m 07s}  -22.83d {-22d 49' 51"}
SUN_DIST:         44.58 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:      151.36d {+10h 05m 27s}  +16.92d {+16d 55' 08"}
MOON_DIST:        92.17 [deg]
MOON_ILLUM:      86 [%]
GAL_COORDS:      341.31, 21.60 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      238.56, -9.14 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210102861/quicklook/glg_lc_medres34_bn210102861.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_631312759.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(63.0<100sec) coincident with the SWIFT_BAT event (trignum=1015728).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 02 Jan 21 20:41:08 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      1
TRIGGER_NUM:     631312759
GRB_RA:          232.700d {+15h 30m 48s} (J2000),
                 233.018d {+15h 32m 04s} (current),
                 231.945d {+15h 27m 47s} (1950)
GRB_DEC:         -27.540d {-27d 32' 23"} (J2000),
                 -27.611d {-27d 36' 37"} (current),
                 -27.370d {-27d 22' 10"} (1950)
GRB_ERROR:       2.55 [deg radius, statistical only]
DATA_SIGNIF:     20.60 [sigma]
DATA_INTERVAL:   14.336 [sec]
GRB_DATE:        19216 TJD;     2 DOY;   21/01/02
GRB_TIME:        74354.40 SOD {20:39:14.40} UT
GRB_PHI:         325.00 [deg]
GRB_THETA:       126.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       283.78d {+18h 55m 07s}  -22.83d {-22d 49' 51"}
SUN_DIST:         45.86 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      151.36d {+10h 05m 28s}  +16.92d {+16d 55' 03"}
MOON_DIST:        90.68 [deg]
MOON_ILLUM:      86 [%]
GAL_COORDS:      341.13, 23.27 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      237.12, -8.26 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210102861/quicklook/glg_lc_medres34_bn210102861.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_631312759.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(63.0<100sec) coincident with the SWIFT_BAT event (trignum=1015728).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 02 Jan 21 20:48:37 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     631312759
GRB_RA:          239.150d {+15h 56m 36s} (J2000),
                 239.489d {+15h 57m 57s} (current),
                 238.346d {+15h 53m 23s} (1950)
GRB_DEC:         -34.580d {-34d 34' 47"} (J2000),
                 -34.640d {-34d 38' 22"} (current),
                 -34.436d {-34d 26' 07"} (1950)
GRB_ERROR:       3.44 [deg radius, statistical only]
GRB_DATE:        19216 TJD;     2 DOY;   21/01/02
GRB_TIME:        74354.40 SOD {20:39:14.40} UT
GRB_PHI:         336.00 [deg]
GRB_THETA:       127.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       283.79d {+18h 55m 09s}  -22.83d {-22d 49' 50"}
SUN_DIST:         40.25 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      151.43d {+10h 05m 44s}  +16.90d {+16d 53' 44"}
MOON_DIST:        97.96 [deg]
MOON_ILLUM:      85 [%]
GAL_COORDS:      340.83, 14.33 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      244.22,-13.86 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210102861/quicklook/glg_lc_medres34_bn210102861.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210102861/quicklook/glg_locplot_all_bn210102861.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(63.0<100sec) coincident with the SWIFT_BAT event (trignum=1015728).

GCN Circular #29226
E. Troja (NASA/GSFC/UMCP), M. G. Bernardini (INAF-OAB), C. Gronwall (PSU), A. Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB), D. M. Palmer (LANL) and T. Sbarrato (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team:
At 20:38:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210102C (trigger=1015728). Swift did not slew due to an observing constraint. The BAT on-board calculated location is RA, Dec 235.737, -37.222 which is
```
   RA(J2000) = 15h 42m 57s
   Dec(J2000) = -37d 13' 19"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a duration of about 100 sec. The peak count rate was ~3000 counts/sec (15-350 keV), at ~65 sec after the trigger.
Due to a Sun observing constraint, Swift cannot slew to the BAT position until 15:14 UT on 2021 January 06. There will thus be no XRT or UVOT data for this trigger before this time.
Burst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov). 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 #29227
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 210102C ( E. Troja et al., GCN 29226) errorbox 14718 sec after notice time and 14840 sec after trigger time at 2021-01-03 00:45:31 UT, with upper limit up to 17.5 mag. The observations began at zenith distance = 78 deg. The sun altitude is -27.8 deg.
The galactic latitude b = 14 deg., longitude l = 337 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1517509
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   14931 |         MASTER-SAAO |   C |   180 | 17.5 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #29228
S. Poolakkil (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 20:39:14.40 UT on 2 January 2021, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 210102C (trigger 631312759 / 210102861), which was also detected by the Swift/BAT (Troja et al. 2021, GCN 29226); GBM triggered on a later, brighter emission. The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 131 degrees.
The GBM light curve consists of multiple peaks followed by some extended emission with a duration (T90) of about 84 s (50-300 keV). The time-averaged spectrum from T0-3.07 s to T0+9.22 s (bright emission which triggered GBM) is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.41 +/- 0.08 and the cutoff energy, parameterized as Epeak, is 209 +/- 39 keV.
The event fluence (10-1000 keV) in this time interval is (5.219 +/- 0.332)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+4.99 s in the 10-1000 keV band is 7.9 +/- 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 #29229
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 210102C ( S. Poolakkil et al., GCN 29228) errorbox 14713 sec after notice time and 14777 sec after trigger time at 2021-01-03 00:45:31 UT, with upper limit up to 17.7 mag. The observations began at zenith distance = 78 deg. The sun altitude is -27.8 deg.
MASTER-OAFA robotic telescope located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 210102C errorbox 37485 sec after notice time and 37549 sec after trigger time at 2021-01-03 07:05:03 UT, with upper limit up to 17.4 mag. The observations began at zenith distance = 75 deg. The sun altitude is -25.8 deg.
The galactic latitude b = 14 deg., longitude l = 341 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1517531
We obtain a following upper limits.

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   14868 | 2021-01-03 00:45:31 |         MASTER-SAAO | (15h 37m 40.48s , -37d 10m 22.5s) |   C |   180 | 17.5 |        
   15229 | 2021-01-03 00:51:33 |         MASTER-SAAO | (15h 37m 40.65s , -37d 11m 17.2s) |   C |   180 | 17.7 |        
   15508 | 2021-01-03 00:56:12 |         MASTER-SAAO | (15h 37m 43.87s , -37d 11m 02.4s) |   C |   180 | 17.7 |        
   37639 | 2021-01-03 07:05:03 |         MASTER-OAFA | (15h 41m 31.97s , -37d 50m 25.5s) |   C |   180 | 16.9 |        
   38059 | 2021-01-03 07:12:02 |         MASTER-OAFA | (15h 41m 30.60s , -37d 52m 29.2s) |   C |   180 | 17.2 |        
   38563 | 2021-01-03 07:20:27 |         MASTER-OAFA | (15h 41m 33.22s , -37d 52m 25.5s) |   C |   180 | 17.2 |        
   38932 | 2021-01-03 07:27:35 |         MASTER-OAFA | (15h 58m 44.82s , -34d 37m 34.2s) |   C |    60 | 16.9 |        
   39011 | 2021-01-03 07:28:55 |         MASTER-OAFA | (15h 39m 27.24s , -34d 39m 06.6s) |   C |    60 | 17.3 |        
   39091 | 2021-01-03 07:30:14 |         MASTER-OAFA | (15h 56m 09.32s , -32d 37m 35.3s) |   C |    60 | 16.9 |        
   39170 | 2021-01-03 07:31:34 |         MASTER-OAFA | (15h 43m 02.44s , -36d 37m 27.2s) |   C |    60 | 17.2 |        
   39249 | 2021-01-03 07:32:53 |         MASTER-OAFA | (15h 37m 14.21s , -32d 36m 54.4s) |   C |    60 | 17.2 |        
   39329 | 2021-01-03 07:34:12 |         MASTER-OAFA | (16h 02m 42.12s , -36d 39m 25.7s) |   C |    60 | 17.0 |        
   39408 | 2021-01-03 07:35:32 |         MASTER-OAFA | (15h 47m 50.85s , -38d 37m 22.4s) |   C |    60 | 16.9 |        
   39488 | 2021-01-03 07:36:52 |         MASTER-OAFA | (15h 54m 49.80s , -30d 37m 41.3s) |   C |    60 | 16.9 |        
   39886 | 2021-01-03 07:43:30 |         MASTER-OAFA | (15h 58m 45.09s , -34d 38m 17.8s) |   C |    60 | 17.0 |        
   39966 | 2021-01-03 07:44:49 |         MASTER-OAFA | (16h 08m 24.29s , -34d 37m 29.7s) |   C |    60 | 16.8 |        
   40045 | 2021-01-03 07:46:09 |         MASTER-OAFA | (15h 39m 33.51s , -34d 37m 53.1s) |   C |    60 | 17.3 |        
   40124 | 2021-01-03 07:47:28 |         MASTER-OAFA | (15h 49m 07.52s , -34d 39m 05.9s) |   C |    60 | 17.1 |        
   40205 | 2021-01-03 07:48:49 |         MASTER-OAFA | (15h 56m 13.18s , -32d 38m 48.1s) |   C |    60 | 17.1 |        
   40285 | 2021-01-03 07:50:09 |         MASTER-OAFA | (16h 05m 35.69s , -32d 37m 31.1s) |   C |    60 | 16.8 |        
   40365 | 2021-01-03 07:51:29 |         MASTER-OAFA | (15h 42m 59.86s , -36d 38m 48.3s) |   C |    60 | 17.2 |        
   40444 | 2021-01-03 07:52:48 |         MASTER-OAFA | (15h 52m 56.54s , -36d 37m 37.3s) |   C |    60 | 17.1 |        
   40524 | 2021-01-03 07:54:07 |         MASTER-OAFA | (15h 37m 15.85s , -32d 37m 51.2s) |   C |    60 | 17.3 |        
   40603 | 2021-01-03 07:55:27 |         MASTER-OAFA | (15h 46m 40.83s , -32d 37m 04.2s) |   C |    60 | 17.2 |        
   40683 | 2021-01-03 07:56:47 |         MASTER-OAFA | (16h 02m 48.12s , -36d 38m 26.4s) |   C |    60 | 17.1 |        
   40842 | 2021-01-03 07:59:26 |         MASTER-OAFA | (15h 47m 53.41s , -38d 38m 51.7s) |   C |    60 | 17.0 |        
   40928 | 2021-01-03 08:00:52 |         MASTER-OAFA | (15h 57m 59.44s , -38d 37m 42.7s) |   C |    60 | 16.7 |        
   41009 | 2021-01-03 08:02:12 |         MASTER-OAFA | (15h 54m 46.80s , -30d 38m 46.7s) |   C |    60 | 17.0 |        
   41088 | 2021-01-03 08:03:32 |         MASTER-OAFA | (16h 04m 03.97s , -30d 37m 57.6s) |   C |    60 | 16.9 |        
   41406 | 2021-01-03 08:08:50 |         MASTER-OAFA | (15h 33m 02.59s , -36d 38m 51.3s) |   C |    60 | 17.2 |        
   41565 | 2021-01-03 08:11:29 |         MASTER-OAFA | (15h 45m 32.45s , -30d 37m 17.1s) |   C |    60 | 17.3 |        
   41803 | 2021-01-03 08:15:27 |         MASTER-OAFA | (15h 58m 44.22s , -34d 38m 25.6s) |   C |    60 | 17.2 |        
   41883 | 2021-01-03 08:16:47 |         MASTER-OAFA | (16h 08m 22.62s , -34d 37m 38.5s) |   C |    60 | 17.0 |        
   41964 | 2021-01-03 08:18:08 |         MASTER-OAFA | (15h 39m 33.08s , -34d 37m 59.5s) |   C |    60 | 17.4 |        
   42044 | 2021-01-03 08:19:28 |         MASTER-OAFA | (15h 49m 05.56s , -34d 39m 13.0s) |   C |    60 | 17.2 |        
   42123 | 2021-01-03 08:20:47 |         MASTER-OAFA | (15h 56m 11.34s , -32d 39m 21.9s) |   C |    60 | 17.0 |        
   42202 | 2021-01-03 08:22:06 |         MASTER-OAFA | (16h 05m 34.89s , -32d 37m 49.7s) |   C |    60 | 16.8 |        
   42282 | 2021-01-03 08:23:26 |         MASTER-OAFA | (15h 42m 58.96s , -36d 39m 00.0s) |   C |    60 | 17.1 |        
   42361 | 2021-01-03 08:24:45 |         MASTER-OAFA | (15h 52m 54.79s , -36d 37m 30.0s) |   C |    60 | 16.9 |        
   42440 | 2021-01-03 08:26:04 |         MASTER-OAFA | (15h 37m 14.12s , -32d 37m 56.0s) |   C |    60 | 17.2 |        
   42520 | 2021-01-03 08:27:24 |         MASTER-OAFA | (15h 46m 40.09s , -32d 37m 09.0s) |   C |    60 | 16.9 |        
   42600 | 2021-01-03 08:28:43 |         MASTER-OAFA | (16h 02m 47.44s , -36d 38m 32.4s) |   C |    60 | 16.9 |        
   42679 | 2021-01-03 08:30:03 |         MASTER-OAFA | (16h 12m 34.07s , -36d 39m 45.9s) |   C |    60 | 16.7 |

Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.

GCN Circular #29231
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), E. Troja (NASA/GSFC/UMCP), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+537 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210102C (trigger #1015728) (Troja et al., GCN Circ. 29226). The BAT ground-calculated position is RA, Dec = 235.747, -37.231 deg which is
```
   RA(J2000)  =  15h 42m 59.2s
   Dec(J2000) = -37d 13' 52.2"
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 76%.
The mask-weighted light curve shows a double-peaked structure. The first peak starts at ~T-2 s, peaks at ~T0, and ends at ~T+8 s. The second peak starts at ~T+55 s, peaks at ~T+67 s, and ends at ~T+100 s. T90 (15-350 keV) is 87.25 +- 4.97 sec (estimated error including systematics).
The time-averaged spectrum from T-2.07 to T+97.42 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.87 +- 0.08. The fluence in the 15-150 keV band is 3.9 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+66.72 sec in the 15-150 keV band is 4.4 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/BATbursts/1015728/bascript/top.html

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Jochen Greiner, last update: 04-Jan-2021 [Disclaimer]