Gamma-ray Burst 100225

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 25 Feb 10 02:45:47 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      46
TRIGGER_NUM:     288758733
GRB_RA:          310.233d {+20h 40m 56s} (J2000),
                 310.440d {+20h 41m 46s} (current),
                 309.210d {+20h 36m 50s} (1950)
GRB_DEC:         -60.683d {-60d 40' 59"} (J2000),
                 -60.647d {-60d 38' 47"} (current),
                 -60.861d {-60d 51' 39"} (1950)
GRB_ERROR:       21.30 [deg radius, statistical plus systematic]
GRB_INTEN:       99 [cnts/sec]
DATA_SIGNIF:     7.80 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        15252 TJD;    56 DOY;   10/02/25
GRB_TIME:        9931.15 SOD {02:45:31.15} UT
GRB_PHI:         329.00 [deg]
GRB_THETA:        55.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      0.73
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      96%  GRB
2nd_MOST_LIKELY:   2%  Generic Transient
DETECTORS:       0,0,0, 1,1,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       338.14d {+22h 32m 34s}   -9.17d {-09d 10' 05"}
SUN_DIST:         55.43 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:      107.97d {+07h 11m 54s}  +22.58d {+22d 35' 04"}
MOON_DIST:       138.85 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      335.78,-36.72 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      294.63,-40.64 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 52.60,5.83 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 25 Feb 10 02:46:00 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      58
TRIGGER_NUM:     288758733
GRB_RA:          302.317d {+20h 09m 16s} (J2000),
                 302.564d {+20h 10m 15s} (current),
                 301.090d {+20h 04m 22s} (1950)
GRB_DEC:         -67.917d {-67d 54' 59"} (J2000),
                 -67.886d {-67d 53' 10"} (current),
                 -68.063d {-68d 03' 46"} (1950)
GRB_ERROR:       10.40 [deg radius, statistical plus systematic]
GRB_INTEN:       149 [cnts/sec]
DATA_SIGNIF:     13.30 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        15252 TJD;    56 DOY;   10/02/25
GRB_TIME:        9931.15 SOD {02:45:31.15} UT
GRB_PHI:         321.00 [deg]
GRB_THETA:        50.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.47
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      95%  GRB
2nd_MOST_LIKELY:   4%  Generic Transient
DETECTORS:       0,0,0, 1,1,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       338.14d {+22h 32m 34s}   -9.17d {-09d 10' 05"}
SUN_DIST:         63.26 [deg]   Sun_angle= 2.4 [hr] (West of Sun)
MOON_POSTN:      107.98d {+07h 11m 54s}  +22.58d {+22d 35' 02"}
MOON_DIST:       133.80 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      327.72,-32.28 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      286.93,-46.37 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 52.60,5.83 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 25 Feb 10 02:46:07 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     288758733
GRB_RA:          312.430d {+20h 49m 43s} (J2000),
                 312.626d {+20h 50m 30s} (current),
                 311.462d {+20h 45m 51s} (1950)
GRB_DEC:         -57.610d {-57d 36' 35"} (J2000),
                 -57.572d {-57d 34' 17"} (current),
                 -57.796d {-57d 47' 45"} (1950)
GRB_ERROR:       6.06 [deg radius, statistical only]
DATA_SIGNIF:     15.70 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        15252 TJD;    56 DOY;   10/02/25
GRB_TIME:        9931.15 SOD {02:45:31.15} UT
GRB_PHI:         332.00 [deg]
GRB_THETA:        57.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   413 (Gnd S/W Version number)
SUN_POSTN:       338.14d {+22h 32m 34s}   -9.17d {-09d 10' 05"}
SUN_DIST:         52.25 [deg]   Sun_angle= 1.7 [hr] (West of Sun)
MOON_POSTN:      107.98d {+07h 11m 55s}  +22.58d {+22d 35' 01"}
MOON_DIST:       140.73 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      339.37,-38.34 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      297.35,-38.13 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 25 Feb 10 02:46:11 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      68
TRIGGER_NUM:     288758733
GRB_RA:          324.030d {+21h 36m 07s} (J2000),
                 324.214d {+21h 36m 51s} (current),
                 323.119d {+21h 32m 29s} (1950)
GRB_DEC:         -58.470d {-58d 28' 11"} (J2000),
                 -58.424d {-58d 25' 26"} (current),
                 -58.694d {-58d 41' 37"} (1950)
GRB_ERROR:       4.05 [deg radius, statistical only]
DATA_SIGNIF:     21.50 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        15252 TJD;    56 DOY;   10/02/25
GRB_TIME:        9931.15 SOD {02:45:31.15} UT
GRB_PHI:         328.00 [deg]
GRB_THETA:        62.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   413 (Gnd S/W Version number)
SUN_POSTN:       338.14d {+22h 32m 34s}   -9.17d {-09d 10' 04"}
SUN_DIST:         50.40 [deg]   Sun_angle= 0.9 [hr] (West of Sun)
MOON_POSTN:      107.98d {+07h 11m 55s}  +22.58d {+22d 35' 01"}
MOON_DIST:       135.82 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      336.13,-44.03 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      304.28,-41.29 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN Circular #10449
S. Foley (MPE) and S. McBreen (UCD/MPE) report on behalf of the Fermi GBM Team:
"At 02:45:31.15 UT on 25 February 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 100225A (trigger 288758733 / 100225115).
The on-ground calculated location, using the GBM trigger data, is RA = 312.5, DEC = -54.9 (J2000 degrees, equivalent to 20 h 50 m, -54 d 54 '), with an uncertainty of 2.4 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 58 degrees.
The GBM light curve consists of two main pulses with a duration (T90) of about 13 (+/-3) s (50-300 keV) starting at -0.256 s. The time-averaged spectrum from T0-3.8 s to T0+13.6 s is well fit by a power law function with an exponential high energy cutoff. The power law index is -0.80 (+0.09/-0.08) and the cutoff energy, parameterized as Epeak, is 527.30 (+105.00/-76.10) keV (CSTAT 438 for 361 d.o.f.).
The event fluence (8-1000 keV) in this time interval is (7.6 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+6.4 s in the 8-1000 keV band is 4.13 +/- 0.20 ph/s/cm^2.
A Band function fits the spectrum equally well (CSTAT 436 for 360 d.o.f.) with Epeak= 428.00 (+130.00/-86.00) keV, alpha = -0.72 (+0.13/-0.12) and beta = -2.15 (+0.21/-0.75).
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #10450
Fred Piron (LPTA), Masanori Ohno (ISAS/JAXA), Francesco de Palma (INFN Bari), Elena Moretti (INFN Trieste) and Julie McEnery (GSFC) report on behalf of the Fermi LAT team
At 02:45:53 (UT) on 25 Feb 2010, the Fermi Large Area Telescope (LAT) detected gamma rays from the GRB 100225A, which was triggered and located by the Fermi Gamma-ray Burst Monitor (GBM) (trigger 288758733 / 100225.115, GCNC 10449). The angle of the GBM position position with respect to the LAT boresight was ~60 degrees at the time of the LAT detection, which is just within the LAT field of view.
The data from the Fermi LAT shows a weak increase in the event rate that is spatially and temporally correlated with the GBM emission. It is a relatively weak detection (~4 sigma) with fewer than 10 excess events.
The best LAT on-ground localization is found to be (RA, Dec = 310.3, -59.4) (J2000) with a 90% containment radius of 1.30 deg (statistical; 68% containment radius: 0.9 deg) which is consistent with the GBM localization.
Further analysis is ongoing.
The point of contact for this burst is Fred Piron (Frederic.PIRON@lpta.in2p3.fr)
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.

Back to JG's homepage

Jochen Greiner, last update: 25-Feb-2010 [Disclaimer]