Gamma-ray Burst 220228A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 28 Feb 22 10:30:30 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      44
TRIGGER_NUM:     667737010
GRB_RA:          302.850d {+20h 11m 24s} (J2000),
                 303.139d {+20h 12m 33s} (current),
                 302.197d {+20h 08m 47s} (1950)
GRB_DEC:          -2.900d {-02d 53' 59"} (J2000),
                  -2.833d {-02d 49' 57"} (current),
                  -3.050d {-03d 02' 58"} (1950)
GRB_ERROR:       24.98 [deg radius, statistical plus systematic]
GRB_INTEN:       79 [cnts/sec]
DATA_SIGNIF:     6.00 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        19638 TJD;    59 DOY;   22/02/28
GRB_TIME:        37805.92 SOD {10:30:05.92} UT
GRB_PHI:          57.98 [deg]
GRB_THETA:        45.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.80
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      44%  Solar Flare
2nd_MOST_LIKELY:  40%  GRB
DETECTORS:       1,1,0, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       341.36d {+22h 45m 26s}   -7.89d {-07d 53' 15"}
SUN_DIST:         38.37 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:      313.48d {+20h 53m 56s}  -22.50d {-22d 30' 04"}
MOON_DIST:        22.08 [deg]
MOON_ILLUM:      7 [%]
GAL_COORDS:       39.66,-19.08 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      304.44, 16.70 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220228438/quicklook/glg_lc_medres34_bn220228438.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 35.15,8.78 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 28 Feb 22 16:08:27 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     667737010
GRB_RA:          321.030d {+21h 24m 07s} (J2000),
                 321.337d {+21h 25m 21s} (current),
                 320.335d {+21h 21m 21s} (1950)
GRB_DEC:         -16.930d {-16d 55' 47"} (J2000),
                 -16.834d {-16d 50' 01"} (current),
                 -17.145d {-17d 08' 42"} (1950)
GRB_ERROR:       8.52 [deg radius, statistical only]
GRB_DATE:        19638 TJD;    59 DOY;   22/02/28
GRB_TIME:        37805.92 SOD {10:30:05.92} UT
GRB_PHI:          31.98 [deg]
GRB_THETA:        27.98 [deg]
E_RANGE:         10.000 - 50.000 [keV]
LOC_ALGORITHM:   415 (Gnd S/W Version number)
SUN_POSTN:       341.58d {+22h 46m 19s}   -7.80d {-07d 47' 55"}
SUN_DIST:         21.72 [deg]   Sun_angle= 1.3 [hr] (West of Sun)
MOON_POSTN:      316.97d {+21h 07m 54s}  -21.61d {-21d 36' 47"}
MOON_DIST:         6.31 [deg]
MOON_ILLUM:      5 [%]
GAL_COORDS:       33.73,-41.22 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      318.08, -1.60 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220228438/quicklook/glg_lc_medres34_bn220228438.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220228438/quicklook/glg_locplot_all_bn220228438.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 has human-in-the-loop processing.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 28 Feb 22 19:23:32 UT
NOTICE_TYPE:     Fermi-LAT Offline Position
TRIGGER_NUM:     220228438
GRB_RA:          311.200d {+20h 44m 48s} (J2000),
                 311.522d {+20h 46m 05s} (current),
                 310.471d {+20h 41m 53s} (1950)
GRB_DEC:         -22.700d {-22d 41' 59"} (J2000),
                 -22.618d {-22d 37' 05"} (current),
                 -22.882d {-22d 52' 54"} (1950)
GRB_ERROR:       41.99 [arcmin radius, 90% containment, statistical only]
GRB_DATE:        19638 TJD;    59 DOY;   22/02/28
GRB_TIME:        37805.92 SOD {10:30:05.92} UT
TRIGGER_ID:      0x0
MISC:            0x40000000
SUN_POSTN:       341.71d {+22h 46m 50s}   -7.75d {-07d 44' 51"}
SUN_DIST:         32.60 [deg]   Sun_angle= 2.0 [hr] (West of Sun)
MOON_POSTN:      318.97d {+21h 15m 52s}  -21.07d {-21d 04' 06"}
MOON_DIST:         7.08 [deg]
MOON_ILLUM:      5 [%]
GAL_COORDS:       22.89,-34.45 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      307.55, -4.47 [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 #31658
The Fermi GBM team reports the detection of a likely LONG GRB
At 10:30:05.92 UT on 28 Feb 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 220228A (trigger 667737010 / 220228438).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 321.0, Dec = -16.9 (J2000 degrees, equivalent to J2000 21h 24m, -16d 54'), with a statistical uncertainty of 8.5 degrees.
The angle from the Fermi LAT boresight is 28.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220228438/quicklook/glg_skymap_all_bn220228438.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220228438/quicklook/glg_healpix_all_bn220228438.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220228438/quicklook/glg_lc_medres34_bn220228438.gif
GCN Circular #31659
N. Omodei, N. Di Lalla (Stanford University), R. Pillera (INFN Bari) report on behalf of the Fermi-LAT team:
On February 28, 2022, Fermi-LAT detected high-energy emission from GRB 220228A, which was also detected by**Fermi-GBM (trigger 667737010 / 220228438, GCN 31658).
The best LAT on-ground location is found to be
RA, Dec = 311.2, -22.7 (degrees, J2000)
with an error radius of 0.7 deg (90 % containment, statistical error only). This was 23 deg from the LAT boresight at the time of the trigger:
T0 = 10:30:05.92 UT.
The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the GBM emission with high significance. The photon flux above 90 MeV in the time interval 0-1000s after the GBM trigger is 4E-6 ą 1E-6 ph/cm2/s.
The estimated photon index above 90 MeV is -2.9 ą 0.4.
The highest-energy photon is a 323 MeV**event which is observed 77 seconds after the GBM trigger.
A Swift ToO has been requested for this burst.
The Fermi-LAT point of contact for this burst is Roberta Pillera**(roberta.pillera@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 #31660
J. Wood (NASA/MSFC) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 10:30:05.92 UT on 28 Feb 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220228A (trigger 667737010 / 220228438) which was also detected by the Fermi LAT (N. Omodei et al. 2022, GCN 31659). The GBM on-ground location (GCN 31658) is consistent with the LAT position.
The GBM light curve consists of a single pulse with a duration (T90) of about 12.5 s (50-300 keV). The time-averaged spectrum from T0-7 s to T0+6 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is 1.7 +/- 0.2 and the cutoff energy, parameterized as Epeak, is 106 +/- 46 keV
The event fluence (10-1000 keV) in this time interval is ((1.1 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.5 s in the 10-1000 keV band is 3.1 +/- 0.2 ph/s/cm^2.
A power law function fits the spectrum equally well with index -1.9 +/- 0.1.
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: 28-Feb-2022 [Disclaimer]