Gamma-ray Burst 221027A

(All information courtesy of the instrument teams.)

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Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 27 Oct 22 04:10:13 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      59
TRIGGER_NUM:     688536579
GRB_RA:          174.517d {+11h 38m 04s} (J2000),
                 174.809d {+11h 39m 14s} (current),
                 173.876d {+11h 35m 30s} (1950)
GRB_DEC:          +0.033d {+00d 01' 60"} (J2000),
                  -0.093d {-00d 05' 34"} (current),
                  +0.310d {+00d 18' 37"} (1950)
GRB_ERROR:       6.23 [deg radius, statistical plus systematic]
GRB_INTEN:       497 [cnts/sec]
DATA_SIGNIF:     44.90 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        19879 TJD;   300 DOY;   22/10/27
GRB_TIME:        14974.35 SOD {04:09:34.35} UT
GRB_PHI:         310.00 [deg]
GRB_THETA:        55.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.50
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:       211.48d {+14h 05m 56s}  -12.76d {-12d 45' 21"}
SUN_DIST:         38.50 [deg]   Sun_angle= 2.4 [hr] (West of Sun)
MOON_POSTN:      233.35d {+15h 33m 25s}  -20.25d {-20d 15' 17"}
MOON_DIST:        60.65 [deg]
MOON_ILLUM:      4 [%]
GAL_COORDS:      266.88, 57.68 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      174.95, -2.15 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221027173/quicklook/glg_lc_medres34_bn221027173.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 105.35,-15.15 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 27 Oct 22 04:19:50 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     688536579
GRB_RA:          189.430d {+12h 37m 43s} (J2000),
                 189.726d {+12h 38m 54s} (current),
                 188.782d {+12h 35m 08s} (1950)
GRB_DEC:         -10.000d {-10d 00' 00"} (J2000),
                 -10.125d {-10d 07' 30"} (current),
                  -9.725d {-09d 43' 29"} (1950)
GRB_ERROR:       1.95 [deg radius, statistical only]
GRB_DATE:        19879 TJD;   300 DOY;   22/10/27
GRB_TIME:        14974.35 SOD {04:09:34.35} UT
GRB_PHI:         332.00 [deg]
GRB_THETA:        52.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       211.49d {+14h 05m 58s}  -12.76d {-12d 45' 29"}
SUN_DIST:         21.49 [deg]   Sun_angle= 1.5 [hr] (West of Sun)
MOON_POSTN:      233.45d {+15h 33m 48s}  -20.29d {-20d 17' 07"}
MOON_DIST:        43.26 [deg]
MOON_ILLUM:      4 [%]
GAL_COORDS:      297.35, 52.72 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      192.60, -5.46 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221027173/quicklook/glg_lc_medres34_bn221027173.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221027173/quicklook/glg_locplot_all_bn221027173.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.

GCN Circular #32861
The Fermi GBM team reports the detection of a likely LONG GRB
At 04:09:34 UT on 27 Oct 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 221027A (trigger 688536579.352978 / 221027173).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 189.4, Dec = -10.0 (J2000 degrees, equivalent to J2000 12h 37m, -10d 00'), with a statistical uncertainty of 1.9 degrees.
The angle from the Fermi LAT boresight is 52.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221027173/quicklook/glg_skymap_all_bn221027173.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/bn221027173/quicklook/glg_healpix_all_bn221027173.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221027173/quicklook/glg_lc_medres34_bn221027173.gif

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 27 Oct 22 08:21:15 UT
NOTICE_TYPE:     Fermi-LAT Offline Position
TRIGGER_NUM:     221027173
GRB_RA:          185.280d {+12h 21m 07s} (J2000),
                 185.574d {+12h 22m 18s} (current),
                 184.637d {+12h 18m 33s} (1950)
GRB_DEC:          -5.690d {-05d 41' 23"} (J2000),
                  -5.816d {-05d 48' 58"} (current),
                  -5.413d {-05d 24' 44"} (1950)
GRB_ERROR:       22.80 [arcmin radius, 90% containment, statistical only]
GRB_DATE:        19879 TJD;   300 DOY;   22/10/27
GRB_TIME:        14974.34 SOD {04:09:34.34} UT
TRIGGER_ID:      0x0
MISC:            0x40000000
SUN_POSTN:       211.65d {+14h 06m 36s}  -12.82d {-12d 48' 53"}
SUN_DIST:         26.65 [deg]   Sun_angle= 1.7 [hr] (West of Sun)
MOON_POSTN:      235.86d {+15h 43m 27s}  -21.04d {-21d 02' 14"}
MOON_DIST:        50.98 [deg]
MOON_ILLUM:      5 [%]
GAL_COORDS:      289.22, 56.37 [deg] galactic lon,lat of the burst (or
+transient)
ECL_COORDS:      187.10, -3.13 [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 #32862
Arimoto M. (Kanazawa University), Bissaldi E. (Politecnico and INFN Bari), Longo F. (University and INFN Trieste), Scotton L. (CNRS/IN2P3/LUPM) and Maheso D. (Johannesburg Univ.) report on behalf of the Fermi-LAT team:
On October, 27, 2022 Fermi-LAT detected high-energy emission from GRB 221027A, which was also detected by Fermi-GBM (trigger 221027173 / 688536579, GCN 32861) at 04:09:34.35 UT .
The best LAT on-ground location is found to be
RA, Dec = 185.3, -5.7 (J2000)
with an error radius of 0.4 deg (90 % containment, statistical error only). This was 51 deg from the LAT boresight at the time of the trigger.
The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the trigger with high significance.
The 100 MeV - 1 GeV photon flux in the time interval 0-500 s after the GBM trigger is (9.1 +/- 2.6)E-06 ph/cm2/s. The estimated integrated photon index above 100 MeV is -2.2 +/- 0.3. The highest-energy photon is a 1.1 GeV event with 96% probability which is observed 26 seconds after the GBM trigger.
A Swift ToO has been requested for this burst.
The Fermi-LAT point of contact for this burst is Dimakatso Jeannett Maheso (d.j.maheso@gmail.com).
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 #32866
O.J. Roberts (USRA/NASA-MSFC) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 04:09:34.35 UT on 27 October 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 221027A (trigger 688536579 / 221027173), which was also detected by Fermi-LAT (M. Arimoto et al. 2022, GCN 32862).
The Fermi GBM Final Real-time Localization (GCN 32861) is consistent with the LAT position.
The angle from the Fermi LAT boresight at the GBM trigger time is 51 degrees.
The GBM light curve consists of a bright pulse with a duration (T90) of about 7 s (50-300 keV). The time-averaged spectrum from T0-1.5s to T0+9.7 s is best fit by a Band function with Epeak = 341 +/- 37 keV, alpha = -0.75 +/- 0.06, and beta = -2.09 +/- 0.14.
The event fluence (10-1000 keV) in this time interval is (9.2 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.2 s in the 10-1000 keV band is 8.5 +/- 0.3 ph/s/cm^2.
A power law function with an exponential high-energy cutoff fits the spectrum equally well. The power law index is -0.81 +/- 0.04 and the cutoff energy, parameterized as Epeak, is 411 +/- 29 keV
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 #32884
A. Ursi, F. Longo (Univ. Trieste and INFN Trieste), C. Pittori, F. Verrecchia (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argancc, M. Cardillo, C. Casentini, Y. Evangelista, L. Foffano, E. Menegoni, G. Piano (INAF/IAPS), A. Bulgarelli, A. Di Piano, V. Fioretti, G. Panebianco, N. Parmiggiani (INAF/OAS-Bologna), F. Lucarelli (SSDC, and INAF/OAR), M. Romani (INAF/OA-Brera), M. Marisaldi (INAF/OAS-Bologna, and Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), A. Giuliani (INAF/IASF-Mi), and P. Tempesta (TeleSpazio), report on behalf of the AGILE Team:
The AGILE satellite detected the GRB 221027A at T0 = 2022-10-27 04:09:34 s (UTC), reported by Fermi GBM (GCNs #32861, #32866) and Fermi LAT (GCN #32862). The burst is clearly visible in the AGILE scientific ratemeters of the MiniCALorimeter (MCAL; 0.4-100 MeV) and AntiCoincidence (AC; 50-200 keV) detectors. The event lasted about 10 s and it released a total number of 11040 counts in the MCAL detector (above a background rate of 1180 Hz), and 30890 counts in the AC detector (above a background rate of 3250 Hz). The AGILE ratemeters light curves can be found at http://www.agilescienceapp.it/notices/GRB221027A_AGILE_RM.png .
The event also triggered a high time resolution MCAL data acquisition, from T0-22.42 s to T0+7.94 s (UTC), and released 5086 counts in the detector, above a background rate of 472 Hz. The MCAL light curve can be found at http://www.agilescienceapp.it/notices/GRB221027A_080667_593928574.000000.png . The time-integrated spectrum of the burst between T0 and T0+3s be fitted in the energy range 0.4-10 MeV with a power-law with ph. ind. = -2.31 (-0.69/+1.26), resulting in a reduced chi-squared of 1.44 (48 d.o.f.) and a fluence of 1.8e-06 ergs/cm^2 (90% confidence level), in the same energy range. At the T0, the event was 67 deg off-axis.
Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html.

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Jochen Greiner, last update: 29-Oct-2022 [Disclaimer]