Gamma-ray Burst 220528A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 May 22 06:13:16 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     675411172
GRB_RA:          313.100d {+20h 52m 24s} (J2000),
                 313.341d {+20h 53m 22s} (current),
                 312.563d {+20h 50m 15s} (1950)
GRB_DEC:         +26.933d {+26d 55' 60"} (J2000),
                 +27.019d {+27d 01' 07"} (current),
                 +26.744d {+26d 44' 39"} (1950)
GRB_ERROR:       6.05 [deg radius, statistical plus systematic]
GRB_INTEN:       577 [cnts/sec]
DATA_SIGNIF:     20.00 [sigma]
INTEG_TIME:      0.512 [sec]
GRB_DATE:        19727 TJD;   148 DOY;   22/05/28
GRB_TIME:        22367.41 SOD {06:12:47.41} UT
GRB_PHI:         238.00 [deg]
GRB_THETA:        65.00 [deg]
DATA_TIME_SCALE: 0.5120 [sec]
HARD_RATIO:      0.26
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      66%  GRB
2nd_MOST_LIKELY:  32%  Cyg X-1
DETECTORS:       0,0,0, 0,0,0, 1,0,1, 0,0,0, 0,0,
SUN_POSTN:        65.09d {+04h 20m 22s}  +21.46d {+21d 27' 45"}
SUN_DIST:         98.11 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       39.92d {+02h 39m 41s}  +14.60d {+14d 35' 42"}
MOON_DIST:        80.45 [deg]
MOON_ILLUM:      5 [%]
GAL_COORDS:       71.21,-11.13 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      325.60, 42.42 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220528259/quicklook/glg_lc_medres34_bn220528259.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 60.62,25.38 [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 28 May 22 06:13:34 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     675411172
GRB_RA:          311.590d {+20h 46m 22s} (J2000),
                 311.839d {+20h 47m 21s} (current),
                 311.034d {+20h 44m 08s} (1950)
GRB_DEC:         +22.140d {+22d 08' 24"} (J2000),
                 +22.223d {+22d 13' 23"} (current),
                 +21.956d {+21d 57' 22"} (1950)
GRB_ERROR:       6.05 [deg radius, statistical only]
DATA_SIGNIF:     20.10 [sigma]
DATA_INTERVAL:   0.512 [sec]
GRB_DATE:        19727 TJD;   148 DOY;   22/05/28
GRB_TIME:        22367.41 SOD {06:12:47.41} UT
GRB_PHI:         238.00 [deg]
GRB_THETA:        70.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:        65.09d {+04h 20m 22s}  +21.46d {+21d 27' 45"}
SUN_DIST:        101.64 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       39.92d {+02h 39m 41s}  +14.60d {+14d 35' 46"}
MOON_DIST:        82.80 [deg]
MOON_ILLUM:      5 [%]
GAL_COORDS:       66.47,-12.97 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      321.69, 38.41 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220528259/quicklook/glg_lc_medres34_bn220528259.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_675411172.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.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 May 22 06:22:05 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     675411172
GRB_RA:          311.210d {+20h 44m 50s} (J2000),
                 311.455d {+20h 45m 49s} (current),
                 310.664d {+20h 42m 39s} (1950)
GRB_DEC:         +24.300d {+24d 18' 00"} (J2000),
                 +24.382d {+24d 22' 57"} (current),
                 +24.118d {+24d 07' 03"} (1950)
GRB_ERROR:       4.91 [deg radius, statistical only]
GRB_DATE:        19727 TJD;   148 DOY;   22/05/28
GRB_TIME:        22367.41 SOD {06:12:47.41} UT
GRB_PHI:         237.00 [deg]
GRB_THETA:        68.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:        65.10d {+04h 20m 24s}  +21.46d {+21d 27' 49"}
SUN_DIST:        100.89 [deg]   Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN:       39.99d {+02h 39m 58s}  +14.62d {+14d 37' 28"}
MOON_DIST:        82.72 [deg]
MOON_ILLUM:      5 [%]
GAL_COORDS:       68.03,-11.39 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      322.22, 40.56 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220528259/quicklook/glg_lc_medres34_bn220528259.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220528259/quicklook/glg_locplot_all_bn220528259.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 Short GRB.

GCN Circular #32147
The Fermi GBM team reports the detection of a likely short GRB.
At 06:12:47.41 UT on 28 May 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220528A (trigger 675411172 / 220528259).
The on-ground calculated location, using the GBM trigger data, is RA = 311.2, DEC = 24.3 (J2000 degrees, equivalent to 20 h 44 m, 24 d 18 '), with a statistical uncertainty of 4.9 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).
The angle from the Fermi LAT boresight at the GBM trigger time is 68 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220528259/quicklook/glg_skymap_all_bn220528259.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/bn220528259/quicklook/glg_healpix_all_bn220528259.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220528259/quicklook/glg_lc_medres34_bn220528259.gif
GCN Circular #32148
Gayathri Raman (PSU), Aaron Tohuvavohu (U Toronto), James DeLaunay (UAlabama), Jamie A. Kennea (PSU), report:
Swift/BAT did not localize GRB 220528B onboard (T0: 2022-05-28T06:12:47 UTC, Fermi/GBM GCN 32147).
The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.
The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu, arXiv:2111.01769), detects the burst with a sqrt(TS) of 12.2 in a 0.512 s analysis time bin. The burst episode as seen by BAT is ~1 s long.
NITRATES results are consistent with a burst coming from outside of the coded FoV, as indicated by the Fermi/GBM localization (GCN 32147).
See Section 9.1 and Figure 20 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.
GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches.
A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/
GCN Circular #32149
The burst detection reported in GCN 32148 "GRB 220528B: Swift/BAT-GUANO detection... " was misnamed. The burst is GRB 220528A (see Fermi/GBM discovery and naming in GCN 32147). I apologize for the mistake.
GCN Circular #32155
J.Mangan (UCD), S. Lesage (UAH) and C.Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 06:12:47.41 UT on 28 May 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220528A (trigger 675411172 / 220528259), which was also detected by the Swift/BAT-GUANO (Raman et al. 2022, GCN 32148 and GCN 32149).
The Fermi GBM Final Real-time Localization has been reported in GCN 32147.
The GBM light curve consists of a single peak with a duration (T90) of about 0.58 s (50-300 keV). The time-averaged spectrum from T0-0.128 s to T0+0.576 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is 0.08 +/- 0.17 and the cutoff energy, parameterized as Epeak, is 467.5 +/- 50.8 keV The event fluence (10-1000 keV) in this time interval is (1.59 +/- 0.11)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.064 s in the 10-1000 keV band is 4.2 +/- 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/"
GCN Circular #32156
D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko, and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, and C. Wilson-Hodge on behalf of the Fermi GBM team,
E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
and
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team, report:
The short-duration GRB 220528A (Fermi-GBM detection: Fermi GBM Team, GCN Circ. 32147; Mangan et al., GCN Circ. 32155; Swift/BAT-GUANO detection: Raman et al., GCN Circ. 32148) was detected by Fermi (GBM trigger 675411172), INTEGRAL (SPI-ACS), Konus-Wind, and Swift (BAT) at about 22367 s UT (06:12:47). The burst was outside the coded field of view of the BAT.
We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:
```
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   312.961 (20h 51m 51s) +18.856 (+18d 51' 22")
  Corners:
   315.010 (21h 00m 02s) +16.077 (+16d 04' 38")
   315.232 (21h 00m 56s) +16.369 (+16d 22' 08")
   310.761 (20h 43m 03s) +21.508 (+21d 30' 30")
   310.547 (20h 42m 11s) +21.215 (+21d 12' 55")
  ---------------------------------------------
```
The error box area is 2.3 sq. deg, and its maximum dimension is 6.8 deg (the minimum one is 21 arcmin). The Sun distance was 102 deg.
This box may be improved.
The IPN localization is consistent with, but reduces the area of, the Fermi-GBM final localization (GCN Circ. 32147).
A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB220528_T22370/IPN
The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.
GCN Circular #32157
D. Svinkin, D. Frederiks, A.Ridnaia, A.Lysenko, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
The short-duration GRB 220528A (Fermi-GBM detection: Fermi GBM Team, GCN Circ. 32147; Mangan et al., GCN Circ. 32155; Swift/BAT-GUANO detection: Raman et al., GCN Circ. 32148; IPN triangulation: Svinkin at al., GCN Circ. 32156) triggered Konus-Wind at T0=22370.380 s UT (06:12:50.380).
The burst light curve shows a multipeaked structure, which starts at T0-0.1 s and has a total duration of ~0.7 s.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB220528_T22370/
As observed by Konus-Wind, the burst had a fluence of 1.85(-0.03,+0.54)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0+0.034 s, of 7.88(-1.57,+2.77)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
Since the main fraction of the burst emission was detected before the trigger, the spectral analysis was performed using the KW 3-channel light curve data.
Modelling the KW 3-channel time-integrated spectrum (measured from T0-0.402 s to T0+0.296 s) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), yields alpha = -0.06(-0.32,+0.38) and Ep = 542(-78,+118) keV.
All the quoted errors are at the 68% confidence level. All the quoted values are preliminary.

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Jochen Greiner, last update: 01-Jun-2022 [Disclaimer]