GRB 210622A
GCN Circular 30297
Subject
GRB 210622A: Fermi GBM Final Real-time Localization
Date
2021-06-22T01:42:57Z (4 years ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
The Fermi GBM team reports the detection of a likely SHORT GRB
At 01:32:35 UT on 22 Jun 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210622A (trigger 646018360.939998 / 210622064).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 242.1, Dec = -14.1 (J2000 degrees, equivalent to J2000 16h 08m, -14d 05'), with a statistical uncertainty of 6.1 degrees.
The angle from the Fermi LAT boresight is 82.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210622064/quicklook/glg_skymap_all_bn210622064.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210622064/quicklook/glg_healpix_all_bn210622064.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210622064/quicklook/glg_lc_medres34_bn210622064.gif
GCN Circular 30302
Subject
GRB 210622A: Swift/BAT-GUANO detection and arcminute localization of a long burst
Date
2021-06-22T13:59:39Z (4 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea
(PSU), Gayathri Raman (PSU) report:
Swift/BAT did not trigger on GRB 210622A (T0: 2021-06-22 01:32:35.9
UTC, Fermi/GBM GCN 30297).
The Fermi/GBM 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 burst is detected in BAT with a duration of at least 25 seconds.
We note this is different from the prompt GBM classification as ���likely short���.
The burst morphology consists of a first bright, short, hard, peak
followed by longer emission with weaker flares.
With a maximum likelihood analysis (DeLaunay et al. 2021, in prep.) on
the event-mode data we detect a location for the burst with a square
root of the test statistic, sqrt(TS), of 18.8. The sqrt(TS) behaves
similarly to SNR.
Using the normal BAT imaging technique, we find the same location for
the GRB with an SNR of 8.1.
The BAT position is
RA, Dec = 233.117, -26.213 deg which is
RA(J2000) = 15h 32m 28.10s
Dec(J2000) = -26d 12��� 47.5���
with an estimated uncertainty of 2.5 arcmin.
This position is consistent with the Ferm/GBM localization (GCN 30297).
XRT and UVOT follow-up has been requested. Prompt followup by Swift is
delayed due to visibility constraints. Results of follow-up
observations will be reported in future circulars.
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 30306
Subject
GRB 210622A: Fermi GBM detection
Date
2021-06-22T22:08:07Z (4 years ago)
From
Stephen Lesage at Fermi-GBM Team <sjl0014@uah.edu>
S. Lesage (UAH) and R. Hamburg (UAH)
report on behalf of the Fermi GBM Team:
"At 01:32:35.94 UT on 22 June 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210622A (trigger 646018360 / 210622064)
which was also detected by the Swift/BAT-GUANO (DeLaunay et al. 2021, GCN 30302)
The Fermi GBM Final Real-time Localization (GCN 30297) is consistent
with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 97 degrees.
The GBM light curve consists of a single peak followed by some
extended emission with a duration (T90) of about 40 s (50-300 keV).
The time-averaged spectrum from T0 s to T0+39.4 s
is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.8 +/- 0.2 and
the cutoff energy, parameterized as Epeak, is 376 +/- 98 keV.
The event fluence (10-1000 keV) in this time interval is
(1.01 +/- 0.12)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.128 s in the 10-1000 keV band
is 3.1 +/- 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 30310
Subject
GRB 210622A: Swift ToO observations
Date
2021-06-24T01:06:05Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the Swift/BAT-GUANO GRB 210622A.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021452
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Swift/BAT-GUANO event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a
GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular 30317
Subject
GRB 210622A: Swift-XRT observations
Date
2021-06-25T16:02:37Z (4 years ago)
From
Antonino D'Ai at IASF-PA <antonino.dai@inaf.it>
A.P. Beardmore (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC
& INAF-OAR), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (PSU), D.N.
Burrows (PSU), J. D. Gropp (PSU), J.P. Osborne (U. Leicester) and P.A.
Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Swift/BAT-GUANO-detected burst GRB 210622A (James DeLaunay et al. GCN
Circ. 30302), collecting 4.5 ks of Photon Counting (PC) mode data
between T0+171.2 ks and T0+221.6 ks.
No X-ray sources have been detected consistent with being within 246
arcsec of the Swift/BAT-GUANO position. The 3-sigma upper limit in the
field is 0.003 ct s^-1, corresponding to a 0.3-10 keV observed flux of
1.0e-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum).
An uncatalogued was detected, however this was too far from the GRB
position to be the afterglow.
The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021452.
This circular is an official product of the Swift-XRT team.