GRB 220909A
GCN Circular 32539
Subject
GRB 220909A: Fermi GBM Final Real-time Localization
Date
2022-09-09T07:02:29Z (3 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 LONG GRB
At 06:52:13 UT on 9 Sep 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 220909A (trigger 684399138.822486 / 220909286).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 212.4, Dec = -17.7 (J2000 degrees, equivalent to J2000 14h 09m, -17d 41'), with a statistical uncertainty of 6.3 degrees.
The angle from the Fermi LAT boresight is 56.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220909286/quicklook/glg_skymap_all_bn220909286.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/bn220909286/quicklook/glg_healpix_all_bn220909286.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220909286/quicklook/glg_lc_medres34_bn220909286.gif
GCN Circular 32543
Subject
GRB 220909A: Swift/BAT-GUANO candidate arcminute localization
Date
2022-09-11T16:22:58Z (3 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
Gayathri Raman (PSU), James DeLaunay (UAlabama), Aaron Tohuvavohu (U
Toronto), Jamie A. Kennea (PSU), report:
Swift/BAT did not localize GRB 220909A onboard (T0: 2022-09-09T06:52:13
UTC, Fermi/GBM GCN 32539).
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, 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 8.9 in a 4.096
s analysis time bin.
NITRATES results, independently, are ambiguous with respect to whether
this burst originates from in or outside the BAT FOV, with a
borderline DeltaLLHOut of 6.7 and a marginally preferred arcminute
location with DeltaLLHPeak of 2.
See Section 9.1 and Figure 20 in the NITRATES paper for brief
descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and
DeltaLLHOut.
The BAT candidate position is
RA, Dec = 216.0448, -8.8551 deg which is
RA(J2000) = 14h 24m 10.75s
Dec(J2000) = -8d 51��� 18.4���
with an estimated uncertainty of 3 arcmin.
This position is consistent with the Fermi/GBM localization (GCN 32539).
Independent spectral and/or fluence measurements of this burst from
other instruments could help determine the preferred spatial origin.
XRT and UVOT follow-up has been requested.
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 32544
Subject
GRB 220909A: Swift ToO observations
Date
2022-09-11T19:01:12Z (3 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 220909A.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021513
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 32547
Subject
GRB 220909A: Swift-XRT observations
Date
2022-09-12T05:51:40Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC &
INAF-OAR), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), D.N. Burrows
(PSU), J.P. Osborne (U. Leicester), K.L. Page (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 220909A, collecting 5.5 ks of Photon
Counting (PC) mode data between T0+216.5 ks and T0+235.1 ks.
One uncatalogued X-ray source has been detected consistent with being
within 296 arcsec of the Swift/BAT-GUANO position (Raman et al, GCN
Circ. 32543), it is below the RASS limit and shows no definitive signs
of fading. Therefore, at the present time we cannot confirm this as the
afterglow. Details of this source are given below:
Source 5:
RA (J2000.0): 216.0407 = 14:24:9.76
Dec (J2000.0): -8.8439 = -08:50:37.9
Error: 7.3 arcsec (radius, 90% conf.)
Count-rate: (1.12 [+0.72, -0.53])e-3 ct s^-1
Distance: 43 arcsec from Swift/BAT-GUANO position.
Seven uncatalogued sources were also detected too far from the GRB
position to be likely afterglow candidates.
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/00021513.
This circular is an official product of the Swift-XRT team.
GCN Circular 32556
Subject
GRB 220909A: Fermi GBM observation
Date
2022-09-14T13:30:13Z (3 years ago)
From
Christian Malacaria at ISSI <cmalacaria.astro@gmail.com>
C. Malacaria (ISSI) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 06:52:13.82 UT on 9 September 2022, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 220909A (trigger 684399138 / 220909286),
which was also detected by Swift/GUANO (Raman et al. 2022, GCN 32543).
The Fermi GBM Final Real-time Localization (GCN 32539) is consistent
with the Swift-BAT GUANO position.
The angle from the Fermi LAT boresight at the GBM trigger time is 46 degrees.
The GBM light curve shows a peak
with a duration (T90) of about 14.6 s (50-300 keV).
The time-averaged spectrum from T0-1.5 s to T0+6.7 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 154 +/- 25 keV.
The event fluence (10-1000 keV) in this time interval is
(1.4 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.69 s in the 10-1000 keV band
is 3.6 +/- 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/"