GRB 220310C
GCN Circular 31735
Subject
GRB 220310C: Fermi GBM Final Real-time Localization
Date
2022-03-10T22:34:09Z (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 22:23:51 UT on 10 Mar 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 220310C (trigger 668643836.426778 / 220310933).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 290.7, Dec = 43.7 (J2000 degrees, equivalent to J2000 19h 22m, 43d 42'), with a statistical uncertainty of 5.4 degrees.
The angle from the Fermi LAT boresight is 27.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220310933/quicklook/glg_skymap_all_bn220310933.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/bn220310933/quicklook/glg_healpix_all_bn220310933.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220310933/quicklook/glg_lc_medres34_bn220310933.gif
GCN Circular 31746
Subject
GRB 220310C: Swift/BAT-GUANO candidate arcminute localization
Date
2022-03-11T20:30:38Z (3 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
Aaron Tohuvavohu (U Toronto), James DeLaunay (UAlabama), Gayathri
Raman (PSU), Jamie A. Kennea (PSU), report:
Swift/BAT did not localize GRB 220310C onboard (T0:
2022-03-10T22:23:51 UTC, Fermi/GBM GCN 31735).
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 in a 8.192 s analysis time bin
with a sqrt(TS) of 9.7.
A candidate arcminute localization is found with DeltaLLHOut of 19.7
and a DeltaLLHPeak of 5.7.
For this reason we can confidently claim detection, and preference for
an in FOV origin, but the best fit arcmin localization is not strongly
preferred over other positions.
A few burst locations with comparable DeltaLLHPeak have been
previously verified with afterglow discovery (eg GRB 211106A).
See Section 9.1 and Figure 20 in the NITRATES paper for brief
descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and
DeltaLLHOut.
No source is found with conventional BAT imaging. This is expected
given the strength of the signal in BAT, and its position near the
edge of the coded FOV.
The BAT position is
RA, Dec = 290.069, +40.253 deg which is
RA(J2000) = 19h 20m 16.62s
Dec(J2000) = +40d 15��� 12.3���
with an estimated uncertainty of 5 arcmin.
This independent position is consistent with the Fermi/GBM
localization (GCN 31735).
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 31747
Subject
GRB 220310C: Swift ToO observations
Date
2022-03-12T02:57:35Z (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 220310C.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021483
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 31749
Subject
GRB 220310C: Swift-XRT observations
Date
2022-03-12T22:45:55Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
D.N. Burrows (PSU), J. D. Gropp (PSU), J.P. Osborne (U. Leicester),
K.L. Page (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo
(INAF-OAB), M.G. Bernardini (INAF-OAB), J.A. Kennea (PSU) 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 220310C, collecting 4.6 ks of Photon
Counting (PC) mode data between T0+102.8 ks and T0+120.2 ks.
Four uncatalogued X-ray sources have been detected, however none of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if any, is the
afterglow. Details of these sources are given below:
Source 1:
RA (J2000.0): 289.9580 = 19:19:49.91
Dec (J2000.0): +40.2093 = +40:12:33.3
Error: 7.9 arcsec (radius, 90% conf. [Enhanced position])
Count-rate: (4.4 +/- 1.2)e-3 ct s^-1
Distance: 344 arcsec from Swift/BAT-GUANO position.
Flux: (9.6 +/- 2.7)e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 2:
RA (J2000.0): 290.2354 = 19:20:56.50
Dec (J2000.0): +40.3333 = +40:19:59.9
Error: 7.6 arcsec (radius, 90% conf.)
Count-rate: (3.7 [+1.4, -1.1])e-3 ct s^-1
Distance: 539 arcsec from Swift/BAT-GUANO position.
Flux: (1.39 [+0.51, -0.42])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 3:
RA (J2000.0): 290.1544 = 19:20:37.05
Dec (J2000.0): +40.2064 = +40:12:23.0
Error: 6.3 arcsec (radius, 90% conf.)
Count-rate: (1.92 [+0.98, -0.76])e-3 ct s^-1
Distance: 288 arcsec from Swift/BAT-GUANO position.
Flux: (4.2 [+2.2, -1.7])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 4:
RA (J2000.0): 289.8727 = 19:19:29.46
Dec (J2000.0): +40.2572 = +40:15:26.0
Error: 6.4 arcsec (radius, 90% conf.)
Count-rate: (1.41 [+0.96, -0.69])e-3 ct s^-1
Distance: 540 arcsec from Swift/BAT-GUANO position.
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/00021483.
This circular is an official product of the Swift-XRT team.
GCN Circular 31755
Subject
GRB 220310C: Fermi GBM observation
Date
2022-03-14T02:11:55Z (3 years ago)
From
Peter Veres at UAH <veresp@gmail.com>
P. Veres and C. Meegan (both UAH)
report on behalf of the Fermi GBM Team:
"At 22:23:51.43 UT on 10 March 2022, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 220310C (trigger 668643836 / 220310933)
which was also detected by the Swift/BAT (Tohuvavohu et al., GCN 31746).
The Fermi GBM Final Real-time Localization (GCN 31735) is consistent
with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 30 degrees.
The GBM light curve shows a single peak
with a duration (T90) of about 16.4 s (50-300 keV).
The time-averaged spectrum from T0-6.1 s to T0+16.4 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.74 +/- 0.30 and
the cutoff energy, parameterized as Epeak, is 180 +/- 51 keV.
The event fluence (10-1000 keV) in this time interval is
(1.52 +/- 0.27)E-6 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-1.7 s in the 10-1000 keV band
is 1.28 +/- 0.18 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/"