| Summary table |
|---|
| Variable |
Value |
Source |
| GRB_name_Fermi |
GRB220421346 |
|
| T0 |
8:17:54.527 UTC |
Fermi_GBM |
| ra |
74.4200° |
Fermi_GBM |
| decl |
23.1400° |
Fermi_GBM |
| pos_error |
4.51e+00° |
Fermi_GBM |
| T90 |
6.429 s |
Fermi_GBM |
| T90_error |
0.586 s |
Fermi_GBM |
| T90_start |
8:17:54.530 UTC |
Fermi_GBM |
| fluence |
6.70e-06 erg/cm² |
Fermi_GBM |
| fluence_error |
2.80e-08 erg/cm² |
Fermi_GBM |
| T100 |
6.432 s |
|
| GBM_located |
True |
|
| mjd |
59690.345769988424 |
Fermi_GBM |
| Fermi GBM table |
|---|
| GRB_name_Fermi |
GRB220421346 |
| trigger_name |
bn220421346 |
| ra |
74.4200° |
| decl |
23.1400° |
| pos_error |
4.51e+00° |
| datum |
2022-04-21 |
| t_trigger |
8:17:54.527 UTC |
| T90 |
6.429 s |
| T90_error |
0.586 s |
| T90_start |
8:17:54.530 UTC |
| fluence |
6.70e-06 erg/cm² |
| fluence_error |
2.80e-08 erg/cm² |
| flux_1024 |
1.32e+01 erg/cm²/s |
| flux_1024_error |
2.75e-01 erg/cm²/s |
| flux_1024_time |
1.06e+00 erg/cm²/s |
| flux_64 |
1.75e+01 erg/cm²/s |
| flux_64_error |
1.27e+00 erg/cm²/s |
| GCN 31934 table |
|---|
| GRB_name |
GRB220421A |
| GCN_number |
31934 |
| Detection_method |
Swift Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 31934
SUBJECT: GRB 220421A: Swift/BAT-GUANO detection outside the coded FOV
DATE: 22/04/21 21:25:41 GMT
FROM: Aaron Tohuvavohu at U Toronto
Gayathri Raman (PSU), Aaron Tohuvavohu (U Toronto), James DeLaunay
(UAlabama), Jamie A. Kennea (PSU), report:
Swift/BAT did not localize GRB 220421A onboard (T0:
2022-04-21T08:17:54.5 UTC, CALET trig #1334564169, Fermi/GBM trig
#672221879).
The CALET and Fermi notices, 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 34.7 in a
4.096 s analysis time bin.
The burst episode as seen by BAT is ~10s long.
NITRATES results indicate a burst coming from outside the coded FoV,
with DeltaLLHOut of -25. An out of FOV origin is consistent with the
Fermi/GBM localization.
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 31936 table |
|---|
| GRB_name |
GRB220421A |
| GCN_number |
31936 |
| Detection_method |
Fermi GBM Det |
| t_trigger |
8:17:54.530 UTC |
| ra |
74.4000° |
| decl |
23.1000° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 31936
SUBJECT: GRB 220421A: Fermi GBM observation
DATE: 22/04/23 15:07:33 GMT
FROM: Andreas von Kienlin at MPE
A. von Kienlin (MPE) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 08:17:54.53 UT on 21 April 2022, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 220421A (trigger 672221879/220421346), which was
also
detected by the Swift/BAT-GUANO (Raman et al. 2022, GCN 31934)
The on-ground calculated location, using the GBM trigger
data, is RA = 74.4, DEC = 23.1 (J2000 degrees,
equivalent to 04 h 57 m, 23 d 06 '), with a statistical uncertainty
of 2.1 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 59
degrees.
The GBM light curve shows a single pulse with a duration (T90) of about 6.4
s (50-300 keV).
The time-averaged spectrum from T0+0.002 s to T0+7.008 s is best fit by a
Band function
with Epeak = 133.20 +/- 5.40 keV, alpha = -0.41 +/- 0.05, and beta = -2.48
+/- 0.11
The event fluence (10-1000 keV) in this time interval is
(7.2 +/- 0.2)E-06. The 1.024-sec peak photon flux measured
starting from T0+1.056 s in the 10-1000 keV band
is 13.2 +/- 0.3 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/"
|