- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Tue 19 Sep 23 16:58:53 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 45
TRIGGER_NUM: 716835508
GRB_RA: 73.733d {+04h 54m 56s} (J2000),
74.146d {+04h 56m 35s} (current),
72.865d {+04h 51m 28s} (1950)
GRB_DEC: +40.567d {+40d 34' 00"} (J2000),
+40.603d {+40d 36' 12"} (current),
+40.487d {+40d 29' 12"} (1950)
GRB_ERROR: 7.72 [deg radius, statistical plus systematic]
GRB_INTEN: 443 [cnts/sec]
DATA_SIGNIF: 17.80 [sigma]
INTEG_TIME: 1.024 [sec]
GRB_DATE: 20206 TJD; 262 DOY; 23/09/19
GRB_TIME: 61103.86 SOD {16:58:23.86} UT
GRB_PHI: 94.00 [deg]
GRB_THETA: 115.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO: 0.35
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 80% GRB
2nd_MOST_LIKELY: 15% GRO_J0422_32
DETECTORS: 1,0,1, 0,0,0, 0,0,0, 0,1,0, 0,0,
SUN_POSTN: 176.79d {+11h 47m 10s} +1.39d {+01d 23' 25"}
SUN_DIST: 98.65 [deg] Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN: 225.80d {+15h 03m 11s} -19.49d {-19d 29' 37"}
MOON_DIST: 147.89 [deg]
MOON_ILLUM: 20 [%]
GAL_COORDS: 164.53, -1.86 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 77.08, 17.85 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230919707/quicklook/glg_lc_medres34_bn230919707.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 257.15,-22.35 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Tue 19 Sep 23 16:59:12 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 57
TRIGGER_NUM: 716835508
GRB_RA: 66.690d {+04h 26m 46s} (J2000),
67.094d {+04h 28m 23s} (current),
65.840d {+04h 23m 22s} (1950)
GRB_DEC: +39.510d {+39d 30' 36"} (J2000),
+39.562d {+39d 33' 43"} (current),
+39.398d {+39d 23' 53"} (1950)
GRB_ERROR: 4.08 [deg radius, statistical only]
DATA_SIGNIF: 20.60 [sigma]
DATA_INTERVAL: 2.048 [sec]
GRB_DATE: 20206 TJD; 262 DOY; 23/09/19
GRB_TIME: 61103.86 SOD {16:58:23.86} UT
GRB_PHI: 100.00 [deg]
GRB_THETA: 116.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 4173 (Gnd S/W Version number)
SUN_POSTN: 176.79d {+11h 47m 10s} +1.39d {+01d 23' 25"}
SUN_DIST: 104.14 [deg] Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN: 225.80d {+15h 03m 12s} -19.49d {-19d 29' 41"}
MOON_DIST: 152.83 [deg]
MOON_ILLUM: 20 [%]
GAL_COORDS: 161.76, -6.61 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 71.32, 17.57 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230919707/quicklook/glg_lc_medres34_bn230919707.gif
POS_MAP_URL: http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_716835508.fits
COMMENTS: Fermi-GBM Ground-calculated Coordinates.
COMMENTS: Bright hard burst in the GBM.
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: Tue 19 Sep 23 17:05:10 UT
NOTICE_TYPE: Fermi-GBM Final Position
RECORD_NUM: 0
TRIGGER_NUM: 716835508
GRB_RA: 58.190d {+03h 52m 46s} (J2000),
58.592d {+03h 54m 22s} (current),
57.344d {+03h 49m 23s} (1950)
GRB_DEC: +41.170d {+41d 10' 12"} (J2000),
+41.239d {+41d 14' 21"} (current),
+41.022d {+41d 01' 17"} (1950)
GRB_ERROR: 6.74 [deg radius, statistical only]
GRB_DATE: 20206 TJD; 262 DOY; 23/09/19
GRB_TIME: 61103.86 SOD {16:58:23.86} UT
GRB_PHI: 106.00 [deg]
GRB_THETA: 120.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 41731 (Gnd S/W Version number)
SUN_POSTN: 176.79d {+11h 47m 11s} +1.39d {+01d 23' 19"}
SUN_DIST: 109.83 [deg] Sun_angle= 7.9 [hr] (West of Sun)
MOON_POSTN: 225.85d {+15h 03m 24s} -19.51d {-19d 30' 49"}
MOON_DIST: 155.72 [deg]
MOON_ILLUM: 20 [%]
GAL_COORDS: 155.84, -9.83 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 64.94, 20.46 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230919707/quicklook/glg_lc_medres34_bn230919707.gif
LOC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230919707/quicklook/glg_locplot_all_bn230919707.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: Bright hard burst in the GBM.
COMMENTS: This is likely a Long GRB.
- GCN Circular #34737
The Fermi GBM team reports the detection of a likely LONG GRB
At 16:58:23 UT on 19 Sep 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230919A (trigger 716835508.857072 / 230919707).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 58.2, Dec = 41.2 (J2000 degrees, equivalent to J2000 03h 52m, 41d 12'), with a statistical uncertainty of 6.7 degrees.
The angle from the Fermi LAT boresight is 120.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230919707/quicklook/glg_skymap_all_bn230919707.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230919707/quicklook/glg_healpix_all_bn230919707.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230919707/quicklook/glg_lc_medres34_bn230919707.gif
- GCN Circular #34742
P. K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of GRB 230919A which was also detected by Fermi-GBM (Fermi GBM Team, GCN Circ. 34737).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2023-09-19 16:58:23.95 UTC. The measured peak count rate associated with the burst is 1118 (+205, -166) counts/s above the background in the combined data of all quadrants, with a total of 921 (+115, -92) counts. The local mean background count rate was 406 (+10, -15) counts/s. Using cumulative rates, we measure a T90 of 1.58 (+1.38, -0.23) s. We caution that there are two 0.3 s readout dead time windows in CZTI data immediately after the detection of the burst. Hence, the T90 can be as large as 2.96 s for this GRB, with a lower limit of 1.35 s as estimated above by cumulative rates.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-09-19 16:58:23.55 UTC. The measured peak count rate associated with the burst is 1196 (+82, -86) counts/s above the background in the combined data of all quadrants, with a total of 1796 (+193, -200) counts. The local mean background count rate was 1280 (+6, -6) counts/s. We measure a T90 of 2.1 (+1.2, -0.5) s from the cumulative Veto light curve. Note that this result is limited due to the 1 s native resolution of veto data.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb
- GCN Circular #34747
James DeLaunay (U Alabama), Aaron Tohuvavohu (U Toronto), Samuele Ronchini (PSU), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report:
Swift/BAT did not localize GRB 230919A onboard (T0: 2023-09-19T16:58:23.86 UTC, Fermi trig 716835508, AstroSat CZTI GCN 34742)
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 90 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 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 16.6 in a 1.5 s analysis time bin, starting at T0 - 0.2 s.
NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of -0.6 and are consistent with Fermi GBM's localization (GCN 34737).
See Section 9.1 and Figures 10 and 17 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 #34750
L. Scotton (UAH), C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 16:58:23.86 UT on 19 September 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230919A (trigger 716835508/230919707).
which was also detected by AstroSat (Navaneeth et al. 2023, GCN 34742)
and Swift/BAT-GUANO (DeLaunay et al. 2023, GCN 34747).
The Fermi GBM Final Real-time Localization was reported in GCN 34737.
The angle from the Fermi LAT boresight is 120 degrees.
The GBM light curve consists of multiple peaks
with a duration (T90) of about 2.9s. The time-averaged spectrum
from T0-0.06 to T0+1.34 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.74 +/- 0.06 and the cutoff energy,
parameterized as Epeak, is 2023 +/- 271 keV.
A Band function fits the spectrum equally well with
Epeak = 1617 +/- 352 keV, alpha = -0.68 +/- 0.08 and beta = -2.43 +/- 0.32.
The event fluence (10-1000 keV) in this time interval is
(3.3 +/- 0.1)E-06 erg/cm^2. The 64-msec peak photon flux measured
starting from T0+0.58 s in the 10-1000 keV band is 12 +/- 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 #34752
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,
A. Ridnaia, D. Frederiks, D. Svinkin, A. Lysenko,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:
The short-duration GRB 230919A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 34737;
Scotton et al., GCN Circ. 34750;
AstroSat CZTI detection: Navaneeth et al., GCN Circ. 34742;
Swift/BAT-GUANO detection: DeLaunay et al., GCN Circ. 34747)
has been detected by Fermi (GBM trigger 716835508), Konus-Wind,
Mars-Odyssey (HEND), Swift (BAT), and AstroSat (CZTI),
so far, at about 61103 s UT (16:58:23).
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:
71.620 (04h 46m 29s) +44.076 (+44d 04' 35")
Corners:
70.812 (04h 43m 15s) +45.562 (+45d 33' 43")
70.802 (04h 43m 12s) +45.703 (+45d 42' 10")
72.402 (04h 49m 37s) +42.484 (+42d 29' 04")
72.411 (04h 49m 39s) +42.324 (+42d 19' 28")
---------------------------------------------
The error box area is 543 sq. arcmin, and its maximum
dimension is 3.6 deg (the minimum one is 3 arcmin).
The Sun distance was 100 deg.
The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM final localization (GCN Circ. 34737).
This localization may be improved.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230919_T61103/IPN/
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
- GCN Circular #34769
Y. Temiraev, D. Svinkin, D. Frederiks, M. Ulanov,
A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:
The short-duration GRB 230919A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 34737;
Scotton et al., GCN Circ. 34750;
AstroSat CZTI detection: Navaneeth et al., GCN Circ. 34742;
Swift/BAT-GUANO detection: DeLaunay et al., GCN Circ. 34747;
IPN triangulation: Kozyrev et al., GCN Circ. 34752)
triggered Konus-Wind at T0=61103.312 s UT (16:58:23.312).
The burst light curve shows a multipeaked structure
which starts at ~T0-0.4 s and has a total duration of ~2.4 s.
The emission is seen up to ~4 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB230919_T61103/
As observed by Konus-Wind, the burst
had a fluence of 8.37(-2.57,+3.19)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.430 s,
of 1.44(-0.72,+0.81)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The spectrum of the burst (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 4 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.88(-0.25,+0.37)
and Ep = 1452(-629,+1078) keV (chi2 = 69/83 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.1
(chi2 = 69/82 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
View this GCN Circular online at https://gcn.nasa.gov/circulars/34769.