GRB 200325A
GCN Circular 27434
Subject
GRB 200325A: Fermi GBM Final Real-time Localization
Date
2020-03-25T03:28:53Z (5 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 03:18:31 UT on 25 Mar 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 200325A (trigger 606799116.742442 / 200325138).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 22.1, Dec = -29.1 (J2000 degrees, equivalent to J2000 01h 28m, -29d 06'), with a statistical uncertainty of 4.2 degrees.
The angle from the Fermi LAT boresight is 102.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200325138/quicklook/glg_skymap_all_bn200325138.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200325138/quicklook/glg_healpix_all_bn200325138.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200325138/quicklook/glg_lc_medres34_bn200325138.gif
GCN Circular 27437
Subject
GRB 200325A: AGILE/MCAL observations
Date
2020-03-25T11:17:45Z (5 years ago)
From
Alessandro Ursi at INAF/IAPS <alessandro.ursi@gmail.com>
A. Ursi (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), M. Tavani
(INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, M. Cardillo, C.
Casentini, Y. Evangelista, G. Piano (INAF/IAPS), F. Lucarelli, C. Pittori,
(SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, F. Fuschino, N.
Parmiggiani (INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen
University), M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), F.
Longo (Univ. Trieste and INFN Trieste), A. Giuliani (INAF/IASF-Mi), report
on behalf of the AGILE Team:
The AGILE satellite detected the short burst GRB 200325A reported by
Fermi/GBM (GCN #27434), that also triggered the automatic AGILE
Mini-CALorimeter (MCAL) GRB alert Notice (ID 512191111), published at:
https://gcn.gsfc.nasa.gov/agile_mcal.html.
The event was detected by MCAL at T0 = 2020-03-25 03:18:31.71 +/- 0.01 s
(UTC), lasting ~1.2 s and releasing a total number of ~1000 counts in the
detector, above a background rate of ~580 Hz. The MCAL light curve can be
found at:
http://www.agilescienceapp.it/notices/GRB_067078_512191111.714274.png. The
time-integrated spectrum of the burst in 1.2 s can be fitted in the energy
range 0.4-10 MeV with a single power-law with ph.ind. = 1.72 -0.17/+0.20,
resulting in a reduced chi-squared of 1.03 (36 d.o.f.). The burst fluence
in the same energy range and time interval is 3.62e-06 erg/cm^2 (90%
confidence level).
The event localization according to Fermi/GBM, RA = 22.1, Dec = -29.1
(J2000; GCN #27434), is within the AGILE Gamma-Ray Imaging Detector (GRID)
Field-of-View, but no detection is obtained in the integrations (T0;T0+5s)
and (T0;T0+10s).
The AGILE-MCAL detector is a CsI detector with a 4 pi FoV, sensitive in the
energy range 0.4-100 MeV. Additional analysis of AGILE data is in progress.
GCN Circular 27438
Subject
GRB 200325A: AstroSat CZTI detection
Date
2020-03-25T11:39:26Z (5 years ago)
From
Soumya Gupta at IUCAA/ASTROSAT <soumya@iucaa>
S. Gupta, V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data showed the detection of a long GRB 200325A, which was also detected by Fermi GBM (GCN #27434) and AGILE/MCAL (Ursi A. e al., GCN #27437).
The source was clearly detected in the 40-200 keV energy range. The light curve shows a single peak of emission peaking at 2020-03-25 03:18:31 UT. The measured peak count rate associated with the burst is 185 +/- 24.5 cts/s above the background in the combined data of four quadrants, with a total of 492 +/- 21.4 cts. The local mean background count rate was 602 +/- 2.2 cts/s. Using cumulative rates, we measure a T90 of 4.9 +/- 0.12 s.
It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.
GCN Circular 27444
Subject
GRB 200325A: Swift/BAT detection and probable arcminute localization of a short GRB from GUANO
Date
2020-03-26T00:52:23Z (5 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), and Jamie Kennea
(PSU) report:
Swift/BAT did not trigger on GRB 200325A.
The Fermi/GBM Flight-Position notice, distributed at T0+8 seconds,
from the Fermi/GBM detected GRB 200325A (GCN. 27434), as well as the
INTEGRAL SPI-ACS notice (Trig #8558) distributed at T0+44 seconds,
both triggered the Swift Mission Operations Center operated Gamma-ray
Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al.
2020, in prep). GRB 200325A was also detected by AGILE/MCAL (GCN.
27437) and AstroSat CZTI (GCN. 27438).
The 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.
Upon trigger by these notices, 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 GRB 200228A.
All the requested event mode data was delivered to the ground.
In a ground analysis of the data, using the normal BAT imaging
technique, we detect GRB 200228A with a SNR of 7.5.
With a more sophisticated maximum likelihood analysis (DeLaunay et
al., 2020 in prep.) on the event-mode data we detect GRB 200325A more
confidently, with a square root of the test statistic, sqrt(TS), of
21.7. The sqrt(TS) behaves similarly to SNR.
The detected duration is ~1.1s.
The BAT ground-calculated position is
RA, Dec = 31.7203, -31.816 deg which is
RA(J2000) = 2h 6m 52.8s
Dec(J2000) = -31d 48��� 57.60���
with an uncertainty of 4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 8.2%.
This arcminute location is consistent with the localization region
distributed by the Fermi/GBM team (GCN. 27434), lying on the 75%
containment contour.
Due to the very low partial coding, we stress that this localization,
while significant, has some additional unquantified uncertainties
associated with it.
No XRT or UVOT follow-up will take place due to the source���s proximity
to the sun (1.5 hours).
We encourage follow-up from instruments capable of observing near the sun.
A live reporting of Swift/BAT event data recovered by GUANO can be found
at: https://www.swift.psu.edu/guano/
GCN Circular 27449
Subject
IPN triangulation of GRB 200325A (short)
Date
2020-03-26T17:15:15Z (5 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
K. Hurley, on behalf of the IPN,
I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak,
and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Ridnaia,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, and C. Wilson-Hodge
on behalf of the Fermi GBM team,
A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team, and
W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:
The short-duration GRB 200325A
(Fermi-GBM detection: The Fermi GBM Team, GCN Circ. 27434;
AGILE-MCAL detection: Ursi, et al., GCN Circ. 27437;
AstroSat-CZTI detection: Gupta et al., GCN Circ. 27438;
Swift-BAT detection: DeLaunay et al., GCN Circ. 27444)
was detected by Fermi (GBM trigger 606799116), Konus-Wind,
INTEGRAL (SPI-ACS), AGILE (MCAL), AstroSat (CZTI),
Mars-Odyssey (HEND), and Swift (BAT)
at about 11912 s UT (03:18:32).
The burst was found in ground analysis of Swift (BAT) data
with very low partial coding.
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
31.754 (02h 07m 01s) -31.920 (-31d 55' 14")
Corners:
31.301 (02h 05m 12s) -30.580 (-30d 34' 50")
32.340 (02h 09m 22s) -32.899 (-32d 53' 58")
32.205 (02h 08m 49s) -33.240 (-33d 14' 25")
31.173 (02h 04m 41s) -30.931 (-30d 55' 53")
---------------------------------------------
The error box area is 2023 sq. arcmin, and its maximum
dimension is 2.77 deg (the minimum one is 13.6 arcmin).
The Sun distance was 41 deg.
This box may be improved.
The Swift-BAT position (GCN 27444) is consistent with the IPN localization.
A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB200325_T11908/IPN
The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.
[GCN OPS NOTE(11apr20): Per author's request, "GRB" was added to the Subject-line.
This will make the auto-grouping of same-object Circular operate better.]
GCN Circular 27453
Subject
GRB 200325A: Fermi GBM observation
Date
2020-03-27T01:55:20Z (5 years ago)
From
Peter Veres at UAH <veresp@gmail.com>
P. Veres (UAH), C. M. Hui (NASA/MSFC), C. Meegan (UAH) and J. Wood
(NASA/MSFC) report on behalf of the Fermi GBM Team:
"At 03:18:31.74 UT on 25 March 2020, the Fermi Gamma-Ray Burst Monitor
(GBM) triggered
and located GRB 200325A (trigger 606799116 / 200325138)
which was also detected by the Swift/BAT (GCN 27444). The Fermi GBM Final
Real-time Localization (GCN 27434) is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 107
degrees.
The GBM light curve consists of a single peak with a duration (T90) of
about 1 s (50-300 keV). The time-averaged spectrum from T0-0.1 s to T0+1.2
s is
best fit by a power law function with an exponential high-energy cutoff.
The power law index is -0.64 +/- 0.11 and the cutoff energy, parameterized
as Epeak, is 913 +/- 192 keV.
The event fluence (10-1000 keV) in this time interval is (2.49 +/-
0.12)E-6 erg/cm^2. The 64 ms peak photon flux measured starting from T0 +
256 ms in the 10-1000 keV band is 9.6 +/- 1.5 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/"