Gamma-ray Burst 200325A

(All information courtesy of the instrument teams.)

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Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Wed 25 Mar 20 03:18:59 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      46
TRIGGER_NUM:     606799116
GRB_RA:           69.567d {+04h 38m 16s} (J2000),
                  69.348d {+04h 37m 24s} (current),
                  70.116d {+04h 40m 28s} (1950)
GRB_DEC:         -77.567d {-77d 34' 00"} (J2000),
                 -77.527d {-77d 31' 37"} (current),
                 -77.663d {-77d 39' 45"} (1950)
GRB_ERROR:       4.83 [deg radius, statistical plus systematic]
GRB_INTEN:       1174 [cnts/sec]
DATA_SIGNIF:     15.50 [sigma]
INTEG_TIME:      0.512 [sec]
GRB_DATE:        18933 TJD;    85 DOY;   20/03/25
GRB_TIME:        11911.74 SOD {03:18:31.74} UT
GRB_PHI:          12.00 [deg]
GRB_THETA:       155.00 [deg]
DATA_TIME_SCALE: 0.5120 [sec]
HARD_RATIO:      0.40
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      94%  GRB
2nd_MOST_LIKELY:   4%  Generic Transient
DETECTORS:       0,0,1, 1,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:         4.54d {+00h 18m 09s}   +1.96d {+01d 57' 51"}
SUN_DIST:         86.65 [deg]   Sun_angle= -4.3 [hr] (East of Sun)
MOON_POSTN:       13.84d {+00h 55m 21s}   +0.61d {+00d 36' 40"}
MOON_DIST:        83.58 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      290.48,-33.40 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      290.29,-77.48 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200325138/quicklook/glg_lc_medres34_bn200325138.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 142.28,22.53 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Wed 25 Mar 20 03:19:13 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     606799116
GRB_RA:           27.220d {+01h 48m 53s} (J2000),
                  27.453d {+01h 49m 49s} (current),
                  26.644d {+01h 46m 35s} (1950)
GRB_DEC:         -27.080d {-27d 04' 47"} (J2000),
                 -26.980d {-26d 58' 47"} (current),
                 -27.328d {-27d 19' 41"} (1950)
GRB_ERROR:       6.32 [deg radius, statistical only]
DATA_SIGNIF:     16.30 [sigma]
DATA_INTERVAL:   0.512 [sec]
GRB_DATE:        18933 TJD;    85 DOY;   20/03/25
GRB_TIME:        11911.74 SOD {03:18:31.74} UT
GRB_PHI:          17.00 [deg]
GRB_THETA:       101.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:         4.54d {+00h 18m 09s}   +1.96d {+01d 57' 51"}
SUN_DIST:         36.41 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:       13.84d {+00h 55m 21s}   +0.61d {+00d 36' 43"}
MOON_DIST:        30.55 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      216.00,-77.22 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       13.67,-35.43 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200325138/quicklook/glg_lc_medres34_bn200325138.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_606799116.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:     Wed 25 Mar 20 03:27:54 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     606799116
GRB_RA:           22.060d {+01h 28m 14s} (J2000),
                  22.296d {+01h 29m 11s} (current),
                  21.477d {+01h 25m 55s} (1950)
GRB_DEC:         -29.090d {-29d 05' 23"} (J2000),
                 -28.986d {-28d 59' 08"} (current),
                 -29.349d {-29d 20' 54"} (1950)
GRB_ERROR:       4.18 [deg radius, statistical only]
GRB_DATE:        18933 TJD;    85 DOY;   20/03/25
GRB_TIME:        11911.74 SOD {03:18:31.74} UT
GRB_PHI:          12.00 [deg]
GRB_THETA:       102.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:         4.54d {+00h 18m 11s}   +1.97d {+01d 57' 60"}
SUN_DIST:         35.32 [deg]   Sun_angle= -1.2 [hr] (East of Sun)
MOON_POSTN:       13.90d {+00h 55m 37s}   +0.64d {+00d 38' 26"}
MOON_DIST:        30.69 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      228.66,-81.65 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        7.58,-35.21 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200325138/quicklook/glg_lc_medres34_bn200325138.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200325138/quicklook/glg_locplot_all_bn200325138.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 Short GRB.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=8558).

GCN Circular #27434
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
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
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
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
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 Circular #27453
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/"

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Jochen Greiner, last update: 30-Mar-2020 [Disclaimer]