- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 10 Apr 21 00:53:41 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 45
TRIGGER_NUM: 639708801
GRB_RA: 284.633d {+18h 58m 32s} (J2000),
284.754d {+18h 59m 01s} (current),
284.350d {+18h 57m 24s} (1950)
GRB_DEC: +53.033d {+53d 01' 60"} (J2000),
+53.063d {+53d 03' 48"} (current),
+52.964d {+52d 57' 49"} (1950)
GRB_ERROR: 4.38 [deg radius, statistical plus systematic]
GRB_INTEN: 893 [cnts/sec]
DATA_SIGNIF: 44.00 [sigma]
INTEG_TIME: 1.024 [sec]
GRB_DATE: 19314 TJD; 100 DOY; 21/04/10
GRB_TIME: 3196.52 SOD {00:53:16.52} UT
GRB_PHI: 243.00 [deg]
GRB_THETA: 40.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO: 0.26
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 76% GRB
2nd_MOST_LIKELY: 22% Cyg X-1
DETECTORS: 0,0,0, 0,0,0, 1,1,1, 1,0,1, 0,0,
SUN_POSTN: 18.83d {+01h 15m 19s} +7.96d {+07d 57' 51"}
SUN_DIST: 86.08 [deg] Sun_angle= 6.3 [hr] (West of Sun)
MOON_POSTN: 359.28d {+23h 57m 06s} -5.66d {-05d 39' 45"}
MOON_DIST: 85.37 [deg]
MOON_ILLUM: 4 [%]
GAL_COORDS: 83.06, 20.35 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 305.12, 74.69 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210410037/quicklook/glg_lc_medres34_bn210410037.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 138.35,24.08 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 10 Apr 21 00:53:50 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 59
TRIGGER_NUM: 639708801
GRB_RA: 284.717d {+18h 58m 52s} (J2000),
284.836d {+18h 59m 21s} (current),
284.436d {+18h 57m 45s} (1950)
GRB_DEC: +53.200d {+53d 12' 00"} (J2000),
+53.230d {+53d 13' 49"} (current),
+53.130d {+53d 07' 48"} (1950)
GRB_ERROR: 4.60 [deg radius, statistical plus systematic]
GRB_INTEN: 739 [cnts/sec]
DATA_SIGNIF: 74.00 [sigma]
INTEG_TIME: 4.096 [sec]
GRB_DATE: 19314 TJD; 100 DOY; 21/04/10
GRB_TIME: 3196.52 SOD {00:53:16.52} UT
GRB_PHI: 243.00 [deg]
GRB_THETA: 40.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO: 0.30
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 76% GRB
2nd_MOST_LIKELY: 22% Cyg X-1
DETECTORS: 0,0,0, 0,0,0, 1,1,1, 1,0,1, 0,0,
SUN_POSTN: 18.83d {+01h 15m 19s} +7.96d {+07d 57' 51"}
SUN_DIST: 86.00 [deg] Sun_angle= 6.3 [hr] (West of Sun)
MOON_POSTN: 359.28d {+23h 57m 06s} -5.66d {-05d 39' 43"}
MOON_DIST: 85.37 [deg]
MOON_ILLUM: 4 [%]
GAL_COORDS: 83.25, 20.36 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 305.54, 74.82 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210410037/quicklook/glg_lc_medres34_bn210410037.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 138.35,24.08 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
- GCN NOTICE
TITLE: GCN/INTEGRAL NOTICE
NOTICE_DATE: Sat 10 Apr 21 00:54:16 UT
NOTICE_TYPE: INTEGRAL SPI ACS Trigger
TRIGGER_NUM: 9133, Sub_Num: 0
GRB_INTEN: 9.47 [sigma]
GRB_TIME: 3194.49 SOD {00:53:14.49} UT
GRB_DATE: 19314 TJD; 100 DOY; 21/04/10
COMMENTS: INTEGRAL SPI_ACS GRB Trigger.
COMMENTS: Time_Scale=2.0000 and Time_Error=1.0000.
COMMENTS:
COMMENTS: NOTE: This SPIACS event is temporally(2.0<100sec) coincident with the FERMI_GBM event (trignum=639708801).
COMMENTS:
COMMENTS: The SPIACS lightcurve can be found at:
COMMENTS: ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2021-04/2021-04-10T00-53-14.2897-01237-11152-0.lc
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 10 Apr 21 00:53:59 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 58
TRIGGER_NUM: 639708801
GRB_RA: 267.010d {+17h 48m 02s} (J2000),
267.154d {+17h 48m 37s} (current),
266.671d {+17h 46m 41s} (1950)
GRB_DEC: +47.360d {+47d 21' 36"} (J2000),
+47.354d {+47d 21' 14"} (current),
+47.375d {+47d 22' 31"} (1950)
GRB_ERROR: 2.58 [deg radius, statistical only]
DATA_SIGNIF: 68.90 [sigma]
DATA_INTERVAL: 4.096 [sec]
GRB_DATE: 19314 TJD; 100 DOY; 21/04/10
GRB_TIME: 3196.52 SOD {00:53:16.52} UT
GRB_PHI: 232.00 [deg]
GRB_THETA: 50.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 4173 (Gnd S/W Version number)
SUN_POSTN: 18.83d {+01h 15m 19s} +7.96d {+07d 57' 52"}
SUN_DIST: 98.39 [deg] Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN: 359.28d {+23h 57m 07s} -5.66d {-05d 39' 41"}
MOON_DIST: 95.60 [deg]
MOON_ILLUM: 4 [%]
GAL_COORDS: 74.13, 30.01 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 263.85, 70.74 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210410037/quicklook/glg_lc_medres34_bn210410037.gif
POS_MAP_URL: http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_639708801.fits
COMMENTS: Fermi-GBM Ground-calculated Coordinates.
COMMENTS: In the LAT Field-of-view.
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: Sat 10 Apr 21 00:54:37 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 2
TRIGGER_NUM: 639708801
GRB_RA: 269.660d {+17h 58m 38s} (J2000),
269.803d {+17h 59m 13s} (current),
269.325d {+17h 57m 18s} (1950)
GRB_DEC: +47.650d {+47d 38' 60"} (J2000),
+47.649d {+47d 38' 58"} (current),
+47.652d {+47d 39' 09"} (1950)
GRB_ERROR: 1.54 [deg radius, statistical only]
DATA_SIGNIF: 80.70 [sigma]
DATA_INTERVAL: 3.072 [sec]
GRB_DATE: 19314 TJD; 100 DOY; 21/04/10
GRB_TIME: 3196.52 SOD {00:53:16.52} UT
GRB_PHI: 234.00 [deg]
GRB_THETA: 49.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 41731 (Gnd S/W Version number)
SUN_POSTN: 18.83d {+01h 15m 19s} +7.96d {+07d 57' 52"}
SUN_DIST: 96.61 [deg] Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN: 359.28d {+23h 57m 08s} -5.66d {-05d 39' 33"}
MOON_DIST: 93.83 [deg]
MOON_ILLUM: 4 [%]
GAL_COORDS: 74.79, 28.29 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 269.29, 71.09 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210410037/quicklook/glg_lc_medres34_bn210410037.gif
POS_MAP_URL: http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_639708801.fits
COMMENTS: Fermi-GBM Ground-calculated Coordinates.
COMMENTS: In the LAT Field-of-view.
COMMENTS: Bright hard burst in the GBM.
COMMENTS: This is likely a Long GRB.
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.
COMMENTS:
COMMENTS: NOTE: This GBM event is temporally(2.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=9133).
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 10 Apr 21 00:54:48 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 3
TRIGGER_NUM: 639708801
GRB_RA: 267.580d {+17h 50m 19s} (J2000),
267.720d {+17h 50m 53s} (current),
267.252d {+17h 49m 00s} (1950)
GRB_DEC: +48.290d {+48d 17' 24"} (J2000),
+48.285d {+48d 17' 07"} (current),
+48.303d {+48d 18' 09"} (1950)
GRB_ERROR: 1.38 [deg radius, statistical only]
DATA_SIGNIF: 94.40 [sigma]
DATA_INTERVAL: 5.120 [sec]
GRB_DATE: 19314 TJD; 100 DOY; 21/04/10
GRB_TIME: 3196.52 SOD {00:53:16.52} UT
GRB_PHI: 232.00 [deg]
GRB_THETA: 49.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 41731 (Gnd S/W Version number)
SUN_POSTN: 18.83d {+01h 15m 19s} +7.96d {+07d 57' 52"}
SUN_DIST: 97.70 [deg] Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN: 359.28d {+23h 57m 08s} -5.66d {-05d 39' 30"}
MOON_DIST: 95.26 [deg]
MOON_ILLUM: 4 [%]
GAL_COORDS: 75.25, 29.77 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 264.87, 71.69 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210410037/quicklook/glg_lc_medres34_bn210410037.gif
POS_MAP_URL: http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_639708801.fits
COMMENTS: Fermi-GBM Ground-calculated Coordinates.
COMMENTS: In the LAT Field-of-view.
COMMENTS: Bright hard burst in the GBM.
COMMENTS: This is likely a Long GRB.
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.
COMMENTS:
COMMENTS: NOTE: This GBM event is temporally(2.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=9133).
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 10 Apr 21 00:55:06 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 4
TRIGGER_NUM: 639708801
GRB_RA: 269.240d {+17h 56m 58s} (J2000),
269.376d {+17h 57m 30s} (current),
268.921d {+17h 55m 41s} (1950)
GRB_DEC: +49.090d {+49d 05' 24"} (J2000),
+49.089d {+49d 05' 19"} (current),
+49.094d {+49d 05' 40"} (1950)
GRB_ERROR: 1.00 [deg radius, statistical only]
DATA_SIGNIF: 89.60 [sigma]
DATA_INTERVAL: 13.312 [sec]
GRB_DATE: 19314 TJD; 100 DOY; 21/04/10
GRB_TIME: 3196.52 SOD {00:53:16.52} UT
GRB_PHI: 233.00 [deg]
GRB_THETA: 48.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 41731 (Gnd S/W Version number)
SUN_POSTN: 18.83d {+01h 15m 19s} +7.96d {+07d 57' 53"}
SUN_DIST: 96.39 [deg] Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN: 359.29d {+23h 57m 09s} -5.66d {-05d 39' 26"}
MOON_DIST: 94.21 [deg]
MOON_ILLUM: 4 [%]
GAL_COORDS: 76.35, 28.81 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 268.34, 72.52 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210410037/quicklook/glg_lc_medres34_bn210410037.gif
POS_MAP_URL: http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_639708801.fits
COMMENTS: Fermi-GBM Ground-calculated Coordinates.
COMMENTS: In the LAT Field-of-view.
COMMENTS: Bright hard burst in the GBM.
COMMENTS: This is likely a Long GRB.
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.
COMMENTS:
COMMENTS: NOTE: This GBM event is temporally(2.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=9133).
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 10 Apr 21 01:02:43 UT
NOTICE_TYPE: Fermi-GBM Final Position
RECORD_NUM: 0
TRIGGER_NUM: 639708801
GRB_RA: 268.070d {+17h 52m 17s} (J2000),
268.215d {+17h 52m 51s} (current),
267.730d {+17h 50m 55s} (1950)
GRB_DEC: +47.240d {+47d 14' 24"} (J2000),
+47.236d {+47d 14' 10"} (current),
+47.250d {+47d 15' 01"} (1950)
GRB_ERROR: 1.55 [deg radius, statistical only]
GRB_DATE: 19314 TJD; 100 DOY; 21/04/10
GRB_TIME: 3196.52 SOD {00:53:16.52} UT
GRB_PHI: 233.00 [deg]
GRB_THETA: 50.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 41731 (Gnd S/W Version number)
SUN_POSTN: 18.84d {+01h 15m 21s} +7.97d {+07d 57' 60"}
SUN_DIST: 97.76 [deg] Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN: 359.35d {+23h 57m 23s} -5.63d {-05d 37' 48"}
MOON_DIST: 94.90 [deg]
MOON_ILLUM: 4 [%]
GAL_COORDS: 74.12, 29.28 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 266.04, 70.65 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210410037/quicklook/glg_lc_medres34_bn210410037.gif
LOC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210410037/quicklook/glg_locplot_all_bn210410037.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: In the LAT Field-of-view.
COMMENTS: Bright hard burst in the GBM.
COMMENTS: This is likely a Long GRB.
COMMENTS:
COMMENTS: NOTE: This GBM event is temporally(2.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=9133).
- GCN Circular #29777
The Fermi GBM team reports the detection of a likely LONG GRB
At 00:53:16 UT on 10 Apr 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210410A (trigger 639708801.519268 / 210410037).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 268.1, Dec = 47.2 (J2000 degrees, equivalent to J2000 17h 52m, 47d 12'), with a statistical uncertainty of 1.6 degrees.
The angle from the Fermi LAT boresight is 50.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210410037/quicklook/glg_skymap_all_bn210410037.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210410037/quicklook/glg_healpix_all_bn210410037.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210410037/quicklook/glg_lc_medres34_bn210410037.gif
- GCN Circular #29778
A. Melandri (INAF-OAB), J. A. Kennea (PSU) and N. J. Klingler (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:
Swift BAT triggered on GRB 210410A, previously reported by Fermi/GBM (GCN #29777).
Due to a telemetry drop-out, no prompt BAT data are available, however XRT has
localized the source.
Using promptly downlinked data we find an uncatalogued X-ray source
located at RA, Dec 269.75417, 45.36339 which is equivalent to:
RA(J2000) = 17h 59m 01.00s
Dec(J2000) = +45d 21' 48.2"
with an uncertainty of 6.1 arcseconds (radius, 90% containment). This
position may be improved as more data are received; the latest position
is available at https://www.swift.ac.uk/sper. No spectrum from the
promptly downlinked event data is yet available to determine the column
density.
Burst Advocate for this burst is A. Melandri (andrea.melandri AT brera.inaf.it).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)
- GCN Circular #29779
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin,
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov, D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gres, N.M. Budnev, O.Ershova
(Irkutsk State University, API),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko
(Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 210410A ( Fermi GBM team, GCN 29777) errorbox 42 sec after notice time and 69 sec after trigger time at 2021-04-10 00:54:26 UT, with upper limit up to 16.8 mag. The observations began at zenith distance = 85 deg. The sun altitude is -50.6 deg.
MASTER-Tavrida robotic telescope located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 210410A errorbox 112 sec after notice time and 139 sec after trigger time at 2021-04-10 00:55:36 UT, with upper limit up to 19.1 mag. The observations began at zenith distance = 15 deg. The sun altitude is -22.5 deg.
The galactic latitude b = 29 deg., longitude l = 74 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1588428
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
75 | 2021-04-10 00:54:26 | MASTER-SAAO | (17h 48m 53.00s , +47d 14m 34.0s) | C | 10 | 16.4 |
110 | 2021-04-10 00:54:56 | MASTER-SAAO | (17h 48m 58.82s , +47d 13m 30.3s) | C | 20 | 16.8 |
155 | 2021-04-10 00:55:36 | MASTER-Tavrida | (17h 47m 38.38s , +48d 29m 25.0s) | C | 30 | 18.4 |
209 | 2021-04-10 00:56:25 | MASTER-Tavrida | (17h 47m 31.30s , +48d 28m 35.5s) | C | 40 | 18.5 |
666 | 2021-04-10 01:03:22 | MASTER-Tavrida | (17h 54m 11.52s , +47d 16m 38.2s) | C | 120 | 19.1 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
- GCN Circular #29780
M. Jelinek, J. Strobl, R. Hudec, C. Polasek (ASU CAS Ondrejov)
report:
We observed the position of the Fermi/GBM GRB 210410A (Fermi, GCNC 29777)
with the D50 robotic telescope of the Astronomical Institute Ondrejov, near
Prague, Czech Republic. We performed a series of 120 s unfiltered
exposures starting 56 min after the trigger.
Within the Swift/XRT error box (Melandri et al. GCNC 29778) we detect a
fading object at (269.7542, 45.3629) (17:59:01.00 +45:21:46.6 J2000
+/-0.3"). The preliminary magnitude 103 min after the trigger was r'(AB) =
21.5 +/- 0.2 and the object seems to fade with alpha ~ 0.95 +/- 0.27.
- GCN Circular #29781
M. Arimoto (Kanazawa Univ.), M. Ohno (Hiroshima Univ. & Eotvos Univ.),
F. Longo (University and INFN, Trieste) and M. Axelsson (KTH &
Stockholm Univ.) report on behalf of the Fermi-LAT team:
On April 10, 2021, Fermi-LAT detected high-energy emission from GRB
210410A, which was also detected by Fermi-GBM (trigger 639708801 /
210410037, Fermi GBM team, GCN 29777) and Swift/BAT&XRT (Kennea et al.
2021, GCN 29778).
The best LAT on-ground location is found to be
RA, Dec = 268.9, 45.2 (J2000)
with an error radius of 0.5 deg (90 % containment, statistical error
only). This position is consistent with the Swift/XRT localization.
This was 51 deg from the LAT boresight at the time of the GBM trigger:
T0 = 00:53:16.5 UT.
The data from the Fermi-LAT show a significant increase in the event
rate after the GBM trigger that is spatially and temporally correlated
with the GBM emission (2 degrees from the GBM location) with high
significance.
The photon flux above 100 MeV in the time interval 0-300s after the
GBM trigger is (4.0 +/- 0.7)e-05 ph/cm2/s, while the flux above 1 GeV
is (1.3 +/- 0.7)e-06 ph/cm2/s.
The estimated photon index above 100 MeV is -2.5 +/- 0.2.
The highest-energy photon is a 4.2 GeV event which is observed 30
seconds after the GBM trigger.
The Fermi-LAT point of contact for this burst is Masanori Ohno
(ohno@astro.hiroshima-u.ac.jp).
The Fermi-LAT is a pair conversion telescope designed to cover the
energy band from 20 MeV to greater than 300 GeV. It is the product of
an international collaboration between NASA and DOE in the U.S. and
many scientific institutions across France, Italy, Japan and Sweden.
- GCN Circular #29782
A. Ursi (INAF/IAPS), F. Verrecchia, C. Pittori (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 (SSDC, and
INAF/OAR), A. Bulgarelli, A. Di Piano, 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 long GRB 210410A at T0 = 2021-04-10
00:53:16.64 +/- 0.01 s (UTC), reported by Fermi/GBM (GCN #29777), Swift/XRT
(GCN #29778), and Fermi/LAT (GCN #29781).
The burst is visible in the AGILE scientific ratemeters of the SuperAGILE
(SA; 20-60 keV), MiniCALorimeter (MCAL; 0.4-100 MeV), and AntiCoincidence
(AC; 50-200 keV) detectors. The event lasted ~15 s and released a total
number of 1050 counts in the SA detector (above a background rate of 60
Hz), 29400 counts in the MCAL detector (above a background rate of 1200
Hz), and 72250 counts in the AC detector (above a background rate of 3320
Hz). The AGILE ratemeter light curves can be found at
http://www.agilescienceapp.it/notices/GRB210410_AGILE_RM.png .
The event also triggered a partial high time resolution MCAL data
acquisition, whose light curve can be found at:
http://www.agilescienceapp.it/notices/072541_GRB_545100796.643050.png .
Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert
Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html.
- GCN Circular #29784
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier
Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora
Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jesús
González (UNAM), Carlos Román-Zúñiga (UNAM), Harvey Moseley (GSFC), John
Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:
We observed the field of GRB 210410A (Fermi GBM team, et al., GCN 29777)
with the Reionization and Transients Infrared Camera (RATIR) on the 1.5m
Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra
San Pedro Mártir from 2021/04 10.30 to 2021/04 10.51 UTC (6.26 to 11.25
hours after the BAT trigger), obtaining a total of 2.16 hours exposure in
the r and i bands and 0.87 hours exposure in the Z, Y, J, and H bands.
We detect one source within the Swift-XRT error circle (Melandri, et al.,
GCN 29778). In comparison with the USNO-B1 and 2MASS catalogs, we find
these magnitudes (in the AB system and not corrected for Galactic
extinction in the direction of the GRB):
r = 23.79 +/- 0.30
i = 22.49 +/- 0.14
Z = 22.07 +/- 0.27
Y = 21.14 +/- 0.18
J = 20.24 +/- 0.11
H = 20.17 +/- 0.15
The source is located at RA, Dec = 17:59:1.00, +45:21:44.6 (J2000,
+/-0.5"), which is 2 arcsec away from the candidate optical afterglow
position reported by Jelinek et al. (GCN 29780). It is possible that an
astrometric cross-comparison could reveal our sources to be the same, in
which case the optical afterglow continues to fade strongly. It is also
possible that we are detecting the GRB host galaxy. A photo-z analysis
suggests the redshift is z<3.6 (90% confidence).
We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.
- GCN Circular #29786
Nat Butler (ASU) and Martin Jelinek (ASU AV CR Ondrejov) report:
We performed a joint inspection of the D50 (Jelinek et al., GCNC29780) and
RATIR (Butler et al., GCNC29784) images and agreed that the object
reported in both circulars is identical. Joint photometric fit of the data
provides a decay rate of 1.18 ± 0.24 (chisq=1.68). Seeing this, we conclude
that this object is indeed the optical afterglow of GRB 210410A (cf. Fermi
team, GCN 29777, Melandri et al., GCN 29778, Arimoto at al., GCN
29781, Ursi et al., GCNC 29782).
The preliminary coordinates reported by the D50 team are flawed and the
RATIR value, i.e. RA, Dec = 17:59:1.00, +45:21:44.6 (J2000, +/-0.5") should
be used.
- GCN Circular #29787
Paul Kuin (MSSL/UCL) and A. Melandri(INAF-OAB) report on behalf
of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210410A
(trigger 01042113; previously reported by Fermi/GBM in GCN #29777)
1113 s after the Fermi trigger at 2021-04-10 00:53:16 UT.
No optical afterglow consistent with the XRT position (Melandri et
al. GCN Circ. 29778) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) mag 3-sigma UL
v 1129 1149 19 >17.0
b 5021 5109 85 >19.7
u 4817 5014 197 >19.9
w1 4610 4809 197 >19.3
m2 4403 4602 197 >19.4
w2 1113 1125 12 >17.0
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).
- GCN Circular #29788
J. Wood (NASA/MSFC) and C.Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 00:53:16.52 UT on 10 April 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210410A (trigger 639708801 / 210410037).
which was also detected by the Swift/XRT (A. Melandri et al. 2021, GCN 29778),
the Fermi/LAT (M. Arimoto et al. 2021, GCN 29781),
and AGILE (A. Ursi et al. 2021, GCN 29782).
The Fermi GBM Final Real-time Localization (GCN 29777) is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 51.0 degrees.
The GBM light curve consists of a single peak
with a duration (T90) of about 48 s (50-300 keV).
The time-averaged spectrum from T0-0 s to T0+50 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.70 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 1300 +/- 100 keV
The event fluence (10-1000 keV) in this time interval is
(4.5 +/- 0.5)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0 s in the 10-1000 keV band
is 12.6 +/- 0.3 ph/s/cm^2.
A Band function fits the spectrum equally well
with Epeak = 1300 +/- 100 keV, alpha = -0.70 +/- 0.03 and beta = 4.0 +/- 1.6.
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 #29790
A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A.
Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester),
J.P. Osborne (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato
(INAF-OAB) and report on behalf of the Swift-XRT team: report on
behalf of the Swift-XRT team:
We have analysed 4.4 ks of XRT data for GRB 210410A, from 61 s to 52.6
ks after the BAT trigger. The data comprise 115 s in Windowed Timing
(WT) mode (the first 8 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. Using 702 s of PC mode data and
1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 269.75437, +45.36192 which is equivalent to:
RA (J2000): 17h 59m 01.05s
Dec(J2000): +45d 21' 42.9"
with an uncertainty of 2.4 arcsec (radius, 90% confidence).
The late-time light curve (from T0+4.3 ks) can be modelled with a
power-law decay with a decay index of alpha=1.5 (+0.5, -0.4).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.33 (+/-0.11). The
best-fitting absorption column is 1.4 (+0.5, -0.4) x 10^21 cm^-2, in
excess of the Galactic value of 4.0 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.47 (+0.18, -0.16)
and a best-fitting absorption column of 7.2 (+6.0, -3.2) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 4.5 x 10^-11 (4.9 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 7.2 (+6.0, -3.2) x 10^20 cm^-2
Galactic foreground: 4.0 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.47 (+0.18, -0.16)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01042113.
This circular is an official product of the Swift-XRT team.
- GCN Circular #29793
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), C. B. Markwardt (GSFC),
A. Melandri (INAF-OAB), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 210410A (trigger #1042113)
(Melandri et al., GCN Circ. 29778). The BAT ground-calculated position is
RA, Dec = 269.741, 45.359 deg which is
RA(J2000) = 17h 58m 57.8s
Dec(J2000) = +45d 21' 31.9"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 55%.
The mask-weighted light curve shows a FRED pulse that starts at ~T0, peaks
at ~T0, peaks at ~T+2 s, and ends at ~T+100 s. T90 (15-350 keV)
is 52.88 +- 4.15 sec (estimated error including systematics).
The time-averaged spectrum from T-0.00 to T+66.06 sec is best fit by a
simple
power-law model. The power law index of the time-averaged spectrum is
1.04 +- 0.06. The fluence in the 15-150 keV band is 5.6 +- 0.2 x 10^-6
erg/cm2.
The 1-sec peak photon flux measured from T+1.74 sec in the 15-150 keV band
is 4.0 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1042113/BA/
- GCN Circular #29797
A. Ridnaia, D. Frederiks, S. Golenetskii, A. Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline, report:
The long-duration GRB 210410A
(Fermi-GBM detection: Fermi GBM team, GCN 29777,
Wood and Meegan, GCN 29788;
Fermi-LAT detection: Arimoto et al., GCN 29781;
AGILE detection: Ursi et al., GCN 29782;
Swift-BAT observation: Lien et al., GCN 29793)
triggered Konus-Wind at T0=3196.651 s UT (00:53:16.651).
The burst light curve starts at ~T0 with a narrow (~128 ms) pulse
followed by a gradually decaying emission until ~T0+85s.
The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB210410_T03196/
As observed by Konus-Wind, the burst
had a fluence of 7.29(-0.44,+0.47)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.002 s,
of 2.95(-0.69,+0.76)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+47.104 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.74(-0.07,+0.08)
and Ep = 1081(-126,+150) keV (chi2 = 72/98 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.7
(chi2 = 72/97 dof).
The spectrum of the initial pulse
(measured from T0 to T0+0.128 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model
with alpha = 0.11(-0.29,+0.38)
and Ep = 1210(-250,+326) keV (chi2 = 38/32 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -1.9
(chi2 = 36/31 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
- GCN Circular #29798
A. Ursi (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), F.
Verrecchia, C. Pittori (SSDC, and INAF/OAR), A. Argan, M. Cardillo, C.
Casentini, Y. Evangelista, G. Piano (INAF/IAPS), F. Lucarelli (SSDC, and
INAF/OAR), A. Bulgarelli, A. Di Piano, 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:
We carried out further analysis of the AGILE/MCAL data of GRB 210410A (GCNs
#29777, #29778, #29779, #29780, #29781, #29782, #29786, #29787, #29788,
#29790, #29793, #29797).
The first 4 s of the burst released 5700 counts in the detector, above a
background rate of 560 Hz.
The spectral analysis shows a clear component up to 100 MeV.
The time-integrated spectrum of the first ~4 s of the burst can be fitted
in the energy range 0.4-100 MeV with a CPL model with alpha = -0.6
-0.25/+0.14 and cutoff energy Ec = 500 keV, plus an extra PL component with
ph.ind. -1.31 -0.04/+0.04. The fit results in a reduced chi-squared of 1.48
(81 d.o.f.) and a fluence of 1.3e-04 ergs/cm^2 (90% confidence level), in
the same energy range.
We divided the data acquisition into three time intervals: interval a
[T0-0.16s - T0+0.70s], interval b [T0+0.70s - T0+2.85s], and interval c
[T0+2.85s - T0+4.00s]. The spectral analysis in the energy range 0.4-100
MeV shows an evolution of the PL high-energy spectral component, evolving
from alpha = -1.91 to alpha = -0.92. Details are reported below:
| model | CPL alpha | Ec | PL ph.ind. | redX^2 (dof)
a | CPL+PL | -0.57 -1.46/+3.84 | 438 keV | -1.91 -0.96/+0.78 | 0.97 (81)
b | CPL+PL | -0.57 -1.68/+0.67 | 365 keV | -0.98 -0.61/+0.39 | 1.38 (81)
c | PL | ----- | --- | -0.92 -0.98/+0.40 | 1.05 (84)
MCAL light curve and spectra in the different time intervals can be found
at:
http://www.agilescienceapp.it/notices/GRB210410A_AGILE-MCAL_intervals.png .
Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert
Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html.
- GCN Circular #29805
K. L. Murata, R. Hosokawa, M. Niwano, N. Ito, H. Takamatsu, Y. Yatsu, and
N.Kawai (TokyoTech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 210410A (The Fermi GBM team et al. GCN
Circular #29777, A. Melandri et al. GCN Circular #29778, V. Lipunov et al.
GCN Circular #29779, M. Jelinek et al. GCN Circular #29780, M. Arimoto et
al. GCN Circular #29781, A. Ursi et al. GCN Circular #29782, Nat Butler et
al. GCN Circular #29784, Nat Butler et al. GCN Circular #29786, Paul Kuin
et al. GCN Circular #29787, J. Wood et al. GCN Circular #29788, A. D'Ai et
al. GCN Circular #29790, A. Y. Lien et al. GCN Circular #29793, A. Ridnaia
et al. GCN Circular #29797, A. Ursi et al. GCN Circular #29798) with the
optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50
cm telescope of Akeno Observatory, Yamanashi, Japan. The observation with a
series of 60 sec exposures started at 2021-04-10 13:35 (9.7 hours after the
Fermi/GBM trigger). We stacked the images with good conditions. We did not
detect the optical afterglow reported previously (Jelinek et al. GCN
Circular #29780, Butler et al. GCN Circular #29784) in all three bands. We
obtained the 5-sigma limits of the stacked images as follows.
T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
10.0 14:00:15 1740 g'>19.3, Rc>19.6, Ic>19.0
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used the PS1 catalog for flux calibration.The magnitudes are expressed
in the AB system. The images were processed in real-time through the
MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1,
Pages 4-24; https://github.com/MNiwano/Eclaire).
- GCN Circular #29812
Paul Kuin (MSSL/UCL) reports on behalf of the Swift/UVOT team:
In our previous report (Kuin & Melandri, GCN Circ 29787) we made
an error computing T0, which affected our T_start and T_stop times.
Below are the corrected values.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) mag 3-sigma UL
v 1070 1095 19 >17.0
b 4967 5055 85 >19.7
u 4763 4960 197 >19.9
w1 4556 4755 197 >19.3
m2 4349 4548 197 >19.4
w2 1059 1071 12 >17.0
- GCN Circular #29816
Y. Aimuratov, C.L. Bianco, L. Li, R. Moradi, F. Rastegar Nia, J.A.
Rueda, R. Ruffini, N. Sahakyan, Y. Wang, S.S. Xue on behalf of the
ICRANet team, report:
GRB 210410A has been announced as a likely long GRB (Fermi GBM Team
2021, GCN 29777), it has been also observed by Swift-XRT (A. Melandri
et al 2021, GCN 29778, and A. D’Ai et al, 2021, GCN 29790), by
Fermi-LAT (M. Arimoto et al 2021, GCN 29781), by AGILE (A. Ursi et al.
2021, GCN 29782), by Swift BAT (A. Y. Lien et al, 2021 GCN 29793) as
well as by Konus-Wind (A. Ridnaia et al 2021, GCN 29797). The
Fermi-GBM has determined T90=48 s in 50-300 keV (J. Wood et al 2021,
GCN 29788). A possible detection of the host galaxy at redshift z<3.6
was indicated by Butler et al 2021 (GCN 29784).
We here propose that GRB 210410A is a twin and covers the
complementary observation to the short GRB 090510, with T90=0.3 s. (R.
Ruffini et al 2016 ApJ 831 178).
We infer that GRB 210410A is a short GRB originating from a black hole
formation in view of its observed GeV emission (M. Arimoto et al
GCN29781) that and no supernova will be detected. We evidence for the
first time an angle dependence of the emission of short GRB: in the
polar observation for GRB 090510, with T90=0.3 s and in the equatorial
observation for GRB 210410A, with T90=48 s.
The spectroscopic determination of the redshift of the host galaxy is
essential for the determination of the GeV luminosity and consequently
the BH mass (R. Ruffini et al 2019 ApJ 886 82). We indicate the
relevance of the redshift determinations in the two enclosed figures.
http://www.icranet.org/documents/GRB210410A-z=0.6-and-GRB090510-z=0.903.pdf
http://www.icranet.org/documents/GRB210410A-z=3.6-and-GRB090510-z=0.903.pdf
- GCN Circular #29817
P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta
(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (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, 2020,
arxiv:2011.07067) showed detection of a long GRB 210410A, which was also
detected by Fermi-GBM (GCN #29777, #29788), Swift-XRT (GCN #29778, #29790),
Fermi-LAT (GCN #29781), Swift-BAT (GCN #29793), Konus-Wind (GCN #29797) and
AGILE-MCAL (GCN #29798).
The source was clearly detected in the 20-200 keV energy range. The light
curve showed multiple peaks of emission with the strongest peak at
2021-04-10 00:53:16.50 UT. Quadrant D was noisy, and we exclude it from
further analysis. The measured peak count rate associated with the burst is
225 (+45, -16) cts/s above the background in the combined data of four
quadrants, with a total of 1808 (+239, -299) cts. The local mean background
count rate was 373 (+2, -2) cts/s. Using cumulative rates, we measure a
T90 of 20 (+6, -7) s.
It was also clearly detected in the CsI anticoincidence (Veto) detector in
the 100-500 keV energy range. The light curve showed multiple peaks of
emission with the strongest peak at 2021-04-10 00:53:15.867 UT. The
measured peak count rate is 1149 (+91, -57) cts/s above the background in
the combined Veto data of four quadrants, with a total of 8483 (+515, -574)
cts. The local mean background count rate was 1580 (+4, -4) cts/s. We
measure a T90 of 18 (+6, -4) s from the cumulative Veto light curve.
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.
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