(All information courtesy of the instrument teams.)
Previous IAU Circulars
TITLE: GCN/SWIFT NOTICE NOTICE_DATE: Thu 27 Mar 25 07:31:43 UT NOTICE_TYPE: Swift-BAT GRB Position TRIGGER_NUM: 1299088, Seg_Num: 0 GRB_RA: 248.197d {+16h 32m 47s} (J2000), 248.280d {+16h 33m 07s} (current), 248.035d {+16h 32m 09s} (1950) GRB_DEC: +61.595d {+61d 35' 43"} (J2000), +61.543d {+61d 32' 36"} (current), +61.699d {+61d 41' 57"} (1950) GRB_ERROR: 3.00 [arcmin radius, statistical only] GRB_INTEN: 0 [cnts] Image_Peak=1424 [image_cnts] TRIGGER_DUR: 88.000 [sec] TRIGGER_INDEX: 20000 E_range: 15-50 keV BKG_INTEN: 0 [cnts] BKG_TIME: 0.00 SOD {00:00:00.00} UT BKG_DUR: 0 [sec] GRB_DATE: 20761 TJD; 86 DOY; 25/03/27 GRB_TIME: 27004.68 SOD {07:30:04.68} UT GRB_PHI: -143.77 [deg] GRB_THETA: 50.63 [deg] SOLN_STATUS: 0x20000013 RATE_SIGNIF: 0.00 [sigma] IMAGE_SIGNIF: 8.75 [sigma] MERIT_PARAMS: +1 +0 +0 +6 +1 -1 +0 +0 +18 +0 SUN_POSTN: 6.33d {+00h 25m 18s} +2.73d {+02d 44' 03"} SUN_DIST: 100.48 [deg] Sun_angle= 7.9 [hr] (West of Sun) MOON_POSTN: 339.69d {+22h 38m 46s} -10.44d {-10d 26' 26"} MOON_DIST: 99.84 [deg] MOON_ILLUM: 7 [%] GAL_COORDS: 92.25, 39.93 [deg] galactic lon,lat of the burst (or transient) ECL_COORDS: 197.39, 79.33 [deg] ecliptic lon,lat of the burst (or transient) COMMENTS: SWIFT-BAT GRB Coordinates. COMMENTS: This is an image trigger. (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.) COMMENTS: A point_source was found. COMMENTS: This does not match any source in the on-board catalog. COMMENTS: This does not match any source in the ground catalog. COMMENTS: This is a GRB. COMMENTS: This trigger occurred at longitude,latitude = 239.02,-18.50 [deg]. COMMENTS: COMMENTS: NOTE: This BAT event is temporally(2.0<100sec) coincident with the FERMI_GBM event (trignum=764753411).
TITLE: GCN/FERMI NOTICE NOTICE_DATE: Thu 27 Mar 25 07:30:54 UT NOTICE_TYPE: Fermi-GBM Ground Position RECORD_NUM: 58 TRIGGER_NUM: 764753411 GRB_RA: 239.780d {+15h 59m 07s} (J2000), 239.878d {+15h 59m 31s} (current), 239.587d {+15h 58m 21s} (1950) GRB_DEC: +61.680d {+61d 40' 48"} (J2000), +61.609d {+61d 36' 34"} (current), +61.821d {+61d 49' 14"} (1950) GRB_ERROR: 5.18 [deg radius, statistical only] DATA_SIGNIF: 24.00 [sigma] DATA_INTERVAL: 4.096 [sec] GRB_DATE: 20761 TJD; 86 DOY; 25/03/27 GRB_TIME: 27006.33 SOD {07:30:06.33} UT GRB_PHI: 233.00 [deg] GRB_THETA: 48.00 [deg] E_RANGE: 44.032 - 279.965 [keV] LOC_ALGORITHM: 4173 (Gnd S/W Version number) SUN_POSTN: 6.33d {+00h 25m 18s} +2.73d {+02d 44' 02"} SUN_DIST: 103.90 [deg] Sun_angle= 8.4 [hr] (West of Sun) MOON_POSTN: 339.69d {+22h 38m 44s} -10.44d {-10d 26' 40"} MOON_DIST: 103.84 [deg] MOON_ILLUM: 7 [%] GAL_COORDS: 94.34, 43.61 [deg] galactic lon,lat of the burst (or transient) ECL_COORDS: 186.20, 76.10 [deg] ecliptic lon,lat of the burst (or transient) LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250327313/quicklook/glg_lc_medres34_bn250327313.gif POS_MAP_URL: http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_764753411.fits COMMENTS: Fermi-GBM Ground-calculated Coordinates. COMMENTS: In the LAT Field-of-view. 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.
TITLE: GCN/FERMI NOTICE NOTICE_DATE: Thu 27 Mar 25 07:30:35 UT NOTICE_TYPE: Fermi-GBM Flight Position RECORD_NUM: 46 TRIGGER_NUM: 764753411 GRB_RA: 244.933d {+16h 19m 44s} (J2000), 244.915d {+16h 19m 40s} (current), 244.973d {+16h 19m 53s} (1950) GRB_DEC: +69.583d {+69d 34' 60"} (J2000), +69.524d {+69d 31' 26"} (current), +69.701d {+69d 42' 04"} (1950) GRB_ERROR: 11.55 [deg radius, statistical plus systematic] GRB_INTEN: 192 [cnts/sec] DATA_SIGNIF: 9.50 [sigma] INTEG_TIME: 1.024 [sec] GRB_DATE: 20761 TJD; 86 DOY; 25/03/27 GRB_TIME: 27006.33 SOD {07:30:06.33} UT GRB_PHI: 235.00 [deg] GRB_THETA: 40.00 [deg] DATA_TIME_SCALE: 1.0240 [sec] HARD_RATIO: 0.84 LOC_ALGORITHM: 3 (version number of) MOST_LIKELY: 96% GRB 2nd_MOST_LIKELY: 2% Cyg X-1 DETECTORS: 0,0,0, 0,0,0, 1,1,0, 0,0,0, 0,0, SUN_POSTN: 6.33d {+00h 25m 18s} +2.73d {+02d 44' 02"} SUN_DIST: 97.90 [deg] Sun_angle= 8.1 [hr] (West of Sun) MOON_POSTN: 339.68d {+22h 38m 44s} -10.45d {-10d 26' 45"} MOON_DIST: 101.45 [deg] MOON_ILLUM: 7 [%] GAL_COORDS: 102.44, 38.18 [deg] galactic lon,lat of the burst (or transient) ECL_COORDS: 150.72, 80.24 [deg] ecliptic lon,lat of the burst (or transient) LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250327313/quicklook/glg_lc_medres34_bn250327313.gif COMMENTS: Fermi-GBM Flight-calculated Coordinates. COMMENTS: This trigger occurred at longitude,latitude = 165.92,18.55 [deg]. COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
TITLE: GCN/FERMI NOTICE NOTICE_DATE: Thu 27 Mar 25 07:30:44 UT NOTICE_TYPE: Fermi-GBM Flight Position RECORD_NUM: 59 TRIGGER_NUM: 764753411 GRB_RA: 259.017d {+17h 16m 04s} (J2000), 258.988d {+17h 15m 57s} (current), 259.075d {+17h 16m 18s} (1950) GRB_DEC: +68.600d {+68d 35' 60"} (J2000), +68.573d {+68d 34' 24"} (current), +68.653d {+68d 39' 10"} (1950) GRB_ERROR: 7.37 [deg radius, statistical plus systematic] GRB_INTEN: 184 [cnts/sec] DATA_SIGNIF: 20.60 [sigma] INTEG_TIME: 4.096 [sec] GRB_DATE: 20761 TJD; 86 DOY; 25/03/27 GRB_TIME: 27006.33 SOD {07:30:06.33} UT GRB_PHI: 243.00 [deg] GRB_THETA: 40.00 [deg] DATA_TIME_SCALE: 4.0960 [sec] HARD_RATIO: 0.70 LOC_ALGORITHM: 3 (version number of) MOST_LIKELY: 94% GRB 2nd_MOST_LIKELY: 3% Generic Transient DETECTORS: 0,0,0, 0,0,0, 1,1,0, 0,0,0, 0,0, SUN_POSTN: 6.33d {+00h 25m 18s} +2.73d {+02d 44' 02"} SUN_DIST: 93.69 [deg] Sun_angle= 7.2 [hr] (West of Sun) MOON_POSTN: 339.68d {+22h 38m 44s} -10.45d {-10d 26' 42"} MOON_DIST: 96.35 [deg] MOON_ILLUM: 7 [%] GAL_COORDS: 99.26, 33.77 [deg] galactic lon,lat of the burst (or transient) ECL_COORDS: 149.03, 85.35 [deg] ecliptic lon,lat of the burst (or transient) LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250327313/quicklook/glg_lc_medres34_bn250327313.gif COMMENTS: Fermi-GBM Flight-calculated Coordinates. COMMENTS: This trigger occurred at longitude,latitude = 165.92,18.55 [deg]. COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
TITLE: GCN/FERMI NOTICE NOTICE_DATE: Thu 27 Mar 25 07:31:29 UT NOTICE_TYPE: Fermi-GBM Ground Position RECORD_NUM: 0 TRIGGER_NUM: 764753411 GRB_RA: 239.950d {+15h 59m 48s} (J2000), 240.038d {+16h 00m 09s} (current), 239.778d {+15h 59m 07s} (1950) GRB_DEC: +62.720d {+62d 43' 12"} (J2000), +62.650d {+62d 38' 59"} (current), +62.860d {+62d 51' 35"} (1950) GRB_ERROR: 4.96 [deg radius, statistical only] DATA_SIGNIF: 24.00 [sigma] DATA_INTERVAL: 4.096 [sec] GRB_DATE: 20761 TJD; 86 DOY; 25/03/27 GRB_TIME: 27006.33 SOD {07:30:06.33} UT GRB_PHI: 233.00 [deg] GRB_THETA: 47.00 [deg] E_RANGE: 44.032 - 279.965 [keV] LOC_ALGORITHM: 41731 (Gnd S/W Version number) SUN_POSTN: 6.33d {+00h 25m 18s} +2.73d {+02d 44' 03"} SUN_DIST: 103.25 [deg] Sun_angle= 8.4 [hr] (West of Sun) MOON_POSTN: 339.69d {+22h 38m 46s} -10.44d {-10d 26' 30"} MOON_DIST: 103.69 [deg] MOON_ILLUM: 7 [%] GAL_COORDS: 95.57, 43.08 [deg] galactic lon,lat of the burst (or transient) ECL_COORDS: 182.61, 76.72 [deg] ecliptic lon,lat of the burst (or transient) LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250327313/quicklook/glg_lc_medres34_bn250327313.gif POS_MAP_URL: http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_764753411.fits COMMENTS: Fermi-GBM Ground-calculated Coordinates. COMMENTS: In the LAT Field-of-view. 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.
TITLE: GCN/FERMI NOTICE NOTICE_DATE: Thu 27 Mar 25 07:31:40 UT NOTICE_TYPE: Fermi-GBM Ground Position RECORD_NUM: 1 TRIGGER_NUM: 764753411 GRB_RA: 244.240d {+16h 16m 58s} (J2000), 244.340d {+16h 17m 22s} (current), 244.043d {+16h 16m 10s} (1950) GRB_DEC: +60.500d {+60d 30' 00"} (J2000), +60.439d {+60d 26' 21"} (current), +60.621d {+60d 37' 17"} (1950) GRB_ERROR: 4.16 [deg radius, statistical only] DATA_SIGNIF: 24.20 [sigma] DATA_INTERVAL: 8.192 [sec] GRB_DATE: 20761 TJD; 86 DOY; 25/03/27 GRB_TIME: 27006.33 SOD {07:30:06.33} UT GRB_PHI: 236.00 [deg] GRB_THETA: 49.00 [deg] E_RANGE: 44.032 - 279.965 [keV] LOC_ALGORITHM: 41731 (Gnd S/W Version number) SUN_POSTN: 6.33d {+00h 25m 18s} +2.73d {+02d 44' 03"} SUN_DIST: 102.68 [deg] Sun_angle= 8.1 [hr] (West of Sun) MOON_POSTN: 339.69d {+22h 38m 46s} -10.44d {-10d 26' 27"} MOON_DIST: 101.71 [deg] MOON_ILLUM: 7 [%] GAL_COORDS: 91.70, 42.10 [deg] galactic lon,lat of the burst (or transient) ECL_COORDS: 195.83, 77.15 [deg] ecliptic lon,lat of the burst (or transient) LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250327313/quicklook/glg_lc_medres34_bn250327313.gif POS_MAP_URL: http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_764753411.fits COMMENTS: Fermi-GBM Ground-calculated Coordinates. COMMENTS: In the LAT Field-of-view. 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.
TITLE: GCN/FERMI NOTICE NOTICE_DATE: Thu 27 Mar 25 07:31:57 UT NOTICE_TYPE: Fermi-GBM Ground Position RECORD_NUM: 2 TRIGGER_NUM: 764753411 GRB_RA: 249.540d {+16h 38m 10s} (J2000), 249.603d {+16h 38m 25s} (current), 249.416d {+16h 37m 40s} (1950) GRB_DEC: +63.160d {+63d 09' 36"} (J2000), +63.111d {+63d 06' 39"} (current), +63.258d {+63d 15' 27"} (1950) GRB_ERROR: 2.22 [deg radius, statistical only] DATA_SIGNIF: 26.40 [sigma] DATA_INTERVAL: 14.336 [sec] GRB_DATE: 20761 TJD; 86 DOY; 25/03/27 GRB_TIME: 27006.33 SOD {07:30:06.33} UT GRB_PHI: 239.00 [deg] GRB_THETA: 46.00 [deg] E_RANGE: 44.032 - 279.965 [keV] LOC_ALGORITHM: 41731 (Gnd S/W Version number) SUN_POSTN: 6.33d {+00h 25m 18s} +2.73d {+02d 44' 03"} SUN_DIST: 99.24 [deg] Sun_angle= 7.8 [hr] (West of Sun) MOON_POSTN: 339.69d {+22h 38m 47s} -10.44d {-10d 26' 22"} MOON_DIST: 99.34 [deg] MOON_ILLUM: 7 [%] GAL_COORDS: 93.95, 38.87 [deg] galactic lon,lat of the burst (or transient) ECL_COORDS: 191.88, 80.72 [deg] ecliptic lon,lat of the burst (or transient) LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250327313/quicklook/glg_lc_medres34_bn250327313.gif POS_MAP_URL: http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_764753411.fits COMMENTS: Fermi-GBM Ground-calculated Coordinates. COMMENTS: In the LAT Field-of-view. 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 SWIFT_BAT event (trignum=1299088).
TITLE: GCN/FERMI NOTICE NOTICE_DATE: Thu 27 Mar 25 07:39:26 UT NOTICE_TYPE: Fermi-GBM Final Position RECORD_NUM: 0 TRIGGER_NUM: 764753411 GRB_RA: 246.110d {+16h 24m 26s} (J2000), 246.189d {+16h 24m 45s} (current), 245.956d {+16h 23m 49s} (1950) GRB_DEC: +62.330d {+62d 19' 48"} (J2000), +62.273d {+62d 16' 23"} (current), +62.443d {+62d 26' 35"} (1950) GRB_ERROR: 3.57 [deg radius, statistical only] GRB_DATE: 20761 TJD; 86 DOY; 25/03/27 GRB_TIME: 27006.33 SOD {07:30:06.33} UT GRB_PHI: 237.00 [deg] GRB_THETA: 47.00 [deg] E_RANGE: 44.032 - 279.965 [keV] LOC_ALGORITHM: 41731 (Gnd S/W Version number) SUN_POSTN: 6.33d {+00h 25m 19s} +2.74d {+02d 44' 11"} SUN_DIST: 101.02 [deg] Sun_angle= 8.0 [hr] (West of Sun) MOON_POSTN: 339.76d {+22h 39m 03s} -10.41d {-10d 24' 19"} MOON_DIST: 100.86 [deg] MOON_ILLUM: 7 [%] GAL_COORDS: 93.58, 40.63 [deg] galactic lon,lat of the burst (or transient) ECL_COORDS: 191.21, 78.95 [deg] ecliptic lon,lat of the burst (or transient) LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250327313/quicklook/glg_lc_medres34_bn250327313.gif LOC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250327313/quicklook/glg_locplot_all_bn250327313.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: This is likely a Long GRB. COMMENTS: COMMENTS: NOTE: This GBM event is temporally(2.0<100sec) coincident with the SWIFT_BAT event (trignum=1299088).
TITLE: GCN/SWIFT NOTICE NOTICE_DATE: Thu 27 Mar 25 07:34:18 UT NOTICE_TYPE: Swift-BAT GRB Lightcurve TRIGGER_NUM: 1299088, Seg_Num: 0 GRB_RA: 248.197d {+16h 32m 47s} (J2000), 248.280d {+16h 33m 07s} (current), 248.035d {+16h 32m 09s} (1950) GRB_DEC: +61.595d {+61d 35' 43"} (J2000), +61.543d {+61d 32' 36"} (current), +61.699d {+61d 41' 57"} (1950) GRB_DATE: 20761 TJD; 86 DOY; 25/03/27 GRB_TIME: 27004.68 SOD {07:30:04.68} UT TRIGGER_INDEX: 20000 GRB_PHI: -143.77 [deg] GRB_THETA: 50.63 [deg] DELTA_TIME: 0.00 [sec] TRIGGER_DUR: 88.000 [sec] SOLN_STATUS: 0x13 RATE_SIGNIF: 0.00 [sigma] IMAGE_SIGNIF: 8.75 [sigma] LC_URL: sw01299088000msb.lc SUN_POSTN: 6.33d {+00h 25m 19s} +2.73d {+02d 44' 06"} SUN_DIST: 100.48 [deg] Sun_angle= 7.9 [hr] (West of Sun) MOON_POSTN: 339.72d {+22h 38m 52s} -10.43d {-10d 25' 44"} MOON_DIST: 99.84 [deg] MOON_ILLUM: 7 [%] GAL_COORDS: 92.25, 39.93 [deg] galactic lon,lat of the burst (or transient) ECL_COORDS: 197.39, 79.33 [deg] ecliptic lon,lat of the burst (or transient) COMMENTS: SWIFT-BAT GRB Lightcurve. COMMENTS: COMMENTS: The next comments were copied from the BAT_POS Notice: COMMENTS: This is an image trigger. COMMENTS: A point_source was found. COMMENTS: This does not match any source in the on-board catalog. COMMENTS: This does not match any source in the ground catalog. COMMENTS: This is a GRB. COMMENTS: This trigger occurred at longitude,latitude = 239.02,-18.50 [deg].
RA(J2000) = 16h 32m 47s Dec(J2000) = +61d 35' 43"with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 40 sec. The peak count rate was ~1648 counts/sec (15-350 keV), at ~3 sec after the trigger.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 22690 | MASTER-Tunka | C | 180 | 19.1 |Filter C is a clear (unfiltred) band.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 22688 | 2025-03-27 13:46:44 | MASTER-Tunka | (16h 33m 04.03s , +61d 29m 19.4s) | C | 180 | 19.1 |Filter C is a clear (unfiltred) band.
RA (J2000) = 16:32:43.2 Dec (J2000) = +61:38:00.5with an uncertainty of 1.0 arcsec.
RA (J2000): 16 32 46.80 Dec(J2000): +61 36 58.9with an uncertainty of 3.6 arcsec (radius, 90% confidence).
Total column: 3.0 (+1.1, -1.0) x 10^21 cm^-2 Galactic foreground: 2.6 x 10^20 cm^-2 Excess significance: 4.6 sigma Photon index: 2.38 (+0.32, -0.29)If the light curve continues to decay with a power-law decay index of 0.92, the count rate at T+24 hours will be 0.016 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.1 x 10^-13 (9.3 x 10^-13) erg cm^-2 s^-1.
--------------------------------------------------------- (t-T0)_mid(hr) exptime(ks) Band upperlim (3sigma) 5.9 7.32 VT_R 23.8 5.9 7.38 VT_B 23.8Deeper or redder observations are encouraged to investigate the nature of the burst.
RA(J2000) = 16h 32m 50.1s Dec(J2000) = +61d 36' 35.4"with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 10%.
Filter T_start(s) T_stop(s) Exp(s) Mag B 25500 43748 1714 >20.88 UVM2 47869 48769 885 >20.28 U 14704 42891 1711 >20.58 V 21282 21402 117 >18.30 UVW1 13797 49176 1885 >20.62 UVW2 20376 21275 885 >20.31 WHITE 26413 27065 633 >20.81The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.053 in the direction of the burst (Schlegel et al. 1998).