Gamma-ray Burst 231028A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Oct 23 04:09:23 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1193078,   Seg_Num: 0
GRB_RA:          214.029d {+14h 16m 07s} (J2000),
                 214.305d {+14h 17m 13s} (current),
                 213.447d {+14h 13m 47s} (1950)
GRB_DEC:         +20.895d {+20d 53' 42"} (J2000),
                 +20.785d {+20d 47' 07"} (current),
                 +21.127d {+21d 07' 36"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       4666 [cnts]    Image_Peak=587 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   148     E_range: 25-100 keV
BKG_INTEN:       14502 [cnts]
BKG_TIME:        14935.73 SOD {04:08:55.73} UT
BKG_DUR:         8 [sec]
GRB_DATE:        20245 TJD;   301 DOY;   23/10/28
GRB_TIME:        14949.55 SOD {04:09:09.55} UT
GRB_PHI:         -118.54 [deg]
GRB_THETA:        26.69 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     63.84 [sigma]
IMAGE_SIGNIF:    18.14 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  +5 -100  +0 -82  +0 
SUN_POSTN:       212.21d {+14h 08m 51s}  -13.01d {-13d 00' 39"}
SUN_DIST:         33.86 [deg]   Sun_angle= -0.1 [hr] (East of Sun)
MOON_POSTN:       23.52d {+01h 34m 05s}   +9.95d {+09d 57' 17"}
MOON_DIST:       147.48 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:       19.62, 69.72 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      203.57, 32.36 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is a rate 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 = 93.46,10.45 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(3.0<100sec) coincident with the FERMI_GBM event (trignum=720158951).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Oct 23 04:13:03 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1193078,   Seg_Num: 0
GRB_RA:          214.029d {+14h 16m 07s} (J2000),
                 214.305d {+14h 17m 13s} (current),
                 213.447d {+14h 13m 47s} (1950)
GRB_DEC:         +20.895d {+20d 53' 42"} (J2000),
                 +20.785d {+20d 47' 07"} (current),
                 +21.127d {+21d 07' 36"} (1950)
GRB_DATE:        20245 TJD;   301 DOY;   23/10/28
GRB_TIME:        14949.55 SOD {04:09:09.55} UT
TRIGGER_INDEX:   148
GRB_PHI:         -118.54 [deg]
GRB_THETA:        26.69 [deg]
DELTA_TIME:      58.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     63.84 [sigma]
IMAGE_SIGNIF:    18.14 [sigma]
LC_URL:          sw01193078000msb.lc
SUN_POSTN:       212.22d {+14h 08m 52s}  -13.01d {-13d 00' 43"}
SUN_DIST:         33.86 [deg]   Sun_angle= -0.1 [hr] (East of Sun)
MOON_POSTN:       23.55d {+01h 34m 13s}   +9.97d {+09d 58' 16"}
MOON_DIST:       147.48 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:       19.62, 69.72 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      203.57, 32.36 [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 a rate 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 = 93.46,10.45 [deg].  
COMMENTS:        The 2nd packet (of 3) was missing in the lightcurve data stream.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 Oct 23 04:09:45 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      59
TRIGGER_NUM:     720158951
GRB_RA:          219.583d {+14h 38m 20s} (J2000),
                 219.836d {+14h 39m 21s} (current),
                 219.053d {+14h 36m 13s} (1950)
GRB_DEC:         +31.833d {+31d 49' 60"} (J2000),
                 +31.731d {+31d 43' 53"} (current),
                 +32.049d {+32d 02' 55"} (1950)
GRB_ERROR:       5.33 [deg radius, statistical plus systematic]
GRB_INTEN:       670 [cnts/sec]
DATA_SIGNIF:     67.30 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        20245 TJD;   301 DOY;   23/10/28
GRB_TIME:        14946.66 SOD {04:09:06.66} UT
GRB_PHI:         300.00 [deg]
GRB_THETA:        15.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.90
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  Generic Transient
DETECTORS:       1,0,0, 1,1,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       212.21d {+14h 08m 51s}  -13.01d {-13d 00' 40"}
SUN_DIST:         45.34 [deg]   Sun_angle= -0.5 [hr] (East of Sun)
MOON_POSTN:       23.52d {+01h 34m 05s}   +9.96d {+09d 57' 23"}
MOON_DIST:       135.48 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:       50.83, 66.33 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      203.66, 44.37 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231028173/quicklook/glg_lc_medres34_bn231028173.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 118.10,-13.27 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the CALET_GBM event (trignum=1382501309).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 Oct 23 04:09:38 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     720158951
GRB_RA:          221.033d {+14h 44m 08s} (J2000),
                 221.294d {+14h 45m 11s} (current),
                 220.486d {+14h 41m 57s} (1950)
GRB_DEC:         +26.950d {+26d 56' 60"} (J2000),
                 +26.850d {+26d 51' 01"} (current),
                 +27.161d {+27d 09' 39"} (1950)
GRB_ERROR:       26.48 [deg radius, statistical plus systematic]
GRB_INTEN:       66 [cnts/sec]
DATA_SIGNIF:     5.50 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        20245 TJD;   301 DOY;   23/10/28
GRB_TIME:        14946.66 SOD {04:09:06.66} UT
GRB_PHI:         320.00 [deg]
GRB_THETA:        15.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      0.00
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:     100%  Unreliable location
2nd_MOST_LIKELY:   0%  n/a
DETECTORS:       1,0,0, 1,1,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       212.21d {+14h 08m 51s}  -13.01d {-13d 00' 40"}
SUN_DIST:         40.83 [deg]   Sun_angle= -0.6 [hr] (East of Sun)
MOON_POSTN:       23.52d {+01h 34m 05s}   +9.96d {+09d 57' 21"}
MOON_DIST:       139.35 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:       39.04, 64.96 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      207.94, 40.44 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231028173/quicklook/glg_lc_medres34_bn231028173.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 118.10,-13.27 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(3.0<100sec) coincident with the SWIFT_BAT event (trignum=1193078).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 Oct 23 04:09:54 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     720158951
GRB_RA:          214.780d {+14h 19m 07s} (J2000),
                 215.053d {+14h 20m 13s} (current),
                 214.207d {+14h 16m 50s} (1950)
GRB_DEC:         +23.000d {+23d 00' 00"} (J2000),
                 +22.891d {+22d 53' 29"} (current),
                 +23.229d {+23d 13' 46"} (1950)
GRB_ERROR:       2.08 [deg radius, statistical only]
DATA_SIGNIF:     51.70 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        20245 TJD;   301 DOY;   23/10/28
GRB_TIME:        14946.66 SOD {04:09:06.66} UT
GRB_PHI:         322.00 [deg]
GRB_THETA:        22.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       212.21d {+14h 08m 51s}  -13.01d {-13d 00' 40"}
SUN_DIST:         36.01 [deg]   Sun_angle= -0.2 [hr] (East of Sun)
MOON_POSTN:       23.52d {+01h 34m 06s}   +9.96d {+09d 57' 25"}
MOON_DIST:       145.27 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:       26.02, 69.75 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      203.35, 34.57 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231028173/quicklook/glg_lc_medres34_bn231028173.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_720158951.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.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the CALET_GBM event (trignum=1382501309).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 Oct 23 04:18:23 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     720158951
GRB_RA:          214.300d {+14h 17m 12s} (J2000),
                 214.575d {+14h 18m 18s} (current),
                 213.722d {+14h 14m 53s} (1950)
GRB_DEC:         +21.820d {+21d 49' 12"} (J2000),
                 +21.711d {+21d 42' 38"} (current),
                 +22.051d {+22d 03' 03"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
GRB_DATE:        20245 TJD;   301 DOY;   23/10/28
GRB_TIME:        14946.66 SOD {04:09:06.66} UT
GRB_PHI:         324.00 [deg]
GRB_THETA:        23.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       212.22d {+14h 08m 53s}  -13.01d {-13d 00' 47"}
SUN_DIST:         34.80 [deg]   Sun_angle= -0.2 [hr] (East of Sun)
MOON_POSTN:       23.60d {+01h 34m 24s}  +10.00d {+09d 59' 42"}
MOON_DIST:       146.51 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:       22.38, 69.81 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      203.42, 33.31 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231028173/quicklook/glg_lc_medres34_bn231028173.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231028173/quicklook/glg_locplot_all_bn231028173.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 CALET_GBM event (trignum=1382501309).

GCN Circular #34893
The Fermi GBM team reports the detection of a likely LONG GRB
At 04:09:06 UT on 28 Oct 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231028A (trigger 720158951.657448 / 231028173).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 214.3, Dec = 21.8 (J2000 degrees, equivalent to J2000 14h 17m, 21d 48'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 23.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231028173/quicklook/glg_skymap_all_bn231028173.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/bn231028173/quicklook/glg_healpix_all_bn231028173.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231028173/quicklook/glg_lc_medres34_bn231028173.gif
GCN Circular #34894
M. A. Williams (PSU), S. Dichiara (PSU), D. M. Palmer (LANL), T. Sakamoto (AGU) and B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team:
At 04:09:09 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 231028A (trigger=1193078). Swift did not slew to the GRB location due to an observing constraint. The BAT on-board calculated location is RA, Dec 214.029, +20.895 which is
```
   RA(J2000) = 14h 16m 07s
   Dec(J2000) = +20d 53' 42"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex peak structure with a duration of at least 18 sec, although the immediately available data is truncated at T+8s due to packet loss. The peak count rate was ~8500 counts/sec (15-350 keV), at ~1 sec after the trigger.
Due to a Sun observing constraint, Swift cannot slew to the BAT position until 15:45 UT on 2023 November 22. There will thus be no XRT or UVOT data for this trigger before this time.
Swift Triggers have recently been re-enabled while we are dealing with attitude problems that can lead to star tracker Loss-of-Lock (LoL). We are confident that this GRB was not caused by an LoL event because:
```
1) The Swift_BAT_Position notice did not indicate a LoL. 
  (See the comments section.)
2) This burst location was not near to a known bright source. 
3) There was a simultaneous trigger by Fermi-GBM. 
4) This is a rate-triggered burst on a 1.024 s timescale, while most LoL
false triggers have been 'Image Triggers' with duration 64 s and longer. 
```
Observers should continue to be cautious (especially checking the comments for LoL) in future GCN notices going forward.
Burst Advocate for this burst is M. A. Williams (mjw6837 AT psu.edu). 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 #34897
V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko, G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij (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. Gress, N.M. Budnev, O.Ershova (Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich (Blagoveschensk Educational State University)
MASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 231028A ( M. A. Williams et al., GCN 34894) errorbox 39827 sec after notice time and 39846 sec after trigger time at 2023-10-28 15:13:16 UT, with upper limit up to 14.5 mag. Observations started at twilight. The observations began at zenith distance = 78 deg. The sun altitude is -12.3 deg.
MASTER-Tunka robotic telescope located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the Swift GRB 231028A errorbox 65649 sec after notice time and 65669 sec after trigger time at 2023-10-28 22:23:38 UT, with upper limit up to 16.0 mag. Observations started at twilight. The observations began at zenith distance = 79 deg. The sun altitude is -14.4 deg.
The galactic latitude b = 69 deg., longitude l = 20 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2291906
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   39937 |   MASTER-Kislovodsk |   C |   180 | 13.6 |        
   40139 |   MASTER-Kislovodsk |   C |   180 | 13.0 |        
   40340 |   MASTER-Kislovodsk |   C |   180 | 14.5 |        
   41732 |   MASTER-Kislovodsk |   C |   180 | 13.0 |        
   65699 |        MASTER-Tunka |   C |    60 | 16.0 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #34899
P. Veres (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 04:09:06.66 UT on 28 October 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231028A (trigger 720158951/231028173), which was also detected by the Swift/BAT (Williams et al. 2023, GCN 34894). The Fermi GBM Final Real-time Localization (GCN 34893) is consistent with the Swift position.
The GBM light curve consists of multiple peaks with a duration (T90) of about 34.8 s (50-300 keV). The time-averaged spectrum from T0-4.1 to T0+43.0 s is best fit by a Band function with Epeak = 157 +/- 11 keV, alpha = -0.72 +/- 0.06, and beta = -2.13 +/- 0.08.
The event fluence (10-1000 keV) in this time interval is (1.95 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+4.0 s in the 10-1000 keV band is 14.8 +/- 0.4 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 #34900
M. Kerr, C.C. Cheung, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A= . Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:
The Glowbug gamma-ray telescope [1,2], operating on the International Space= Station, reports the detection of GRB 231028A, which was also detected by = Fermi/GBM (GCN 34893, 34899) and Swift/BAT (GCN 34894). =20 Using an adaptive window with a resolution of 32-ms, the burst onset is det= ermined to be 2023-10-28 04:09:01.344 with a duration of 47.1 s and a total= significance of about 91.2 sigma. The light curve comprises a structured = main peak with at least two following peaks. =20 Using a standard power-law function with an exponential high-energy cutoff = [3] to model the emission over this duration results in a photon index dN/d= E~E^x of x=3D1.9 and a cutoff energy ("Epeak") of 198 keV. The modeled 10-= 10000 keV fluence is 9.8e-06 erg/cm^2.
The analysis results presented here are preliminary and use a response func= tion that lacks a detailed characterization of the surrounding passive stru= cture of the ISS.
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost ga= mma-ray transient telescopes developed, built, and operated by the U.S. Nav= al Research Laboratory (NRL) with support from the University of Alabama in= Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard = the Department of Defense Space Test Program=E2=80=99s STP-H9 to the ISS. = The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering= the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length= ) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2= /3 sky) over a wide energy band of 50 keV to >2 MeV.
```
[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006
```
Distribution Statement A: Approved for public release. Distribution is unlimited.
GCN Circular #34901
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 a long GRB 231028A which was also detected by Fermi-GBM (Fermi GBM Team, GCN Circ. 34893, Veres et al., GCN Circ. 34899), Swift-BAT (Williams et al., GCN Circ. 34894), and Glowbug (Kerr et al., GCN Circ. 34900).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2023-10-28 04:09:14.25 UTC. The measured peak count rate associated with the burst is 66 (+42, -4) counts/s above the background in the combined data of two quadrants (out of four), with a total of 273 (+88, -85) counts. The local mean background count rate was 156 (+1, -4) counts/s. Using cumulative rates, we measure a T90 of 7.8 (+0.9, -3.0) s. We caution that there was a 0.3 s readout dead time in CZTI after the detection of the burst. Hence, the T90 can be as large as 8.7 s for this GRB, with a lower limit of 4.8 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 2023-10-28 04:09:13.77 UTC. The measured peak count rate associated with the burst is 605 (+74, -72) counts/s above the background in the combined data of all quadrants, with a total of 2924 (+529, -560) counts. The local mean background count rate was 1508 (+6, -7) counts/s. We measure a T90 of 6.2 (+2.3, -1.3) s from the cumulative Veto light curve.
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 #34909
A. Yoshida, T. Sakamoto, S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena), and the CALET collaboration:
The long GRB 231028A (Fermi GBM Final Real-time Localization: Fermi GBM team, GCN Circ. 34893; Swift detection: Williams et al., GCN Circ. 34894; Fermi GBM Detection: Veres et al., GCN Circ. 34899; Glowbug gamma-ray detection: Kerr et al., GCN Circ. 34900; AstroSat CZTI detection: Navaneeth et al., GCN Circ. 34901) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 04:09:04.43 UTC on 28 October 2023 (http://cgbm.calet.jp/cgbm_trigger/flight/1382501309/index.html). The burst signal was seen by all CGBM detectors.
The burst light curve shows a multi-peaked structure that starts at T+0.25 sec, peaks at T+6.5 sec, and ends at T+47.5 sec. The T90 and T50 durations measured by the SGM data are 36.1 +/- 1.2 sec and 6.9 +/- 1.1 sec (40-1000 keV), respectively.
The ground-processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1382501309/
The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at Waseda University.
GCN Circular #34914
H. A. Krimm (NSF), S. D. Barthelmy (GSFC), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 231028A (trigger #1193078) (Williams et al., GCN Circ. 34894). The BAT ground-calculated position is RA, Dec = 214.016, 20.897 deg which is
```
   RA(J2000)  =  14h 16m 03.8s
   Dec(J2000) = +20d 53' 47.8"
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 68%.
The mask-weighted lightcurve shows a broad initial pulse with subsequent extended emission. T90 (15-350 keV) is 37.23 +- 0.98 sec (estimated error including systematics).
The time-averaged spectrum from T-6.86 to T+41.95 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.40 +- 0.04. The fluence in the 15-150 keV band is 7.2 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+1.06 sec in the 15-150 keV band is 8.6 +- 0.4 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/1193078/BA/

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Jochen Greiner, last update: 30-Oct-2023 [Disclaimer]