Gamma-ray Burst 211023A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 23 Oct 21 13:06:07 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      47
TRIGGER_NUM:     656687148
GRB_RA:          105.950d {+07h 03m 48s} (J2000),
                 106.569d {+07h 06m 16s} (current),
                 104.526d {+06h 58m 06s} (1950)
GRB_DEC:         +71.050d {+71d 02' 60"} (J2000),
                 +71.016d {+71d 00' 58"} (current),
                 +71.123d {+71d 07' 23"} (1950)
GRB_ERROR:       25.85 [deg radius, statistical plus systematic]
GRB_INTEN:       40 [cnts/sec]
DATA_SIGNIF:     5.10 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        19510 TJD;   296 DOY;   21/10/23
GRB_TIME:        47143.17 SOD {13:05:43.17} UT
GRB_PHI:         258.00 [deg]
GRB_THETA:        70.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.81
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      83%  GRB
2nd_MOST_LIKELY:  13%  Generic SGR
DETECTORS:       0,0,0, 0,1,0, 0,1,0, 0,0,0, 0,0,
SUN_POSTN:       208.24d {+13h 52m 59s}  -11.59d {-11d 35' 32"}
SUN_DIST:        104.74 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:       60.47d {+04h 01m 54s}  +20.81d {+20d 48' 32"}
MOON_DIST:        56.85 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:      144.18, 26.54 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       97.67, 48.04 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211023546/quicklook/glg_lc_medres34_bn211023546.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 99.03,-6.62 [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 23 Oct 21 13:07:56 UT
NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
TRIGGER_NUM:    9459,   Sub_Num: 0
GRB_INTEN:      9.05 [sigma]
GRB_TIME:       47194.59 SOD {13:06:34.59} UT
GRB_DATE:       19510 TJD;   296 DOY;   21/10/23
COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.  
COMMENTS:       Time_Scale=2.0000 and Time_Error=1.0000.  
COMMENTS: 
COMMENTS:       NOTE: This SPIACS event is temporally(51.0<100sec) coincident with the FERMI_GBM event (trignum=656687148).  
COMMENTS:          
COMMENTS:       The SPIACS lightcurve can be found at:  
COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2021-10/2021-10-23T13-06-34.4285-23621-64400-0.lc

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 23 Oct 21 13:06:25 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     656687148
GRB_RA:          105.960d {+07h 03m 50s} (J2000),
                 106.579d {+07h 06m 19s} (current),
                 104.536d {+06h 58m 09s} (1950)
GRB_DEC:         +71.050d {+71d 02' 60"} (J2000),
                 +71.016d {+71d 00' 58"} (current),
                 +71.123d {+71d 07' 24"} (1950)
GRB_ERROR:       11.07 [deg radius, statistical only]
DATA_SIGNIF:     5.30 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        19510 TJD;   296 DOY;   21/10/23
GRB_TIME:        47143.17 SOD {13:05:43.17} UT
GRB_PHI:         258.00 [deg]
GRB_THETA:        70.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       208.24d {+13h 52m 59s}  -11.59d {-11d 35' 32"}
SUN_DIST:        104.74 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:       60.48d {+04h 01m 54s}  +20.81d {+20d 48' 34"}
MOON_DIST:        56.85 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:      144.18, 26.55 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       97.67, 48.04 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211023546/quicklook/glg_lc_medres34_bn211023546.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_656687148.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
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 23 Oct 21 13:07:14 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      87
TRIGGER_NUM:     656687148
GRB_RA:           83.550d {+05h 34m 12s} (J2000),
                  84.980d {+05h 39m 55s} (current),
                  80.296d {+05h 21m 11s} (1950)
GRB_DEC:         +84.000d {+84d 00' 00"} (J2000),
                 +84.012d {+84d 00' 44"} (current),
                 +83.961d {+83d 57' 39"} (1950)
GRB_ERROR:       4.47 [deg radius, statistical plus systematic]
GRB_INTEN:       826 [cnts/sec]
DATA_SIGNIF:     78.70 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        19510 TJD;   296 DOY;   21/10/23
GRB_TIME:        47143.17 SOD {13:05:43.17} UT
GRB_PHI:         260.98 [deg]
GRB_THETA:        55.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.11
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       0,0,0, 0,1,0, 0,1,0, 0,0,0, 0,0,
SUN_POSTN:       208.24d {+13h 52m 59s}  -11.59d {-11d 35' 33"}
SUN_DIST:        104.83 [deg]   Sun_angle= 8.2 [hr] (West of Sun)
MOON_POSTN:       60.48d {+04h 01m 56s}  +20.81d {+20d 48' 41"}
MOON_DIST:        63.76 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:      129.18, 25.01 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       88.63, 60.59 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211023546/quicklook/glg_lc_medres34_bn211023546.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 99.03,-6.62 [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 23 Oct 21 13:07:43 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      0
TRIGGER_NUM:     656687148
GRB_RA:          112.580d {+07h 30m 19s} (J2000),
                 113.156d {+07h 32m 38s} (current),
                 111.251d {+07h 25m 00s} (1950)
GRB_DEC:         +69.380d {+69d 22' 48"} (J2000),
                 +69.333d {+69d 19' 58"} (current),
                 +69.484d {+69d 29' 02"} (1950)
GRB_ERROR:       8.22 [deg radius, statistical only]
DATA_SIGNIF:     8.10 [sigma]
DATA_INTERVAL:   21.504 [sec]
GRB_DATE:        19510 TJD;   296 DOY;   21/10/23
GRB_TIME:        47143.17 SOD {13:05:43.17} UT
GRB_PHI:         260.00 [deg]
GRB_THETA:        72.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       208.24d {+13h 52m 59s}  -11.59d {-11d 35' 33"}
SUN_DIST:        102.63 [deg]   Sun_angle= 6.3 [hr] (West of Sun)
MOON_POSTN:       60.49d {+04h 01m 57s}  +20.81d {+20d 48' 45"}
MOON_DIST:        57.83 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:      146.24, 28.67 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      101.40, 46.83 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211023546/quicklook/glg_lc_medres34_bn211023546.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_656687148.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
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.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 23 Oct 21 13:07:06 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      84
TRIGGER_NUM:     656687148
GRB_RA:           83.600d {+05h 34m 24s} (J2000),
                  85.063d {+05h 40m 15s} (current),
                  80.270d {+05h 21m 05s} (1950)
GRB_DEC:         +84.167d {+84d 10' 00"} (J2000),
                 +84.179d {+84d 10' 43"} (current),
                 +84.128d {+84d 07' 39"} (1950)
GRB_ERROR:       10.38 [deg radius, statistical plus systematic]
GRB_INTEN:       150 [cnts/sec]
DATA_SIGNIF:     10.10 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        19510 TJD;   296 DOY;   21/10/23
GRB_TIME:        47143.17 SOD {13:05:43.17} UT
GRB_PHI:         260.98 [deg]
GRB_THETA:        55.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.36
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       0,0,0, 0,1,0, 0,1,0, 0,0,0, 0,0,
SUN_POSTN:       208.24d {+13h 52m 59s}  -11.59d {-11d 35' 33"}
SUN_DIST:        104.73 [deg]   Sun_angle= 8.2 [hr] (West of Sun)
MOON_POSTN:       60.48d {+04h 01m 56s}  +20.81d {+20d 48' 40"}
MOON_DIST:        63.92 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:      129.01, 25.07 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       88.67, 60.76 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211023546/quicklook/glg_lc_medres34_bn211023546.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 99.03,-6.62 [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 23 Oct 21 13:15:11 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     656687148
GRB_RA:           78.790d {+05h 15m 10s} (J2000),
                  79.950d {+05h 19m 48s} (current),
                  76.155d {+05h 04m 37s} (1950)
GRB_DEC:         +82.270d {+82d 16' 12"} (J2000),
                 +82.292d {+82d 17' 33"} (current),
                 +82.210d {+82d 12' 34"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
GRB_DATE:        19510 TJD;   296 DOY;   21/10/23
GRB_TIME:        47143.17 SOD {13:05:43.17} UT
GRB_PHI:         259.00 [deg]
GRB_THETA:        56.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       208.25d {+13h 53m 00s}  -11.59d {-11d 35' 40"}
SUN_DIST:        106.30 [deg]   Sun_angle= 8.6 [hr] (West of Sun)
MOON_POSTN:       60.55d {+04h 02m 12s}  +20.83d {+20d 49' 48"}
MOON_DIST:        61.93 [deg]
MOON_ILLUM:      92 [%]
GAL_COORDS:      130.64, 23.77 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       87.09, 58.94 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211023546/quicklook/glg_lc_medres34_bn211023546.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211023546/quicklook/glg_locplot_all_bn211023546.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:        This is likely a Long GRB.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(51.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=9459).

GCN Circular #30958
The Fermi GBM team reports the detection of a likely LONG GRB
At 13:05:43 UT on 23 Oct 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 211023A (trigger 656687148.17411 / 211023546).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 78.8, Dec = 82.3 (J2000 degrees, equivalent to J2000 05h 15m, 82d 17'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 56.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211023546/quicklook/glg_skymap_all_bn211023546.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/bn211023546/quicklook/glg_healpix_all_bn211023546.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211023546/quicklook/glg_lc_medres34_bn211023546.gif
GCN Circular #30961
N. Di Lalla (Stanford Univ.), F. Longo (Univ. and INFN, Trieste) and M. Ohno (Hiroshima Univ. & Eotvos Univ) report on behalf of the Fermi-LAT Collaboration:
On October 23rd, 2021, Fermi-LAT detected high-energy emission from GRB 211023A, which was also detected by Fermi GBM (trigger 656687148 / 211023546, GCN 30958). The best LAT on-ground location is found to be:
RA, Dec = 72.3, 85.3 (degrees, J2000)
with an error radius of 0.1 deg (90% containment, statistical error only).
The position was 54 deg from the LAT boresight at the time of the GBM trigger:
T0 = 13:05:43 UT.
The data from the Fermi-LAT show a significant increase in the event rate after the trigger that is temporally and spatially correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0-2500 s after the trigger is 3.4 (-/+ 0.6) e-06 ph/cm2/s.
The estimated photon index above 100 MeV is -1.8 (-/+ 0.1).
The highest-energy photon is a 8.6 GeV event which is observed at 1832 seconds after the GBM trigger.
A Swift ToO has been requested for this burst.
The Fermi-LAT point of contact for this burst is Donggeun Tak (takdg123@gmail.com).
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 #30965
S. Lesage (UAH), S. Poolakkil (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 13:05:43 UT on 23 October 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 211023A (trigger 656687148/211023546) which was also detected by Fermi-LAT (N. Di Lalla et al. 2021, GCN 30961). The Fermi GBM Final Real-time Localization (GCN 30958) is consistent with the Fermi-LAT position.
The angle from the Fermi LAT boresight is 53 degrees.
The GBM light curve consists of two emission episodes with a duration (T90) of about 80 s (10-1000 keV). The time-averaged spectrum from T0+53 to T0+158 s is best fit by a Band function with Epeak = 92 +/- 2 keV, alpha = -1.74 +/- 0.01, and beta = -2.55 +/- 0.07.
The event fluence (10-1000 keV) in this time interval is (1.114 +/- 0.007)E-08 erg/cm^2. The 1-sec peak photon flux measured starting from T0+72.1 s in the 10-1000 keV band is 27.4 +/- 0.7 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 #30969
A. Ursi, M. Cardillo (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, C. Casentini, Y. Evangelista, E. Menegoni, L. Foffano, G. Piano (INAF/IAPS), F. Lucarelli, C. Pittori, F. Verrecchia (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 211023A at T0 = 2021-10-23 13:07:58 s (UTC), reported by Fermi GBM (GCNs #30958, #30965) and Fermi LAT (GCN #30961).
The burst is clearly 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 about 45 s and it released a total number of 5300 counts in the SA detector (above a background rate of 90 Hz), 64325 counts in the MCAL detector (above a background rate of 1200 Hz), and 233020 counts in the AC detector (above a background rate of 2810 Hz). The AGILE ratemeter light curves can be found at http://www.agilescienceapp.it/notices/GRB211023A_AGILE_RM.png .
The event also triggered a partial high time resolution MCAL data acquisition, from T1 = 2021-10-23 13:07:32.91 s +/- 0.01 (UTC) to T2 = 2021-10-23 13:08:05.20 +/- 0.01 s (UTC), and released 12480 counts in the detector, above a background rate of 620 Hz. The time-integrated spectrum of the first 17 s of the burst can be fitted in the energy range 0.4-50 MeV with a single power-law with ph. ind. = -2.45 (-0.27/+0.34), resulting in a reduced chi-squared of 0.89 (75 d.o.f.) and a fluence of 1.3e-05 ergs/cm^2 (90% confidence level), in the same energy range. The MCAL light curve can be found at: http://www.agilescienceapp.it/notices/075364_GRB211023A_562079268.000000.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 #30970
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-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) started inspect of the Fermi GRB 211023A ( Fermi GBM team, GCN 30958) errorbox 7595 sec after notice time and 7627 sec after trigger time at 2021-10-23 15:12:50 UT, with upper limit up to 18.9 mag. Observations started at twilight. The observations began at zenith distance = 53 deg. The sun altitude is -11.0 deg.
The galactic latitude b = 24 deg., longitude l = 131 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1762531
We obtain a following upper limits.

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

    7657 | 2021-10-23 15:12:50 |   MASTER-Kislovodsk | (04h 49m 25.33s , +80d 59m 06.4s) |   C |    60 | 17.6 |        
    7657 | 2021-10-23 15:12:50 |   MASTER-Kislovodsk | (05h 14m 59.29s , +80d 31m 48.1s) |   C |    60 | 18.0 |        
    7737 | 2021-10-23 15:14:10 |   MASTER-Kislovodsk | (06h 05m 53.66s , +82d 52m 16.2s) |   C |    60 | 17.6 |        
    7738 | 2021-10-23 15:14:10 |   MASTER-Kislovodsk | (06h 38m 00.47s , +82d 24m 21.4s) |   C |    60 | 18.1 |        
    7818 | 2021-10-23 15:15:30 |   MASTER-Kislovodsk | (04h 03m 55.16s , +82d 55m 29.7s) |   C |    60 | 17.6 |        
    7818 | 2021-10-23 15:15:30 |   MASTER-Kislovodsk | (04h 35m 48.63s , +82d 26m 44.7s) |   C |    60 | 18.3 |        
    7898 | 2021-10-23 15:16:50 |   MASTER-Kislovodsk | (06h 14m 35.51s , +84d 16m 43.5s) |   C |    60 | 18.5 |        
    7978 | 2021-10-23 15:18:11 |   MASTER-Kislovodsk | (06h 26m 03.45s , +80d 59m 05.9s) |   C |    60 | 17.8 |        
    8739 | 2021-10-23 15:30:52 |   MASTER-Kislovodsk | (04h 49m 49.99s , +81d 01m 17.2s) |   C |    60 | 17.9 |        
    8739 | 2021-10-23 15:30:52 |   MASTER-Kislovodsk | (05h 15m 18.70s , +80d 34m 03.5s) |   C |    60 | 18.9 |        
    8820 | 2021-10-23 15:32:12 |   MASTER-Kislovodsk | (06h 06m 13.17s , +82d 53m 02.8s) |   C |    60 | 17.9 |        
    8820 | 2021-10-23 15:32:12 |   MASTER-Kislovodsk | (06h 38m 08.10s , +82d 25m 14.9s) |   C |    60 | 18.8 |        
    8900 | 2021-10-23 15:33:32 |   MASTER-Kislovodsk | (04h 04m 13.51s , +82d 56m 18.7s) |   C |    60 | 18.1 |        
    8900 | 2021-10-23 15:33:32 |   MASTER-Kislovodsk | (04h 35m 54.56s , +82d 27m 46.4s) |   C |    60 | 18.9 |        
    8980 | 2021-10-23 15:34:52 |   MASTER-Kislovodsk | (05h 32m 37.45s , +84d 47m 34.5s) |   C |    60 | 18.1 |        
    8980 | 2021-10-23 15:34:52 |   MASTER-Kislovodsk | (06h 14m 59.02s , +84d 17m 59.9s) |   C |    60 | 18.9 |        
    9060 | 2021-10-23 15:36:13 |   MASTER-Kislovodsk | (06h 26m 19.59s , +80d 57m 45.3s) |   C |    60 | 18.2 |        
    9822 | 2021-10-23 15:48:54 |   MASTER-Kislovodsk | (04h 49m 45.52s , +80d 59m 47.8s) |   C |    60 | 17.9 |        
    9822 | 2021-10-23 15:48:54 |   MASTER-Kislovodsk | (05h 15m 14.78s , +80d 32m 34.9s) |   C |    60 | 18.8 |        
   10503 | 2021-10-23 16:00:16 |   MASTER-Kislovodsk | (06h 08m 19.72s , +82d 54m 05.0s) |   C |    60 | 18.0 |        
   10503 | 2021-10-23 16:00:16 |   MASTER-Kislovodsk | (06h 38m 33.51s , +82d 25m 32.3s) |   C |    60 | 18.8 |        
   10583 | 2021-10-23 16:01:36 |   MASTER-Kislovodsk | (04h 06m 04.03s , +82d 55m 51.3s) |   C |    60 | 18.0 |        
   10583 | 2021-10-23 16:01:36 |   MASTER-Kislovodsk | (04h 35m 57.28s , +82d 27m 01.3s) |   C |    60 | 18.9 |        
   10664 | 2021-10-23 16:02:56 |   MASTER-Kislovodsk | (05h 35m 10.07s , +84d 49m 07.8s) |   C |    60 | 18.1 |        
   10664 | 2021-10-23 16:02:56 |   MASTER-Kislovodsk | (06h 15m 13.89s , +84d 18m 52.0s) |   C |    60 | 18.9 |        
   10744 | 2021-10-23 16:04:16 |   MASTER-Kislovodsk | (06h 27m 59.93s , +80d 59m 13.0s) |   C |    60 | 18.1 |

Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.

GCN Circular #30977
K.Zhirkov, V. Lipunov, E.Gorbovskoy, P.Balanutsa, A.Kuznetsov, O.Gress, G.Antipov, D. Vlasenko, N.Tiurina, D.Zimnukhov, V.Senik,V.Topolev, A.Chasovnikov, E.Minkina, V.Grinshpun, D.Cheryasov (Lomonosov MSU,SAI,PhysicsDepartment), R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev (Irkutsk State University, API), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico FelixAguilar OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
MASTER Global robotic net (MASTER-Net:http://observ.pereplet.ru Lipunov et al.,2010,Advances in Astronomy,2010,30L) started inspect of the FERMI GRB 211023A ( Fermi GBM team, GCN 30958,ttrigger=13:05:43, Fermi LAT GCN 30961) errorbox just after sunset at 2021-10-23 15:12:50 UT (Lipunov et al. GCN 30970).
MASTER OT J045237.07+851925.2 discovery
MASTER-Kislovodsk auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source - optical counterpart of this GRB at (RA, Dec) = 04h 52m 37.07s +85d 19m 25.2s at 2021-10-23.65385 UT.
Fast changing OT unfiltered magnitude at one of first images is 15.6m (mlim=18.9).
There is no minor planet in MPC and any sources in VIZIER at this place.
We have reference image on 2017-01-28.75669 UT with unfiltered mlim=19.9m.
Deep images and possibly host galaxy spectral observations are required.
GCN Circular #30982
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/DARK/NBI), C. C. Thoene, M. Blazek, J. F. Agui Fernandez (all HETH/IAA-CSIC), Iglesias-Marzoa, R., and Lacruz, E. (both OAJ) report:
We observed the Fermi-LAT position (Di Lalla et al., GCN #30961) of the bright Fermi GRB 211023A (Fermi detection: Fermi GBM Team, GCN #30958; Lesage et al., GCN #30965; AGILE detection: Ursi et al., GCN #30969) with the JAST/T80 telescope of OAJ, Teruel, Spain. We obtained 3 x 300 s images each in g', r', and i' under good conditions.
At the position of the MASTER afterglow candidate (Zhirkov et al., GCN #30977), we detect a bright source which is not visible in Pan-STARRS archival imaging. Against three Pan-STARRS comparison stars, we measure r' = 18.03 +/- 0.02 mag (AB mag) at 0.5704 d after the GRB.
We note this is an exceedingly bright afterglow, just slightly fainter at similar times than those of GRBs 130427A and 181201A. We also note a resemblance in prompt emission shape, fluence (S. Poolakkil, priv. comm.), and peak energy to the famous GRB 030329. Spectroscopic observations and further follow-up are encouraged.
GCN Circular #30990
Y.-D. Hu, V. Casanova, T.-R. Sun, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado and E. Fernandez-Garcia (IAA-CSIC), on behalf of a larger collaboration, report:
Following the detection of GRB 211023A by Fermi (GCN 30958) and AGILE (Ursi et al. GCNC 30969), images in BVRI bands were obtained at the 1.5m OSN telescope in Sierra Nevada Observatory (Granada, Spain) starting on 24 Oct 22:57 UT. In the first R-band 90 s exposure image, the optical afterglow discovered by MASTER (Zhirkov et al. GCNC 30977) and also reported at OAJ (Kann et al. GCNC 30982) is clearly detected, for which we measure R = 19.27 +/- 0.14 (~1.4 d after trigger). Further observations are ongoing.
We thank the staff at OSN for their excellent support.
GCN Circular #30998
S. Poolakkil (UAH) reports on behalf of the Fermi GBM Team:
"The Fermi Gamma-ray Burst Monitor (GBM) GCN circular for GRB 211023A (S. Lesage et al. 2021, GCN 30965) had the event fluence stated incorrectly. The event fluence (10-1000 keV) for this trigger is (1.114 +/- 0.007)E-04 erg/cm^2."
GCN Circular #31004
S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (HSE), report on behalf of GRB IKI FuN:
We observed the GRB 211023A (Fermi GBM team, GCN 30958) with AZT-33IK telescope of Sayan observatory (Mondy) starting on 2021-10-25 (UT) 15:16:32. We obtained 17 images in R-filter. The afterglow of the GRB 211023A (Lipunov et al., GCN 30977; Kann et al. GCN 30982; Hu et al. GCN 30990) is clearly detected. Preliminary photometry of the afterglow in a stacked image is following
```
Date       UT start   t-T0       Filter Exp.   OT    Err.  UL(3sigma)
                     (mid, days)        (s)

2021-10-25 15:16:32  2.10265    R      17*120  19.87 0.15  21.0
```
The photometry is based on the nearby USNO-B1.0 stars
```
RA DEC R2
04:53:23.10336 +85:19:26.4720 14.09
04:52:47.26344 +85:22:52.1508 15.75
```
Based on photometry reported early (Kann et al. GCN 30982; Hu et al. GCN 30990) we can approximate a light curve of the afterglow as a power law with the index of 1.49+/-0.03. See also the figure of the light curve in
http://grb.rssi.ru/GRB211023A/GRB211023A_LC.png
GCN Circular #31008
J. Vinko, A. Pal, L. Kriskovics, R. Szakats, K. Vida, Zs. Szabo (Konkoly Observatory, Hungary) report:
We observed the field of GRB211023A (Fermi GBM team, GCN 30958) with the RC80 robotic telescope at Piszkesteto Station of Konkoly Observatory on 2021 Oct 25 starting at 17:46:47 UT. A series of 5x300 sec. frames were collected through Sloan r'- and i' bands. The optical afterglow (Zhirkov et al., GCN #30977; Kann et al. GCN #30982; Hu et al. GCN #30990; Belkin et al. GCN #31004) was detected on the stacked frames with the following magnitudes, calibrated. via nearby PS1 stars:
```
Date         UT-middle   t-T0(hr)  Exp(s)   r'(AB-mag)           i'(AB-mag)
2021-10-25   18:07:19    53.03     5x300    20.104 +/- 0.089  19.634 +/- 0.081
```
We measure the flux decline power-law index as -1.43 +/- 0.03, in accord with. Belkin et al. (GCN #31004).
GCN Circular #31018
S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (HSE), report on behalf of GRB IKI FuN:
We observed the GRB 211023A (Fermi GBM team, GCN 30958) with AZT-33IK telescope of Sayan observatory (Mondy) starting on 2021-10-26 (UT) 14:47:57. We obtained 17 images in R-filter. The afterglow of the GRB 211023A (Lipunov et al., GCN 30977; Kann et al. GCN 30982; Hu et al. GCN 30990; Belkin et al., GCN 31004) is clearly detected. Preliminary photometry of the afterglow in a stacked image is following
```
Date       UT start   t-T0       Filter Exp.   OT    Err.  UL(3sigma)
                     (mid, days)        (s)

2021-10-26 14:47:57  3.09182    R      30*120  20.57 0.06  22.7
```
The photometry is based on the nearby USNO-B1.0 stars
```
RA DEC R2
04:53:23.10336 +85:19:26.4720 14.09
04:52:47.26344 +85:22:52.1508 15.75
```
GCN Circular #31020
S. Belkin (IKI, HSE), I. Sokolov (INASAN, KIAM), D. Berezin (IC AMER NASU), A. Pozanenko (IKI), N. Pankov (IKI, HSE), G. Butenko (IC AMER NASU) report on behalf of GRB IKI FuN:
We observed the GRB 211023A (Fermi GBM team, GCN 30958) with Zeiss-2000 telescope and Zeiss-600 telescope of Terskol observatory. The afterglow of the GRB 211023A (Lipunov et al., GCN 30977; Kann et al. GCN 30982; Hu et al. GCN 30990; Belkin et al., GCN 31004,31018) is clearly detected with Zeiss-2000 and marginally detected with Zeiss-600. Preliminary photometry of the afterglow is following.
```
Date       UT start  t-T0     Filter Exp.  OT   Err. UL.  Telescope
(mid, days)      (s)

2021-10-26 15:08:26  3.11542   R  29*180  20.59 0.16 21.8 Zeiss-2000
2021-10-28 01:06:22  4.51191   R  11*180  20.91 0.10 22.5 Zeiss-2000
2021-10-28 00:15:55  4.47895   R  39*60   20.80 0.40 20.7 Zeiss-600
```
The photometry is based on the nearby USNO-B1.0 stars
```
RA DEC R2
04:53:23.10336 +85:19:26.4720 14.09
04:52:47.26344 +85:22:52.1508 15.75
```
The updated light curve can be found in http://grb.rssi.ru/GRB211023A/GRB211023A_LC.png
GCN Circular #31022
A. Ridnaia, D. Frederiks, S. Golenetskii, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 211023A (Fermi-GBM detection: Fermi GBM Team, GCN 30958; Lesage et al., GCN 30965; Fermi-LAT detection: Di Lalla et al., GCN 30961; AGILE detection: Ursi et al., GCN 30969) triggered Konus-Wind at T0=47199.142 s UT (13:06:39.142).
The burst light curve shows a multipeaked structure started at ~T0-65.3 s with a total duration of ~207.9 s. The emission is seen up to ~6 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB211023_T47199/
As observed by Konus-Wind, the burst had a fluence of 1.13(-0.04,+0.05)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+6.368 s, of 5.12(-1.01,+1.01)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+103.936 s) is best fit in the 20 keV - 6 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.85(-0.03,+0.03) and Ep = 122(-12,+15) keV (chi2 = 100/79 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.4 (chi2 = 99/78).
The spectrum near the maximum count rate (measured from T0+5.888 to T0+10.496 s) is best fit in the 20 keV - 6 MeV range by a power law with exponential cutoff model with alpha = -1.27(-0.06,+0.06) and Ep = 267(-22,+27) keV (chi2 = 76/72 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.6 (chi2 = 75/71).
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN Circular #31023
Amit Kumar, Rahul Gupta, Amit Ror, Dimple, Ankur Ghosh, Arpan Ghosh, Amar Aryan, Brajesh Kumar, S. B. Pandey, and Kuntal Misra (ARIES) report:
We observed the Fermi GBM and LAT detected GRB 211023A (Fermi GBM Team, GCN 30958; Lesage et al. 2021, GCN 30965; and N. Di Lalla et al. 2021, GCN 30961) with 1.3m Devasthal Fast Optical Telescope (DFOT) located at Devasthal observatory of Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2021-10-28 at 19:22:54 UT, i.e., ~ 5.26 days after the Fermi trigger. We have taken multiple frames having an exposure time of 300 sec in the R filter. We clearly detected the optical afterglow of GRB 211023A (Lipunov et al. 2021, GCN 30970; Zhirkov et al. 2021, GCN 30977; Kann et al. 2021, GCN 30982; Hu et al. 2021, GCN 30990; Belkin et al. 2021, GCN 31004, 31018, 31020; and Vinko et al. 2021, GCN 31008) in our stacked image. The preliminary photometric estimate of the afterglow is the following :
```
Date Start UT   T-T0 (mid, days) Filter  Exp time (sec)   Magnitude

====================================================================
2021-10-28 19:22:54   ~5.28       R           300*15    21.37 +/- 0.08
```
Further observations are requested with 1.3m DFOT.The magnitude is not corrected for the Galactic extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalog.
This circular may be cited.
GCN Circular #31041
Rahul Gupta, S. B. Pandey, Amit Ror, Amit Kumar, Dimple, Ankur Ghosh, Amar Aryan, Bhavya, and Kuntal Misra (ARIES) report:
We further observed the bright GRB 211023A (Fermi GBM Team 2021, GCN 30958; Lesage et al. 2021, GCN 30965; N. Di Lalla et al. 2021, GCN 30961; Ursi et al. 2021, GCN 30969; and Ridnaia et al. 2021, GCN 31022) with 1.3m Devasthal Fast Optical Telescope (DFOT) located at Devasthal observatory of Aryabhatta Research Institute of Observational Sciences (ARIES), India, starting on 2021-10-29 at 19:19:13 UT, i.e., ~ 6.26 days after the Fermi trigger. We obtained 24 and 18 frames having an exposure time of 300 sec in the R and I filters, respectively. We detected the optical afterglow of GRB 211023A (Lipunov et al. 2021, GCN 30970; Zhirkov et al. 2021, GCN 30977; Kann et al. 2021, GCN 30982; Hu et al. 2021, GCN 30990; Belkin et al. 2021, GCN 31004, 31018, 31020; Vinko et al. 2021, GCN 31008; and Kumar et al. 2021, GCN 31023) in our stacked images of both the filters. The preliminary photometric estimate of the afterglow in the R filter is following :
```
Date Start UT   T-T0 (mid, days) Filter  Exp time (sec)   Magnitude

=======================================================================
2021-10-29 19:19:13   ~6.28      R           300*24      22.58 +/- 0.33
```
Based on the preliminary photometry reported by using various ground-based optical telescopes (Kann et al. 2021, GCN 30982; Hu et al. 2021, GCN 30990; and Belkin et al. 2021, GCN 31004, 31018, 31020) and our first epoch observations using 1.3m DFOT (Kumar et al. 2021, GCN 31023), we measure the optical flux decay power-law index of the afterglow light curve (Galactic extinction corrected) of GRB 211023A equal to 1.49 +/- 0.04, consistent with those reported earlier (Belkin et al. 2021, GCN 31004, 31020; and Vinko et al. 2021, GCN 31008). However, we noticed that our second epoch observations are fainter than the extrapolation of the early temporal decay index of ~1.5, suggesting a possible break in the light curve. However, due to the unavailability of near-simultaneous X-ray afterglow observations, we could not confirm if this optical steeping is due to the jet break. Further deeper and multiwavelength observations with larger telescopes will be helpful to establish the possible jet break.
The reported magnitude value is not corrected for the Galactic extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalog.
This circular may be cited.
GCN Circular #31042
Jan Strobl, Martin Jelinek, Rene Hudec, Cyril Polasek (ASU CAS Ondrejov, CZ)
We observed the optical afterglow of The Fermi/GBM/AGILE GRB 211023A (Fermi GBM team, GCN 30958, Di Lalla et al. GCN 30961, Lesage et al. GCN 30965, Ursi et al. GCN 30969, Poolakkil GCNC 30998) with the double 20cm wide-field Small Binocular Telescope (SBT, cf. Strobl et al., AN 340,7,p.633, 2019) in Ondrejov observatory starting October 25 at 1:19 UT, 36.2h after the GRB detection. The afterglow (Vladimirov et al. GCN 30970, Tiurina et al. GCN 30977, Kann et al. GCN 30982, Hu et al. GCN 30990, Belkin et al. GCN 31004, Vinko et al. GCN 31008, Belkin et al. GCN 31018, Belkin et al. GCN 31020, Ghosh et al. GCN 31023) is well detected in our 2x80x120s coadded exposure from both tubes:
```
Tmid-T0   Texp    mag   dmag   filter
1.5706d  10762s  19.61  0.13   clear, calibrated as SDSS-r'(AB)
```
GCN Circular #31053
A. Pozanenko (IKI), A. Moiseev (SAO RAS), A. Moskvitin (SAO RAS), E. Malygin (SAO RAS), S. Belkin (IKI, HSE), N. Pankov (IKI, HSE), V. Kim (HSE, FAI) on behalf of GRB IKI FuN, A. Rossi (INAF-OAS), D. A. Kann (HETH/IAA-CSIC) report:
We observed the afterglow of GRB 211023A (Zhirkov et al, GCN 30977, see also Kann et al, GCN 30982; Hu et al, GCN 30990; Belkin et al, GCN 31004; Vinko et al, GCN 31008; Belkin et al, GCN 31018; Belkin et al, GCN 31020; Kumar et al, GCN 31023; Gupta et al., GCN 31041; Strobl et al., GCN 31042) with BTA SAO RAS telescope equipped with SCORPIO-2 (VPHG940@600 grism). A total of 7200 s (6x1200 s) of spectra were obtained starting on 21-11-05 (UT) 20:50:00, i.e. approximately 13.3016 days after burst. The afterglow is well detected in the acquisition imaging with R = 21.61 +/- 0.04 (3 x 90 sec. 21-11-05 (UT) 20:43:59 -- 20:50:58), and a continuum is visible across the bandwidth of a spectrum 4000 - 8500 A. The spectrum contain significant emission lines H_beta, [OII] 3727, [OIII] 5007, at a common redshift of z=0.390. We assume that the lines are from a host galaxy and, therefore, this is the redshift of GRB 211023A. No evident lines of a possible SN were found.
Calibration of photometry is preliminary and based on nearby stars of PS1 catalogue, gri -> R by Lupton transformations.
We are grateful to the directorate of SAO RAS for the TOO allocation.
GCN Circular #31056
Y. Aimuratov, L. Becerra, C.L. Bianco, Y-C. Chen, C. Cherubini, S. Eslamzadeh, S. Filippi, M. Karlica, Liang Li, G.J. Mathews, R. Moradi, M. Muccino, G.B, Pisani, F. Rastegar Nia, J.A. Rueda, R. Ruffini, N. Sahakyan, Y. Wang, S.S. Xue, on behalf of the ICRANet and ICRA-USTC team, report:
The identification of the redshift z=0.36 of GRB 211023A (A. Pozanenko et al. 2021, GCN 31053), with the isotropic energy of Eiso~6x10^52 erg in 10-1000 keV (S. Lesage et al. 2021, GCN 30965, S. Poolakkil et al. 2021, GCN 30998), qualify GRB 211023A as a BdHN I, confirmed by the observation of the GeV emission (N. Di Lalla et al. 2021, GCN 30961), originated from the black hole (R. Ruffini et al. 2019 ApJ 886 82, Moradi et al 2021. Phys. Rev. D 104, 063043) and the afterglow emission (Jan Strobl et al. 2021 GCN 31042) originated from the newborn neutron star (J.A. Rueda et al. 2020 ApJ 893 148).
Following Ruffini et al. 2021 (MNRAS, 504, 5301, doi:10.1093/mnras/stab724) we indicate the appearance of the peak of optical supernova to be observed at (18.4+/-2.6) days after the trigger (November 10th 2021, uncertainty from November 8th 2021 to November 12th 2021), with the bolometric optical luminosity of L=(9.0+/-2.7)x10^42 erg/s.
The follow-up optical observations for the SN are recommended.
--
```
Prof. Remo Ruffini
APS Fellow
Google Fellow
Director of ICRANet
Piazza della Repubblica 10
65122 Pescara (PE)  Italy
mobile: +39 339 4752566
Tel. Rome +39 06 49914304
Tel. Pescara +39 085 23054201
Fax: +39 085 4219252
e-mail: ruffini@icra.it
```
GCN Circular #31066
A. S. Moskvitin and O. I. Spiridonova (SAO RAS), on behalf of the GRB follow-up team report:
We observed the field of GRB 211023A (Fermi GBM team, GCN 30958, Di Lalla et al. GCN 30961, Lesage et al. GCN 30965, Ursi et al. GCN 30969, Poolakkil GCN 30998, Ridnaia et al., GCN 31022) with the SAO RAS 1-m telescope Zeiss-1000 + CCD-photometer on November 9. We obtained 6 x 300 sec. frames in Rc band (00:25:41 -- 01:31:04 UT, T_mid-T0 = 16.4949 days) and 6 x 300 sec. frames in Ic (00:31:28 -- 01:36:45 UT, T_mid-T0 = 16.4989 days).
The afterglow (Zhirkov et al. GCN 30977, Kann et al. GCN 30982, Hu et al.GCN 30990, Belkin et al. GCN 31004, Vinko et al. GCN 31008, Belkin et al. GCN 31018, Belkin et al. GCN 31020, Amit Kumar et al. GCN 31023, Rahul Gupta et al. GCN 31041, Strobl et al. GCN 31042, Pozanenko et al. GCN 31053) is clearly detected in our stacked frames with the following brightness: R = 21.69 +/- 0.09, I = 21.27 +/- 0.14 (the preliminary photometry is based on nearby stars of PS1 catalogue, gri -> R and I by Lupton 2005 transformations).
GCN Circular #31098
S. Belkin (IKI), A. Pozanenko (IKI), I. Sokolov (INASAN, KIAM), E. Klunko (ISTP), A. S. Moskvitin (SAO RAS), V. Kim (HSE, FAI), V. Rumyantsev (CrAO), R. Ya. Inasaridze (AbAO), M. Krugov (FAI), D. Berezin (IC AMER NASU), G. Butenko (IC AMER NASU), N. Pankov (HSE), D. Datashvili (AbAO), V. R. Ayvazian (AbAO), G. V. Kapanadze (AbAO) report on behalf of GRB IKI FuN:
We observed the field of the GRB 211023A (Fermi GBM team, GCN 30958; Di Lalla et al., GCN 30961; Lesage et al, GCN 30965; Ursi et al, GCN 30969; Poolakkil, GCN 30998; Ridnaia et al., GCN 31022) with Zeiss-2000 and Zeiss-600 telescopes of Terskol observatory, AZT-33IK telescope of Sayan observatory (Mondy), AZT-20 telescope of Assy-Turgen observatory, ZTSh 2.6m-telescope of CrAO observatory, AS-32 telescope of AbAO observatory, and Zeiss-1000 1-m telescope of SAO RAS. The optical counterpart (Lipunov et al., GCN 30970; Zhirkov et al, GCN 30977; Kann et al, GCN 30982; Hu et al, GCN 30990; Belkin et al, GCN 31004; Vinko et al, GCN 31008; Belkin et al, GCN 31018; Belkin et al, GCN 31020; Kumar et al, GCN 31023; Gupta et al., GCN 31041; Strobl et al., GCN 31042; Pozanenko et al., GCN 31053; Moskvitin et al., GCN 31066) was detected in most of the stacked images. A preliminary light curve based on our observations and GCN Circulars cited above can cab be found at
http://grb.rssi.ru/GRB211023A/GRB211023A_LC.png
Starting from the fifth day, a systematic flux excess over the approximation of the afterglow by a single power law is observed. After subtraction of the afterglow approximated by the light curve with a power law (Belkin et al, GCN 31020), and neglecting a contribution of the host galaxy we determine a preliminary light curve of possible SN, see
http://grb.rssi.ru/GRB211023A/GRB211023A_AG_subtracted_LC.png
Using redshift of GRB 211023A (Pozanenko et al., GCN 31053) we calculated an absolute magnitude at the maximum of the supposed supernova (M_R=-19.9 +0.40 -0.29; adjusted by a Galactic extinction (Schlafly & Finkbeiner, 2011)) and a time since the burst trigger in the observer frame (t-T0 = 16.9+/-1.5). These parameters are in agreement with parameters of known SN-GRB (e.g. see Figure 12 from Belkin et al., Astronomy Letters, 2020). The supernova associated with GRB 211012A is in agreement with early predictions (Kann et al, GCN 30982; Aimuratov et al., GCN 31056; Minaev et al., GCN 31081).

GCN Circular #31133

TITLE:   GCN CIRCULAR
NUMBER:  31133
SUBJECT: GRB 211023A: Xinglong 2.16m optical observations
DATE:    21/11/29 05:06:21 GMT
FROM:    Liping Xin at NAOC, SVOM      

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GCN Circular #31134
L. P. Xin (NAOC), J. Wang(GXU), C. Gao(GXU), Y. L. Qiu(NAOC), J. Y. Wei(NAOC), B. Ren(GXU), L. H. Li (NAOC), C. Wu(NAOC), E. W. Liang(GXU), X. H. Han (NAOC) and J. S. Deng(NAOC) report:
We observed the field of the GRB 211023A (Fermi GBM team, GCN 30958; Di Lalla et al., GCN 30961; Lesage et al, GCN 30965; Ursi et al, GCN 30969; Poolakkil, GCN 30998; Ridnaia et al., GCN 31022 ) with 2.16m optical telescope at Xinglong observatory, China. Ten images in R band were obtained from 2021-11-12T16:46:10 UT to 2021-11-12T17:32:18 UT, about 20.16 days after the burst. The exposure time for each image was 300 sec.
The optical counterpart (Lipunov et al., GCN 30970; Zhirkov et al, GCN 30977; Kann et al, GCN 30982; Hu et al, GCN 30990; Belkin et al, GCN 31004; Vinko et al, GCN 31008; Belkin et al, GCN 31018; Belkin et al, GCN 31020; Kumar et al, GCN 31023; Gupta et al., GCN 31041; Strobl et al., GCN 31042; Pozanenko et al., GCN 31053; Moskvitin et al., GCN 31066, , Belkin et al., GCN 31098) was clearly detected in our the stacked image with a brightness of 22.0 magnitude in R-band. The photometry was calibrated with several nearby USNO B1.0 catalogs.
GCN Circular #31596
A. Rossi, E. Pian, E. Palazzi (INAF-OAS), A. Melandri (INAF-OAB), on behalf of the CIBO collaboration, B. Rothberg (LBTO/GMU), A. Pozanenko, S. Belkin (IKI), and D. A. Kann (HETH/IAA-CSIC) report :
We report the results of the photometric and spectroscopic follow-up observations of GRB 211023A (Fermi GBM team, GCN 30958; Di Lalla et al., GCN 30961; Lesage et al, GCN 30965; Ursi et al, GCN 30969; Poolakkil, GCN 30998; Ridnaia et al., GCN 31022) at z = 0.390 (Pozanenko et al., GCN 31053) obtained with the Multi-Object Double Spectrographs (MODS) instrument mounted on the 2x8.4-m LBT telescope (Mt. Graham, AZ, USA). Data were obtained at ~12 UT on 2021-11-05, ~13 days (i.e. 9 rest-frame days) after the burst trigger.
Spectroscopy of the source was obtained for a total of 4x900 s, covering the wavelength range 3200-10000 AA. The spectrum has been corrected for Galactic extinction (A_V = 0.45 mag). The contribution of the host galaxy was removed via a galaxy template matching the emission line fluxes. The low S/N spectrum shows features similar to those exhibited by XRF-associated SN2006aj at a similar phase (Mazzali et al. 2006, Nature, 442, 1018). This confirms the bump observed by Belkin et al. (GCN 31098), as due to the emerging contribution of the SN.
We acknowledge the excellent support from the LBTO in particular O. Kuhn and S. Allanson, and from the LBT-INAF staff, particularly F. Cusano, S. Paiano, and E. Marini in obtaining these observations.

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