TITLE: GCN CIRCULAR NUMBER: 31081 SUBJECT: GRB 211023A: classification and SPI-ACS/INTEGRAL registration DATE: 21/11/13 19:43:24 GMT FROM: Alexei Pozanenko at IKI, Moscow P. Minaev (IKI), A. Pozanenko (IKI), S. Grebenev (IKI), I. Chelovekov (IKI) report on behalf of GRB IKI FuN We analyzed GRB 211023A (Di Lalla et al. GCN 30961; Lesage et al. GCN 30965; Ursi et al. GCN 30969; Ridnaia et al. GCN 31022) using publicly available data of GBM/Fermi and SPI-ACS/INTEGRAL. Using GBM/Fermi we clearly detect early emission, starting about 80 s before the GBM trigger. The extended emission (possibly associated with the activity detected by LAT, Di Lalla et al. GCN 30961, and/or its extremely bright afterglow, Zhirkov et al. GCN 30977; Kann et al. GCN 30982) was also found, becoming dominant since approximately 150 s the trigger. Thus, a time profile consists of three episodes with a total burst duration of more than 300 s in GBM/Fermi (7 - 850 keV), while T90 = 117 +/- 0.5 s. GRB 211023A was also registered by SPI-ACS/INTEGRAL with marginal detection of the early and the extended emission (T90 = 120 +/- 9 s). Time profiles of GBM and SPI-ACS are presented at http://grb.rssi.ru/GRB211023A/GRB211023A_GBM_ACS_light_curve.png We performed spectral analysis of the burst using GBM/Fermi data in the time interval of (-20, 160) s after the GBM trigger, covering the main part of GRB activity. The best parameters of Band model are following: Ep = 96 +/- 5 keV, alpha = -1.67 +/- 0.03, beta = -2.21 +/- 0.05 and fluence F = (1.341 +/- 0.004)*10^-4 erg/cm^2 in 10 - 1000 keV range. Assuming a redshift z = 0.390 (Pozanenko et al., GCN 31053) we estimated Eiso = (7.45 +/- 0.05)*10^52 erg in the 1 keV - 10 MeV energy band. The position of the burst at Ep,i - Eiso and T90,i - EH diagram [1,2] is shown by black annuli at http://grb.rssi.ru/GRB211023A/GRB211023A_Ep-Eiso_two_episodes_SN.png and http://grb.rssi.ru/GRB211023A/GRB211023A_EHD_two_episoses_SN.png The position is typical for type II (long) GRBs, although it is in the lower bound of their 2 sigma correlation region. This is because of its relatively low value of the Ep,i parameter. Note that low values of Ep,i are typical for the nearby bursts (z < 0.5), associated with supernovae (shown by red annuli at http://grb.rssi.ru/GRB211023A/GRB211023A_Ep-Eiso_two_episodes_SN.png and http://grb.rssi.ru/GRB211023A/GRB211023A_EHD_two_episoses_SN.png ) [1] - Minaev et al., MNRAS, 492, 1919, 2020 [2] - Minaev et al., Astronomy Letters, 46, 9, 573, 2020