{
  "bibcode": "2021GCN.31230....1M",
  "body": "P. Minaev (IKI), A. Pozanenko (IKI) report on behalf of GRB IKI FuN:\n\nWe analyzed GRB 211211A (D'Ai et al. GCN 31202; Mangan et al. GCN 31210; \nTamura et al. GCN 31226) using publicly available data of GBM/Fermi and \nSPI-ACS/INTEGRAL. Using GBM/Fermi we estimate a duration in 7 - 850 keV \nenergy band T_90 = 50.6 +/- 0.1 s, while the emission is seen at least \nup to 130 s after the trigger. We performed spectral analysis in time \ninterval of (-0.5, 60) s, covering the main part of GRB activity. The \nbest fit is obtained for (Band model + thermal component) with following \nparameters: E_p = 758 +/- 13 keV, alpha = -1.21 +/- 0.01, beta = -2.54 \n+/- 0.03 and thermal spectral component with kT = 13.9 +/- 0.3 keV. The \nfluence of F = (5.47 +/- 0.01)E-4 erg/cm**2 is obtained in 10 - 1000 keV \nenergy band. The  parameter E_p = 758 +/- 13 keV is higher than \npreliminary value presented by GBM team (Mangan et al., GCN 31210) due \nto inclusion of the thermal component in the fit.\n\nAssuming a redshift of z = 0.076 (Malesani et al., GCN 31221) we \nestimated E_iso = (1.161 +/- 0.006)E52 erg in the 1 keV - 10 MeV energy \nband. The burst is placed very close but outside the 2 sigma correlation \nregion at E_p,i - E_iso and T_90,i - EH diagrams [1,2], see the Figures in\n\nhttp://grb.rssi.ru/GRB211211A/GRB211211A_Ep-Eiso-2.png\nhttp://grb.rssi.ru/GRB211211A/GRB211211A_EHD.png\n\nUsing T_90,i - EH diagram we found minimal possible redshift value of z \n= 0.080, very close to the redshift of z = 0.076 (Malesani et al., GCN \n31221). Therefore, we consider GRB 211211A as not a significant outlier.\n\nThe burst was also detected by SPI-ACS/INTEGRAL. Its duration in the \nSPI-ACS energy band (> 80 keV) is T_90 = 30.0 +/- 0.2 s, while the \nemission is seen up to 70 s. Comparing fluences of long-duration GRBs \nsimultaneously recorded by SPI-ACS and Fermi/GBM (Chelovekov et al., in \npreparation) we estimated the GRB 211211A fluence to be 5.5E-4 erg/cm**2 \nin the 10-1000 keV energy band (the 95% confidence region 1.6-4 ��� 1.9E-3 \nerg/cm**2, incl. systematics). GRB 211211A is one of the brightest GRBs \nof SPI-ACS/INTEGRAL sample in terms of peak flux (about 40000 cnts/50 \nms). The SPI-ACS light curve of GRB 211211A can be found in\n\nhttp://grb.rssi.ru/GRB211211A/GRB211211A_SPI-ACS_lc-2.png\n\n[1] - Minaev et al., MNRAS, 492, 1919, 2020\n[2] - Minaev et al., Astronomy Letters, 46, 9, 573, 2020",
  "circularId": 31230,
  "createdOn": 1639503339000,
  "email": "apozanen@iki.rssi.ru",
  "subject": "GRB 211211A: redshift estimation and SPI-ACS/INTEGRAL detection",
  "submitter": "Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>",
  "eventId": "GRB 211211A"
}