TITLE:   GCN CIRCULAR
NUMBER:  33609
SUBJECT: GRB 230328B: redshift lower limit estimating
DATE:    23/04/13 00:02:47 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

P. Minaev (IKI), A. Pozanenko (IKI) report on behalf of GRB IKI FuN:

We analyzed GRB 230328B detected by Swift (Gropp et al., GCN 33527), 
Fermi (Dalessi et al., GCN 33531), Astrosat (Waratkar et al., GCN 
33532), GRBAlpha (Dafcikova et al., GCN 33543), Konus (Svinkin et al., 
GCN 33544). Using publicly available data of GBM/Fermi we estimate the 
duration T_90 = 25.7 +/- 0.5 s in (10 - 300) keV energy band. We also 
performed spectral analysis in a time interval of (-7, 30) s since GBM 
trigger, the best fit is obtained for CPL model with following 
parameters: E_p = 164 +/- 13 keV, alpha = -1.22 +/- 0.04. The fluence of 
F = (1.02 +/- 0.04)E-5 erg/cm**2 is obtained in 10 - 1000 keV energy 
band. Using T_90,i - EH diagram [1] we can classify the burst as type II 
(long) and find the minimal possible redshift value of z = 0.09.

The T_90,i - EH diagram for GRB 230328B can be found in
http://grb.rssi.ru/GRB230328B/GRB230328B_T90i-EH.png

[1] - Minaev, Pozanenko, MNRAS, 492, 1919, 2020