TITLE: GCN CIRCULAR NUMBER: 44053 SUBJECT: GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90 DATE: 26/03/20 01:38:39 GMT FROM: Alexei Pozanenko at IKI, Moscow <grb.alex@gmail.com> P. Minaev (IKI) , A. Pozanenko (IKI) on behalf of GRB follow-up team We analyzed GRB 260310A (Hamburg et al., GCN 43975; Salunke et al., GCN 43958; Atteia et al., GCN 43981) using publicly available data of GBM/Fermi. The burst consists of several emission episodes with a total duration of T_90 = 86 s. Time integrated energy spectrum, constructed in the time interval (-4, 70) s since GBM trigger, is best described by Band model with E_p = 175 keV and fluence F = 1.74e-5 erg cm^-2 in 1 keV - 10 MeV range. Using z = 0.153 (Hinds et al., GCN 43977; de Ugarte Postigo et al., GCN 43984) we obtain E_iso = 9.8e50 erg. GRB 260310A is placed above the correlation fit for type II (long) bursts on Ep,i – Eiso diagram, as mentioned in (Atteia et al., GCN 43981), but it is inside 2 sigma correlation regions for both type I (short) and type II (long) bursts, therefore we cannot consider it as a clear outlier. Indeed, at the EH – T_90,i diagram (see [1-2] for details) GRB 260310A is well classified as type II (long) burst. The Ep,i – Eiso and EH - T90,i diagrams can be found at https://heaiki.ru/lvc/GRB260310A/ [1] - Minaev et al., MNRAS, 492, 1919, 2020 [2] - Minaev et al., Astronomy Letters, 46, 9, 573, 2020 View this GCN Circular online at https://gcn.nasa.gov/circulars/44053. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...