TITLE:   GCN CIRCULAR
NUMBER:  29823
SUBJECT: GRB 210411C: A very significant early X-ray afterglow
DATE:    21/04/16 15:47:13 GMT
FROM:    Remo Rufinni at ICRA  <ruffini@icra.it>

Y. Aimuratov, C.L. Bianco, L. Li, R. Moradi, F. Rastegar Nia, J.A. Rueda,
R. Ruffini,  N. Sahakyan, Y. Wang, S.S. Xue on behalf of the ICRANet team,
report:

GRB 210411C (trigger=1042398) with a redshift z=2.826 (A. de Ugarte Postigo
et al, 2021, GCN29806) was triggered and located by Swift Burst Alert
Telescope (BAT) (T. Sbarrato et al, 2021, GCN 29794) with T90=12.8 sec in
15-150 keV (C. B. Markwardt et al, 2021, GCN29810).

The corresponding luminosity light curves of Swift-BAT and Swift-XRT (J.D.
Gropp et al, 2021, GCN29807) show this source is a twin of GRB 190114C
(Ruffini et al, 2021, https://doi.org/10.1093/mnras/stab724). A new
additional feature is identified in the early luminosity of Swift-XRT data
of GRB 210411C (see enclosed Fig.1).

We recommend to check for the possible existence of a yet unobserved GeV
radiation and to follow up the late keV and possible GeV temporal power-law
luminosities.

Fig. 1:
http://www.icranet.org/documents/Swift_GRB210411C-Fermi_GRB190114C.pdf