TITLE:   GCN CIRCULAR
NUMBER:  6460
SUBJECT: GRB 070521: pseudo-z ~ 2.28 from prompt emission spectrum
DATE:    07/05/24 04:32:52 GMT
FROM:    Jean-Luc Atteia at Lab d Astrophys.,OMP,Toulouse  <atteia@ast.obs-mip.fr>

A. Pelangeon & J-L. Atteia (LATT-OMP) report:

We have used the spectral parameters obtained with the Konus
spectrum of GRB 070521 (Golenetskii et al., GCNC 6459)
to compute the spectral pseudo-redshift(**) of this burst
detected by Swift-BAT (Guidorzi et al., GCNC 6431).

We obtain: pz= 2.28 +/- 0.45

We note that this value cannot be made compatible with the spectroscopic
redhift z=0.553 found by Hattori et al. for source S1 (GCNC 6444).

We thank V. Pal'shin (Ioffe Inst.) for information on the spectral
parameters of the most intense part of this burst.


(**) cf. http://www.ast.obs-mip.fr/grb/pz