[AAVSO-HEN] GRB 090423: Fermi GBM T90 follow-up analysis results

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
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TITLE:   GCN CIRCULAR
NUMBER:  9416
SUBJECT: GRB 090423: Fermi GBM T90 follow-up analysis results
DATE:    09/05/21 14:26:47 GMT
FROM:    Andreas von Kienlin at MPE  <azk at mpe.mpg.de>

A. von Kienlin (MPE), C. Kouveliotou (NASA/MSFC) and V. Connaughton (UAH) 
report on behalf of the Fermi GBM Team:

"We performed a detailed follow-up analysis of the T90 of the high redshift 
GRB 090423 (H. Krimm et al., GCN Circ. # 9198) to determine the nature of 
the extended pulse centered at T+30s as reported earlier (A. von Kienlin, 
GCN # 9229). Due to the low significance of the detection, we were not able 
to accurately locate this later pulse (the emission was only significantly 
seen with one of the two triggered detectors). We conclude, therefore, that 
this pulse is most probably due to background fluctuations.

The final GBM T90 derived between 10-300 keV is 11.5 +/- 2.0 sec. This 
duration agrees within the error with the value of 10.3 +/- 1.1 sec reported

by the Swift team (H. Krimm et al., GCN Report 211.2)"