GCN Circular 9649
Subject
GRB 090709A: confirmation of the periodicity in the SPI-ACS data
Event
Date
2009-07-10T12:15:28Z (17 years ago)
From
Diego Gotz at CEA <diego.gotz@cea.fr>
D. Gotz (CEA-Saclay), S. Mereghetti (IASF-Milano), A. von Kienlin (MPE
Garching), M. Beck (ISDC Versoix) report:
The Swift GRB 090709A (Morris at al., GCN 9625) is clearly detected
also in the data of Anticoincidence System (ACS) of the spectrometer
SPI on board INTEGRAL. SPI-ACS consists on 91 BGO detectors that are
sensitive to photons above 100 keV, and their light curves are
continuously stored in 50 ms bins. No directional or spectral
information is available. The light curve of GRB 090709A can be found
here
http://ibas.iasf-milano.inaf.it/090709Alc.jpg
The ~8 s periodicity reported by Markwardt et al. (GCN 9645) in the
Siwft/BAT data and by Golenetskii et al. (GCN 9647) in Konus-Wind data
is clearly detected also in the SPI-ACS data. A periodogram over the
entire burst duration can be found here
http://ibas.iasf-milano.inaf.it/090709A.jpg
By fitting the peak of the periodogram using a gaussian function one
obtains a best period of 8.11 s. A light curve folded to the best
period can be fond here
http://ibas.iasf-milano.inaf.it/090709A_folded.jpg
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