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A&A 411, L101-L105 (2003)
DOI: 10.1051/0004-6361:20031394
Letter
Testing SPI imaging of high-energy and extended sources
C. B. Wunderer1, P. Connell2, J. W. Hammer3, V. Schönfelder1 and A. W. Strong11 Max-Planck-Institute for extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany
2 University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
3 Institut für Strahlenphysik, University Stuttgart, Allmandring 3, 70569 Stuttgart, Germany
(Received 7 July 2003 / Accepted 10 September 2003)
Abstract
INTEGRAL's main instruments employ coded apertures to obtain
directional information on the incoming radiation. In order to
experimentally better determine the imaging capabilities of the
spectrometer SPI, the SPI Imaging Test Setup (SPITS) has been
built at MPE. It consists of the SPI coded mask and two
SPI-identical Ge detectors on an
XY-table which allows us to
move them to cover the 19 Ge detector positions.
The SPI flight model imaging calibration only covered the energy
range up to 2.7 MeV and did not include extended emission. SPITS
was used to explore the performance of such a coded aperture
system - combined with the SPI image analysis software -
for higher-energy point sources and extended sources.
We find that a 2.4° diameter disk emitting 511 keV emission
is reconstructed well. For the high signal-to-noise ratios of
laboratory measurements, positions of point sources above 4 MeV
could be reconstructed to better than 0.1°.
Key words: INTEGRAL -- spectrometer SPI -- instrumentation: imaging -- gamma rays
Offprint request: C. B. Wunderer, wunderer@ssl.berkeley.edu
© ESO 2003