A new method of observing weak extended x-ray sources with the Reuven Ramaty High-Energy Solar Spectroscopic Imager

We present a new method, fan-beam modulation, for observing weak extended x-ray sources with the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI). This space-based solar x-ray and γ -ray telescope has much greater sensitivity than previous experiments in the 3 – 25   keV range, but is n...

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Bibliographic Details
Published in:Review of scientific instruments 2007-02, Vol.78 (2), p.024501-024501-6
Main Authors: Hannah, Iain G., Hurford, Gordon J., Hudson, Hugh S., Lin, Robert P.
Format: Article
Language:English
Subjects:
CRAB NEBULA
GAMMA RADIATION
GRIDS
HARD X RADIATION
INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
KEV RANGE
MODULATION
SENSITIVITY
SIGNALS
SOLAR FLARES
SPACE
SPECTRA
SUN
TELESCOPES
X-RAY SOURCES
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Summary:We present a new method, fan-beam modulation, for observing weak extended x-ray sources with the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI). This space-based solar x-ray and γ -ray telescope has much greater sensitivity than previous experiments in the 3 – 25   keV range, but is normally not well suited to detecting extended sources since their signal is not modulated by RHESSI’s rotating grids. When the spacecraft is offpointed from the target source, however, the fan-beam modulation time-modulates the transmission by shadowing resulting from exploiting the finite thickness of the grids. In this article we detail how the technique is implemented and verify its consistency with sources with clear known signals that have occurred during RHESSI offpointing: microflares and the Crab Nebula. In both cases the results are consistent with previous and complementary measurements. Preliminary work indicates that this new technique allows RHESSI to observe the integrated hard x-ray spectrum of weak extended sources on the quiet Sun.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.2437120