The Reuven Ramaty High Energy Solar Spectroscopic Imager Rhessi

by Lin, Robert P.; Dennis, Brian R.; Benz, A. O.

• ISBN13: 9781402011078
• ISBN10: 1402011075
• Format: Hardcover
• Copyright: 2003-07-01
• Publisher: Kluwer Academic Pub

Summary

The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) satellite was launched on 5 February 2002. Its objective is to study the energy release and particle acceleration in solar flares through observations of X-rays and gamma rays. Two novel technologies are combined to obtain both spectra and images over a broad energy range. For the spectroscopy, cooled hyperpure germanium detectors are used to cover the energy range from 3 keV to 17 MeV with unprecedented keV-class resolution. Since focusing optics are not possible for making images with such high energy photons, tungsten and molybdenum absorbing grids are used to modulate the X-rays and gamma-rays coming from the Sun as the spacecraft rotates. This allows the spatial Fourier components of the source to be determined so that images can be made in spectral ranges where astronomical images have never been produced before. These new instrumental techniques require equally innovative software to reconstruct X-ray and gamma-ray spectra and images from the observations. Ample solar activity, abundant observations, and an open data policy have attracted many researchers. Astronomers face in the RHESSI mission an exciting new scientific potential. It has unusually broad possibilities for improving our understanding of the enigmatic solar flare phenomenon that is becoming increasingly important as society depends more and more on space-based technologies. In this volume, the functioning of RHESSI is explained, the data analysis techniques including spectroscopy and image reconstruction are introduced, and the experiences of the first few months of operation are summarized. First scientific results are presented that provide the essential base for more extended studies using RHESSI data and complementary observations by instruments on other spacecraft and at ground-based solar observatories. The accompanying CD-ROM contains X-ray and EUV movies showing the dynamics of several solar flares. It also contains color versions of the graphics in the printed papers and additional material. Scientists and students will find here the latest discoveries in solar flare research, as well as inspiration for future work. The papers will serve as references for the many new discoveries to come from the continuing RHESSI observations.

Table of Contents

Preface	p. 1
The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI)	p. 3
The RHESSI Spectrometer	p. 33
The RHESSI Imaging Concept	p. 61
RHESSI Aspect Reconstruction	p. 87
The PMTRAS Roll Aspect System on RHESSI	p. 101
The RHESSI Spacecraft Instrument Data Processing Unit	p. 115
RHESSI as a Hard X-Ray Polarimeter	p. 125
The RHESSI Experimental Data Center	p. 143
RHESSI Data Analysis Software: Rationale and Methods	p. 165
Reconstruction of RHESSI Solar Flare Images with a Forward Fitting Method	p. 193
Time-Domain Demodulation of RHESSI Light Curves	p. 213
Relative Timing and Spectra of Solar Flare Hard X-Ray Sources	p. 229
Modeling Images and Spectra of a Solar Flare Observed by RHESSI on 20 February 2002	p. 245
Hard X-Ray and Metric/Decimetric Radio Observations of the 20 February 2002 Solar Flare	p. 261
RHESSI Observations of the Size Scales of Solar Hard X-Ray Sources	p. 273
Energy Budget and Imaging Spectroscopy of a Compact Flare	p. 287
Spectral and Spatial Variations of Flare Hard X-Ray Footpoints	p. 307
Energy Dependence of Electron Trapping in a Solar Flare	p. 323
RHESSI and TRACE Observations of the 21 April 2002 X1.5 Flare	p. 341
RHESSI Observation of Atmospheric Gamma Rays from Impact of Solar Energetic Particles on 21 April 2002	p. 357
Chromospheric Height and Density Measurements in a Solar Flare Observed with RHESSI. I. Theory	p. 373
Chromospheric Height and Density Measurements in a Solar Flare Observed with RHESSI. II. Data Analysis	p. 383
Empirical Correction of RHESSI Spectra for Photospheric Albedo and Its Effect on Inferred Electron Spectra	p. 407
Nonuniform Target Ionization and Fitting Thick-Target Electron Injection Spectra to RHESSI Data	p. 419
Microflares and Hot Component in Solar Active Regions	p. 431
Hard X-Ray Microflares Down to 3 keV	p. 445
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