Yohkoh Analysis Guide
Volume 3: Instrument Guide
Ver 1.06 M. Morrison 6-Nov-92
Ver 2.00 M. Morrison 25-Jan-94
This Copy Printed: Wed Feb 1 14:57:03 GMT 1995

LMSC-P098510

• Contents
• List of Figures
• 1 Bragg Crystal Spectrometer (BCS)
  • 1.1 Instrument Characteristics
    • 1.1.1 Wavelength Range
    • 1.1.2 Data Compression
  • 1.2 Instrument Calibration
    • 1.2.1 Sensitivity Functions
    • 1.2.2 Wavelength Resolution
  • 1.3 Detector Performance
    • 1.3.1 Detector Gain and Energy Resolution
    • 1.3.2 Position Resolution
    • 1.3.3 Digitization Spikes
  • 1.4 Detector Background
    • 1.4.1 Energy Discrimination
    • 1.4.2 Particle Background
    • 1.4.3 Germanium Fluorescence
    • 1.4.4 Effect of Gain Depression
  • 1.5 Dynamic Range and Count Rate Effects
    • 1.5.1 Deadtime Correction
    • 1.5.2 Saturation
    • 1.5.3 Gain Depression
    • 1.5.4 Rate-dependent Distortion
  • 1.6 Data Features
    • 1.6.1 Queued Data
    • 1.6.2 Timing of Spectra
    • 1.6.3 Last Spectral Bin
    • 1.6.4 Medium-rate Spectral Data in Autumn 1991
    • 1.6.5 Single Event Upsets
  • 1.7 Contact Persons
  • 1.8 References
• 2 Hard X-Ray Telescope (HXT)
  • 2.1 Overview
  • 2.2 General information
    • 2.2.1 Observations with HXT
    • 2.2.2 Detector gain calibration
    • 2.2.3 Background counts
  • 2.3 Some detailed information
    • 2.3.1 Modulation patterns
    • 2.3.2 Spectral Energy Response
    • 2.3.3 Pre-storage of HXT data in DP
    • 2.3.4 Data compression
  • 2.4 Contact Persons
  • 2.5 References
• 3 Soft X-Ray Telescope (SXT)
  • 3.1 Overall Response Function for SXT
    • 3.1.1 CCD Camera Signal
    • 3.1.2 SXT Effective Area
    • 3.1.3 Reading the SXT Effective Area File
    • 3.1.4 SXT Response to Thermal Plasma
    • 3.1.5 Reading the SXT Response Function File
    • 3.1.6 Relative Alignment of X-Ray and Optical Images
  • 3.2 The CCD Camera
    • 3.2.1 Saturation Effects
    • 3.2.2 Effect of CCD Contamination
    • 3.2.3 SXT Images Taken with the CCD Warm
    • 3.2.4 Artifacts in Optical Images from Radiation Damage
    • 3.2.5 SAA Effects on Images
    • 3.2.6 Subtleties of Background Subtraction
    • 3.2.7 Charge Bleed-back
    • 3.2.8 CCD Pixelization
    • 3.2.9 What is Really Zero Signal Level in Data Numbers (DN)?
  • 3.3 The Mirror, Lens or Filters
    • 3.3.1 Scattering by ND X-ray Filter
    • 3.3.2 Point Spread Function
    • 3.3.3 Mirror Scatter
    • 3.3.4 Vignetting Correction
    • 3.3.5 Stray Visible Light
  • 3.4 Other Instrument and Operations Features
    • 3.4.1 Data Compression
    • 3.4.2 Use of Low-8 Images in Optical Data
    • 3.4.3 Filter Alternation During AEC
    • 3.4.4 The Roll Angle in the SXT Images
    • 3.4.5 Incorrect Location of Image Pieces in Some PFIs
    • 3.4.6 Preparation of SFD images
  • 3.5 Contact Persons
  • 3.6 References
• 4 Wide Band Spectrometer (WBS)
  • 4.1 Basic Instrument Characteristics
  • 4.2 Soft X-Ray Spectrometer (SXS)
  • 4.3 Hard X-Ray Spectrometer (HXS)
  • 4.4 Gamma-Ray Spectrometer (GRS)
  • 4.5 WBS Output Data
  • 4.6 Contact Persons
  • 4.7 References
• A Details on the Time Tags on the Data
  • A.1 Bragg Crystal Spectrometer (BCS)
  • A.2 Hard X-Ray Telescope (HXT)
  • A.3 Soft X-Ray Telescope (SXT)
  • A.4 Wide Band Spectrometer (WBS)
• B Details of the SXT CCD Pixels
• About this document ...

The cover shows an image of the Sun obtained with the Yohkoh Soft X-ray Telescope on 11 November 1991 using the thin Al filter. The intensity range of this image varies by over 100,000 as represented by the black-red-white color scheme. Solar North is up and East is to the left. The brightest areas are solar active regions where sunspots would be seen in visible light; the darkest regions are coronal holes where the gas density is extremely low and from which the solar wind emerges.

Some suggested reference books, material, and methods of finding more information:

• The ``Red'' Book: ``The Yohkoh (Solar-A) Mission,'' Solar Physics, Volume 136, No.1 1991
• The `Blue' Book: Solar-A (M-3SII-6) Engineering Reference Book (written in Japanese)
• The Yohkoh File Control Document (FCD)
• The Interactive Data Language (IDL) User's Guide
• See the .INC files which are in the /ys/gen/soft/rel/ref_access directory for details on the definitions of the IDL data structure tags and contents.
• The official Yohkoh IDL software should have a detailed description of the routine in the header of the source file. It is possible to access this header from within IDL by using DOC_LIBRARY. A sample call is:
  IDL> doc_library,'sxt_prep'
  

The Yohkoh Analysis Guide is intended as an introduction and quick reference to the Yohkoh software, databases and instruments. This document describes the organization of the software, format of the data, instrument characteristics, and a list of the most commonly used programs.

Version 1 of this guide was compiled from information provided by a small number of people, starting from earlier guides by Keith Strong and Alan McAllister.

Version 2 of this guide was compiled from contributions provided from each Yohkoh instrument team and from Co-I's in Japan, the U.K., and the U.S. The number of individuals is too large to list here, but we are thankful for each contribution and suggestion. The LPARL team would also like to thank Prof. Yoshiaki Ogawara, the Yohkoh Project Manager, for his kind encouragement during the compilation of this guide. We are thankful to Drs. Loren Acton, George Doschek, James Klimchuk, and John Mariska who reviewed the final version and made many helpful comments.

As noted above, this document was compiled from a large number of sources. In the case of software, it was not always possible to verify the correctness of the information contained here. We would welcome any comments or corrections which can be sent to the E-mail address given below. Specific questions or comments will be re-directed to the appropriate individuals as necessary.

The Yohkoh team plans to make future software and documentation updates. If you would like to register to receive notification of significant software or instrument calibration updates, please send your name, postal address, and E-mail address to the E-mail address shown below.

If you have general comments, suggestions, or questions regarding this document or software, please send them to:

software@isass0.solar.isas.ac.jp