Yohkoh Analysis GuideYohkoh Analysis Guide

Instrument Manual


Ver 1.06  Ed: M.D. Morrison  6-Nov-92
Ver 2.00  Ed: M.D. Morrison 25-Jan-94
Ver 2.9x  Ed: R.D. Bentley - Date below

This Copy Produced: Apr 14, 1999

Prepared at
Mullard Space Science Laboratory
University College London

Note: This Guide is still under Development!!


Introduction to the Yohkoh Instruments
    1.1  Yohkoh Observing Modes
    1.2  Bragg Crystal Spectrometer (BCS)
        1.2.1  Instrument Modes
    1.3  Hard X-Ray Telescope (HXT)
    1.4  Soft X-Ray Telescope (SXT)
        1.4.1  Sequence Tables
        1.4.2  Automatic Exposure Control (AEC)
        1.4.3  Automatic Region Selection (ARS)
    1.5  Wide Band Spectrometer (WBS)
    1.6  Spacecraft Attitude Control System (ACS)
Bragg Crystal Spectrometer (BCS)
    2.1  Instrument Characteristics
        2.1.1  Wavelength Range
        2.1.2  Data Compression
    2.2  Instrument Calibration
        2.2.1  Sensitivity Functions
        2.2.2  Wavelength Resolution
    2.3  Detector Performance
        2.3.1  Detector Gain and Energy Resolution
        2.3.2  Position Resolution
        2.3.3  Digitization Spikes
    2.4  Detector Background
        2.4.1  Energy Discrimination
        2.4.2  Particle Background
        2.4.3  Germanium Fluorescence
        2.4.4  Effect of Gain Depression
    2.5  Dynamic Range and Count Rate Effects
        2.5.1  Deadtime Correction
        2.5.2  Saturation
        2.5.3  Gain Depression
        2.5.4  Rate-dependent Distortion
    2.6  Data Features
        2.6.1  Queued Data
        2.6.2  Timing of Spectra
        2.6.3  Last Spectral Bin
        2.6.4  Medium-rate Spectral Data in Autumn 1991
        2.6.5  Single Event Upsets
    2.7  Contact Persons
    2.8  References
Hard X-Ray Telescope (HXT)
    3.1  Overview
    3.2  General information
        3.2.1  Observations with HXT
        3.2.2  Detector gain calibration
        3.2.3  Background counts
    3.3  Some detailed information
        3.3.1  Modulation patterns
        3.3.2  Spectral Energy Response
        3.3.3  Pre-storage of HXT data in DP
        3.3.4  Data compression
    3.4  Contact Persons
    3.5  References
Soft X-Ray Telescope (SXT)
    4.1  Overall Response Function for SXT
        4.1.1  CCD Camera Signal
        4.1.2  SXT Effective Area
        4.1.3  Reading the SXT Effective Area File
        4.1.4  SXT Response to Thermal Plasma
        4.1.5  Reading the SXT Response Function File
        4.1.6  Relative Alignment of X-Ray and Optical Images
    4.2  The CCD Camera
        4.2.1  Saturation Effects
        4.2.2  Effect of CCD Contamination
        4.2.3  SXT Images Taken with the CCD Warm
        4.2.4  Artifacts in Optical Images from Radiation Damage
        4.2.5  SAA Effects on Images
        4.2.6  Subtleties of Background Subtraction
        4.2.7  Charge Bleed-back
        4.2.8  CCD Pixelization
        4.2.9  What is Really Zero Signal Level in Data Numbers (DN)?
    4.3  The Mirror, Lens or Filters
        4.3.1  Scattering by ND X-ray Filter
        4.3.2  Point Spread Function
        4.3.3  Mirror Scatter
        4.3.4  Vignetting Correction
        4.3.5  Stray Visible Light
    4.4  Other Instrument and Operations Features
        4.4.1  Data Compression
        4.4.2  Use of Low-8 Images in Optical Data
        4.4.3  Filter Alternation During AEC
        4.4.4  The Roll Angle in the SXT Images
        4.4.5  Incorrect Location of Image Pieces in Some PFIs
        4.4.6  Preparation of SFD images
    4.5  Contact Persons
    4.6  References
Wide Band Spectrometer (WBS)
    5.1  Basic Instrument Characteristics
    5.2  Soft X-Ray Spectrometer (SXS)
    5.3  Hard X-Ray Spectrometer (HXS)
    5.4  Gamma-Ray Spectrometer (GRS)
    5.5  WBS Output Data
    5.6  Contact Persons
    5.7  References
Spacecraft Attitude, Ephemeris and Coordinate Systems
    6.1  Spacecraft Attitude Control System (ACS)
        6.1.1  Inertial Reference Unit (IRU)
        6.1.2  Two-dimensional Fine Sun Sensor (TFSS)
        6.1.3  Star Tracker (STT)
        6.1.4  Geomagnetic Sensors (GAS)
        6.1.5  HXT Aspect Sensor (HXA)
        6.1.6  Attitude Determination Software (ADS)
    6.2  ACS Performance
        6.2.1  Pointing Accuracy
        6.2.2  Spacecraft Jitter
        6.2.3  Sensor Problems
    6.3  Instrument and Spacecraft Co-alignment
    6.4  Spacecraft Ephemeris
    6.5  Contact Persons
    6.6  References

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)
Details of the SXT CCD Pixels
Dates of Significant SXT Activities
    C.1  Dates that SXT CCD was Baked Out
    C.2  Table of Number of SXT Images and Dark Current Levels
    C.3  Dates of SXT Entrance Filter Failures
Attitude Control System (ACS) Related Items
    D.1  Dates When Yohkoh was at non-zero Roll
Miscellaneous Yohkoh Information
    E.1  Amount of Yohkoh Data per Week
Web Version of the YAG

Converted at the YDAC on Apr 14, 1999
(from LaTEX using TTH, version 1.92, with postprocessing)