Contents

• Contents
• List of Figures
• List of Tables
• 1. Introduction
  • 1.1 Purpose
  • 1.2 Structure
  • 1.3 How to Contact Us
  • 1.4 LWS Publications
    • 1.4.1 Acknowledgements and guidelines
    • 1.4.2 Inventory of ISO publications
• 2. Instrument Overview
  • 2.1 Introduction
  • 2.2 Overall Design
  • 2.3 The LWS Optics
  • 2.4 The Grating Spectrometer
  • 2.5 The Fabry-Pérot Spectrometers
  • 2.6 The LWS Detectors
    • 2.6.1 LWS readout electronics (integrating amplifiers)
    • 2.6.2 Particle hits
• 3. Instrument Modes and Observing Templates
  • 3.1 Summary of the Observing Modes
  • 3.2 Description of the Observing Modes: the Astronomical Observation Templates (AOTs)
    • 3.2.1 Medium-resolution wavelength range (AOT L01)
    • 3.2.2 Medium-resolution line spectrum (AOT L02)
    • 3.2.3 Narrow-band photometry (AOT L02)
    • 3.2.4 High-resolution wavelength range (AOT L03)
    • 3.2.5 High-resolution line spectrum (AOT L04)
    • 3.2.6 Parallel and serendipity modes
  • 3.3 History of AOT Changes throughout the Mission
• 4. Data Processing
  • 4.1 Processing Overview
  • 4.2 Quality Check of the Data
  • 4.3 Derive-SPD Processing Steps
    • 4.3.1 Introduction
    • 4.3.2 Construction of ramps and discarding unusable readouts
    • 4.3.3 Conversion of readouts to voltages
    • 4.3.4 Flag saturated ramps
    • 4.3.5 First level deglitching
    • 4.3.6 Extraction of ramp slopes and conversion to photocurrent
    • 4.3.7 Illuminator processing
  • 4.4 Auto-Analysis Processing Steps
    • 4.4.1 Absolute responsivity correction and responsivity drift correction
    • 4.4.2 Dark current/background straylight subtraction
    • 4.4.3 Grating scan wavelength calibration
    • 4.4.4 Grating spectral responsivity calibration
    • 4.4.5 Spectral bandwidth correction
    • 4.4.6 Fabry-Pérot scan wavelength calibration
    • 4.4.7 Fabry-Pérot throughput correction
    • 4.4.8 Velocity correction to wavelength
    • 4.4.9 Write LSNR data product (only in OLP versions earlier than 8)
    • 4.4.10 Calculation of uncertainties
  • 4.5 Processing of the Parallel and Serendipity Modes
    • 4.5.1 Dark current subtraction and drift removal
• 5. Calibration and Performance
  • 5.1 Introduction
  • 5.2 Absolute Flux Calibration and Grating Relative Response
    • 5.2.1 Absolute flux calibration
    • 5.2.2 Relative spectral response function
  • 5.3 Fabry-Pérot Flux Calibration
  • 5.4 Dark Current Determination
  • 5.5 In-orbit Sensitivity of the LWS - Detector Performance
  • 5.6 Photometric Accuracy
    • 5.6.1 Calibration sources used for photometric purposes
    • 5.6.2 LWS photometric stability checked with observations of Mars
    • 5.6.3 Comparison with IRAS fluxes
    • 5.6.4 Checking the Fabry-Pérot photometric accuracy
  • 5.7 The Strong Source Correction
    • 5.7.1 The reason for the correction
    • 5.7.2 The correction
    • 5.7.3 Future
  • 5.8 Quarter-Second Processing
    • 5.8.1 LW5: quarter- versus half-second processing
    • 5.8.2 Summary of processing for various strength sources
  • 5.9 Instrumental Field of View: The Beam Profile
    • 5.9.1 The beam profile
    • 5.9.2 Asymmetry
    • 5.9.3 Flux correction for extended sources
    • 5.9.4 Extended source flux per unit area
    • 5.9.5 Effect of the ISO PSF at large distances: check of the straylight around Jupiter
  • 5.10 Grating Wavelength Calibration
    • 5.10.1 Basic principles and calibration strategy
    • 5.10.2 Calibration sources and types of observations
    • 5.10.3 Detector angles
    • 5.10.4 Time dependence
    • 5.10.5 Assessment of the achieved wavelength accuracy
  • 5.11 Grating Resolution and Characterisation of the Line Profiles
    • 5.11.1 Preparation of the data
    • 5.11.2 Stability of the line profiles
    • 5.11.3 Characteristics of the profiles. Comparison to Gaussians.
    • 5.11.4 Effect of a lower spectral sampling
  • 5.12 Fabry-Pérot Wavelength Calibration
    • 5.12.1 Introduction
    • 5.12.2 Strategy of calibration
    • 5.12.3 Calibration for OLP Version 10
    • 5.12.4 Monitoring the Fabry-Pérot wavelength calibration
    • 5.12.5 Fabry-Pérot wavelength accuracy
  • 5.13 Fabry-Pérot Resolution and Line Profiles
  • 5.14 Accuracy of the Parallel and Serendipity Mode Calibration
    • 5.14.1 Prime mode observations coincident with parallel observations
    • 5.14.2 Comparison with prime mode from stabilisation periods
    • 5.14.3 Comparison between overlapping parallel rasters
    • 5.14.4 Comparison with other instruments
• 6. Caveats and Unexpected Effects
  • 6.1 Glitches
  • 6.2 Response to Off-axis and Extended Sources: Fringes in the Data
  • 6.3 Response to Off-axis and Extended Sources: Spectrum Fracturing
  • 6.4 Dark Current Subtraction
  • 6.5 Differences between Overlapping Sub-spectra
  • 6.6 Spurious Features Introduced by the RSRF
  • 6.7 The Near-Infrared Leak
  • 6.8 `Detector Warm-up Features' in the Long Wavelength Detectors
  • 6.9 Transients and Memory Effects
    • 6.9.1 Description
    • 6.9.2 The correction procedure
  • 6.10 Detector Non-linearity: the Strong Source Correction
    • 6.10.1 Does your data require the correction?
    • 6.10.2 Getting the correction applied to your data
  • 6.11 57.16 m SW2 Feature in the Fabry-Pérot Spectra
  • 6.12 FP Wavelength Calibration
  • 6.13 Removal of the Grating Resolution Element in FP Observations
  • 6.14 Use of `Non-prime Data' in FP Observations
  • 6.15 Side Order Contamination in FP Data
  • 6.16 Responsivity Drift in Long FP Observations
• 7. Guide to Instrument Related Data Products
  • 7.1 Inventory and Naming Convention
  • 7.2 Product Files - Description of Content and Use
    • 7.2.1 Timing information in the products: the ITK
    • 7.2.2 General FITS header keywords for LWS data
    • 7.2.3 Transparent data
    • 7.2.4 Edited Raw Data (ERD files)
    • 7.2.5 Standard Processed Data (SPD product files)
    • 7.2.6 LSPD and LIPD status words
    • 7.2.7 Auto-Analysis results (AAR product files)
    • 7.2.8 LSAN status words
  • 7.3 Calibration Files
    • 7.3.1 SPD calibration files
    • 7.3.2 Auto-Analysis calibration files
• 8. Getting Started with LWS Data
  • 8.1 Retrieving and Reading the Data
  • 8.2 Analysing the Data
    • 8.2.1 LWS data reduction recipes
    • 8.2.2 The ISO Spectral Analysis Package (ISAP)
    • 8.2.3 The LWS Interactive Analysis (LIA)
  • 8.3 Analysing Parallel/Serendipity Mode Data
  • 8.4 Where to Find the Calibration Parameters
  • 8.5 Useful Web Addresses
• A. List of Acronyms
• Bibliography
• Index