HIFI Observers' Manual

Update for Start of OT2 Call for Proposals

version 2.4, 1-June-2011

HERSCHEL-HSC-DOC-0784, version 2.4
Revision History
Revision version 2.4 APM, DT
Update for changes made for the OT2 call including in-flight calibration information updates.
Revision version 2.3 APM, DT
Update for changes made for the GT2 call including HSpot 5.3 updates.
Revision version 2.2 APM, DT
Update for changes made for the GT2 call
Revision version 2.1 APM, DT
Update for changes made starting OT1 observations
Revision version 2.0 APM, DT
Update for initial Open Time call (OT1)
Revision version 1.1 APM, DT
Update for initial Open Time Key Projects
Revision version 1.0 APM, DT
Initial version

Table of Contents

1. The HIFI Instrument Observer's Manual
1.1. Purpose of this Document
1.2. Preparing HIFI for Operations
1.3. Acknowledgements
2. HIFI Instrument Description
2.1. Instrument and Concept
2.1.1. What is HIFI?
2.1.2. How Does HIFI Work?
2.2. Instrument Configuration
2.3. HIFI Focal Plane Unit
2.3.1. The Common Optics Assembly
2.3.2. The Beam Combiner Assembly (Diplexer Unit)
2.3.3. HIFI Mixers
2.3.4. The Focal Plane Chopper
2.3.5. The Calibration Source Assembly
2.4. The HIFI Signal Chain
2.5. HIFI Spectrometers
2.5.1. The Wide Band Spectrometer (WBS)
2.5.2. The High Resolution Spectrometer (HRS)
3. HIFI Scientific Capabilities and Performance
3.1. What Science Is Possible With HIFI?
3.1.1. HIFI's Scientific Objectives
3.2. Primary Instrument Characteristics
3.3. General Instrument Description
3.4. Available Spectrometer Setups
3.4.1. Wide Band Spectrometers (WBSs)
3.4.2. High Resolution Spectrometers (HRSs)
3.5. Mixer Performance
3.5.1. System Temperatures
3.5.2. Tuning Ranges
3.5.3. Sensitivity Variations Across the IF Band
3.5.4. Overall Noise Performance
3.5.5. Mixer Stabilities
4. Observing with HIFI
4.1. Introduction
4.2. The HIFI Observing Modes
4.2.1. Modes of the Single Point AOT I
4.2.2. Modes of the Mapping AOT II
4.2.3. Modes of the Spectral Scan AOT III
4.3. Standing Wave Residuals after Calibration (Pipeline Level 2)
4.3.1. Bands 1-5 (SIS mixers)
4.3.2. Position Switch, Frequency Switch and Load Chop modes
4.4. Bands 6-7 (HEB mixers)
4.4.1. DBS Modes
4.4.2. Position Switch, Frequency Switch and Load Chop Modes
4.5. "Grouping" or "Clustering" of Observations
4.6. Solar System Target Modes
5. HIFI Calibration
5.1. Introduction:
5.2. The Intensity Calibration of HIFI
5.2.1. Context
5.3. The HIFI Calibration Scheme
5.3.1. Internal Load Calibrations
5.3.2. OFF calibration
5.3.3. Differencing observations:
5.3.4. Non-linearity:
5.3.5. Blank-sky contribution:
5.3.6. Conversion between Antenna Temperature and Janskys:
5.4. The Frequency Calibration of HIFI:
5.4.1. Context:
5.4.2. Frequency accuracy:
5.4.3. Determination of Frequency Calibration:
5.4.4. Frequency resolution:
5.4.5. Frequency and Velocity Verifications
5.4.6. Spurious Responses in HIFI
5.5. The Spatial Response Calibration of HIFI:
5.5.1. Context:
5.5.2. Beam Characteristics
5.5.3. Chopper Calibration
5.6. Mixer Side-band Ratio
5.6.1. IF Spectrum Repeatability (Sideband Line Ratios)
5.6.2. Summary Sideband Ratio Information
5.6.3. Intrinsic sideband ratio IF dependence
5.7. Summary: overall calibration of HIFI and error budget:
5.7.1. Strategy summary:
5.7.2. Error budget
6. Using HSpot to Create HIFI Observations
6.1. Overview
6.2. HSpot Components for Setting Up a HIFI Observation
6.2.1. Working with A HIFI Pointed or Mapping Observation Template
6.2.2. HIFI Spectral Scan AOT
6.3. Example HIFI Single Point Observation Setups
6.3.1. Example 1: Observing the [CII] line using Frequency Switch in a photodissociation region
6.3.2. Example 2: A Dual Beam Switch (DBS) mode AGB Observation
6.4. Example Setup of a HIFI Mapping AOR
6.4.1. Example 3: Scan Mapping of the Spectral Lines CO(7-6) and CI(2-1) in the Centre of M51 .
6.5. Example Setup of a HIFI Spectral Scan Observation
6.5.1. Example 4: Spectral Survey of a Hot Core.
7. Pipeline and Data Products Description
7.1. Data to be Passed on to the User
7.2. Additional Observatory Meta Data
7.3. Example HIFI data products
7.3.1. Level 0 products
7.3.2. Level 1 products
7.4. Pipeline Processing
7.4.1. WBS Pipeline Processing Steps
7.4.2. HRS Pipeline Processing Steps
7.5. Deconvolution Processing of Spectral Scan Data
7.5.1. Solving the Deconvolution Problem
8. References:
A. Change Log

List of Figures

2.1. Dual sideband spectrum superposition
2.2. Dual sideband spectrum changes with LO frequency
2.3. General HIFI component diagram.
2.4. HIFI Focal Plane Unit (FPU).
2.5. Back side of the HIFI FPU.
2.6. HIFI telescope relay optics.
2.7. Channel splitting optics
2.8. Beamsplitter and diplexer mixing with sample diplexer unit.
2.9. A HIFI mixer sub-assembly.
2.10. The HIFI Focal Plane Chopper (FPC).
2.11. The HIFI signal chain.
3.1. Water in Comet Garradd
3.2. HIFI spectral scan of the Orion nebula
3.3. Example of the use of high resolution spectroscopy in the Orion-Irc2 region.
3.4. Double sideband system temperatures of HIFI mixers.
3.5. Bands 1a and b system temperature.
3.6. Bands 2a and b system temperature.
3.7. Bands 3a and b system temperature.
3.8. Bands 4a and b system temperature.
3.9. Bands 5a and b system temperature.
3.10. Bands 6a and b system temperature.
3.11. Bands 7a and b system temperature.
3.12. Band 1b IF mismatch.
3.13. Variation of IF sensitivity in band 4a
4.1. Overview of available AOT observing modes.
4.2. Timeline of HIFI position switch AOT.
4.3. HIFI Dual Beam Switch positions on the sky.
4.4. Timeline of the HIFI Dual Beam Switch observing mode.
4.5. Timeline for HIFI Frequency Switch observations.
4.6. Timeline for the HIFI load chop observing mode.
4.7. Timeline of the path on the sky for a HIFI OTF mapping mode. The green dots indicate regular data readouts of the spectrometers. The OFF position is returned to at the end of an integer number of scan legs. This is typically 1 or 2 except in the case of small OTF maps.
4.8. Standing wave residual fit
4.9. Standing waves at 92 and 98 MHz
4.10. Standing waves using Frequency Switch in 3b
4.11. Full standing wave fitting in band 4b
4.12. Standing wave residuals in Bands 6a and 7b.
4.13. Large standing waves in V polarization
4.14. Standing waves in HEB Load Chop observation
5.1. Frequency consistency
5.2. Spur illustration and HSpot warning
5.3. Band 1a spur around water line
5.4. Band 4b spur near 1113 GHz water line
5.5. ILT focal plane measurements
5.6. Saturn map for band 6 aperture
5.7. NML Tau profiles.
5.8. LDN1157-B1 profile comparisons.
5.9. LDN1157-B1 profile differences.
5.10. LDN1157-B1 reference emission.
5.11. LDN1157-B1 profiles from ON and OFF positions 1.
5.12. LDN1157-B1 profiles from ON and OFF positions 2.
5.13. (H-Haverage)/Haverage for the Off position for 1342190184.
5.14. (H-Hav)/Hav for the On position for 1342190184.
5.15. Chopper throw calibration
5.16. CO line and IF intensity variation.
5.17. Water line and IF intensity variation.
5.18. Overall IF line intensity variations.
5.19. Side-band ratios
5.20. Sideband ratio variation across the IF
6.1. HSpot "Observation" menu on the "Observations" screen.
6.2. HIFI pointed observation AOT window.
6.3. HIFI mixer band selection.
6.4. HIFI redshift selection.
6.5. HIFI HRS resolution choice.
6.6. HIFI Frequencies window.
6.7. Frequency Editor window components.
6.8. Spectral line identification via mouse click.
6.9. Example HIFI frequency editor setup
6.10. HIFI pointed mode selection.
6.11. HIFI position switch mode.
6.12. HIFI mapping mode selection.
6.13. HIFI raster map setup.
6.14. The spectral scan AOT setup window.
6.15. Time estimator settings window.
6.16. Time estimator return information window.
6.17. Observation breakdown information .
6.18. Target name resolution for example 1.
6.19. Instrument setup screen for Example 1.
6.20. Spectral line selection for Example 1.
6.21. The H2O(331-404) line is shown available under the dark area to top left.
6.22. Final frequency selection for Example 1 with [CII] position marked. Note that the [CII] line is NOT at the centre of the sideband, this is due to the fact that there is slope to the sensitivity within the IF for bands 6 and 7. The position shown is believed to be the best for sensitivity and coverage (see the Chapter 3, HIFI Scientific Capabilities and Performance for details).
6.23. Selection of frequency switch with offset.
6.24. Setup of time estimate for the example observation.
6.25. Appearance of the final AOR on the "Observations" screen.
6.26. Observation overlaid on Band A MSX image (8 microns).
6.27. Instrument setup for Example 2.
6.28. Frequency editor initial setup on water line.
6.29. Final setup of the frequency editor.
6.30. Frequency editor setup for the second set of water lines.
6.31. Image overlay of the two dual beam switch AOR examples on a DSS image of the region. The two chopped positions are shown in blue and green for the two phases of DBS mode. The target is marked by a red square.
6.32. Instrument settings prepared for example 3.
6.33. Frequency editor setup for the M51 example.
6.34. Final mapping mode setup for example 3.
6.35. Overlay of AOR example 3 on DSS image.
6.36. Filled in AOT for the example spectral scan observation.
7.1. Typical level 0 raw calibration data for HIFI
7.2. Typical level 0 raw science data for HIFI
7.3. Typical calibrated scans
7.4. Level 1 science data with velocity scale.
7.5. Calibrated frequency switch scans
7.6. Redundant LO settings.
7.7. MEM deconvolution examples

List of Tables

3.1. HIFI frequency coverage
3.2. List of HRS configurations available in each polarization
3.3. Allan stability times
4.1. Frequency throw values available by HIFI subband.
5.1. Internal load couplings presently used
5.2. Frequency accuracy budget
5.3. HIFI resolutions using the WBS and HRS in two of its modes.
5.4. Beam coalignment results
5.5. HIFI beam efficiencies
5.6. Sideband ratios for the HIFI mixers
5.7. Overall error budget.