Chapter 5. The Framework for HIFI Calibration

Table of Contents

5.1. Introduction:
5.2. The Intensity Calibration of HIFI
5.2.1. Context
5.3. The HIFI Calibration Scheme
5.3.1. Load Calibration
5.3.2. OFF calibration
5.3.3. Differencing observations:
5.3.4. Non-linearity:
5.3.5. Blank-sky contribution:
5.4. The frequency calibration of HIFI:
5.4.1. Context:
5.4.2. Frequency accuracy:
5.4.3. Frequency calibration:
5.4.4. Frequency resolution:
5.4.5. Spurious responses:
5.5. The Spatial Response Calibration of HIFI:
5.5.1. Context:
5.5.2. HIFI/Herschel spatial response:
5.6. Summary: overall calibration of HIFI and error budget:
5.6.1. Strategy summary:
5.6.2. Error budget

5.1. Introduction:

This chapter gives a general view of the calibration concepts chosen for the HIFI instrument. This chapter is intended to provide an overview of how HIFI is calibrated the full details of which are contained elsewhere.

The HIFI calibration approach can be broken down into three main areas:

  • intensity calibration

  • frequency calibration

  • spatial response calibration

It is the combination of each of these three steps that provides the most accurately calibrated HIFI spectrum (see summary in section Section 5.5, “The Spatial Response Calibration of HIFI:”). For each of these areas, a framework document has been produced, describing in extensive details the calibration strategy and equations applying to HIFI. In the following, we summarise the content of this framework.