Chapter 4. The Meta Data and FITS Keywords

Table of Contents

4.1. Introduction
4.2. Where are the Meta data?
4.3. Meta data and FITS keywords
4.4. Meta data and FITS keywords to help identify spectroscopy slices

4.1. Introduction

An ObservationContext has Meta data that give information about the observation: details taken from the observation planning tool (HSPOT), coordinates, the instrument configuration, some processing information, wavelength information, dates, etc. Each context and each product that is contained within an ObservationContext also has Meta data, some of which is copied from (or to) that of the ObservationContext, and other of which is specific to that context or product. For products which can be exported to FITS files—maps, cubes, TableDatasets—the FITS keywords are created from the Meta data. When these FITS files are read back in (whether Herschel data or that from another observatory) the FITS keywords become Meta data. HCSS and each instrument has a dictionary that links the Meta data to the FITS keywords: any Meta datum that is not in that dictionary not lost, but is translated as META_## in the FITS header.

In this chapter we list the Meta data and FITS keywords that are most likely to be encountered by the astronomer. We list these in alphabetical order for the ObservationContext, the Levels in the ObservationContext, and for the science products that astronomers will use, for both photometry and spectroscopy.

[Note] Note
A CSV file containing all the AOT-related Meta data that an astronomer needs to know in order to figure out what type of observation they are looking at has been posted on the PACS pages of the HSC web-site, currently at herschel.esac.esa.int/twiki/bin/view/Public/PacsCalibrationWeb.