Chapter 2. Herschel products

Table of Contents

2.1. Herschel product types
2.2. Observational products levels
2.3. Herschel product generic definition
2.3.1. Product basic structure
2.4. Datasets in Herschel products
2.5. Spectrum specialised datasets
2.5.1. Spectrum1d
2.5.2. Spectrum2d
2.6. Image and cube generic products
2.6.1. SimpleImage product
2.6.2. SimpleCube product
2.6.3. SpectralSimpleCube product
2.7. Context products
2.8. Product metadata keywords
2.9. The Herschel Observation Context
2.10. Product naming convention for exported FITS files
2.10.1. Observation products
2.10.2. Calibration products
2.10.3. Auxiliary products
2.10.4. Quality Control products

A Herschel Pipeline product consists of metadata keywords, tables or datasets with the actual data, and the history of the processing that generated the product. Metadata keywords have been specified to allow an optimal identification and characterisation of the products, both for information to you, and to provide the required items to the processing software. They have been defined so that compatibility with standard keywords used in Astronomy and commonality across Herschel products are ensured. Whenever possible, product formats have been defined to be consistent with similar scientific products used by the astronomical community (for instance, images and spectra).

2.1. Herschel product types

The following types of Herschel products are defined:

1. Observational products

Observational products contain the scientific data resulting from the Herschel observations. Observational products are classified depending on the level of the processing of the data they contain, ranging from raw data (Level 0) to highly processed scientific data (Level 3). Observational products are generated per observation, although highly processed products may result from the combination of data from several observations. Browse products are also available in the Herschel Science Archive to allow you to quickly look at the contents of the data. The browse products are generated automatically. Therefore the quality of these products may not be good enough for science analysis.

2. Calibration products

These products contain the parameters that characterise the behaviour of the satellite and the instruments. There are uplink and downlink calibration products. Uplink calibration products are used for the specification of the commands that are uplinked to the satellite for the execution of the observations. Downlink calibration products are used in the processing of the raw data to produce astronomically calibrated products in which the instrument artifacts have been removed. In this document, only the downlink calibration products are described.

3. Auxiliary data products

These products contain all Herschel non-science spacecraft data required in the processing and analysis of the scientific data. Auxiliary data products are normally generated per Herschel Operational Day, with the exception of the Uplink product and the Pointing product, which are generated per observation.

4. Quality Control products

Each observation is associated with two Quality Control products, which gather the information required to evaluate the technical quality of the executed observation. The Quality Control Report is automatically created during the Data processing for each observation. The Quality Control Report Summary is generated at the end of the quality control analysis as a result of this process.

5. User Provided Data Products (UPDPs), Highly Processed Data products (HPDPs) and Ancillary products

UPDPs are interactively reduced data provided to the Herschel Science Centre by the observers (initially from the Herschel Key Program consortia only, that commited to do that explicitly, but not excluding other programmes as well, on a voluntary basis). They must follow provided guidelines in terms of format and associated documentation which are available here.

HPDPs are interactively reduced data provided by Instrument Experts. They include data which have been processed beyond the Pipeline and/or using specific algorithms and therefore have been improved to any degree compared to the Pipeline products, as well as any resulting catalogues.

Ancillary Products are data (products, tables, plots, etc..) generated in the course of the different phases of the Herschel mission which are not necessarily linked to a particular observation, but which contain valuable additional information like e.g. the planetary, asteroid and stellar models used by the various instruments for their calibration, PSFs, trend analysis plots, etc...

UPDPs, HPDPs and Ancillary products are also stored in the Herschel Science Archive and made available to the astronomical community. They are out of the scope of this document which is only referring to products created by the Herschel Data processing system.

6. Standalone Browse Products

Standalone Browse Products are data provided through the Herschel Science Archive in an 'standalone' and easy way (using the standard retrieval options or by right clicking on the postcard, both from the Herschel User Interface and from the Postcard Gallery). They are not necessarily 'science ready' products. They are provided for 'quick look' purposes. At this point, Level 2 and Level 2.5 FITS products generated by the standard Herschel data processing pipelines are distributed as 'Standalone Browse Products'. They will evolve in the future with the objective to become simpler and easier-to-use products.