Chapter 8. Herschel Data Processing

Table of Contents

8.1. Herschel Data Products
8.2. Standard Product Generation
8.3. Quality Control
8.4. Herschel Science Archive
8.5. Herschel Interactive Processing Environment

The scientific analysis of the Herschel observations requires the handling of the Herschel Data Products, which are stored in the Herschel Science Archive. This chapter explains the contents and structure of these products, which include raw and processed data, plus calibration and quality information. It also presents the infrastructure that generates and store them as well as the software provided to the users to analyze them.

8.1. Herschel Data Products

All Herschel telemetry and auxiliary data will be automatically processed at the HSC with the Standard Product Generation software (SPG), to produce the observational data products, stored in the Herschel Science Archive (HSA). The following four levels of Herschel data products are defined:

  • Level-0 data product: Raw telemetry data, as measured by the instrument, minimally manipulated and ingested into the mission data base/archive as Data Frames.

  • Level-1 data product: Detector readouts calibrated and converted to physical units, in principle instrument and observatory independent. It is expected that level-1 data processing can be performed without human intervention.

  • Level- 2 data product: Level-1 data further processed to such a level that scientific analysis can be performed. For optimal results many of the processing steps involved to generate level-2 data may require human interaction, based both on instrument understanding, as well as understanding of the scientific aims of the observation. These data products are at a publishable quality level and should be suitable for Virtual Observatory access.

  • Level-3 data product: These are the publishable science products, where level-2 data products are used as input. These products are not only from the specific instrument, but are usually combined with theoretical models, other observations, laboratory data, catalogues, etc. Their formats should be Virtual Observatory compatible and these data products should be suitable for Virtual Observatory access.

While the generation of level-0 and level-1 data products will be automatic (although, in some circumstances, some manual intervention may be needed even in Level 1 products), good quality Level-2 products often need a degree of manual intervantion. Level-3 data products can only be generated by interactive processing. It is expected that the degree of human intervention necessary to generate these products will continue to decrease with time, as the knowledge of the instruments' behaviour has increased during and since the mission. This is the same as saying that the quality of the automatically generated products will be progressively enhanced. However, in many cases, it will not be possible to discard interactive processing, especially in the derivation of level-3 data products.

In addition to these observational products, calibration, auxiliary and Quality Control products were provided. For more information on the Herschel products, please see the corresponding Instrument Observer Users' Manual. The Herschel Products Definitions document and the Herschel Data Users' Manual document contain detailed descriptions of all Herschel data products.