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Herschel Data Products
Overview of Herschel standard products
A wide range of Herschel data products are foreseen, both in 'scope' and 'level'. Some of them will be automatically generated by systematic pipeline processing performed at the Herschel Science Centre (HSC) using the Herschel Data Processing system and made available through the Herschel Science Archive (HSA) shortly after the observation has been executed. Others, interactively generated, may eventually become part of the HSA at a later stage of the mission.
The Herschel products (not all of direct interest for the observers)
consist of:
- Observational products
- Contain the scientific data resulting from the Herschel observations
- 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) see below
- Observational products are generated per observation (per AOR), although highly processed products may result from the combination of data from several observations
- Catalogue products
- Derived from the scientific data; contain lists of astronomical objects or spectral features with their characterisation (Point source catalogue, Line list catalogue). They are the result of highly advanced processing of the data, and may be based on one or several observations.
- Auxiliary products
- Contain all Herschel non-science spacecraft data required directly or indirectly in the processing and analysis of the scientific data.
- Normally generated per Herschel Operational Day, with the exception of
the Herschel Pointing Product that is generated per observation
- Calibration products
- Contain the parameters that characterise the behaviour of the satellite and the instruments.
- There are uplink and downlink calibration products. Downlink calibration products are used in the processing of the raw data to produce astronomically calibrated products in which the instrument artefacts have been removed.
- Quality control products
- Gather a summary of the information required to evaluate the technical
quality of the executed observation and the products generated, and provide a
global quality assessment
- User generated products
- Provided to the Herschel Science Centre by the observers (especially expected from the Herschel Key Program consortia)
- Will be stored in the HSA and made available to the astronomical community after validation
- Must follow provided guidelines
Overview of Herschel Data Product levels
The various Herschel Data Product levels can be briefly described as follows:
- Level-0 data products
- Raw telemetry data as measured by the instrument. They might be minimally formatted before its ingestion into the Herschel Science Archive. They will be automatically generated by the data processing pipeline
- Level-1 data products
- 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 and eventually become part of the pipeline (but this may not be possible in the early phases of the mission).
- Level-2 data products
- 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
- Suitable for Virtual Observatory access
- Level-3 data products
- Publishable science products where level-2 data products are used as input.
- These products are not only from the specific instrument, but may be combined with theoretical models, other observations, laboratory data, catalogues, etc.
- Their formats are required to be Virtual Observatory (VO) compatible and these data products must be suitable for VO access
- They will always be user generated products
It is expected that the degree of human intervention necessary to generate
observational products will decrease with time, as the knowledge of the
instrumental behaviour improves as the mission progresses and more and more
experience is gained. Thus, the quality and fidelity of the automatically
generated products will be progressively enhanced with time. Therefore the
whole contents of Herschel observations in the Herschel Science Archive will
be reprocessed at least annually.
Data proprietary rights
All observations made in the first year of the routine phase will have
proprietary times of 12 months, while for all observations made later,
the proprietary time will be 6 months, with a simple 'bridging
scheme' so that no observation will become public before observations
that were executed earlier become public as well. The proprietary time
applies to each observation individually, counted from the day when
the data are made available to the data owner. However, a scheme will be
put in place whereby the Herschel Project Scientist and the HOTAC Chair in
consultation can grant additional proprietary time to certain large
programmes, in order to prevent the release of improperly or
inhomogeneously calibrated or processed data. Note that data resulting
from routine calibration observations will generally enter the public
domain immediately after they are processed unless duplicating a science
observation.
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