The LSST data products are organized into two groups, distinguished by the cadence with which they are generated. Level One products are generated by pipeline processing the stream of data from the camera system during normal observing. Level One products are therefore being continuously generated and / or updated every observing night. This process is of necessity highly automated, and must proceed with absolutely minimal human interaction. Level One data products are divided into Images, Catalogs, and Alerts, as color coded below.
The Functional Requirement Specifications of the data management system include the following:
1) The incoming stream of images generated by the camera system during observing is processed to generate and archive the nightly data products
- Raw science images
- Catalog of variable sources
- Transient alerts
2) Periodically the accumulated nightly data products are processed to
- Generate coadded images of several types.
- Optimally measure the properties of fainter objects.
- Perform astrometric and photometric calibration of the full survey object catalog
- Classify objects based on both their static properties and time-dependent behavior.
Level Two products, including calibration images, co-added images, and the resulting catalogs, are generated on a much slower cadence, and their release will be driven by data quality assessments. Although many of the steps that generate Level Two products will be automated, they need not all be so, and significant human interaction may be tolerated.