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Working with nonSurvey databases

• A new model for archiving synoptic data in VDFS - Cross et al., 2009, ASP Conf. Ser. ADASS XVIII gzipped postscript
• Automated data releases for the WFCAM Science Archive - Collins et al., 2009, ASP Conf. Ser. ADASS XVIII gzipped postscript

To ease the amount of manual intervention required the publication of nonSurvey databases was standardised and largely automated towards the end of 2008/early 2009.

The availability of standard nonSurvey database products enables users to benefit from the data access methods available to UKIDSS users. For example powerful SQL queries to mine the data and image cut-out services.

Database content

Each database holds the relevant image metadata and object catalogues in tables. The data overview whilst mainly aimed at UKIDSS users explains the basic layout and content. The full schema and database content for a given nonSurvey project can be explored using the schema browser and expanding the nonSurvey menu.

As part of the nonSurvey database generation the metadata for the processed multiframes and each detector are automatically quality controlled to flag (deprecated > 0) sub-optimal products.

Stack frames produced from the dither and micro-stepping recipe each have an associated object catalogue, these are all further processed to produce calibrated magnitudes and coordinates prior to being ingested into the relevant detection table eg u05a100Detection. If the release curation detects that observations were made at the same position with the same filter then the intermediate stacks produced by the pipeline are coadded to form a deepStack. A catalogue extractor is run on any deepStack produced and the resultant objects are also ingested into the detection table.

The objects held in the detection table are then source merged and seamed to produce the source table eg u05a100Source. This process is more fully explained in data overview but essentially this procedure matches objects across wavebands and flags objects that appear more than once in overlap regions. For example if a project has single epoch obervations in J and H but multiple observations in K then a row in the source table will contain the J and H magnitudes from the pipeline stacks and a K magnitude from the deepStack. Multiframes or detectors that have been deprecated do not appear in the source merged table.

To help with variablity studies projects that are considered to be multi-epoch also contain a variability and varFrameSet table eg u05a100Variability, u05a100VarFrameSetInfo . Their use is described in the SQL cookbook.

Other science tables in release databases includes:

• SourceNeighbourse eg u05a100SourceNeighbours: Contains all sources within a given radius of each merged source
• SourceXDetection eg u05a100SourceXDetection:All detections within a given radius of each source
• SourceXtwomass_psc eg u05a100SourceXtwomass_psc: All 2MASS point sources within a given radius of each source