Overview of database structure
Data in APPLAUSE are stored in separate tables. For DR2, some tables are different from DR1 tables.
For DR3, some tables have more columns, and some additional tables have been added. Most example queries
from this page work on the tables of every data release.
We recommend to use the DR3 tables, but for consistency, we also keep the DR1 and DR2 tables available.
Where there are differences between the data releases, this is indicated.
- archive : data on plate archives/collections (one row per plate archive)
- exposure : exposures on plates (one row per each exposure): date, time, sky coordinates, object/field name
- exposure_sub (DR2) : information on individual sub-exposures for photoplates, in case of interrupted exposures
- healpix : HEALPix centers (one row per HEALPix) – helper table that matches HEALPix number with sky coordinates
- logbook : logbooks and observer notebooks (one row per book)
- logpage: logbook pages, plate covers/envelopes and loose note pages (one row per page)
- plate : plate metadata (one row per plate): plate dimensions, emulsion, number of exposures
- plate_logpage : associations between plates and log-pages (one row per plate-page pair)
- process : data on processing of plate images (one row per process)
- raw_lightcurve (DR1) : raw magnitudes of extracted sources and observation times (one row per source) – table provided for convenience by combining data from other tables
- lightcurve (DR2) : observation times and calibrated magnitudes of extracted sources from astronomical photoplates
- phot_calib (DR2) : data on photometric calibration that was carried out on whole scanned photoplates and in annular bins.
- phot_color (DR2) : data on estimated color terms for photoplates.
- phot_cterm (DR2) : raw data on color term estimation for photoplates.
- phot_rmse (DR2) : photometric error estimates for individual magnitude ranges in annular bins of scanned photoplates.
- scan : high-resolution images of plates (one row per scan)
- solution : astrometric solutions (one row per solution)
- source : raw data on extracted sources (one row per source)
- source_calib : calibrated data on extracted sources (one row per source)
The APPLAUSE database structure follows the logic of plates and the digitizing process. A plate may contain multiple exposures, there may be multiple scans of the same plate, and a scan may be processed several times with different parameters. The downside is that one often needs to combine data from different tables, making queries more complex.
An archive in APPLAUSE is a collection of plates, scans, logbook pages, etc, that belong to the same series and originate at the same telescope. For example, the Zeiss Triplet series in Potsdam constitutes an archive and plates from the Hamburg Large Schmidt telescope make another archive. Every archive has an entry in the archive table and has its own unique
The plate table is the main table for storing data on photographic plates. Each plate has a unique
plate_id number. But the plate table also has a column for
archive_id, making it possible to select only plates belonging to a specific archive.