Archives of Photographic PLates for Astronomical USE

APPLAUSE DR4 (applause_dr4)


The APPLAUSE Data Release 4 contains metadata about photographic plates and data extracted from digitized plates.

The source catalogue contains 4.486 billion extracted sources. The majority of extracted sources have their positions (right ascension and declination) calibrated with the help of Gaia EDR3 catalogue. Since EDR3 is the current astrometric catalog with the higest precision and coverage, it is the reference catalog for most astrometry matching. The database contains 2.132 billion sources with matched Gaia EDR3 designations, 1.256 billion unique matches.

The APPLAUSE DR4 database is organised in 20 tables.

Along with the data we publish the 4.x version of the pyplate software which was used to process the scanned material.


If you have made substantial use of the data provided by APPLAUSE DR4, kindly include this acknowledgement

Funding for APPLAUSE has been provided by DFG (German Research Foundation, Grant), Leibniz Institute for Astrophysics Potsdam (AIP), Dr. Remeis Sternwarte Bamberg (University Nuernberg/Erlangen), the Hamburger Sternwarte (University of Hamburg) and Tartu Observatory. Plate material also has been made available from Thüringer Landessternwarte Tautenburg, and from the archives of the Vatican Observatory.


  • Archives of photographic plates (applause_dr4.archive)

    An archive in APPLAUSE is a collection of plates, logbooks, and extracted data that originate from a specific instrument. The archive table contains one row for each plate archive. Unique identifier: archive_id.

  • Photographic plates as physical objects (applause_dr4.plate)

    The table contains data on photographic plates or films as physical objects. An entry in this table does not guarantee that a scan of the plate is available. Unique identifier: plate_id.

  • Exposure data (applause_dr4.exposure)

    The table contains data on individual exposures for each plate, including start and end times, mid-exposure times, coordinates of telescope pointings. One row in the table corresponds to one exposure on the plate/film. Thus, multiple-exposure plates have multiple entries. Exposures are related with plates by the plate_id. Unique identifier: exposure_id.

  • Sub-exposures (applause_dr4.exposure_sub)

    The table contains data on interrupted exposures, e.g. due to passing clouds, or due to continuation of a long exposure during another night. Each row in the sub-exposure table corresponds to a continuous fragment of a full exposure. Unique identifier: subexposure_id.

  • Previews of photographic plates (applause_dr4.preview)

    Catalogue of preview images of photographic plates. Previews were often captured before cleaning plates from handwritten annotations, so preview images may contain additional information that are not present in scans. For some archives, previews were created from high-resolution scans. Previews are related with plates by plate_id. Unique identifier: preview_id.

  • Scans of photographic plates (applause_dr4.scan)

    Catalogue of high-resolution images of photographic plates. A row in the table corresponds to a scan of a plate. If a plate was scanned multiple times, usually to overcome scanner limitations, then there are multiple entries in the scan table belonging to the same plate, identified by plate_id. Unique identifier: scan_id.

  • Extracted sources (applause_dr4.source)

    Table of extracted sources. A row in the source table corresponds to an extracted source from a plate scan. The table contains raw data, obtained with the SExtractor software in the processing pipeline. Calibrated data can be found in the source_calib table, which shares the same source identifiers. Unique identifier: source_id.

  • Extracted sources with calibrated positions and magnitudes (applause_dr4.source_calib)

    Extracted sources with calibrated sky coordinates, magnitudes, and cross-matches with the Gaia EDR3 catalogue. Astrometric and photometric calibration has been carried out using Gaia EDR3. Unique identifier: source_id. The identifier is the same as in the source table.

  • Logbooks (applause_dr4.logbook)

    Information about logbooks that contain data on photographic plates or notes about observations. Digitized logbook pages are catalogued in the logpage table. There is no direct relation between a plate and a logbook. Instead, plates are related with logpages and logpages are related with logbooks. Unique identifier: logbook_id.

  • Logbook pages and plate envelopes (applause_dr4.logpage)

    The logpage table contains data on individual digitized logbook pages and also images of plate covers/envelopes. Logbook pages are related with logbooks by the logbook_id. The relation between logpages and plates is given in the plate_logpage table. Unique identifier: logpage_id.

  • Relation between plates and logpages (applause_dr4.plate_logpage)

    The plate_logpage table contains links between plates and logbook pages / plate envelopes. Each row in the table corresponds to one plate-logpage pair. A single plate may have multiple related logpages and a single logpage may be related to multiple plates.

  • Plate image processes (applause_dr4.process)

    The process table contains summary data on the processing of the plate scan with the astrometric and photometric pipeline, using the PyPlate software. Unique identifier process_id.

  • Astrometric solutions of plate scans (applause_dr4.solution)

    The table contains astrometric solutions of plate scans. Unique identifier is solution_id.

  • Photometric calibration on whole scans (applause_dr4.phot_calib)

    This table contains data on photometric calibration. Unique identifier calib_id.

  • applause_dr4.phot_calib_curve

    Derived photometric calibration curves that were used for transforming extracted source magnitudes to the plate natural photometric system. Unique identifier calibcurve_id.

  • applause_dr4.scanner_pattern

  • applause_dr4.solution_healpix

  • applause_dr4.solution_set

    This table provides summary data on all astrometric solutions found during processing of the plate image. Unique identifier solutionset_id.

  • Crossmatch helper table (applause_dr4.source_xmatch)

    Crossmatch helper table, assembles plate_id, source_id, scan_id, process_id, gaiaedr3_id and crossmatch values like dist, coordinates