Archives of Photographic PLates for Astronomical USE

Data Release 2

Data Release 2 (DR2) was published on February 29, 2016. It contains data from the Bamberg, Hamburg, Potsdam, and Tartu plate collections. DR2 in numbers: 51517 scans, 42789 plates, 2.59 billion extracted sources, 58115 digital images of plate covers and logbook pages, 149 logbooks. The total size of the published files is 30 TB.

Please refer to the contents of APPLAUSE DR2 for more details on what is included in the data release.
Mollweide plots of the archives and their plates FOV in APPLAUSE DR2 see Archives of DR2

The following images illustrate that 99.92% of the sky is covered by plates in DR2. The most observed region is located in the constellation Cygnus, with a total number of 1093 plates. Areas with no data are shown in grey.

Astrometric solutions to the plate scans have been derived with the software on the basis of the Tycho-2 catalogue. Source coordinates have been improved with the SCAMP program, using the UCAC4 astrometric catalogue. Extracted sources with assigned right ascension and declination have been cross-matched with the UCAC4, Tycho-2, and APASS catalogues. APPLAUSE DR2 contains 1.407 billion sources with matched UCAC4 designations, 182 million sources with Tycho-2 designations, and 907 million sources matched with APASS DR9.

Raw magnitudes and fluxes have been extracted from scans by the SExtractor software. Magnitudes have been calibrated using the UCAC4 and Tycho-2 catalogues. From UCAC4, which contains photometry from the APASS DR6, we have used B and V magnitudes for stars fainter than the 10th magnitude: B > 10 and V > 10. Brighter calibration stars have been taken from Tycho-2, transforming the BT and VT magnitudes into B and V.

Plate scans and metadata were processed with PyPlate version 2.0 (subversions 2.0.0 through 2.0.7).

The data processing workflow that was used to prepare DR2, except the photometric calibration, is described in the following conference paper:

  • Tuvikene T., Edelmann H., Groote D., Enke H., and the APPLAUSE Collaboration. Workflow for plate digitization, data extraction and publication. Astroplate 2014 proceedings (link to PDF), pp. 127-130.

Please refer to the contents of APPLAUSE DR2 for more details on what is included in the data release.