Information on resource 'HDAP -- Heidelberg Digitized Astronomical Plates'

Scans of plates kept at Landessternwarte Heidelberg-Königstuhl. They were obtained at location, at the German-Spanish Astronomical Center (Calar Alto Observatory), Spain, and at La Silla, Chile. The plates cover a time span between 1880 and 1999. Specifically, HDAP is essentially complete for the plates taken with the Bruce telescope, the Walz reflector, and Wolf's Doppelastrograph at both the original location in Heidelberg and its later home on Königstuhl.

The scanning of the plate archive at Landessternwarte Heidelberg was initiated by Holger Mandel and Kurt Birkle in 2006 and was funded by the Klaus-Tschira-Foundation. Almost all usable direct plates in the archives are now scanned, and the funded phase of the project is over. Only minor additions are expected any more.


The plate archive consists of plates from many different sources. The following table gives an overview of the instruments at which the plates were taken:

plate letter name eff. focal length [mm] aperture ratio scale [as/mm] plate size latitude longitude height
A Calar Alto Schmidt telescope 2400 f/3 86 24x24cm 37.22417 N +2.5375 W 2168 m
B Königstuhl Bruce telescope 2000 f/5 103 24x30cm or 30x30cm 49.39861 N -8.72083 E 560 m
C 1.23m in Casseg. focus with corrector 9857 f/8 20.9 24x24cm 37.22361 N +2.5461 W 2138 m
D 72cm Walz- Reflektor 2815 f/3.9 73.3 13x18cm or 9x12cm 49.39861 N -8.72083 E 560 m
E 2.2m in Cassegrain focus with corrector 17037 f/7.744 12.1 20x25cm (8x10in) or 24x24 cm 37.22361 N +2.5461 W 2138 m
F 3.5m in primary focus with 3-lens corrector 13761 f/3.93 15 20x25cm (8x10in) 37.22361 N +2.5461 W 2138 m
F 3.5m in primary focus with 2-lens corrector 12195 f/3.48 16.9 12.5x20 (5x8in) 37.22361 N +2.5461 W 2138 m
H 2.2m MPG ESO/La Silla 17679 f/8 12 20x25cm -29.257225 S +70.734595 W 2335 m
G Wolf's Doppel- astrograph (15cm) on Königstuhl (7/1897-1909) 900mm f/6 230 13x18cm or 9x12cm +49.39861 N -8.72083 E 560m
G Wolf's Doppel- astrograph (15cm) in Märzgasse (1887-7/1897) 900mm f/6 230 13x18cm or 9x12cm +49.60988 N -8.69387 E 110m

Unfortunately, instrument data on the 2.2m MPG telescope on La Silla are lost. If anyone can help out, please contact

The Observation logs of the more ancient observations are available from UB Heidelberg.

More Information

The project was discussed on a poster shown at the 2007 meeting of the Astronomische Gesellschaft in Würzburg.

A slightly more technical article appeared in the proceedings of the 2014 Astroplate conference.


This is what the photographic plates these scans were prepared from look like --


The archive of plates from Wolf's eight-inch telescope --


The Bruce archive -- the rack's bend indicates the plates are kept beneath an observatory dome --


The scanner used by this project (Heidelberg Nexscan F4100; the resolution is 100 pixels per millimeter at 200 pixels per millimeter optical scanner resolution) --


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