Data Release DR3s

The APPLAUSE Data Release 3s (DR3s) is a addendum to the third release of digitized astronomical photographic plates.

The photographic plates of solar full-disk images were digitized and are provided with metadata describing plates, observations, and digitization process. In addition, calibrated and science-ready full-disk images were created, which are compatible with contemporary full-disk data.

APPLAUSE DR3s contains images and metadata from plate archives/collections of the Solar Observatory Einstein Tower in Potsdam, Germany. In total 3620 scans of photographic plates with broad-band images of the solar disk

• original scans converted to photographic positives with 7086 × 7086 pixels in FITS format (Level 0),
• calibrated full-disk images resampled to 2048 × 2048 pixels with an image scale of 1′′ pixel−1 and standard solar orientation (Level 1),
• limb-darkening corrected full-disk derived from Level 1 with enhanced contrast (Level 2)

The image below is a calibrated and centered image after removal of background artifacts (Level 1) obtained at Solar Observatory Einstein Tower on 1949 February 3.

Data coverage of photographic plates for the years 1943 – 1991 is shown in the below diagram.

The solar full-disk plates were recorded at the Einstein Tower during the years 1943 – 1991 (Solar Cycles 18 – 22). High-school students from Potsdam and Berlin digitized more than 3500 full-disk images during internships at AIP. The various calibration steps include accurate measurements of the solar radius, centering of the solar disk, correction of the solar position angle, determination of the limb-darkening function, and establishing an accurate coordinate system.

An example of Level 1 data is shown below along with a 10-day time-series zooming-in on an active region during its disk passage starting at the eastern limb on 1957 June 20 and reaching western limb on 1957 June 30

References

• Denker, C., Heibel, C., Rendtel, J., Arlt, K., Balthasar, H., Diercke, A., González Manrique, S. J., Hofmann, A., Kuckein, C., Önel, H., Senthamizh Pavai, V., Staude, J., Verma, M. 2016: Solar Physics at the Einstein Tower. Astronomische Nachrichten 337, 1105 DOI: 10.1002/asna.201612442 arXiv: 1609.06949 ADS: 2016AN....337.1105D
• Pal, P., Verma, M., Rendtel, J., González Manrique, S.J., Enke, H., Denker, C. 2020: Solar Observatory Einstein Tower — Data Release of the Digitized Solar Full-disk Photographic Plate Archive. Astronomische Nachrichten, in press DOI: 10.1002/asna.202013791 arXiv: 2007.14744 AN Early View: 10.1002/asna.202013791