The Catalogs and Surveys Branch of the Space Telescope Science Institute has been digitizing the photographic Sky Survey plates from the Palomar and UK Schmidt telescopes in order to support HST operations and provide a service to the astronomical community. We have a few examples of typical astronomical objects from these scans on-line. In order to provide convenient access to these data, the images have been compressed using a technique based on the H-transform to reduce the data volume. Although the technique is lossy, it is adaptive so that it preserves the signal very well. We typically compress the data by a factor of 10 but much higher compression ratios are possible.
Users can then easily retrieve image data for any part of the sky.
We have completed a revised photometric calibration for the DSS data. They currently publish two products. This is primarily for Observatories, Astronomical Institutions and professional astronomers as this retains virtually all the detail in the original data. Both are suitable for amateur astronomers and educators. National Astronomical Observatory of Japan.