RealSky/DSS Copyright

The eight CD-ROMs of the RealSkyCD contain the 1949-58 epoch Palomar Observatory Sky Survey E band (red plates), compressed 100 times. For the first time, the public has access to actual deep-sky survey plates used by research astronomers. The unprecedented level of detail, especially of extended images like galaxies, clusters, and nebulae, is not available with any other astronomical software package.

Uncompressed, current storage technology would require over 800 CD-ROMs to accommodate this enormous data storehouse; but the 100x compression makes distribution of this essential resource both feasible and affordable. The 100X compressed data provides a basically faithful reproduction of the original data, but the critical user is advised of the following caveats:

(1) At extreme contrast enhancements, the sky background takes on a patchy or tiled appearance; this is due to the discretization of sky noise required by this high degree of compression.  In crowded fields both this effect and a tendency to blend close pairs near the sky limit are exacerbated.

(2) Photometrically, the flux limit is about 1 magnitude brighter than the limit of the original plates
and the precision may be degraded by up to 15% for the brighter objects.

(3) Astrometrically, the positions are consistent with the original material to within 0.8".

For comments and suggestions, contact the Software Bisque Support Corner

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