DENIS Data Storage

The primary DENIS images, taken from La Silla, are stored on DAT tapes then they are sent to Paris. After processing (flat-field, bia... ), the secondary data are stored on DLT tapes.

For each image (FITS format file), there is a header in which are noticed some scientific and processing paramaters. Theses datas are read and, for the most of them, are stored in the FOURBI (Follow Up Relationnal Base of Image) database. So we keep, for each strip, the corresponding tape number where we can restore processing data on disk.

The DLT tapes most recent are placed in a tapes robot (60 tapes) so the most recent processed images are available for DENIS scientific communauty from the web, from which the  user can ask to extract some images from these tapes after a simple request to the FOURBI database. Then, the extracted images are recoverable by  FTP.

From these images, scientists extracted the point sources (stars) and extended sources (galaxies). The positions and scientific parameters associated to these sources are stored in catalogs and databases.