6.1. The Data Archive and Distribution Service
The engineering data (temperatures and voltages in different places of the spacecraft, orbital data, jitter), ephemerides, observations plans are also written to optical disks. Finally, also included in the Archive are the reference files used to calibrate the science data.
As of 15 February 1999 there were 6.08 Tbytes stored in the HDA corresponding to more than 10,000 sources in 230,000 datasets. Most of this data is already public. Twenty percent of the data vbolume correspond to NICMOS observations which in 2.5 years of operations produced more than 103,000 observations.
The different tables that are part of DAD are populated by the parameters in the headers of the images, the spectra and the tables that are part of the datasets.