What are some conditions under which the pipeline might unexpectedly fail?
• 108.1 Image reconstruction failure. In less than 1% of observations, attitude control information from the spacecraft is not sufficient to recover accurate positions and small PSFs. A pipeline step called “deltaphot” uses stars in the field of view to track spacecraft motion more accurately than the spacecraft attitude control system. If presented with an arrangement of stars or spacecraft motion outside its envelope, deltaphot will fail. In most cases, deltaphot can recover good PSFs in such cases, but the astrometry will be poor. In very rare cases, the PSFs are also poor and the data will be very hard to use. • 108.2 Corrupt or missing data. If a bad ground station contact results in key data being corrupted or missing, the pipeline may be unable to complete. The pipeline is usually robust enough to simply ignore time periods with missing or corrupt data, so most of the time an afflicted observation simply suffers from reduced exposure time. But in unlucky situations, the pipeline
