7: DEIMOS Data Storage Formats

7.1: Introduction

The mosaic design of the DEIMOS CCDs brings a new level of complexity to the task of storing the data. There are 8 CCDs. As mounted in the dewar each CCD will have small rotations and offsets. The incoming light will enter through two separate and non-coaxial optical systems, each of which has noticeable distortions. This implies that 8 different World Coordinate Systems will be needed to describe the data in one exposure.

There are 16 CCD amplifiers, each of which has differing gain, bias, and noise characteristics. The readout may create as many as 64 rectangular sections of data which are not part of the astronomical image but are part of essential calibration information.

The size of the DEIMOS CCD mosaic also presents a challenge. Each readout threatens to produce 140 Mbytes of image data. The manner in which such quantities of data are stored will have notable effect on the speed of processing.

This chapter addresses the issues of storage of these data from the time of readout, through processing, and into archival storage.

Steve Allen <sla@ucolick.org>
$Date: 1996/03/18 19:19:18 $