Although the naming conventions used for IUESIPS and NEWSIPS files differ, they generally include the camera name, the image sequence number, and some descriptor indicating the type of data in the file. Depending on the format of the file, this information may appear only in the filename, or in both the filename and the extension. As a shorthand notation, the appropriate part(s) of the name are referred to as the ``imaget'' throughout this manual.
There are six IUE cameras. Two of them are Fine Error Sensors that do not return spectral data. They are used for target acquisition and attitude control, but sometimes their images are archived. The other four cameras are for spectra, but only three of them were ever really operational. Each camera has a name and a number, as shown in Table 1.1.
For each camera, every image has been assigned a unique Image Sequence Number. This number will have usually have five digits, zero-filled as necessary. The numbering scheme starts with 1000 (a handful of images, originally mis-numbered, have numbers starting with 500).
Data types vary with processing software, but generally several stages of processing are preserved. First there are the raw data files. There are intermediate stages preserved as well--a photometrically corrected image, a spatially resolved spectrum, and finally an extracted spectrum. These files may contain data from either or both the large and small apertures. Aperture designations often appear in the file names.