Chapter 2:
STIS Data Structure
2.1 Overview
2.2 Types of STIS Files
2.2.1 Trailer Files
2.2.2 Understanding Associations
2.3 STIS File Structures
2.3.1 STIS FITS Image Extension Files
2.3.2 STIS FITS Table Extension Files
2.4 Headers, Keywords, and Relationship to Phase II
2.5 Error and Data Quality Array
2.5.1 The Error Array
2.5.2 Data Quality Flagging
2.6 STIS Coordinate Systems
2.6.1 Spacecraft, User, and Aperture Frames
2.6.2 CCD Binned Pixel and Sub-array Coordinates
2.7 STIS Paper Products
This chapter explains how STIS observations are stored in STIS data files. STIS data files received from the Archive will be in FITS format, and they should remain in FITS format (i.e., do not convert the format with strfits). Chapter 2 of the HST Introduction describes the structure of FITS files, explains how images and tables are stored in FITS extensions, and shows how to access data in these extensions. If you are not familiar with FITS extensions, please read Chapter 2 of the Introduction to Reducing HST Data Section of this Handbook.
