ACQUIRING AND PROCESSING ASTRONOMICAL CCD IMAGES
Last updated on March 31, 2007

by Al Kelly

(with narrative contributions from Ed Grafton and editorial contributions by Bert Katzung)

TABLE OF CONTENTS (NOTE: use browser "back" button to return to this page from any section of the document)

INTRODUCTION
GLOSSARY OF TERMS
JUST THE BASICS
SYSTEMS, ISSUES, AND PROCEDURES
The Camera and Its Attachment to the Telescope
The Telescope
The Sky
Taking Images
Processing Images
Post-processing

INTRODUCTION

This e-publication is intended to assist beginners and intermediates in learning what they need to know to make good astronomical CCD images. Based on our perceptions of the community of amateur astronomers on the Internet and on specific requests we had received, it had become obvious in the late 1990's that there remained a need for step-by-step instruction on CCD imaging. Most CCD imagers had learned their trade by reading bits and pieces about cameras and imaging issues in the popular periodical media, reading camera construction and user guides (such as the CCD Camera Cookbook by Berry, Kanto, and Munger), reading books and software user guides on image processing, and visiting Internet discussion forums and websites; but a single, relatively complete instructional guide did not seem to exist. (NOTE: the publication of Richard Berry and Jim Burnell's "Handbook of Astronomical Image Processing" by Willmann-Bell in November, 2000 invalidated this last statement. The Handbook is complete in most regards on the subject of CCD imaging and image processing and, in my opinion, is destined to become a classic.)

By mid-2000, much of this document had been drafted and had been online for several months; thus, regardless of the advent of the Handbook of AIP, our goal remained to prepare and publish an online guide based on our study and experience. This guide is organized to lead the imager from a basic understanding of an astronomical CCD system, to coupling it to a telescope, to acquiring image data, through processing the data for best presentation on output media such as a video monitor or a printer. We admit to being fallible and propose that our words be the starting point for others to forward their corrections and additions, which we will review and incorporate, as appropriate and with appropriate credit, into the basic document. This guide exists as an easily updated document for the benefit of all amateur CCD imagers.

For those anxious to get started as soon as possible, JUST THE BASICS -- a section containing short descriptions of basic image acquisition and processing steps -- follows the GLOSSARY OF TERMS. For those who are ready to read deeper descriptions, recognizing that each arcane term or procedure must be understood in much greater detail to improve CCD imaging expertise and image quality, the main body of this document, entitled SYSTEMS, ISSUES, and PROCEDURES, contains more in-depth discussion, pictures, and Internet references. Even though this will still be short of the level of detail some would like, there may be something for everyone here. By the way, if you get confused by undefined terms or acronyms as you read through the other sections, refer back to the GLOSSARY.