Online Astronomy eText: Introduction to This eText
Preface
History and Long-Term Goals
 This work began as a series of handouts intended to summarize topics that were covered in my astronomy lectures differently than in the required textbook. Over time the number of handouts became so large that they exceeded the department's duplicating budget, and for a few years they were sold in the bookstore as a supplement to the text. During the summer and fall of 2002 I moved all existing handouts to my web site, considerably revising and enlarging them in the process, and since then have continually added new material. At the moment the Astronomy eText contains over a thousand images and diagrams, and the equivalent of two or three hundred pages of notes. As time and energy permit, it should grow to five to ten thousand images and diagrams, and the equivalent of fifteen hundred to two thousand pages of material related to introductory and lower-division astronomy classes, and background material from related sciences. However, I am also working on a decades-long project involving a Celestial Atlas and catalog of thousands of so-called NGC/IC and other deep-sky objects, so progress on the eText has been slower than I might like.

Use of This eText in My Lecture Classes
 Despite many additions and revisions the eText remains as it was -- uneven in the quality of its presentation, and breadth of content. Pages which are extensively referred to in class should be studied as if they were part of a textbook, but this work is not an adequate substitute for a textbook. So for the foreseeable future, students in my lecture classes must buy the required textbook, for use as their main reference.

Use of This eText in My Lab Classes
 Although some parts of this work are useful as background material for lab class presentations, there is no need for my lab students to study any part of the eText unless otherwise stated in class.