The International Occultation Timing Association (IOTA) has just released a new book, Chasing the Shadow: The IOTA Occultation Observer's Manual. It's free, online, and ready for downloading.

Written by IOTA's most experienced astronomers, this is the only manual you'll need to observe occultations by the Moon, by asteroids, and by other solar-system bodies. The 385-page book includes extensive appendices and more than 120 color figures and diagrams.

The book is available at

From the Preface

"Occultations are fun to observe. There is perhaps nothing more exciting than watching
a star vanish and return from behind a lunar mountain, or to see the star disappear for several seconds as an asteroid passes in front of it. Anyone with a small telescope, tape recorder or camcorder, and shortwave radio can make valuable scientific observations to help determine the sizes and shapes of asteroids and to aid in new discoveries about these mysterious objects, including some of the elusive small moons that orbit them.

"This observer’s manual is the first comprehensive book of its kind to help beginning observers get started in occultation observations. It also shows advanced observers the latest in video and GPS time insertion techniques. It is a “how to” guide in observing total and grazing occultations of the Moon, asteroid occultations and Solar eclipses. Whether you are an observer with a small telescope or an experienced observer with a video system this book will show you how to set up your equipment, predict, observe, record, report and analyze occultation observations whether you are at a fixed site or have mobile capabilities....

"The novice occultation observer will find basics of occultations including how to observe and to record them accurately using simple, inexpensive equipment. Advanced observers will find video methods of recording occultations. This includes the use of the GPS satellites along with video time inserters that can provide frame by frame analysis of observations providing timings accurate to several hundredths of a second!

"The potential for new discoveries continues with every new occultation observation. Astronomers, both professional and amateur are encouraged to get involved in this exciting field and get in on the one of several online occultation discussion groups to see what events are to occur in their area. Information on how to get involved with IOTA and contact information is given in Appendix A, along with the many IOTA organizations worldwide."

A Living Book

After another round of editing, we expect to print some paperback versions of the book for those who really want a hard copy. Comments and suggestions are always welcome, as the online version will be updated from time to time.

Richard Nugent
Executive Secretary
International Occultation Timing Association
[email protected]


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