History

Lick Observatory sits atop Mount Hamilton, East of San Jose California, and Silicon Valley. It dominates the horizon to the east and is visible from much of the bay side of the San Francisco peninsula. Since the mountain is to the East, and the moon rises in the East, it seemed that it would be an easy thing to take a picture of the moon rising behind the observatory. It wasn't. With a working knowledge of neither astronomy nor cartography, it took the author and his son nearly two years to capture the first shots of that elusive moonrise. In the process we learned a lot about both topics, and spent many enjoyable evenings chasing that first much-prized photograph. More than a decade later, there is still an indescribable satisfaction in being there when the rim of the moon first peeks over the horizon in precisely the predicted spot.

The original version of Moonchaser was written for the Radio Shack TRS-80 PC-3 "pocket computer" in 1987. Despite the name, the PC-3 was really a programmable calculator. It featured a 24 character LCD display, BASIC in 24K bytes of ROM and 2.2K bytes of RAM for main system memory. Of that, a whopping 1,438 bytes was available for program and data storage. The optional thermal printer provided output on 2-inch paper tape, and included a cassette-tape interface that permitted programs to be stored off-line.

Version 2 was written for the somewhat more capable PC-6 pocket computer which had a reasonably compatible BASIC in ROM and expanded RAM with 7,520 bytes available for program and data storage.

The introduction of the Apple Powerbook 140 in 1992 with 4 Megabytes of RAM and both a hard disk and a floppy drive in a portable, battery powered package proved the impetus for Moonchaser Version 3 which was a minimal rewrite of the calculator-based version.

Peter Duffett-Smith's Astronomy on Your Personal Computer provided the code base for Version 4, a ground-up rewrite of the program. This version also ran on the Powerbook.

The photograph of the moonrise behind Lick Observatory shown on the Moonchaser home page took third prize in the landscape division of the photo competition at the Santa Clara County Fair the year or two after it was taken.

After lying dormant for several years, Version 5 of the Moonchaser program was rewritten in the summer of 2000 as a WinCGI application to run under O'Reilly's WebSite Pro web server. The availability of wireless internet services such as Metricom's Ricochet service mean that all of the resources of the net are available in the field, so making Moonchaser a web application not only provides a convenient way to use the program, but makes it easy to share with other photographers as well.

Version 6 went live in November of 2000. The spherical earth model used for UTM to Lat/Long conversions was replaced with routines rewritten in VB based on Chuck Gantz's C++ program. This substantially improves precision, and supports 27 different commonly used mapping ellipsoids. Links to show the camera and target positions using the MapTech MapServer were also added. This should make it possible to shoot a moonrise without the need for any paper maps, and without the use of a portable GPS.

Plans for Version 7 include a top to bottom re-write, probably in Perl or Python, based on the Duffett-Smith Second Edition routines.

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Current Status

MoonChaser was ported to the WWWeb because the aging Powerbook 145 on which the previous version was implemented is no longer operational, and because the topic of chasing moonrises never quite seems to go away. Like most web sites, the Moonchaser site is in a constant state of reconstruction. It will, however, receive little maintenance and even less ongoing development unless users who find it useful make the effort to contact the author. Please advise of any problems you uncover and let us know if you find this site useful. Of particular interest would be links to pictures you have taken using Moonchaser, or suggestions you have for changes and enhancements.

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Why Not Just Use Photoshop?

Since the Moonchaser project started, digital photography and digital editing tools such as Adobe Photoshop have blossomed. The cut-and-paste image manipulation capabilities of these products make it easy to produce a fake moonrise behind a photo of any landmark. Wouldn't that be less trouble? Yes, but...         Oh well, if we really have to explain, you would never understand.