Issue 157 August 2003
Palm-Enabled Telescope

Start • Palming the Problem • The Palm Application • The Galileo Protocol • Sources and PDF

Galileo achieved lasting fame by being one of the first to turn a telescope toward the heavens to have a closer look. Such innovative applications of technology were his specialty, and I wonder what he would do with today’s telescopes. Modern telescopes are smaller, higher powered, and have computer-controlled pointing, but they could still use the hand of a master.

The controls on my Meade ETX-105 telescope (with Autostar controller), for instance, include a sophisticated star location and tracking algorithm. Unlike my Palm Pilot, however, the user interface for the telescope is a primitive set of buttons and a two-line display. What would Galileo do? I like to think he would do what I did, which was to create an adapter that enables a Palm to run the telescope.

Of course, you may be wondering why someone would want to use a computer to control a telescope. After all, you just point and look, right? Well, that’s true if you know where you want to look. But many interesting objects in the night sky cannot be seen with the naked eye, which makes it difficult to figure out where to point the telescope. Fortunately, astronomers have cataloged the positions of sky objects so you can find them. Unfortunately, the position is given in the celestial coordinates of declination and right ascension, the latitude and longitude of the sky, which remain fixed in space while the Earth moves underneath.

The Meade telescope’s Autostar controller helps locate objects in the sky by compensating for this motion. The compensation depends on your location as well as the Earth’s daily and annual movement, so the Autostar needs to know latitude and longitude as well as time and date. With this information, and a little alignment, the Autostar can point the telescope to any celestial coordinate.

The alignment process is relatively simple, at least in concept. You enter the day and time, your location, and choose one of the alignment modes. The two-star alignment mode, for instance, picks two easily identifiable stars as its reference marks in the sky. With the alignment mode picked, the telescope points itself at the first star, and then you make fine adjustments to bring the star to the center of the telescope’s field of view. When you’re done fiddling, the telescope moves to the second star and has you make fine adjustments. At that point, the Auto-star can automatically point toward any of several thousand objects it has listed in an on-board database.

The trouble is that, like so many product designs, usability was sacrificed to save cost. As you can see in Photo 1, the controller unit has a simple two-line display and a numeric keypad as its user interface. It uses a nested menu, which gives you access to all of its operating modes as well as the thousands of items in its star catalog. This is an inconvenient interface for entering the date, time, and location, and it’s extremely clunky when trying to find an object in the database. Scrolling two lines at a time through a list of thousands of stars is not my idea of usability.

What my telescope really needed was a graphical user interface that made it simple to find what I was looking for. Automating the entry of set-up information also seemed like a good idea, because I can hardly keep track of time much less my latitude and longitude. The Autostar includes an RS-232 port for using a laptop computer to handle the interface, but I didn’t want to have cables that I could trip over in the dark connecting my laptop to the telescope. With my luck I’d trip, pull the telescope over, crash into the computer, and destroy them both.