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StarCalc – Still Around and Still Useful

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Anyone familiar with astronomy software knows that free planetarium programs are a dime a dozen. There’s Google Sky, Microsoft WorldWide Telescope, Cartes du Ciel, and a host of others. This review focuses an oldie but a goody, StarCalc.

Many folks have strong feelings and attachments regarding their planetarium software and it often suits their individual needs. For casual sky observers, Google Sky often suffices. Observational astronomers like the sky chart feel of Cartes du Ciel. Others who enjoy more serious armchair stargazing enjoy Microsoft WorldWide Telescope for its versatility and ability to dig ever deeper into a stellar object. And there are yet many other programs available too.

Astrophotographers are another group with their own requirements. They’re usually folks on a mission. They know what they want to shoot and they know how they’re going to get it. They wait patiently for good skies and when there’s an opportunity, they pounce.

StarCalc isn’t like the other free planetarium programs. It has no lofty goals. It displays no spectacular photos of night sky objects. Its display is a very simple rendering of the night sky as shown.

Memory and Configuration

Memory usage of StarCalc is very small compared to other free planetarium programs. Compare for example StarCalc with the following programs in terms of private bytes memory usage:


Private Bytes

Requires Internet

Telescope Control

Help Docs

Google Sky





Microsoft WorldWide Telescope





Cartes du Ciel










Even more impressive, StarCalc’s statistics above were running with numerous optional plug-ins including a full Tycho-2 star catalog, SkyMap’s asteroids and comets catalog, as well as the NGC 2000 catalog.

My field set up for astrophotography is simple and my laptop is a brutally old eMachines running Windows XP with only 458 megabytes. It doesn’t have an option for upgrading the memory and has a tendency to overheat at normal temperatures. StarCalc is a wonderful way to breathe new life into old hardware.

StarCalc has an extensible interface that allows users to add new modules as plugins. Plugins are varied and include interfaces to the SAO Star Catalog, a compact StarCalc version of the SAO star catalog, an interface to the Tycho-2 catalog, an interface to the Guide Star Catalog, an interface to the USNO-A2 Star Catalog, SkyMap’s Asteroids and Comets database, interfaces to calculate solar and lunar eclipses, an NGC 2000 catalog plugin, a Milky Way overlay, and an ecliptic line overlay. I usually run StarCalc with the Tycho-2 catalog and ecliptic line overlay. Rendering is very fast, even on old hardware.

Configuration of StarCalc during the first run or site relocation is relatively simple. Under the Parameters->Options menu, it’s best to put in your current location.

It’s very straightforward and there’s a nice helper button for converting GPS coordinates to decimal format. And like Cartes du Ciel, StarCalc helps you improve accuracy near the horizon by specifying ambient temperature and pressure for your location.

When you load plugins such as the Tycho-2 Star Catalog, you can control when the catalog is loaded based on the zoom level as well as set a threshold for the magnitude brightness display. This is handy when you’re doing final navigations and framing for your astrophotography sessions.

Data Displays

Navigation in StarCalc is simple and intuitive. Your mouse’s scroll wheel controls the zoom and holding down the left mouse button allows you to pan the view as desired. I’ve always been puzzled by Cartes du Ciel’s decision to require one to hold down the scroll wheel in order to pan the view.

Right clicking after selecting a stellar object allows you to extract more information about the object including type, ephemeris, rising and setting, and other data. If you’re familiar with the description legend of Burnham’s Celestial Handbook series, you’ll find that this program also uses the same legend for detailed object descriptions.

Though StarCalc doesn’t produce photography quality imagery of the sky, it’s still possible to infer the general size of objects when you’re doing imaging, particularly for objects that require low focal lengths.

When you zoom into objects, StarCalc will draw a circle outlining the general size of a given object.

Highlighting an object and right clicking allows you to obtain more information.

StarCalc also provides plenty of copy/paste functionality for its data.

Solar System Objects

StarCalc provides good support for solar system objects. For example, Jupiter’s position is accurately displayed relative to the ecliptic and provides good data on its satellites.

Zooming in on Jupiter provides a simple display of where satellites are located relative to the time selected.

Do you live in an area that provides poor visibility when the ecliptic is low? You can easily set the date to anytime in the future to see if your luck will improve.

Telescope Integration

StarCalc, like Cartes du Ciel and Microsoft WorldWide Telescope allows you to connect your telescope as a substitute for your GOTO hand controller.

Using free planetarium programs for GOTO navigation can be very handy for astrophotographers because you’re not beholden to a fixed set of bright stars listed in the hand controller. You can align your scope to any object in the sky.

StarCalc is fully ASCOM compliant. Once you’ve installed your telescope control drivers, you simply select Telescope->Choose option to select your particular mount interface after ensuring that your mount is connected to the correct port on your computer.

Slewing to an object in StarCalc is as simple as right clicking on an object and selecting, “Slew To…”.


StarCalc is an older free planetarium program that still works wonders in the field. The beauty and elegance of StarCalc is in its simplicity. It simply gives you a straightforward sky chart and keeps the user close and involved with the basic motions of the night sky. It doesn’t require any internet connection which makes it ideal for quick set ups and configurations in remote locations. When you’re doing astrophotography in a remote location, simplicity is your friend.

StarCalc’s last release was in September 2003. Recently I spoke with the author of StarCalc and he indicated that he was preparing to write another planetarium program. It will be interesting to see what he comes up with.

StarCalc and its associated plugins can be downloaded from:


There are also two mirrors located at the following links:




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