November DAS Focus

COMPUTERS IN ASTRONOMY by Don Shedrick

At the last DAS meeting, Scott Jackson gave a demo of the software program Dance of the Planets. The DOS based program has been around a long time, but is still available as a CD by ordering from ARC Science at their web site:

http://www.arcscience.com/frameset.htm

It is a working dynamic model of the solar system with an impressive collection of features hard to duplicate all in one program, including orbital simulations of planets, moons, comets and more. Data for 9,300 stars are included (approximately twice what can be seen with the naked eye), as well as some 1,500 comets, 6000 asteroids, and all known satellites. The program is, however, a bit pricey at $95, plus $90 to get the full magnitude 10+ star catalog. Be sure to download the Dance of the Planets Patch, which fixes the Runtime Error 200 on machines that are faster than 200MHz.

While I dont know of another program combining all of Dances features, several individual programs have been featured in this column in the past that have similar capabilities, and they are freeware available off the Internet. Many are on the DAS Astro BBS, but I will review them again here with their web site addresses, so you can download them by simply clicking on the hot links in this article.

Home Planet is a Microsoft Windows application that calculates for any time or location the position of the Earth, Sun, Moon, planets, asteroids, comets, and Earth satellites with high accuracy and provides many features, including the following capabilities:

Sky map -- Shows stars, planets, satellites, constellations, deep sky objects, track selected asteroid or comet. Click on object in sky map to display a telescope view

Animate -- Watch Earth rotate and orbit, planets move, Earth precess, stars drift over millennia.

Telescope display -- Shows stars, planets, satellites, and asteroids/comets, deep sky objects at selected magnifications, pan and zoom the aim point

Horizon view -- Select viewing direction

Orrery -- View solar system from any viewpoint

Believe it or not, all this capability is completely free, and I highly recommend it. The smaller star data base version is posted on the ASTRO BBS. In addition to this, a larger data base version to Magnitude 10 and more info can be obtained from the web at:

http://www.fourmilab.ch/homeplanet/homeplanet.html

Your Sky is a web based version of Home Planet requiring no download of software to your PC, and has most of the planetarium features of Home Planet. Your Sky is much easier than Home Planet for printing of star charts after you set them up just like you want. It is on the web at:

http://www.fourmilab.ch/yoursky/

SkyGlobe is a DOS program available on the DAS Astro BBS. Emil Volcheck, Manager of Mt. Cuba Observatory, has a version on a floppy disc customized for the Mt. Cuba location available for $5. It is also available many places on the web, such as from the Bradford Robotic Telescope Observatory site at:

http://www.telescope.org/rti/guide/brad/lo0.html

It is the planetarium program that will give you the most accurate feeling of sitting under the night sky or in a true planetarium. SkyGlobe is very easy to use, with almost no inputs or adjustments needed. It is excellent for giving the user a real understanding of how the stars and planets track across the sky, as you can set the sky in motion by tapping the "A" on the keyboard. Explore how all the keyboard letter and function keys, and ctrl B and alt B, change the display. SkyGlobe, however, does not have the vast array of features that Home Planet or Sky Charts have. A Windows version is available, but harder to find on the web. Villanova University Astronomy & Astrophysics web site has it at:

http://astro4.ast.vill.edu/skyglobe.htm

This is a much larger file to download (1.29MB), and getting the program up and running is tricky - it does not seem to want to run on all PCs, but the interface is much nicer and there are some added features.

Sky Charts is a very powerful sky charting freeware program. This program enables you to draw sky charts with a vast array of options, including the choice of data in 15 catalogs of stars and nebulae, and the position of planets, asteroids and comets. The large number of options allow you to choose which catalogs to use, the color and the dimension of stars and nebulae, the representation of planets, the display of labels and coordinate grids, the superposition of pictures, the condition of visibility and more. The user can enter the specifications for personal eyepieces for accurate projection of eyepiece fields, and there is a red shading mode for night field use with your laptop. All these features make this celestial atlas more complete than a conventional planetarium program, but also make it more difficult to use. Home Planet is easier to use and has easier to read charts. But one big advantage of Sky Charts is it has a flexible print function, something missing in Home Planet. With Home Planet, you need to print by capturing the screen to a utility such as MS Paint. Sky Charts is too large a file for the DAS Astro BBS, so go to the French authors web site at:

http://www.stargazing.net/astropc/

to get more info and download the program.

PlanetWatch, is available on the DAS Astro BBS, and on the web site of the author of this software at:

http://ourworld.compuserve.com/homepages/galen_raben/

It is an entertaining and educational shareware program featuring an atlas of the solar system with a very nice sky chart of the region +/- 30 degrees, or the region of the sky containing the ecliptic. In this region of the sky, the motion of the sun, moon, and planets can be observed by setting the map in motion. The phases of the moon even change as it passes along the ecliptic. With PlanetWatch you can also see each planet's motions in an Orrery style display, photographs of the planets, and learn about planetary atmospheres, geology, and internal structure. For $20, a pro version is available with a few added features and more photos. For more info visit the web site.

Lunar Phase, available on the DAS Astro BBS and (a newer version) at the web site of the author of the software:

http://indigo.ie/~gnugent/LunarPhase/

This program displays, for any selected date and time, the moon & sunrise, set & transit times, as well as the lunar location coordinates, phase, illumination fraction, distance, and age. There's even a graphic that shows you exactly what the moon looks like, with the option to view through binoculars or a telescope. Flipping through the months will pop up an eclipse icon when a lunar eclipse occurs; clicking on that icon brings up a screen detailing the circumstances of that eclipse. It also calculates and displays start and end times for Civil, Nautical and Astronomical Twilight.

 Next month Ill review the programs for tracking the satellites and other features of Jupiter and Saturn.