![]() XEphem instead uses a zoom slider, located at the left of the screen between the star map and the icons. For example, most other planetarium programs use the same method for zooming the displayâdraw a box on screen and click inside the box. ![]() XEphem definitely marches to its own drummer. At first, that is.Īs you begin to explore XEphem, youâll discover its oddities. ![]() Anyone whoâs used other planetarium software will feel right at home. Although the X-Windows interface differs slightly from Windows, KDE, and Gnome, XEphem uses the standard conventions of a star map surrounded by icons on the left, top, and right, with status lines at the bottom. For example, Figure 4-41 shows the same area of sky, but with the Messier Catalog disabled and the Herschel 400 catalog enabled.įigure 4-48. XEphem control center dialogĬhoosing Sky View displays the planetarium screen shown in Figure 4-49. Itâs easy to switch among different catalogs when you want to chart different types of objects. For example, Figure 4-40 shows Cartes du Ciel displaying a section of the southern summer sky with the Messier Catalog activated. There are also many specialized catalogs available, including ones that correspond to the various Astronomical League observing programs. For example, weâve installed the full Tycho2 catalog (2.5 million stars to magnitude 12), the Hipparcos catalog (118,000 stars to magnitude 8.5 with very precise position data), the Catalog of Principal Galaxies, the Washington Double Star Catalog, and many more. Cartes du Ciel makes it easy to download and install supplemental catalogs, of which dozens are available and many are indexed and searchable. The complete program is a 15 MB download ( ), which includes the Bright Star Catalog of 9,096 stars to magnitude 6.5 the Sky2000 catalog of 300,000 stars to magnitude9.0 the full NGC catalog the SAC (Saguaro Astronomy Club) 7.2 catalog of 10,000 nebulae and ephemerides for the planets, comets, and asteroids, which can be updated online.īut the complete program is only the beginning. ![]() Cartes du Ciel is attractive, powerful, and immensely flexible. The premier free planetarium program for Windows is the extraordinary Cartes du Ciel (Sky Charts), written by Swiss astronomer Patrick Chevalley. If you find that none of them are completely suitable, then you can begin exploring the commercial alternatives. We suggest that you try the free alternatives first. But we do think that nearly any amateur astronomer will be completely happy with one or more of the free programs. All of these programsâfree and commercialâhave their own strengths and weaknesses. If that were true, no one would ever buy the commercial programs. We wonât say that free planetarium programs are superior to the commercial products in every respect, or even necessarily their equals. Some of the best and most powerful planetarium programs cost nothing. Fortunately, you probably wonât need to. You can pay hundreds of dollars for commercial planetarium software. You can zoom, rotate, and flip charts on-screen to correspond to the view in your finder or telescope, and then print them for use during the observing session. With planetarium software, you can specify the field of view, the level of detail, the types of objects to be plotted, the limiting magnitude, and so on. With printed charts, what you see is what you get. The major advantage of planetarium software relative to printed charts is flexibility. Astronomers use planetarium software at home to plan future sessions, and in the field to provide updated charts of how the sky appears as of that moment and to provide detailed data about the objects they are observing. Unlike static charts, planetarium software can provide a simulation of the night sky as viewed from any specified location, in real time or for some past or future date. Planetarium software is an almost indispensable adjunct to traditional printed charts. Choose the best planetarium software and start planning observing sessions. ![]()
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