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and amount of its motion over 1000 years. By increasing this value, you can get the motions of slower stars to be apparent. A value of 1000 years is used in the charts of the Millennium Star Atlas, and seems to work well in most Guide charts as well. Some people find these vectors to be distracting; therefore, the default length is 0 years (that is, no vector at all.) By default, Guide shows bright stars using their visual magnitudes on the Johnson photometric system, called "Vj". (This is true for stars from the USNO A2.0 catalogues, described on page 58, or the Tycho catalogue, described on page 66.) Click on the "Vj" box, and you get a choice of alternative photometric systems. Select one, and Guide will switch to use of that system. Please be aware that this is far from a perfect system, mostly because the data is far from perfect. Stars from some catalogues are unaffected by your choice of magnitude system, because the data simply doesn't exist. In other cases, for example when computing Ic (Cousins infrared) magnitudes, Guide has to estimate a magnitude using (for Tycho stars) VT and BT data. For UCAC-3 stars, Guide relies on the "instrumental" magnitude (not quite equivalent to a red magnitude) plus infrared color data from 2MASS to get a color conversion. The result is usually in the right area, but shouldn't be relied upon for precision work. If you select "Color stars", Guide defaults to showing them with very bright, saturated colors. Red stars are fire-engine red, yellow stars are canary yellow, and so forth. Of course, stars actually appear visually to have much milder colors. You can replicate this effect by changing the "saturation" value. It defaults to 100%, full color saturation. Turn it to, say, 50%, and the stars will appear to be somewhat more realistically colored. The "blurring" option is another gesture toward realism. Set it to a non-zero value, and Guide will draw stars with softer edges, making them look a little more circular. A value of 1 to 3 is usually considered visually pleasing. As with many of the settings in this dialog, though, your personal preferences may be very different. 7b: The Data Shown dialog First, a very important tip: if you see an object on the screen, and wish to turn it off, or change its color, or change the fields of view at which it is displayed, the simplest thing to do is almost always to just click on it with the right mouse button. You will get a small dialog box describing that object, and a "Display" button. Clicking on this will lead you to the controls for that type of object. (For example, right-click on a galaxy, then on "Display", and you can adjust such things as the limiting magnitude for display of galaxies.) This is an immensely simple and powerful way to deal with objects
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