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5' * 10s 10' 30s 20' 1m 30' 2m 1 5m 2 10m 5 30m 10 1h 30 2h Epoch: J2000.0 [Equ] Ecl Alt Gal First, a check-box is provided to let you turn the marking in question on or off. The currently set spacings in declination and right ascension will have check marks beside them. This menu lets you adjust the spacing and epoch of the marking. By default, the menu will show "Automatic Spacing" checked. This means that Guide will judge the ideal spacing for the amount of area covered by a given chart, using a small spacing for small fields of view and a larger spacing for large fields. You will probably be content to leave automatic spacing on at first. If you would like to override Guide's judgment, click on the spacing desired in each column, and automatic spacing will be turned off. After having adjusted the spacing to what you think it should be, you can click "Automatic Spacing" on again, and Guide will follow your judgment when you change levels. Similarly, by default, the marking will be shown in the J2000.0 epoch. Click on the Epoch line, however, and you will be prompted to enter the new epoch for this marking. The fact that different markings can use different epochs allows you to, for example, use a J2000.0 grid with B1950.0 ticks. Also, by default, all markings are in equatorial coordinates (that is, they define spacings in RA/dec). But you do have the option of selecting ecliptic, alt/az (horizon), or galactic coordinate markings instead. Finally, you'll notice a box to select the color of the marking in question. The remaining seven items each bring up fairly simple submenus, in which only the color selection and "on/off" radio buttons are available. The only exception is the "Aperture" option. This option lets you specify the size of a circle, to be drawn superimposed at the center of the chart. In this case, the submenu lets you enter the size of this circle. This is usually used to show the apparent angular field of view of a telescope. For example, if your telescope has (with a particular eyepiece) a .74 degree field of view, you could turn the aperture on and set that size. The resulting circle would let you see how much of
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