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people use one encoder to measure the hour angle at which a telescope is pointed; with the drive motor on, this encoder reads a changing value as the scope moves. Other people, though, will use one encoder to measure the RA at which the telescope is pointed. In such a case, the drive motor doesn't force the encoder to move. Unfortunately, Guide has no way to determine which system you're using. So when you add the first alignment star, it will ask you for this information. Click on the "Scope Pad" option, and you'll get a small dialog box with assorted scope control commands. The next step is to add at least two alignment stars. To add an alignment star, you first find it in Guide (by panning, or using "Go To..." commands, or whatever you wish) and clicking on it with the right mouse button. When you get the short dialog box describing the star, click OK. Next, point the telescope at this alignment star. Once you have it centered, click "Add Alignment Star" in the scope pad. Guide will add that point in the sky to its alignment database. After you have added at least two alignment stars, you can actually get some pointing feedback from the telescope. Click on "Slew Telescope". Guide will read the encoders at one-second intervals, putting a red circle on the screen to indicate where the scope is pointed. If the scope is pointed off-screen, Guide will force a redraw and then put the red circle on the screen. This is useful in aiming the telescope; you set a wide field of view, click "Slew Telescope", and push the telescope until the indicator circles the target. Once you're done with this, clicking on "Slew Telescope" again will shut off the red-circle updates. Alternatively, clicking on "Slew Guide" will cause it to read the encoders once, resulting in the chart being redrawn at the current telescope position. Adding still more alignment stars can improve pointing accuracy considerably. If you find that the accuracy is poor in a given part of the sky, it's advisable to find a nearby bright star and to add it as another alignment star. This gives Guide an idea as to the amount of error in that part of the sky; it can then compensate accordingly. At present, there is no command to delete the alignment data; and this is something you'll want to do if you move the scope or shut down the encoders. To clear alignment data, delete the file ALIGN.DAT in the Guide directory. 12: PRINTER SETUP AND PRINTING
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