Meade LX200-ACF 12 inch User Manual - Page 40
Periodic Error Correction PEC Training
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Periodic Error Correction (PEC Training) If you wish to perform high-precision astrophotography, you may wish to "train" your telescope in order to keep objects that you are imaging dead center in the telescope's mirror during the photographic exposure. Periodic error correction (PEC) helps to remove the slight perturbations from center that occur due to the mechanical nature of a telescope. To perform this procedure, you need to use a high-power reticle, such as the 9mm reticle (see OPTIONAL ACCESSORIES, page 44). PEC training is available for both drives. Train Menu Option If you perform this procedure in alt/az alignment, you can train the telescope in both the R.A. and the Dec. axes; in polar alignment, you need only train the telescope's R.A. axis. If you train the telescope in polar alignment, make sure that "Polar" is selected in the "Telescope: Mount" menu ("Alt/Az" is the default setting). To perform the procedure on the Dec. axis, pick a bright star in the East or West that is about about 20° above the horizon. To perform the procedure on the R.A. axis, pick a bright star in the South that has minimal movement and is about 30° above the horizon (Note: If in the Southern hemisphere, pick a star in the North that is about 30° above the horizon). Important Note: The Train option overwrites any previous PEC data. 1. Select "Train" from the Dec. PEC menu (in the "Setup: Telescope" menu) and press ENTER. 2. Look through the reticle. Use the Arrow keys to keep the star centered in the reticle cross-hairs. AutoStar II displays a count of the 200 positions of the worm gear. When the count reaches 200, one cycle is complete. A full cycle takes about 8 minutes. 3. Select "Train" from the R.A. PEC menu (in the "Setup: Telescope" menu) and press ENTER. 4. Look through the reticle. Use the Arrow keys to keep the star centered in the reticle cross-hairs. AutoStar II displays a count of the 200 positions of the worm gear. When the count reaches 600, one cycle is complete. A full cycle takes about 24 minutes. 5. Press MODE to exit. Update Menu Option Use the Update option to further refine your training; it is recommended that you update your original training two or three times when first using your telescope. Update does not overwrite the data, but updates the training using information gathered from both the last and the current training sessions. Press the MODE key to exit from this option. If you wish to further refine your training, select this menu again and repeat the procedure. Erase Menu Option Select this option to erase all PEC training data. On and Off Menu Options Select "On" when you want the telescope to use the training information. Select "Off" when you do not want for the telescope to use the training information. Select "On" to enable the Smart Drive. - 40 -