Celestron CGEM II Mode D'emploi page 28

Note: Once the worm gear is indexed, it will not need to
be positioned again until the telescope is turned off To give
yourself more time to prepare for guiding, it may be necessary
to restart PEC recording after the worm gear has found its
index
6 After 10 minutes, PEC will automatically stop recording
7 Point the telescope at the object you want to image and
center the guide star on the illuminated cross hairs You
are ready to play back the periodic error correction
8 Once the drive's periodic error has been recorded, use
the Playback function to begin playing back the correction
for future imaging guiding If you want to re-record the
periodic error, select Record and repeat the recording
processes again The previously recorded information
will be replaced with the current information Repeat
steps 7 and 8 to playback the PEC corrections for your
next object
Does the PEC function make unguided astroimaging
possible? Yes and no For solar (filtered), lunar and piggy-
back (up to 200 mm), the answer is yes However, even
with PEC, autoguiding is still mandatory for long exposure,
deep sky astroimaging
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