Meade Instruments LX850 - Manual (Page 53)

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AutoStar #497 HANDBOX
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Appendix C
APPENDIX C:
Automatic Rate
Calibration (ARC)
Using StarLock’s Automatic Rate Calibration
(ARC) Feature
Obtaining best performance from StarLocked
telescopes requires that the guiding aggressiveness
be optimally set for current viewing/imaging conditions.
A guide rate calibration routine has been included in
the StarLock software that automatically determines
the best rate based on viewing conditions. Calibrating
your guide rate is a two-step process. First you will
need to train and update the mount’s Periodic Error
Correction (PEC). Then you will run the Automatic
Rate Calibration (ARC) routine. If you have already
trained your mount’s PEC you may go directly to
running ARC.
Periodic Error Correction (PEC)
First set-up and align you scope. Now slew to a bright
star near the celestial equator. Using your AutoStar
II handbox, press the "
7/Ret" key to bring up the
StarLock menu and Set RA Rate and Set Dec Rate
to 33%. Exit the
StarLock menu by pressing MODE.
Wait for the StarLock light to come on continuously
to indicate that it has locked up on the star. At this
point, simply go the hand box menus and select
Setup/Telescope/RA PEC/Train and press ENTER.
The StarLock will lock onto the current star and
watch it for one worm revolution, about 6.4 minutes,
and calibrate your drive’s PEC. For even better PEC
training, add one or more cycle’s worth of data. Select
Setup/Telescope/RA PEC/Update and the scope
will then run one more 6.4 minute worm revolution,
refining the PEC.
PEC training will be retained in the telescope’s
database and will not require retraining providing that
you use the “Park” routine before turning the power
off. The “Park” routine can be accessed through the
“Utilities” menu in AutoStarII. PEC is retained even
if you loosen the clutches, reposition the RA or DEC
axis or disassemble and reassemble the telescope.
Realignment will be required, but PEC training will not
be required.
Automatic Rate Calibration (ARC)
Slew to a bright star near the celestial equator or you
can use the same star that was used to train PEC.
Go to the StarLock Menu by pressing the "7" key.
Then scroll down to Auto Rate Cal. The hand box will
initially display Test Dec 33%. The percentage value
will change about once a minute while it evaluates
different rates. It will then display
Test RA 33% and
evaluate several rates. Finally, the scope will beep
indicating calibration is complete and display the
result on the hand box. Press the ENTER button to
continue.
If you need to abort automatic calibration, just press
the mode key. The process will stop and the default
values will be used as the guide rate.
When to use Automatic Rate Calibration (ARC)
ARC calibration should be repeated at the start of
an imaging session, if you have changed the optical
tube assembly or if environmental conditions have
significantly changed during an imaging session.