Celestron CGX-L Mode D'emploi page 19

HINT: In order to minimize the affect of gear backlash on
pointing accuracy, the settings for Button Direction should
ideally match the settings for GoTo Approach. By default,
using the up and right direction buttons to center alignment
stars will automatically eliminate much of the backlash in the
gears. If you change the GoTo approach of your telescope,
it is not necessary to change the Button Direction as well.
Simply take notice of the direction the telescope moves
when completing its final GoTo approach. If the telescope
approaches its alignment star from the west (negative
azimuth) and clockwise (negative altitude) then make sure
that the buttons used to center the alignment stars also move
the telescope in the same directions.
Autoguide Rate – Allows the user to set an autoguide
rate as a percentage of sidereal rate This is helpful when
calibrating your telescope to a CCD autoguider for long
exposure astroimaging
Meridian – This feature instructs the mount on how to
respond when it is slewing to objects that are accessible
from both sides of the Meridian The Meridian feature allows
the telescope tube to remain on a desired side of the mount
when slewing, and continue to track according to the R A
slew limits the user has set See R A Limits below The
Meridian feature allows for four choices:
• Favor Current – Allows the mount to favor whatever side
of the mount that it is currently on when slewing to objects
close to the Meridian For example, if your R A slew limits
are set to allow the mount to track 10° past the meridian,
then the telescope will continue to stay on its current side
of the Meridian when slewing to objects that are as far as
10° beyond your Meridian
• Favor West – If the target object is accessible from both
sides of the mount, selecting "Favor West" instructs the
mount to point to the object as if it were on the west side
of the meridian The optical tube will then be positioned on
the east side of the mount and pointing west
• Favor East – If the target object is accessible from both
sides of the mount, selecting "Favor East" instructs the
mount to point to the object as if it were on the east side
of the meridian The optical tube will then be positioned on
the west side of the mount and pointing east
• Disable – This is the default setting, which instructs the
mount to always swing around to the other side of the pier
as required to view objects on the opposite side of the
Meridian However, once at the desired object, the mount
will continue to track past the Meridian according to the
R A slew limits that have been set
Mount Settings – Once the mount settings have been
calibrated (see Utilities section below) the values are stored
and displayed in the hand control It is not recommended
that the calibration values be changed However each setting
can be changed if necessary to improve the performance of
the telescope
• Cone Value – This is the cone error value set when
Utilities/Calibrate Mount/DEC Switch – Cone is carried out
• DEC Index – This is the declination index error value that
is stored when calibration stars are added after your initial
star alignment
• R.A. Index – This is the R A index error value set when
Utilities/Calibrate Mount/R A Switch is carried out
R.A. Limits – Sets the limits that the telescope can slew or
track in Right Ascension (R A ) before stopping The slew
limits are represented in degrees and by default set to 0°,
being the position of the telescope when the counterweight
bar is extended out horizontally However, the slew limits can
be customized depending on your needs For example, if
you are using CCD imaging equipment that has cables that
are not long enough to move with the telescope as it slews
across the sky, you can adjust the slew limit on the side of
the mount that is restricted by the cables, and command the
mount the stop slewing before it reaches this point Or if you
are taking an image of an object that has just crossed the
Meridian, you can set the limit to allow the mount to continue
tracking in the same direction past the Meridian without the
need to "flip" the telescope around to the opposite side of
the mount (see Meridian feature above) Using the first example
above, the user could slew the telescope in R A (azimuth)
until it reaches the point that the cables are extended to their
maximum Then by displaying the telescope's azimuth in this
position (by looking at Get Axis Position under the Utilities
menu) you can determine the telescope's azimuth at its most
extended position Enter this azimuth reading for either the
maximum or minimum azimuth slew limit to ensure that the
telescope will not slew beyond this point The telescope slew
limits can be set to automatically stop anywhere between
40° above level to 20° below level To set the R A slew limit
select the following:
• R.A. East Limit – Enter a number between +40° to -20°
to define the slew limit when the tube is on the east side of
the mount
• R.A. West Limit – Enter a number between +40° to -20°
to define the slew limit when the tube is on the west side
of the mount
• Disable Limits – This disables any pre-defined values
that have been entered and allows the mount to track
the maximum amount pass the Meridian (i e , -20° on
both sides)
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