Celestron C80ED-R, C100ED-R manual Scope Setup Features, Precise GoTo

AZM RATE

ALT RATE

AZIMUTH LIMITS

AZM MIN LIMIT

AZM MAX LIMIT

E/W FILTERING

FILTERING ON

FILTERING OFF

Note: Some of the databases contain thousands of objects, and can therefore take several minutes to return the closest objects.

Precise GoTo

The Advanced Series telescopes have a precise goto function that can assist in finding extremely faint objects and centering objects closer to the center of the field of view for astrophotography and CCD imaging. Precise Goto automatically searches out the closest bright star to the desired object and asks the user to carefully center it in the eyepiece. The hand control then calculates the small difference between its goto position and its centered position. Using this offset, the telescope will then slew to the desired object with enhanced accuracy. To use Precise Goto:

1. Press the MENU button and use the Up/Down keys to select Precise Goto.	SCOPE SETUP
• Choose Database to select the object that you want to observe from any of		SETUP TIME-SITE
the database catalogs listed or;
		ANTI-BACKLASH

•Choose RA/DEC to enter a set of celestial coordinates that you wish to slew

	to.			AZM POSITIVE
2. Once the desired object is selected, the hand control will search out and display				AZM NEGATIVE
				ALT POSITIVE
	the closest bright star to your desired object. Press ENTER to slew to the bright			ALT NEGATIVE
	alignment star.		FILTER LIMITS
3.	Use the direction buttons to carefully center the alignment star in the eyepiece.			ALTMAX IN LIST
4.	Press ENTER to slew to the desired object.
				ALTMIN IN LIST
		DIRECTION BUTTONS
Scope Setup Features					AZM BUTTONS
					ALT BUTTONS
Setup Time-Site- Allows the user to customize the telescope's display by changing		GOTO APPROACH
					AZM APPROACH
time and location parameters (such as time zone and daylight savings).					ALT APPROACH
		AUTOGUIDE RATES

Anti-backlash– All mechanical gears have a certain amount of backlash or play between the gears. This play is evident by how long it takes for a star to move in the eyepiece when the hand control arrow buttons are pressed (especially when changing directions). The Advanced GT's anti-backlash features allows the user to compensate for backlash by inputting a value which quickly rewinds the motors just enough to eliminate the play between gears. The amount of compensation needed depends on the slewing rate selected; the slower the slewing rate the longer it will take for the star to appear to

move in the eyepiece. There are two values for each axis, positive and negative. Positive is the amount of compensation applied when you press the button, in order to get the

gears moving quickly without a long pause. Negative is the amount of compensation applied when you release the button, winding the motors back in the other direction to resume tracking. Normally both values should be the same. You will need to experiment with different values (from 0-99); a value between 20 and 50 is usually best for most visual observing, whereas a higher value may be necessary for photographic guiding.

To set the anti-backlash value, scroll down to the anti-backlashoption and press ENTER. While viewing an object in the eyepiece, observe the responsiveness of each of the four arrow buttons. Note which directions you see a pause in the star movement after the button has been pressed. Working one axis at a time, adjust the backlash settings high enough to cause immediate movement without resulting in a pronounced jump when pressing or releasing the button. Now, enter the same values for both positive and negative directions. If you notice a jump when releasing the button, but setting the values lower results in a pause when pressing the button, go with the higher value for positive, but use a lower value for negative. The telescope will remember these values and use them each time it is turned on until they are changed.

Filter Limits – When an alignment is complete, the telescope automatically knows which celestial objects are above the horizon. As a result, when scrolling through the database lists (or selecting the Tour function), the hand control will display only those objects that are known to be above the horizon when you are observing. You can customize the object database by selecting altitude limits that are appropriate for your location and situation. For

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