ASTRO-PHYSICS GTO - Tweak Your Pointing Accuracy; Sync Explained in Detail and Compared to Re-Calibrate

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6. Double check to be sure the object is still centered and that your mount’s orientation is correct. Press “1=Sync current
object”. The Keypad will beep and display an – Object Synced – message. Press MENU to exit.
Your mount is polar-aligned and you were moving the telescope manually to look at a few objects before slewing with the
go-to feature.
Use the same procedure as above, beginning with step 2.
Tweak Your Pointing Accuracy
You slew to an object and center it in your eyepiece with your N-S-E-W directional buttons. You have two choices, either
re-calibrate (preferred) or sync. Both are possible; however re-calibrate is safest and easiest and involves the least
number of keystrokes. Many things can affect the pointing accuracy of your system. The accuracy of your clock and
location settings and especially the orthogonality of your entire system can play a role. Don’t drive yourself crazy trying to
make every slew hit the dead center of a high power eyepiece.
If orthogonality issues are affecting your pointing accuracy, use a smart strategy to compensate. Organize your observing
around one or several regions of sky. The regions can be on opposite sides of the meridian, but slews within the region
should not require you to cross the meridian. When you nish a region, slew to a bright star in the next region and re-
calibrate. As long as you are not swapping sides by crossing the meridian, you should be able to slew to objects within a
reasonable radius of your calibration star with satisfactory accuracy. The useful radius will simply depend on the degree
to which your system is not orthogonal, but you should be able to observe in a radius of 20 to 30 degrees before re-
calibrating.
Re-calibrate
Re-calibrate is used to calibrate the position of the mount if an object does not appear in the center of the eld. Re-
calibrate can be used even when the object is past the meridian and the telescope is below the mount.
“9=Re-Calibrate” calibrates on the last object to which the telescope was sent.
Let’s say that you slew to “3=Caph” and center using N-S-E-W buttons. Simply press the RA/DEC REV button and select
“9=Re-Calibrate”.
Note: You can only use the re-calibration option if the Keypad has the target object in its memory, i.e. you just gave a slew
command and the Keypad already knows it should be at that object. You CANNOT use this option if you manually move
the telescope to another position, since the Keypad would have no way of knowing what that object is. In this situation, use
sync as described below.
Sync
As in the example above, let’s say that you slew to Caph, then, by hand, center the object in your eyepiece. From the
“Star Object” screen for Caph, press the NEXT> button which will display the “Sync Conrmation” screen – make sure
your telescope is positioned correctly (see below). Press “1=Sync”, the Keypad will beep, and then press MENU to exit.
Before syncing:
● Make sure your mount and telescope are properly oriented.
● You must be polar aligned
● Do NOT have your Meridian Delay feature turned on
The sync procedure is outlined above and the command is described further in the following section.
Sync Explained in Detail and compared to Re-Calibrate
Sync and Re-calibrate are often used as synonyms in everyday use, but to the Keypad and GTO Control Box directing the
movements of your mount, they are different and distinct. Understanding this distinction will aid you in enjoying your Astro-
Physics GoTo system.
The Sync command is typically used at the beginning of an observing or imaging session. Sync tells the mount where it is
pointing and denes which is the telescope side and which is the counterweight side. It is a powerful command in that it
disregards earlier slewing commands and starts over. It does not take the last entered position into account, but tells the
mount – “You are here,” based on the object displayed on the Keypad screen. It assumes that the telescope is correctly
pointed with the sync object and the telescope on opposite sides of the meridian. Each time you use sync, you redene
the orientation of the telescope and counterweight to the mount. If used in the wrong way, the sync command will cause
the mount to slew incorrectly and possibly cause damage to equipment. It should therefore be used with caution.
Star: Caph
RA: 00:09:11
DEC: +59:09:00
Menu=Exit 1=BkMk
Star Object Screen - Caph