iOptron SMARTSTAR IEQ45TM - Manual (Page 29)

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Follow the on-screen instruction to bring the object back to center again and press ENTER. The
screen will show
If you want to save this anti-backlash number, press ENTER. Otherwise press BACK. This will bring
the hand controller to DEC backlash testing screen. Follow the on-screen instruction to test the DEC
backlash.
5.5.6. Pole Star Position
This shows Polaris position in northern hemisphere or Sigma Octantis position in southern
hemisphere, which is used for Quick Polar Alignment.
5.6. PEC Option
5.6.1. PEC Playback
You can turn “PEC Playback On” while you do the tracking, especially for long time astro-
photography. A “PEC” indicator will displayed on the LCD main screen when it is turned on. The default
status is PEC Playback Off when the mount is turned on. It is not recommended to use PEC Playback while
autoguiding.
5.6.2. Record PEC
All Equatorial mounts have a small variation in the worm gears which can be corrected by using
Period Error Correction or PEC. PEC is a system which improves the tracking accuracy of the mount by
compensating for variations in the worm gear and is especially useful when doing astrophotography without
autoguiding. Because the variations are regular, it is possible to record the corrections required to cancel
out the worm gear variations and to play them back.
In order to use the PEC function, the Go2Nova ® hand controller needs to record the PE first. The
periodic error of the worm gear drive will be stored and used to correct periodic error. There is no need to
record the PE value again unless it is necessary, such as wearing of worm gear after extended use.
Here’s how to use the PEC function.
1. Setup the mount with a telescope in autoguiding condition by connecting a guiding camera to a
computer via ST-4 autoguiding port or ASCOM protocol;
2. Press MENU, select “Auto Guide” and press ENTER. Select a guiding speed from 0.20X to
1.00X;
3. Then press the BACK button and select “PEC Option” from the menu. Use the ▲ and ▼ scroll
buttons to display the “Record PEC” option and press ENTER to start record the PE.
4. It takes the worm gear 400 seconds to make one complete revolution. After 400 seconds PEC will
automatically stop recording. The PEC value will permanently stored inside PEC chip on R.A. motor drive
until a new data are recorded.
5. If you want to re-record the periodic error, select “Record PEC” and repeat the recording
processes again. The previously recorded information will be replaced with the current information.
R.A. anti-backlash
0250 steps
Save test value?