Pec option – iOptron SMARTSTAR IEQ45TM User Manual

Page 29

background image


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

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

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


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?