User's Manual

5.4.11. Set RA Guiding

The function is for the EC version of the CEM40 only. You can turn off R.A. guiding by selecting “Inhibit

R.A. Guiding” to allow the high precision encoder to correct the tracking error, or turn the R.A. guiding

on by selecting “Allow RA Guiding” to allow the mount to receive guiding corrections from the guiding

software. The power on default setting is “Allow RA Guiding”.

5.4.12. Language

Select one of supported menu languages. Currently it has English and Chinese.

5.5. Electric Focuser

This function controls an iOptron electric focuser.

5.6. PEC Option

This function only works for the standard CEM40 mount.

5.6.1. PEC Playback

You can turn “PEC Playback On” to improve tracking accuracy which is especially useful for long

exposure astrophotography. The default status is “PEC Playback Off” when the mount is turned on.

5.6.2. Record PEC

All equatorial mounts have a small variation in the worm gears which may 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 to correct the periodic error caused by the

variations.

In order to use the PEC function, the Go2Nova

hand controller first needs to record the periodic error.

The periodic error of the worm gear drive will be used to correct periodic error.

To use the PEC function:

1. Setup the mount with a telescope in autoguiding configuration by connecting a guiding

camera via the mount’s Guide Port or using the ASCOM protocol;

2. Select “MENU=>Settings => Set Guiding Rates”. Set a guiding speed from 0.10X to 0.90X.

The default setting is 0.50X;

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 recording the periodic

error.

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 be 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.

5.6.3. PEC Data Integrity

This function will check the recorded PEC data integrity.