What is PEMPro?

PEMPro is short for Periodic Error Management Professional. It is a Windows software application that makes it very easy to characterize and reduce the periodic error of your telescope/ mount.

New features in PEMPro V2.x

Frequency Spectrum - Allows you to analyze what fundamental frequencies are present in your mount.

Polar Alignment Wizard - Quickly, accurately, and easily helps you dial in polar alignment.

Backlash Exerciser - Checks the backlash of your mount.

Star Finder - Helpful if you have a small CCD field of view to locate a star or other object when your mount's alignment is not perfect.

Video Interface - Provides a low cost way to use PEMPro using a webcam. No extra software is required.

Meade DSI Support - Native support for the full line of Meade DSI cameras.

What is Periodic Error and why should I care about it?

All telescope drives, including professional drives, have mechanical imperfections in the gears and worm, and the worm wheel that ultimately points the telescope.  These imperfections occur with a period determined by the rotational speed of the driving worm gear, but there can also be significant effects from other gears in the RA gear train.  If not corrected it makes taking unguided images impossible with even moderate focal length telescopes. Even auto-guided imaging is made more difficult because of periodic error. It is much better if the periodic error is corrected before the auto-guider gets a crack at it. Then guided imaging can be more accurate and produce tighter stars.

What is Periodic Error Correction?

Almost all telescope drives made for astrophotography have some sort of Periodic Error Correction (PEC) facility, even inexpensive mounts. The purpose of PEC is to compensate for the mechanical imperfections in the RA motion of the telescope caused by imperfections in the drive.  Note that some mounts have a different name for PEC such as PEM (Astro-Physics, Inc.) and SmartDrive (Meade).

Typical ways to “train” your mount’s PEC  

PEMPro Workflow

The process of using PEMPro is very simple, but you will need a telescope and CCD camera that optimally provides at least 1.5 arc-seconds/pixel resolution for the best results.

  1. Acquire PE Data. Details...
  2. Load the PE data for analysis. Details...
  3. Create a fitted PE curve to the data. Details...
  4. Program the mount with the PE curve. Details...
  5. Verify PE has been corrected by acquiring PE data again (Step 1).
 

Software required/supported by PEMPro

Required Software and System Configuration:

 

Mounts supported by PEMPro

Please click this link for a list of mounts supported by PEMPro.

IMPORTANT: PEMPro can upload PEC data directly to some mounts. You should use the procedure below if your mount is one of these types:

Astro-Physics 1200GTO with GTOCP3, 900GTO with GTOCP3, Mach1 GTO, and other mounts using the AP GTOCP3 controller

Celestron CGE, CPC, and Nextstar Mounts

EQMOD controlled mounts including Orion Sirius EQ-G, Orion Atlas EQ-G, EQ6, EQ5, etc.

Gemini G-42 Pulsar Equipped Mounts

Mounts with Gemini Level 4

Meade LX-200GPS and LX-200R with Firmware 2.x or later

Meade RCX-400 and MaxMount

Meade Classic 16"

Software Bisque Paramount GT1100S and ME

 

Hardware required by PEMPro

  500 MHz PIII or faster PC (2.0 GHz P4 or faster is recommended)