Orion EQ-G instruction manual Appendix B Periodic Error Correction PEC, PEC Training

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view (Figure 19). This will determine which direction (left or right) moves Polaris closer to the center of the eyepiece field of view.

12.Carefully and gently loosen both the tube ring attachment screws (Figure 3) by a couple of turns.

13.Make adjustments to the optical axis offset adjustment screws (the socket head cap screws located at each corner of the mounting plate, (Figure 3) according to the results of step 11. If Polaris moves toward the center when the telescope is pushed as indicated in Figure 19, loos- en the adjustment screws near the front of the tube and tighten the adjustment screws closer to the back of the tube (Figure 20a). If Polaris moves away from the center when the telescope is pushed as in Figure 19, loosen the adjustment screws near the back of the tube and tight- en the adjustment screws closer to the front of the tube (Figure 20b). Look into the eyepiece. Adjust the adjust- ment screws just enough to place Polaris HALF the dis- tance back to the center of the illuminated reticle eyepiece (Figure 21).

14.Repeat steps 7 to 12 until Polaris remains in the center of the eyepiece field of view, or moves slightly around the center, when the mount is rotated about the R.A. axis.

Note: This calibration method can be applied to both refract- ing and reflecting telescope designs. Differences in the optical path of telescopes do not affect how the telescope tube and tube rings should be adjusted on the mounting plate.

Figure 21. Using the optical axis offset screws move Polaris halfway to the eyepiece’s center.

ing method to reduce the amplitude of the worm gear errors. By recording a full cycle of guiding actions, the Atlas EQ- G can compensate for drifting in the R.A. sidereal tracking caused by periodic errors. The following instruction will lead you on a step-by-step procedure for performing the PEC.

Note:The PEC training function is recommended for advanced users with interest in long-exposure astrophotography only. Careful guiding is required. Standard sidereal tracking is suf- ficient for all casual visual applications of the Atlas EQ-G, and PEC training is not required.

PEC Training

1.Perform an accurate polar alignment using the polar axis finder scope.

2.Manually point or electronically slew the telescope mount- ed on the Atlas EQ-G to a star with a small value Dec. coordinate (Dec. between +10° and –10°). This object will be used as the guide star.

3.Activate “Sidereal Tracking” from the Setup menu (see “Setup Functions”). Once tracking has initiated, press ESC to return to the Setup menu.

4.Rotate the reticle eyepiece in the focuser (or diagonal) until the R.A. movement of the star becomes parallel to one of the illuminated crosshairs

5.Move the guide star designated in step 2 to the center of the eyepiece field of view using the direction buttons.

6.On the hand controller, select “PEC Training” in the Utility Functions and press ENTER.

Note: Utility Functions can be accessed by pressing the UTILITY quick rererence button on the hand controller.

7.Select the R.A. guide speed for the PEC Training.You have two guide speed choices: 1) 0.25X and 2) 0.5X. Press the numeric button 1 to choose a guide speed of 1.25X or press 2 to choose a guide speed of 1.5X.

8.The Atlas EQ-G hand controller will display the current time once the guide speed has been selected, indicating the recording has begun.

9.Using the left or right direction button only, move the tele- scope so the guide star remains centered in the eyepiece field of view (Figure 21). Repeat as necessary.

The Atlas EQ-G hand controller will record the manual guid- ing actions for 8 minutes in order to characterize the periodic

Appendix B: Periodic Error

Correction (PEC)

Using the PEC functions requires an illuminated reticle eye- piece capable of producing at least 300X magnification when used with your telescope. For best results, the true field of view should not exceed 10 arcminutes.

Periodic errors are inherent in almost all worm gears due to

 

slight eccentricities and misalignments. The PEC (Periodic

Figure 22. Drifting caused by periodic error.

Error Correction) Training function provides a manual correct-

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Contents #9996 Orion Atlas EQ-GPage Unpacking Table of ContentsAssembly Parts ListBalancing a Telescope Attaching a TelescopeTurns, until you can slide the telescope tube forward Setting Up and Using the Equatorial MountAlignment of the Polar Axis Finder Scope Polar AlignmentPolar Axis Finder Scope Confused About Pointing the Telescope? Using the Polar Axis Finder ScopeAtlas EQ-G Dual-Axis Controller Atlas EQ-G Dual-Axis hand controller Setting the Slewing SpeedAtlas EQ-G GoTo Hand Controller Attaching the GoTo Hand Controller Installing the hand controller bracketGoTo Hand Controller Operation Telescope and mount in their home position AlignmentTips for Choosing Alignment Stars Three-Star AlignmentTwo-Star Alignment One-Star AlignmentShortcut Buttons Object CatalogPointing Accuracy Enhancement PAE Selecting an ObjectOther Functions Auto Guiding Recalling a User Defined ObjectIdentifying an Unknown Object Linking with a ComputerUpdating the GoTo Hand Controller Preparing the Computer for the Update#7796 GoTo hand controller Technical Specifications#7795 Dual-Axis hand controller Atlas EQ-G GoTo Hand Controller Menu Tree Appendix a Enhancing the Pointing Accuracy Cone Error CalibrationTesting for Cone Error Calibration ProcedureB.Rotate the telescope 180 about the R.A.axis PEC Training Appendix B Periodic Error Correction PECPlay Back the PEC Record Appendix C RS-232 Connection Additional RS-232 Commands Sending a Tracking RateSending a Slow-GoTo Command Resetting the Position of Azimuth or AltitudeAppendix D Standard Time Zones of the World One-Year Limited Warranty

EQ-G specifications

The Orion EQ-G Equatorial Mount is a popular choice among amateur astronomers and astrophotographers seeking a reliable and versatile platform for their telescopes. Known for its robust build and advanced technology, the EQ-G mount can support a wide range of telescope sizes, making it ideal for both visual observations and astrophotography.

One of the standout features of the Orion EQ-G is its precision go-to capability. Equipped with a computer-controlled system, users can easily locate and track celestial objects with remarkable accuracy. The mount comes with a database that includes thousands of celestial objects, allowing users to automatically point their telescope to stars, planets, galaxies, and more with the push of a button.

The EQ-G mount features a sturdy aluminum construction, ensuring stability even under heavy loads. It can support telescopes weighing up to 30 lbs, making it suitable for medium to large telescopes. The mount's adjustable altitude and azimuth motions allow for smooth tracking of celestial objects as they move across the sky, a vital characteristic for long-exposure astrophotography.

To enhance user experience, the EQ-G is equipped with a built-in dual-axis servo motor drive system. This drive system delivers precise movement control, ensuring that the telescope can be accurately guided to desired targets. Furthermore, the mount is compatible with various control options, including hand controllers and computer software, allowing for a customizable and convenient observing experience.

Another notable technology within the EQ-G is the polar alignment scope. This feature aids in achieving accurate polar alignment, which is crucial for minimizing tracking errors during long exposures. By correctly aligning the mount, users can take stunning astrophotographs with minimal star trails.

For portability, the EQ-G mount comes with a quick-release design that allows for easy setup and takedown. Its adjustable tripod legs provide a stable base on various terrains, making it possible to observe from different locations, whether in the backyard or at a remote dark-sky site.

In summary, the Orion EQ-G Equatorial Mount combines an intuitive design with high-quality features, making it a fantastic choice for astronomy enthusiasts. With its go-to capability, sturdy construction, precise tracking, and user-friendly setup, the EQ-G stands out as a reliable and effective tool for exploring the wonders of the night sky. Whether you are capturing stunning images of celestial objects or simply enjoying visual astronomy, the Orion EQ-G meets the diverse needs of astronomers at all levels.
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