Orion EQ-G instruction manual Polar Alignment, Alignment of the Polar Axis Finder Scope

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Polar Alignment

For Northern Hemisphere observers, approximate polar align- ment is achieved by pointing the mount’s right ascension axis at the North Star, or Polaris. It lies within 1° of the north celes- tial pole (NCP), which is an extension of the Earth’s rotational axis out into space. Stars in the Northern Hemisphere appear to revolve around the NCP.

To find Polaris in the sky, look north and locate the pattern of the Big Dipper (Figure 6). The two stars at the end of the “bowl” of the Big Dipper point right to Polaris.

Observers in the Southern Hemisphere aren’t so fortunate to have a bright star so near the south celestial pole (SCP). The star Sigma Octantis lies about 1° from the SCP, but it is barely visible with the naked eye (magnitude 5.5).

For general visual observation, an approximate polar align- ment is sufficient.

1.Level the equatorial mount by adjusting the length of the three tripod legs.

2.There are two latitude adjustment L-bolts (see Figure 5); loosen one while tightening the other. By doing this you will adjust the latitude of the mount. Continue adjusting the mount until the pointer on the latitude scale is set at the latitude of your observing site. If you don’t know your lati- tude, consult a geographical atlas to find it. For example, if your latitude is 35° North, set the pointer to 35. The lati- tude setting should not have to be adjusted again unless you move to a different viewing location some distance away.

3.Loosen the Dec. lock lever and rotate the telescope’s opti- cal tube until it is parallel with the right ascension axis, as it is in Figure 5.

4.Move the tripod so the telescope tube and right ascen- sion axis point roughly at Polaris. If you cannot see Polaris directly from your observing site, consult a compass and rotate the tripod so the telescope points north.

The equatorial mount is now polar aligned for casual observ- ing. More precise polar alignment is recommended for astrophotography. For this we recommend using the polar axis finder scope.

From this point on in your observing session, you should not make any further adjustments to the latitude of the mount, nor should you move the tripod. Doing so will undo the polar alignment. The telescope should be moved only about its R.A. and Dec. axes.

The Polar Axis Finder Scope

The Atlas EQ-G mount comes with a polar axis finder scope (Figure 7) housed inside the right ascension axis of the mount. When properly aligned and used, it makes accurate polar alignment quick and easy to do. Unthread the cover at the rear of the mount’s right ascension axis and remove the cap on the front opening of the equatorial mount (Figure 5) to view through the polar axis finder scope.

Alignment of the Polar Axis Finder Scope

1.Loosen the Dec. lock lever and rotate the optical tube about the declination axis until you have a clear view through the polar axis finder scope (Figure 8). Tighten the Dec. lock lever.

2.Look through the polar finder at a distant object (during the day) and center it in the crosshairs. You may need to adjust the latitude adjustment L-bolts and the tripod posi- tion to do this. Focus the polar finder by rotating the eye- piece.

3.Rotate the mount 180° about the R.A. axis. It may be con- venient to remove the counterweights and optical tube before doing this.

4.Look through the polar finder again. Is the object being viewed still centered on the crosshairs? If it is, then no further adjustment is necessary. If not, then look through the polar finder while rotating the mount about the R.A. axis. You will notice that the object you have previously centered moves in a circular path. Use the three alignment set-screws on the polar axis finder (Figure 7) to redirect the crosshairs of the polar finder to the apparent center of this circular path.

5.Repeat this procedure until the position that the crosshairs point to does not rotate off-center when the mount is rotat- ed in R.A.

Eyepiece

Alignment

Focus

Objective

focus ring

setscrew (3)

lock ring

lens

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 7. The polar axis finder scope.

Figure 8. The optical tube must be rotated about the declination

axis in order to view through the polar axis finder.

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Contents Orion Atlas EQ-G #9996Page Parts List Table of ContentsAssembly UnpackingAttaching a Telescope Balancing a TelescopeSetting Up and Using the Equatorial Mount Turns, until you can slide the telescope tube forwardPolar Alignment Polar Axis Finder ScopeAlignment of the Polar Axis Finder Scope Using the Polar Axis Finder Scope Confused About Pointing the Telescope?Atlas EQ-G Dual-Axis Controller Setting the Slewing Speed Atlas EQ-G Dual-Axis hand controllerAtlas EQ-G GoTo Hand Controller Installing the hand controller bracket Attaching the GoTo Hand ControllerGoTo Hand Controller Operation Alignment Telescope and mount in their home positionOne-Star Alignment Three-Star AlignmentTwo-Star Alignment Tips for Choosing Alignment StarsSelecting an Object Object CatalogPointing Accuracy Enhancement PAE Shortcut ButtonsOther Functions Linking with a Computer Recalling a User Defined ObjectIdentifying an Unknown Object Auto GuidingPreparing the Computer for the Update Updating the GoTo Hand ControllerTechnical Specifications #7795 Dual-Axis hand controller#7796 GoTo hand controller Atlas EQ-G GoTo Hand Controller Menu Tree Calibration Procedure Cone Error CalibrationTesting for Cone Error Appendix a Enhancing the Pointing AccuracyB.Rotate the telescope 180 about the R.A.axis Appendix B Periodic Error Correction PEC PEC TrainingPlay Back the PEC Record Resetting the Position of Azimuth or Altitude Additional RS-232 Commands Sending a Tracking RateSending a Slow-GoTo Command Appendix C RS-232 ConnectionAppendix 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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