Orion 7817 Object Catalog, Pointing Accuracy Enhancement PAE, Selecting an Object

1.From the alignment screen, select “1-Star Align” using the scroll buttons. Press ENTER to confirm your choice.

2.The hand controller will provide a list of stars available in your current sky for you to choose as the first alignment star. Using the scroll buttons, choose a star you are familiar with and press ENTER to confirm your choice. The mount will start slewing the telescope towards the chosen star. When the telescope stops slewing, adjust its position with the controller’s directional buttons until the star is centered on the crosshairs of the finderscope. Now look in the eye- piece and adjust the position of the telescope (again using the directional buttons) so the chosen star is centered in the field of view of the eyepiece. Press ENTER to confirm the star is centered.

3.Once the alignment star has been entered and alignment is complete, the hand controller will display “Alignment Successful”. Press ENTER to access the Main Menu.

Tips for Choosing Alignment Stars

If possible, use the following tips when choosing alignment stars for best pointing accuracy.

One-star alignment: Choose a star close to the Celestial Equator (Dec close to 0°).

Two-star alignment: Choose two stars on the same side of the meridian, and at least 3 hours apart in right ascension and 3° apart in declination. If you suspect your polar alignment is poor, choose two stars that are 20° to 60° apart in declina- tion.

Three-star alignment: For the first two stars, follow the tip above for two-star alignment. For the third alignment star, choose a star on the other side of the meridian. The first and third alignment stars should have declination coordinates between +30° and +70° or between -30° and -70°.

Pointing Accuracy Enhancement (PAE)

The three-star alignment should provide excellent point- ing accuracy for visual observation. For other applications, such as CCD imaging, even better pointing accuracy can be obtained in a specific region of the sky by use of the Pointing Accuracy Enhancement (PAE) function. Perform the following procedure to use the PAE function.

1.Choose a bright star near the area of interest in the night sky. Consult a planisphere or software program to choose this bright star, if necessary.

2.Find this star in the hand controller’s object database. This is easily done by pressing the OBJECT button, which will take you directly to the Named Star database. Press ENTER to access the list of named stars. Use the scroll buttons to peruse the list, and press ENTER to select the star. Press ENTER again, and the LCD will ask “View Object?” Press ENTER to issue a command to the mount to GoTo the star. If the mount is under the control of a computer running planetarium software, click on the star to slew the mount to it.

3.Use the directional buttons (and RATE button) to accu- rately center the star in a high-powered eyepiece (10mm or less focal length).

4.Press the ESC button, then press and hold the ESC but- ton for 2 seconds. The hand controller LCD will read “Re- center”, and the name of the chosen bright star will blink three times. If the GoTo command was sent by a computer running planetarium software, the LCD will read “Last goto object” instead of the star’s name.

5.Make sure the chosen star is still centered in the eyepiece, and press the ENTER button. If you don’t want to record the star position, press the ESC button to exit the PAE function.

After the PAE function is performed, the hand controller will recalculate its model of the sky. The pointing accuracy in the area of sky around the chosen bright star should now be improved. To improve pointing accuracy in another region of the sky, perform the PAE function again, this time choosing a bright star in the new region of interest.

Note: If the mount is “parked” before it is powered off (see “Utility Functions”), the star alignments and PAE corrections will remain stored in the hand controller. As long as the mount is not moved between uses, the alignment will not need to be performed again when the mount is subsequently powered on.

Object Catalog

The GoTo hand controller boasts a vast database of over 13,400 object coordinates and information. The database contains the following catalogs:

Named Star - A list of 212 well-known bright stars.

Solar System - The other 8 planets of our solar system, and the Moon.

NGC - 7,840 of the brightest deep sky objects from the NGC 2000.0 database (edited by Roger W. Sinnott, copyright by Sky Publishing Corp., used with permission).

IC - 5,386 objects from the Index Catalog.

Messier - Complete list of all 110 Messier objects. These are some of the most spectacular objects to view in the night sky.

Caldwell - Complete list of all 109 Caldwell objects. Double Stars - Includes 55 of the best double stars to view.

Variable Stars - Includes 20 of the most well-known variable stars.

User Defined - Up to 25 objects can be saved in the User Defined database (see “Using the User Defined Database”).

Selecting an Object

Once the telescope has been aligned, you can access and view the variety of different objects in the GoTo hand con- troller’s database. There are three methods of selecting a celestial object to view.

1. Shortcut Buttons

TOUR: Takes you on a preset tour across the night sky. The brightest and most beautiful deep-sky objects will auto-

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