Nexstar SynScan instruction manual One-Star Alignment, Pointing Accuracy Enhancement PAE

One-Star Alignment

It requires only one alignment star but, without accurate polar alignment and cone error calibration (see Appendix A), it may produce lesser pointing accuracy than the other alignment methods. Refer to the HEQIEQG manual for information on how to perform accurate polar alignment. Below describes a step- by-step procedure on how to perform the One-Star Alignment:

1.Make sure the telescope has been polar aligned.

2.In the alignment screen, select I-StarAlign using the scroll keys. Press ENTER to confirm.

3.The SynScanTMwill provide a list of stars available in your current sky for alignment. Using the scroll keys, choose a star you are most familiar with and press ENTER. When the telescope stops slewing, adjust its position with the directional keys until the star is centered on the crosshairs in the finderscope. Now look through the eyepiece and adjust the telescope so that the object is centred in the field of view of the eyepiece. Press ENTER to confirm.

4.Once completed, SynScanTMwill display "Alignment Successfui".

w Following is some pointers on how to choose appropriate alignment stars:

One Star: Choose a star closer to the Celstrial Equator (smaller declination absolute value).

Two Star: Choose two stars that are on the same side of the meridian. and at least 3 hours apart in RA and 3"apart in Dec. If J ou suspect that the polar alignment is off bylo and above, choose two stars that are well more than 3" but less than 60"apart in Dec.

Three Star For the first two alignment stars, follow the same guideline as choosing for the Tmo Star Alignment. For the third alignment star, choose a star that is on the opposite side of the meridian of the first two stars. Both first alignment star and third alignment stcv should have an absolute value of 30 "to 70 "in Dec. If the first chosen star has a small Dec (<30°). the Dec of the third star should be at least 50".The following formula can be used as a guideline when determining the correlation between the first and third stars in Dec. 140' >Abs(Dec 1)+Abs(Dec2)>6O0

Pointing Accuracy Enhancement (PAE)

The three star alignment methods provide alignment adequate for any visual observing purpose. For applications that require extra high precision in a particular part of the sky, the SynScanT"provides a Pointing Accuracy Enhancement (PAE) function to further improve the accuracy. The PAE can be performed in up to 85 zones to cover the whole sky. The area(s) where the chosen alignment star(s) is located should be already mapped out accurately by the SynScanTMFurther. accuracy enhancement is not necessary. The following provides a step-by-step procedure on how to perform PAE:

1.Choose a star as reference object from a star chart or planetarium software. This star should be a known, bright object that is currently located in the same part of the sky with the object of your interest.

2.Find the reference object in the SynScanTMhand control database and go-to the object. If the mount is under the control of the planetarium software, click on the object to slew to it.

3.Adjust the telescope so that the reference object is in the center of the eyepiece or CCD view.

4.Press and hold down the ESC key for 2 seconds. The hand control will display "Re-center" and the name of the reference object will appear in a blinking mode (3 times). If the go-to command is sent from the planetal-iumsoftware, instead of the name of the object, the hand control will display "Last goto object".

5.Make sure that the reference object is still in the center of the view and press ENTER. If you do not wish to record the result, press ESC to abort the operation. After pressing ENTER, the SynScanT" will record the amount of pointing inaccuracy and recalculate the model of the sky. Now the pointing accuracy of this particular part of the sky should be greatly improved.

The result for the star alignments and PAE is stored in the hand control even after the power has been shut off. You will only need to perform the star alignment once as long as these two criteria are met: 1 The telescope is moved to its home position (Park the telescope) before turning off the power. 2. The telescope setup. including the mount, has not been moved. Accessory change is acceptable as long as it is done with great caution. When thc hand control is turned on for the ncxt time. make sure that the time entered during initial setup is based on the same source as last time. For example, if you enter the time on your watch during this observing session, the time you enter next time should also be read from your watch.