Nexstar SynScan Linking with A Computer, A u t o Guiding, Periodic Error Correction, C b

Linking with A Computer

Another feature of SynScanTMis the ability to connect to a computer via a serial communication cable. Many commercially available planetarium softwares can be used to control SynScanTM. SynScanT"Version 3.00 and later is compatible with Celestron 5i/8i and NexStar GPS command protocol.

1.	Make sure that the telescope has been aligned.		Hand Control
2.	Connect the RS-232 cable to the RJ-11 connector on the	C b 5 3
	hand control and to the COM-port of your computer (Fig.p)
		-

Do not use RS-232 cable other than the one provided to connect between the hand control and your computer. It may damage your computer or the hand control. If you are making your own cable based on the information provided in Appendix B, make sure that only pin 2, 3 and 5 connect to the com connectoron your computer.

3.In the planetarium software of your choice, choose "Celestron NexStar 5i" or "Celestron 8/9/11 GPS" in the driver setup menu and follow the instructions provided by your program to establish the connection to the telescope. The SynScan'" should be under the full control of your computer once the connection is successfully established.

4.When you are finished, follow the instructions provided by your software to close the connection to the telescope.

RJ- 11

aRJ-11 Pin-outs

I = EXPD+ 2= -rD

3= GND 4= EXPD- 5= RD

6 5 4 3 2 1 6= +12v

See Appendix B for

more information on

RS-232 connection.

A u t o Guiding

The SynScanrMhas a designated autoguider interface on the mount for use with

an auto guider (see Fig.a, a-I). The pin-outs on the 6 pin modular connector is		I = NC
		2= Ground
ST-4 compatible and can be used for most autoguiders on the market. Refer to
		3= +RA (left)
Fig.q when connectirlg the autoguider cable to the SynScanTM and calibrating the		4= +DEC (up)
autoguider. Relay box can be added for extra protection. Note that the four inputs	654321	5= -DEC (down)
are active-low, with internal pull-ups. Guiding speed can be adjusted using the		6= -RA (right)

Auto Guide Speed function in the Setup Menu.

Periodic Error Correction

Periodic Errors are found in almost all worm gears due to slight eccentricities and misalignments. The PEC (Periodic Error Correction) function provides a manual correcting method to reduce the amplitude of the worm errors. By recording a full cycle of guiding actions versus motor shaft angle, SynScanTMcan work to compensate for the drifting in the RA sidereal tracking caused by the periodic errors. Below describes a step-by-step procedure on how to perform the PEC:

PEC Training function is recommended for advanced users interested in long-exposure astrophotograhy only. Careful guiding is required. Regular sidereal tracking is adequate for all casual visual use of the SynScan" and PEC Training is not required.

Required acccssory: Illuminated reticle eycpiccc with double crossline pattern capable of producing at least 300X magnification in combination with your telescope. The true field of view should not exceed 10 arc min. See "Choosing the appropriate eyepiece" in the HEQ5lEQ6 manual for more information on calculating the field of view.