Celestron Compustar Manuál s instrukcemi stáhnout pdf (Strana 30)

There is a fourth speed, and that is “AUTO”. As the name implies, “AUTO” is for autoguiding.

The computer module beeps four times when “AUTO” speed is selected. This selection switches

control from the front right DB-9 port on the Computer module, where a joystick may be

plugged in, to the middle DB-9 port, which is the autoguiding input port. Thus, when “AUTO”

speed is selected, the computer module is enabled to receive autoguiding commands from

autoguiding software through the middle DB-9 port and then transmit those commands to the

drive motors in the mount to make the commanded guiding corrections.

It should be noted that when “AUTO” speed is selected, the four motion control buttons on the

upper right corner of the computer module are still active. This is very useful for fine positioning

of the guide star on the guide camera chip. This is why the push buttons on the relay box are not

necessary. This is not the case when a joystick is plugged into the joystick port on the right side

of the computer module. When a joystick is active in the right hand port, the Compustar assumes

you will be using it to electronically control movement of the mount and therefore the motion

control buttons are inactivated. The joystick is sensed by the Compustar computer module if pin

9 in right hand port is grounded when the system is booted up. If a joystick is connected after the

system is booted up, it checks for it each time the user hits the “ABORT” key. Thus, hitting the

“ABORT” key with a joystick connected to the right hand port will inactivate the 4 motion

control buttons. If you intend to have an autoguider and a joystick connected simultaneously,

neither the 4 motion control keys nor the joystick will function to move the mount when you hit

“AUTO”. The only way you can electronically move the mount is by disconnecting the joystick

or switching back to the joystick port by hitting “SPEED”, then “GUIDE”, “SET‟, or “SLEW”.

You will have to key in “SPEED”, “AUTO” when you are ready to go back to autoguiding.

Note that the statement on the wiring diagram that „“SPEED” must be set to “GUIDE” or

“AUTO” on Compustar‟ depends upon which port you will be using, i.e., the right hand port for

a joystick or the center port for autoguiding (remember, the wiring diagram also includes

instructions for wiring a joystick for the right hand port). Neither the author nor Tom Sorbel

could confirm that the Compustar computer can autoguide when set to “GUIDE”. Only “AUTO”

works.

Calibrating the Autoguider

Once the autoguider is enabled, it must be calibrated for it to guide properly. Calibration

determines how far the autoguiding computer needs to move each axis of the mount to correct

for a given guiding error.

The autoguiding software will provide some type of calibration menu (Figure 17). This may be

listed under the camera control menu or a separate menu. Calibration routines vary slightly from

one software package to the next, but will generally resemble the following steps. First, the user

acquires a suitably bright star on the guiding camera chip. Use a star that is fairly bright and

isolated. The software can get confused if another star of similar brightness moves onto the

guiding chip during calibration. Exposure time for the guiding camera is usually controlled

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Celestron Compustar Manuál s instrukcemi Strana 30