Equinox Systems GEMINI Manuel d'utilisateur télécharger pdf (Page 38)

Gemini Users Manual 33

outside the allowed range. Use the Hand Controller to carefully move beyond the old

limit to the new limit position, and select the Set Safety Limit command. The buzzer

won't stop until you go back inside the allowed range or set the new limit with this menu

item.

Alternatively, if you already know the values of the Safety Limit angles to be set, you can

use the Set Safety Limits submenus “Set East” and “Set West” to store them without

having to move the mount.

IMPORTANT: The limits are stored in CMOS SRAM. Whenever the "CMOS reset"

message is displayed during startup, all values are reset to the factory default. If you

need different limits to be set, you will have to set them again!

While tracking, an audible warning (a short beep about every 20 seconds) sounds some

minutes before the western safety limit is reached. This gives you an opportunity to close

the camera shutter or take whatever other action is necessary. If you want to continue

your observation of this object, you’ll need to perform a meridian flip. This can easily be

done using the “Meridian Flip” command in the QuickMenu.

3.3.4 GoTo Commands and Meridian Flips

By default, if you attempt to GoTo an object (using either the menus on the hand

controller or a command transmitted via the serial port), Gemini will attempt to point to

the object without doing a meridian flip if the safety limits allow it. If the telescope is on

the east side of the mount and the object can be reached without moving past the east

safety limit, Gemini will point without a meridian flip. Similarly, if the telescope is on

the west side of the mount and the object can be reached without getting closer than 2.5

degrees from the western safety limit, it will point without a meridian flip. In all other

cases, the mount will do a meridian flip before pointing to the object.

For example, if the western safety limit is set to the default value of 122 degrees from the

CWD position, a GoTo command to any object from the eastern horizon to 29.5 (122 –

90 – 2.5 = 29.5) degrees west of the meridian will not cause a meridian flip. This could

be a problem if you want to start imaging an object that is, say, 25 degrees west of the

meridian. If the telescope is on the west side of the mount, a GoTo command will not

cause a meridian flip since the object can be safely reached without it. However, you

probably want to perform the meridian flip before you GoTo this object to give you more

time to image before reaching the western safety limit. If you are controlling the

telescope manually, you can use the QuickMenu “Meridian Flip” command to force a

flip. Alternatively, if you are using telescope control software that understands Gemini’s

serial commands, it could check which side of the meridian the mount is on, and issue a

meridian flip command. However, this does not work with most control software that

uses only the Meade command set without Gemini’s extensions. For these programs, the

only solution is to GoTo an object that is past the western safety limit to force the

meridian flip, and then go back to the object of interest.

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Equinox Systems GEMINI Manuel d'utilisateur Page 38