Starting with Level 3 version 1.01, you are able to change the Longitude and Latitude 

immediately after a Cold Start.  Refer to section 2.3.2.1 Cold Start Setup Options for an 

explanation of how this is done. 

The  "Geogr. Location" menu item allows you to input the longitude, latitude and time 

zone of the telescope's geographic location.  Setting the geographic coordinates 

accurately is important because they are used to calculate the initial pointing model 

during a Cold Start, and are also used to calculate the position of the Moon.  The 

longitude is measured from Greenwich, England; eastern longitudes have the designation 

'E', and western longitudes (including the American continent) have the designation 'W.' 

From the sign of the latitude, Gemini knows the hemisphere; northern latitudes are 

"plus," and southern latitudes are "minus.    You should set your longitude and latitude 

first, because the tracking direction in RA depends on the sign of the latitude. 

5.3.10.9.1  Longitude 

The "Longitude" display is as follows: "E/Wddd

mm' " where E/W = either E or W, ddd 

= degrees, and mm = minutes.  Each digit of the "Longitude" is scrolled to the correct 

value using the DEC buttons.  Pressing the RA+ button from the right most digit enters 

the "Longitude." 

5.3.10.9.2  Latitude 

The "Latitude" display is as follows:  "+/ ddd

mm' " where +/  = either plus or minus, 

ddd = degrees, and mm = minutes.  Each digit of the "Latitude" is scrolled to the correct 

value using the DEC buttons.  Pressing the RA+ button from the right most digit enters 

the "Latitude." 

5.3.10.9.3  Timezone 

The "Timezone" display contains a list of time zones that can be scrolled through with 

the DEC buttons and selected with the RA+ button. 

5.3.10.9.4  Query GPS Receiver 

Use this menu to get Longitude, Latitude and UTC Date/Time by querying a GPS 

receiver connected to the serial port.  This is the same function that occurs automatically 

when Gemini is powered on. 

IMPORTANT:

  If you use the   Setup   menu to change Gemini 

s Geographic Location 

or Timezone immediately after a Cold Start, the new values are not used to set the initial 

pointing model or calculate Local Time until Gemini is powered off, powered back on, 

and Cold Started again.  This does not apply to geographic coordinates that are changed 

when prompted during a Cold Start. 

5.3.10.10  Coordinate Epoch  

Equinox of Date

Epoch J2000.0

Gemini Users Manual 

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