Meade LXD 750, LXD 650 instruction manual →TELESCOPE Object Library, →Lat, Long, →1 Site 2 Align

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system’s computer memory. It is also necessary to learn the menu structure of the Keypad Hand Controller, which is described beginning on page 8.

Basic CDS Setup:

This section explains what keys to push to get the minimum data required into the computer system, without any detailed explanation. The detailed explanation can be found later in the manual. These steps will only take a few minutes and will allow immediate use of all of the CDS features.

In order for the CDS to utilize the stellar coordinate system, Right Ascension (R.A.) and Declination (Dec), the system needs to know three pieces of information: the location (latitude and longitude) of the observing site; the local time; and the date. This information only needs to be entered one time — the CDS remembers the data even when the power is off.

1)Entering the Latitude and Longitude of the Observing Site.

The position of your observing site should be determined as accurately as possible, to within 1 or 2 minutes of arc in both latitude and longitude. Many automobile, pilot, and topographical maps, as well as most atlases show latitude and longitude in 15 minute increments or better. The accuracy of the CDS depends on the accuracy of the data that is entered.

Once the above information is determined, it is easiest to enter the data into the system while the telescope and CDS are indoors where there is light—do not try to do it outside at night.

The following example is for an observing site in Costa Mesa, CA (LAT=33°35', LONG=117°42'). If a mistake is made during entry, simply turn off the telescope and restart this procedure. (A more detailed description of the procedure shown below can be found on page 11, "SITE".)

1.Turn "On" the #1697 CDS. After a few seconds (after the self-diagnostic test is complete), the display will look like Display 1.

→TELESCOPE OBJECT LIBRARY

Display 1

2.Press the ENTER key to select the TELESCOPE functions. The display should look like Display 2.

→1) A A A ✔ 2) A A A

Display 4

5.Press the ENTER key. The display should look like Display 5. (Number values may vary.)

→LAT	= +	0	0°	00’
LONG	=	000°		00’

Display 5

6.Use the number keys to enter your latitude. Mistakes may be corrected by moving the curser back, using the “E” and “W” keys. A negative latitude may be entered by positioning the cursor under the “+” and hitting the NEXT key. When the latitude is correctly entered, press ENTER. The curser moves to the LONG line. The display will look like Display 6.

LAT = +33°			35’
→LONG =	0	00°	00’

Display 6

7.Use the number keys (as described above) to enter your longitude. When complete, the display will look like Display 7.

LAT = +33° 35’ →LONG = 117° 42’

Display 7

NOTE: The longitude standard used in the CDS starts at 0 degrees in Greenwich U.K. and increases Westerly only to 359 degrees 59 minutes. Many maps will show Easterly longitudes which cannot be entered into the Keypad Display (e.g., if the map indicates an observing site at an Easterly longitude of 18 degrees 27 minutes, it is necessary to enter the position as 341 degrees 33 minutes).

The differences in longitude and latitude as they pertain to different map spheroid projections are minor differences that are too small to adversely affect the longitude and latitude data input.

→1) SITE 2) ALIGN

Display 2

3.Press the ENTER key to select the SITE functions. The display should look like Display 3.

→1) A A A ✔ 2) A A A

Display 3

4.Press and Hold the ENTER key until the Keypad Hand Controller beeps. This selects the first site for editing. The display should look like Display 4, with the first “A” flashing

NOTE: To edit the letters "AAA", press the NEXT or PREV keys on the Keypad Hand Controller to cycle through the letters of the alphabet. Use the "E" and "W" keys to move between positions.

8.Press ENTER to complete the site information input. The display will go back to Display 3.

9.Press MODE to go back to Display 2.

10.Press MODE again to go back to Display 1.

2) Entering the Local Time and Date.

The local time should be set as accurately as possible using the 24 hour format. The pointing accuracy of the telescope depends on the accuracy of the time entered because the local time and date are used to determine sidereal time (star time). Choose a reliable source as a reference for accurate time such as your local airport, or telephone company. In the U.S.A. you can double check the accuracy of the exact minutes by dialing WWV for the universal coordinated time at (303) 499-7111 (be sure to enter your local time hour information, not the U.T. hour).

The following example is for 4:25:00 P.M. on Jan. 15, 1998.

1.The display should look like Display 1. If it does not, press the MODE key until it does.