Meade 2080/LX6 Instruction Manual download pdf (Page 19)

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9. HI-PRECISION: The High-Precision Pointing feature of

LX200 allows for very precise pointing of the telescope.

By incorporating the unique LX200 SYNC command, 0.3

arc-sec resolution encoders, and high-speed DC servo

motors, observers can now place objects in the

telescope’s field of view with 1 arc-minute or better

pointing accuracy. This makes critical image placement

applications, such as CCD imaging, possible.

Normal telescope pointing accuracy is better than 5 arc-

minutes when doing a casual alignment, which is more

than accurate enough for most observing applications. (A

“casual” alignment is one that uses the UNKNOWN SITE

or one that is done without the use of a reticle eyepiece to

exactly center the alignment stars.) This type of alignment

will put objects into the field of view of most eyepieces

and is more than adequate for almost any visual

observing application.

A “critical” alignment will improve the pointing accuracy of

the telescope to 2 arc-minutes or better. This type of

alignment requires accurate SITE information, time, date,

proper selection of the two alignment stars, and a reticle

eyepiece to exactly center the alignment stars. These

steps generally require only a few extra seconds to

accomplish, and will improve the telescope’s positioning

by a substantial amount. Using the “critical” alignment will

provide telescope positioning suitable for all but the most

demanding pointing applications — including CCD

imaging with larger chip cameras, like the Meade Pictor

416 and Pictor 1616 CCD cameras.

The HI-PRECISION feature increases the pointing

accuracy of the LX200 to 1 arc-minute or better and also

requires the “critical” alignment described above. This will

yield the best pointing accuracy possible, placing objects

onto the active area of the even the smallest CCD

cameras available.

It should be stressed that for most applications, using the

HP feature is NOT required to get maximum enjoyment

out of the telescope. For an evening of simple visual

observations, the “casual” alignment is all that is required.

Don’t let the pointing precision of the telescope become

more important than the fun of observing the night sky!

The High-Precision Pointing mode requires the “critical”

alignment, described above, to maximize the telescope’s

pointing ability. The LX200 default condition is with HP

disabled. To activate the HP mode, select the “hi-

precision” option from the TELESCOPE menu (option #9).

When selected, “HI-PRECISION” will change to upper

case letters.

When HP is active, the LX200 automatically does several

things whenever a GO TO is initiated.

a. HP will search the alignment star database and find

the three closest stars to the object (or position)

entered. This process takes about 10 seconds and

the keypad will show Display 26:

Display 26

b. The telescope will slew to the nearest alignment

star. These are all bright (brighter than 3rd

magnitude) stars and far enough apart to insure

that there will only be one in the field of view.

The keypad display will show Display 27:

Display 27

Using a reticle eyepiece, center the star in the field of

view. (Or center the star on the CCD chip if using a

CCD camera.) Press GO TO when the star is

centered.

NOTE: If this star is not in the field of view or if it is obstructed

by a land object, the other two stars are available. Use the

PREV and NEXT keys to cycle through the three closest stars.

c. The telescope will slew to the selected object or

position.

10. SLEW RATE: Option #10 in the TELESCOPE menu is for

changing the slew rate of the LX200 telescope. Slowing

down the slew rate will result in less noise as the

telescope moves and will also use a little less power. To

change the slew rate, follow these steps:

a. Press the MODE key on the keypad until the

TELESCOPE/OBJECT LIBRARY menu appears.

The cursor should be next to the TELESCOPE

option — if not, press the PREV key to move the

cursor up one space.

b. Press ENTER to select the TELESCOPE functions.

c. Press the PREV or NEXT keys to move the cursor to

option #10: SLEW RATE. On the right hand part of

the display, the number 4 is displayed. This

represents the current slew rate in degrees per

second.

d. Press the ENTER key to change the slew rate. Each

successive ENTER key press increments the slew

rate by 1 degree per second.

e. After setting the desired rate, press the MODE key to

return to the TELESCOPE/OBJECT LIBRARY menu.

NOTE: The slew rate is NOT stored in permanent memory and

needs to be reset each time the telescope is powered up. The

default slew rate is 4 degrees per second.

11. BACKLASH: The Backlash feature is only available in the

POLAR mode.

When taking long exposure astrophotographs, it is

necessary to “guide” the photograph to make sure the

telescope is tracking perfectly, otherwise stars will appear

as ovals instead of pinpoints. This is done by setting the

LX200 keypad to the GUIDE speed, monitoring the star

location (e.g. with an off-axis guider), and making small

corrections to the telescope position by using the N, S, E,

and W keys.

When making these corrections, the R.A. motor will speed

up or slow down (by pressing the “E” and “W” keys). The

Declination motor, however, when activated (by pressing

the “N” and “S” keys) will actually stop and reverse

direction. Because of backlash in the Declination motor

gearbox, there will be a few seconds delay before the

telescope begins to move when reversing direction.

The Dec. backlash feature compensates for the Dec.

motor gearbox backlash and provides instant telescope

movement when the motor is reversed.

To program the Dec. backlash, use this procedure:

a. Move to option #11 from the TELESCOPE menu.

The keypad display will show:

“

’11) BACKLASH 00”

The “00” in the display shows the number of arc-

seconds of backlash the LX200 is set to compensate

for (the default setting is 0 arc-seconds).

b. While observing a star at high power, time the

Declination movement delay when reversing the

motor directions (by pressing the “N” and “S” keys).

Typical values are 2 to 4 seconds.

c. The GUIDE speed for the Declination motor is 15

arc-seconds per second. Therefore, multiply the

number of seconds delay by 15.

d. Press and hold the ENTER key for 1 second. The

keypad will beep and a blinking cursor will appear on

the keypad display. Enter the number determined in

HI-PRECISION

Searching. . .

Center STAR XXX

then press GO TO

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Meade 2080/LX6 Instruction Manual Page 19

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