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menu selection, the OBJECT INFORMATION menu
selection, or the FIELD menu selection.
4. PARAMETERS: It is here that you can edit the Press
ENTER to find eight options which can be reviewed by
scrolling through this menu selection using the PREV or
NEXT key. To edit an option, move the arrow to the
desired option and press and hold ENTER until a double
beep is heard and a blinking cursor appears (except in the
BETTER option) Where numerical values are to be input,
simply type them in from the keypad. If you make a
mistake, you can move the cursor backward using the W
key, then re-enter the data. To exit to the main option
menu, press the ENTER key once again. A description of
the eight options and how to set them is below:
a. TYPE GPDCO: This menu file option allows you to
select the type of CNGC objects that you wish to
locate. GPDCO represent:
OBJECT SYMBOL LEGEND
SYMBOL DESCRIPTION
G GALAXIES
P PLANETARY NEBULAE
D DIFFUSE NEBULAE
C GLOBULAR STAR CLUSTERS
O OPEN STAR CLUSTERS
Initially, the blinking cursor appears over the G
symbol. If you decide not to look for galaxies, press
NEXT and the symbol will change from an upper
case letter (G) to a lower case letter (g), to deselect
the GALAXIES category. If you wish to leave
GALAXIES selected, then move the blinking cursor
over to one of the other category symbols by
pressing the W or E key on the keypad. You can then
deselect the undesired categories.
If you wish to recall a category symbol, move the
blinking cursor over the symbol and press the PREV
key. After your selections are made, press ENTER.
b. BETTER: The BETTER menu file option allows you
to define the visual object quality range. At power up,
the range is set at the bottom of the scale on VP,
when using the START FIND menu selection, it will
select all objects that are very poor through super or
what could be considered an “ALL” setting. The
object quality symbols are:
QUALITY SYMBOL LEGEND
SYMBOL DESCRIPTION
SU SUPER
EX EXCELLENT
VG VERY GOOD
G GOOD
FR FAIR
PR POOR
VP VERY POOR
If you wish to define the object quality range to Very
Good and better, press the ENTER key until the
symbol VG is displayed. From the VP setting to VG
requires three ENTER key presses. The LX200 will
now select objects that look Very Good through
Super.
c. HIGHER: The Higher menu file option sets the
horizon setting for the telescope. At power up, the
setting is 00 degrees, which assumes that you have
an unobstructed line-of-site to the horizon in every
direction. If, however, there are things obstructing a
level horizon, or if the sky quality is poor due to haze
or light pollution, you can set an artificial horizon level
so that your LX200 will not try to find objects below
your setting.
Enter the number of degrees above the horizon that
will clear the obstructions in the sky. To roughly judge
how many degrees the obstruction is taking up of the
sky, merely hold your fist at arms length. Each fist
diameter is approximately 5 degrees. So, if a tree is
three fists high, you would make a setting of 15
degrees in the HIGHER setting. Once the setting is
finalized, press ENTER.
d. LOWER: The LOWER menu file option sets the
zenith limit setting for the telescope. At power up, the
setting is 90 degrees, which assumes that you point
the telescope straight up. If, however, you have
instruments on the telescope which will not clear the
fork arms, or if you want to avoid the 10° Field De-
Rotator limit, this setting can be used.
Enter the number of degrees from the zenith that you
want to limit. Once the setting is finalized, press
ENTER.
e. LARGER: The LARGER menu file option allows
settings of the lower apparent size limit of the objects
you wish to see. At power up it is set to 000’ (arc
minutes). In order to make a decision as to the size
limits that you may impose, it helps to have a clear
understanding of exactly what an arc minute of sky
is. A good example is the apparent size of the Moon,
which could be expressed as 1/2 of a degree, 30 arc
minutes, or 1800 arc seconds. Each arc minute is 60
arc seconds, and there are 60 arc minutes for each
degree of sky.
Some beginning observers have a tough time
discerning objects less than about 1 arc minute in
size unless it is a double star or a planet.
Astrophotographers and those involved with CCD
imaging may want to set a higher value based on the
desired image scale coverage that would be most
impressive with different types of films or CCD
cameras. Enter the new value in arc minutes, then
press ENTER to exit to the option file.
f. SMALLER: This menu option is the upper size object
limit. At power up the setting is for 200 arc minutes or
3.33 degrees. This setting is high enough to cover
the largest objects in the OBJECT LIBRARY. You
may want to lower the value because of true field-of-
view limitations of a particular eyepiece (see the
RADIUS parameter option for calculating true field).
Other reasons for limiting the value in SMALLER is
for astrophotographic or CCD imaging requirements
where we don’t want the object to exceed the
imaging area of the film or the CCD chip.
g. BRIGHTER: The lower brightness limits based on
stellar magnitude can be limited in the BRIGHTER
menu. At power up, the magnitude value is set to a
very faint level of +20.0.
You may want to adjust the magnitude level to a
brighter value starting at perhaps the limiting visual
magnitude of your LX200, which is approximately
15.5 for the 16” LX200. If you are taking
astrophotographs, the limiting magnitude is about
18.0. Sky conditions also greatly affect the limiting
magnitude due to atmospheric haze, high clouds,
light pollution, or combinations thereof.
h. FAINTER: The upper level of brightness may also be
adjusted with the FAINTER menu file option,
although you may find few applications for limiting it
to a lower value.
i. RADIUS: The RADIUS value sets the boundaries of
what and how many objects the LX200 recognizes is