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information about them. This is especially useful with the Moon,  which has
thousands of named craters.

   You can also add a lat/lon grid,  of specified spacing and color.

   In the case of Mars,  you can select among three bitmaps.  Two are
based on visual observations;  one is based on Viking data.  Few
objects have three bitmaps.  Venus has two:  one shows it as a
cloud-covered planet,  the other as it appeared to the radar-mapping
Magellan probe.  If your viewing location is not on the earth,  you can
look back at the earth and see it with any of three different bitmaps.

   The Moon has an extremely detailed bitmap.  Unfortunately,  it is
about 90 MBytes and had to be put on the second CD-ROM.  For details
on how to access data from the second CD-ROM,  see page 58.

   Alternatively,  you can switch from the bitmapped views to a "line
figure" view,  where the planet is just shown as an outlined figure;  or
in "shaded" mode,  where it is drawn as a shaded,  single-colored sphere.
Both options are considerably faster than the bitmapped options.  (And
for most smaller satellites,  these are the _only_ options.)

   Using the slider bars,  you can modify the brightness and contrast
used for the planet bitmap.
                                           
   Set "Earthshine" to 0%,  and parts of the Moon and other objects that
are not in sunlight will appear black.  Set it to 100%,  and they'll
appear as if fully illuminated,  and none will show phases.  You usually
want something bright enough that you can make out features on the dark
side,  but dark enough that you can tell which side is illuminated at a
given time.  For some special project,  you may decide you want a very
dark setting for realism,  or a 100% setting for use in an "atlas" mode.
                                          
   Jupiter has a special option all of its own in this dialog:  the
"GRS longitude" entry.  By default,  the Great Red Spot is shown at
System II longitude 77 degrees,  but like any other cloud,  it does
move a little.  Updated longitudes are occasionally given in _Sky &
Telescope_ when that magazine gives a list of GRS transits,  and are
also given on the Project Pluto Web site (see page 2.)  The value
you provide here is used in displaying Jupiter on-screen,  and when Guide
gives data on GRS transit times.

7d:  The Camera Frame menu                       

   When you toggle the "CCD Frame" in the Display menu, Guide puts a
rectangle on the screen.  You can set the size, position,  and tilt
of the rectangle. This may be used to show the area covered by a
camera or CCD image. A dialogue box will now appear with the items:

Show Frame
Angle:

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