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information about the remarks in the same way.  Again,  you can save
the data to a file or print it.

   After the raw data from Hipparcos, some information such as
distance and luminosity derived from that data is shown. Then, Guide
gives information from the Tycho,  GSC,  PPM,  SAO,  WDS, HD, and
Yale Bright Star catalogs. This serves several purposes.  Some of the
other catalogs just give data backing up the information from
previous catalogs.  A few provide unique information;  for example,
the WDS (Washington Double Star) catalog tells us that this is a
double star, with magnitudes 4.25 and 11.8. A catalog such as the
GCVS will tell you what type of variable star this is,  how much it
varies by, and its period of variation.

   This amount of detail may be much more than you really want to know,
and some of the terms used will be somewhat baffling. The links to the help
system will help you, though; if terms such as "proper motion" are new to
you, a mouse-click on them will bring up a definition.
                                                                
   When you click for more info on a planet,  Guide will give you some
data as to its position,  distance from you,  apparent size, and what
percentage of its surface is illuminated.  In the case of the Sun,  it
will also give you times when the three different kinds of twilight
begin and end.
                                                        
   "More info" on the Moon also includes data about phases, lunar eclipses,
and librations. The Moon rotates at a constant rate, but its orbital speed
is not exactly constant; this makes it appear to rock back and forth.
Also,  its poles alternately tip toward and away from us slightly. The end
result is that we see a little more than 50% (about 59%) of its surface.
The libration data will tell you what part of the moon is currently tipped
toward you and therefore more easily observed than it might usually be.
                                                            
   "More info" on Jupiter includes satellite events (eclipses,  transits,
etc.) over the next week.
                                                      
6a:  Measuring angular distances on the screen

   Angular distances between pairs of points on the screen may be easily
measured.  Click with the RIGHT mouse button on the first point; holding
the mouse button down,  drag the mouse over to the second point.  A line
will "rubber band" between where you clicked and where the mouse is.

   When you release the right mouse button,  the distance and position
angle between the two points will show up in a box in the center of the
screen. Click any mouse button or hit any key to get rid of the box.  The
"position angle" is the angle formed by the line you drew and a line
running straight north from the first point. The term is commonly used to
describe how a pair of double stars is oriented, how the long axis of a
galaxy is oriented, and so forth.


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