At 16:19 2003-06-24 +0000, Lawrence Harris wrote:
>How feasible is it to use Guide to predict the transit of any
>interesting object eg., large asteroids or satellites?
Here is a thought you might try:
Locate Bill Gray's discussion of filtering asteroids by their orbital data.
There is an ASTFILTER command where you can filter out all but those
asteroids that come inside the earth's orbit. Unfortunately you will
filter out all of the large asteroids in the process. Angular size is what
is important here; think about how small Mercury looks during a transit of
the Sun.
In Guide go to the sun and set the display to line figure. This gives you
a transparent (I think) circle representing the sun. You can add a line of
motion for all of the asteroids in the display box when you right click on
any asteroid that will put a trail on each asteroid of any length you wish.
Set it for one day and it will show you the direction of travel. when you
click on the sun you can then go to the animation box and click on center
of the moving object, in this case the sun. Let it run for many days and
look for anything that crosses the suns image. Now the problem..... I
think that the answer to your question deals with the word
"feasible". There aren't many asteroids that cross the earth's orbit and
the chance that one of those will pass in front of the sun for an observer
on Earth is quite small. Add to that the small angular size and you have a
very small chance of observing the transit.
1991 VE just missed the southern limb of the sun for MPC 762 on May 31 but
it has a diameter of 1.4 Km and was 0.7 AU from the Earth.
You always ask such interesting questions.
Best regards,
Bob Elliott