Hi folks,
Some replies to posts about: conjunctions of satellites with other
objects, disappearing side labels at 90-degree rotations, entering
orbital elements without perihelion dates, and duplicated asteroid
crosses:
Alex, about satellite conjunctions with other objects in Guide:
you can 'sort of' do this. If you click on the satellite, then on
(for example) the Moon, you can use "Extras... Find Conjunction"
to locate their closest separation _from the current time_. The
fact that there may be a still closer conjunction when the satellite
goes overhead 100 minutes later will be ignored.
The same is true for all conjunction-finding in Guide. You can
click on, for example, Mars and Jupiter, and Guide can then find
when they are next in conjunction with one another. But it can't
then find the next or previous conjunction. Something I may fix...
Bernd, about the side labels disappearing at a 90-degree rotation:
you're right, this is a bug. Guide assumes that it will draw dec
labels on the vertical edges of the chart and RA labels on the
horizontal ones. Rotate things by +/-90 degrees, and labels will
almost entirely vanish.
This is a more serious bug than you might initially think, because
you can get the same +/-90 degree effect if you've got the chart in
"zenith up" mode, or are showing alt/az or galactic side labels on
a "north-up" chart. After a little puzzling, though, I figured
out a way to fix it, and it seems to work. So with the next update,
this should go away.
Roger, about the orbital elements: if you select "Add New Comet",
Guide will indeed prompt you to enter a perihelion date. Select "Add
New Asteroid" (which is, after all, what we've got here), and it will
ask for an epoch and mean anomaly. (That epoch of JD 2452400.5 is
6 May 2002.)
Elements for comets are usually given with a perihelion date and no
mean anomaly (one reason being that, if they're parabolic, there is no
real "mean anomaly"). Asteroid elements are usually given in the epoch
plus mean anomaly form you got from JPL.
John, about the double asteroid crosses: this has come up a few
times, prompting me to do something I ought to have done a while ago,
namely, write a really thorough answer and put in on an FAQ. See:
http://www.projectpluto.com/faq_curr.htm#double_asteroids
-- Bill