Sorry this one is so long. I thought I'd sent one part of it a day or
two ago, and just now realized that it never got sent.
LX200 ENHANCEMENTS:
Of the three things Andre mentioned...
"(1) LX200 constant position update
(2) Continuous LX200 slews (satellite tracking)
(3) Scope mechanical compensation by guide for LX200"
...the first and last are fairly likely to happen. Each involves
various tricky pieces that I've been avoiding so far, but LX200s and
LX200-like systems (including the Autostar) are too common for me to
evade this forever.
I'd rather like to do the second, but as best I can tell, you can't
really get the LX200 to do this. You can send the LX200 a command to
"move here", but you can't tell it to "move on each axis at thus-and-such
a rate". (You _can_ get it to move at any of four different speeds.)
If anyone knows of a way around this, I'm all ears.
COAA/TELESCOPE SYSTEMS:
James, thanks for the details about the COAA system. I didn't realize
this was a two-PC setup with one older PC serving to turn the COAA system
into an LX-200 clone... such things have been done quite frequently, though.
I think one motivation is that, once your system is LX-200, almost _any_
software will control it.
It also evades some timing issues in tracking. If your PC is handling
the stepper motors, there would be a risk that Windoze would decide that
the time had come to perform garbage collection. Suddenly, your scope
stops tracking. Having the scope controlled by an older PC running DOS
evades that problem.
SATELLITE TRACKING:
Greg, getting Guide to track satellites with Mel's ALTAZ system is (as
far as I know) not possible yet. The main reason is that I send Mel's
software an RA/dec, not an RA/dec plus rates of motion on each axis.
Andre, you mentioned that "...continous RA & DEC positions as well as
rates from guide would help track satelites." What might work best, I
suspect, would be if Guide produced an ephemeris for the satellite in
advance, to be read by your software. This may also make tracking a
little smoother, since Guide wouldn't have to run at the same time
you were tracking. Having multiple apps running while the scope is
tracking invites the 'real-time' problem discussed in the preceding
paragraph.
Which causes me to return to Greg's use of an ALTAZ scope. Meade is
not apt to respond to the pleas of satellite observers... but Mel Bartels
is much more likely to consider adding something like this. You might
ask him to consider a feature wherein ALTAZ would read a satellite
ephemeris generated by Guide, and track that satellite by interpolating
positions.
Andre also wrote: "...I am also interested in tracking these beasts.
The only thing that worries me is that after I've done so, the interest
will wane quickly as you can track only so many satelites..." I dunno
about that... when I first added satellites to Guide, I set it up to
a level 1, horizon-to-horizon view, with satellites to mag 6. I
sat down with 7x50 binox and went from one satellite to the next. If
you've a decent knowledge of the naked-eye stars, it's not too tough
to find three or four a minute. There's a lot of junk up there.
Ideally, you would be able to track them, then determine orbits
from the resulting astrometry. I've made a few steps in that direction:
http://www.projectpluto.com/find_orb.htm#Mir
but not as much as you would really need to do the job.
ASTROMETRIC PROBLEMS:
The way Bob Elliott used the new 'display astrometric data in Guide'
ability, as a sanity check, is about the sort of thing I intended when
I wrote it. One thing to keep in mind, if you see large, consistent
residuals in Charon, is that it may be a good idea to visit the MPC site
and get the latest orbital elements for the comet:
http://cfa-www.harvard.edu/iau/Ephemerides/Soft02.html
Gareth Williams of the MPC has kindly provided elements in Guide's own
format. This does make matters easier. You can just download the file(s)
and click on "Extras... Add MPC Comets/Asteroids" to bring the fresh element
sets in.
Also, if you're using older elements, you'll generally see just the
sort of thing Bob mentions: the position predicted by Guide (or Charon)
will show a consistent error, with the error lying right on the line of
variation.
OVE'S MYSTERIOUS CRASHING:
This does sound quite odd... Hartwig's suggestion of using chkdsk is
always my first move (under Win95, scandisk is a slightly better option).
Failing that, I'll ask the usual 'debugging' question: what did you
do between the time it worked, and the time it _didn't_ work? (Install
new software? Add a new dataset or update to Guide? ...)
PIERRE'S INVERTED HORIZON:
Pierre, I assume that by 'inverted', you mean that areas that should
be filled are not, and areas that should not be filled in _are_ filled in?
If so, it may help to break the horizon up into pieces. Whenever
an horizon object is larger than a certain area, Guide can get confused
as to which side is 'inside' and which side is 'outside'. As a result,
I try to make sure that no one object is larger than about 30 degrees
across.
A better way to make horizon objects such as walls and mountains is
described here:
http://www.projectpluto.com/update7c.htm#easier_horizon
It does not have this size limitation, and figuring out how you are
adding a given wall or mountain range is _much_ less confusing.
.BMP PROBLEMS:
James mentioned that "...I had to do a screen capture as I cannot get
any graphics program to read the 'make bmp' bmp files from Guide." You're
not alone. Fortunately, there are fixes/workarounds:
http://www.projectpluto.com/faq_curr.htm#bmp_failure
ASTEROID PROBLEMS:
Stephen Kerr mentioned some problems with imported asteroids. First,
the positional errors: the difficulty here is that Guide's built-in data
has been numerically integrated, so you get 'fresh' orbital elements at
50-day intervals. The elements you get from MPC are at a fixed epoch;
use them to predict positions a few months away, and an error begins to
accumulate. As a result, using the MPC elements (in this case) is not
a good idea.
There _are_ situations where the MPC elements describe newly-found
objects, or incorporate new observations that aren't reflected in Guide's
built-in elements. In such cases, the MPC elements do indeed have an
advantage. But that will never happen for the sort of low-numbered,
well-observed minor planets that are used for asteroid occultations.
Speaking of which: you mention that "...several minor planet occultations
predicted by Edwin Goffin for [Australia]..." Can you direct me to this
list? You may have seen that, in the current version of Guide on the
Web site, you can get lists of asteroid occultations for Europe, North
America, and Japan for the year 2000. If there is a similar list
available for Antarctica, I'd like to use it.
CROSS-REFERENCING CATALOGS:
You also wrote: "...I was wondering how Bill manages to crossreference
difficult catalogues like the Washington Double Star list. It must be
prone to errors." All too much so...
The WDS comes with a cross-reference. It's a good thing, too; my
usual methods of cross-referencing catalogs would not work too well here.
For example, I cross-referenced the GSC to the PPM on the basis of
position: if a PPM star lay within a tolerance of a GSC star, I could
pretty safely assume they were one and the same. I expect to be able to
similarly cross-reference the GSC to the A2.0. But WDS positions are so
poor that such a method wouldn't work. And the fact that double stars,
by their nature, consist of two "nearby" stars would make it even tougher.
I assume the compilers of the WDS did the cross-index by hand. Better
them than me...
LUNAR ECLIPSES FROM THE FAR SIDE:
James, nifty way to show the 'eclipse as seen from the moon'... one
thing you may want to play with would be a variation on this:
http://www.projectpluto.com/interest.htm#lagrange
It describes a way to view the solar system from all five of the
Earth-Moon Lagrange points. One of these, L2, is 92,000 km above
the far side of the moon (lunar longitude = 180 degrees, latitude = 0.)
The '500000 km above the earth' viewpoint rotates with the earth...
use a '100000 km above the moon', or maybe a bit more than that, and
you've got a viewpoint that rotates with the _moon_, and keeps the moon
basically between you and the earth.
-- Bill