[guide-user] Blinking/lunar features/etc.

Bill J. Gray Jan 13, 2000

Hmmm... let's see... all sorts of things have been going on in my
absence:

CLICKING ON LUNAR FEATURES:

True, if you click on the disk of the moon (or any planet), you
get that object first, and only get features on it when you click
'next'. The main reason for that was that otherwise, it's nearly
impossible to actually click on the moon; you get some crater instead.
This is one of the rare times I can actually say: it's not a bug,
it's a feature.

BLINKING IN CHARON:

Bob Elliott pointed out (via private e-mail) that CHARON2.ZIP wasn't
displaying blinked images correctly; they were offset by about half a
screen. I've fixed this, but still need to fix one other problem: on
slower machines ('486s, for example), blinking is _really_ slow. The
reason is that Charon now makes a list of stars found in the image each
time you blink. I expect to evade that problem; once I do, we _should_
be all set. (If you're using a faster machine, you should be able to
use CHARON2.ZIP right now.)

Andre Germain proposed an interesting mechanism for contrast adjustment.
The one I just added looks pretty decent so far, and the code is simple...
the 'contiguous area in a histogram' method might have its points, though.

I've not posted fresh source code for Charon yet, by the way. I will
once Charon becomes 'stable' enough. On the bright side, the assorted
changes I've made ought to make the source a lot easier to follow.

GALAXIES WITHOUT MAGNITUDES:

Owen, regarding "how does one force galaxies with no magnitude to be
displayed": turn galaxies On. If there is any magnitude limit at all
(Auto or Fixed settings), galaxies with no mag data will be skipped.
(This is true of other classes of objects, such as globulars, open
clusters, etc.)

GEONAMES AND "ERRATA" FOR GEONAMES:

Oliver Kloes pointed out, correctly, that the DGEO_ERR.DAT cities
aren't showing up. That's a result of a new feature that I was testing
at the time of the last update, and should have fixed before posting.

The names in GEONAMES.DAT have 'level of importance' (LOI) data now.
If you're in eclipse mode, you can hit '+' to show more cities, and '-'
to omit the least important cities. You can keep doing that until all
cities are gone, or hit '+' until all cities are shown. (Normally,
'+' and '-' affect magnitude limits, of course, but we don't need to
adjust magnitude limits when we're looking at geographic data.)

Cities with no LOI are automatically put in the least important
category, and by default, Guide didn't show these. You can hit '+',
and they will appear.

The problem is that DGEO_ERR.DAT (right now) has _no_ LOIs set. The
new GEONAMES.DAT on the Web site does have LOIs, of course, but some
people tried running the current version of Guide with an older GEONAMES.DAT
and saw all the geographic text vanish. For the moment, you can evade
all these problems by hitting '+'.

TABLES OF VARIABLE DATA:

Oliver suggested "a table of the dates of minima/maxima of the most
prominent variables..." At present, the best I can suggest is to mention
that there is such a table on the AAVSO Web site, listing long-period
variables and their maxima/minima in 2000:

http://www.aavso.org

This is copyrighted material, so we can't use it in Guide. But this
is only a small limitation to its use.

"...If I am clicking on a variable, there is a option to calculate the
next date of ninima/maxima for this star." I did this, once upon a time,
using the epoch and period data from the General Catalogue of Variable
Stars (GCVS). The problem was that the GCVS is about 30 years old now,
and in almost all cases, the predictions were terrible. This isn't a
hopeless case, though; I can probably get current data for at least
some variable stars.

CLICKING ON BIG OBJECTS:

Oliver mentioned that "...it is still difficult at high level to click on
objects with a big area (e.g. open clusters, hitting stars all the time,
not the object info). A small cross, which marks the center position would
help." Or, better still (in my humble opinion), the ability to click
on the perimeter of the large circle or square.

OFF-AXIS GUIDER FOVs:

Oliver also suggested that it would be nice to see where an off-axis
guider was pointing, similar to the way guide chips on ST7-9s are shown.
At present, adding a new CCD is very easy (read the end of CCDS.NAM to
see how), but adding new off-axis fields is not; it is built into Guide.
Something for me to contemplate...

SOLAR SYSTEM OVERVIEWS:

"A view from the 'top' of the solar system (90 degrees to the ecliptic)
for checking planet positions to each other. (Good for animation too)"

This is possible, sort of, in a very clumsy manner.

http://www.projectpluto.com/useless.htm#Viewpoints

Next step is getting Guide to shift stars correctly for views _really_
far from the earth; and, of course, to show them at relativistic
speeds, clustered and blue-shifted in the direction of your motion.
(That would be another case of my doing something no one is particularly
interested in, just because the math interests me. I want to see how
much of freshman physics stuck to my brain...)

-- Bill