[guide-user] Tycho-2, fixed mags,

Bill J. Gray Feb 14, 2000

Hi folks,

TYCHO-2 USE IN CHARON:

I just received my Tycho-2 CD-ROM today, and have posted a beta
version of Charon that is capable of using it (or the Tycho-2 data
available via Internet, to those who can download >500 MByte files.)
I've put information about it at

http://www.projectpluto.com/charon2.htm

GETTING STS-99 TO SHOW UP:

Masaki Kouda pointed out that "STS-99 elset has no data for calculating
magnitude, so Guide didn't show 'Visible' prediction." I hadn't thought
about that! To fix this, change the .TLE file to read:

STS-99 2.1 v 300
1 26088U 00010A 00044.71026157 .00075662 23632-7 55340-4 0 72
2 26088 57.0071 297.7926 0013247 277.7054 41.5133 16.14834215 324

This tells Guide that the Shuttle is half a magnitude fainter than
Mir, which I think is about right... I remember seeing them, not too
far apart, on one of the Shuttle-Mir visits. You may have to adjust
the '2.1' up (to get a fainter value) or down to match reality.

FIXED STAR MAGNITUDES:

Frank, I apologize. You've been caught by a mistake I made.

Quite a while back, somebody strongly suggested that Guide's default
behavior of adjusting magnitudes as you zoom in and out was a terrible idea;
he believed that if you set stars to display to mag 12.4, they ought to go
to mag 12.4 no matter what zoom level you were at.

I explained why I disagreed, but he still wanted to give it a try. So
I made a small change and told him: Hit Alt-Minus, and Guide will toggle
to the behavior you desire.

He tried it, and decided pretty quickly that it was a bad idea, for
exactly the reason you found: it's too easy to set a faint limit, then
accidentally back out to a wide field of view. But I never did get around
to removing that Alt-Minus hotkey, until you mentioned it.

Anyway, hit Alt-Minus, and you'll toggle back to 'normal' behavior.

OVERLAY FORMAT:

I've had some requests for information about the overlay format in Guide.
The documentation for it is on the CD-ROM, in the file \COMPRESS\OVL_FMT.DOC.

SUN DATA:

Ton Spaninks, I don't quite follow you... what sort of solar data would
you be looking for? (Physical ephemeris? Sunspot counts?) I must admit
that my knowledge of solar observing is minimal. The most I've done is
to observe through filtered binoculars.

I probably should beef up Guide's data regarding the Sun, considering
that it's approaching an interesting year of activity.

SWEDISH KEYBOARDS/ALT-; DOESN'T WORK:

Claes, interesting point... some hotkeys are not going to work on
non-US keyboards. I intend to tackle this by (a) reducing the need for
hotkeys (remembering Alt-; and Alt-. to adjust planet features is a pain!)
and by (b) allowing people to reassign hotkeys.


-- Bill