Hi folks,

Three items: an update to Charon, handling of cross-indexing and
other data errors, and an inquiry about porting Guide to Linux.

CHARON UPDATE:

I just posted a new CHARON2.ZIP (the 'test' version of Charon). This
fixes a problem where Charon blinked _very_ slowly on older machines. The
problem was that, at each blink, Charon processed the image to look for
stars in it. This is a slow process.

The solution is that Charon now only shows image stars (red circles) in
the original image... a pretty minor limitation, since you couldn't measure
or generate reports for 'blink' images anyway.

CROSS-INDEXING/DATA ERRORS:

Carlos, regarding data/cross-index errors... the catalogues used by
Guide (and any other program) are full of them. I have some hopes to allow
for 'errata' files to correct at least the most blatant of them. This would
let you say that, for example, "NGC XYZ is really at this RA/dec, not
the one shown by Guide, and has this magnitude. NGC ABC doesn't actually
exist at all." And so forth.

This particular error is better handled using a "user-added note" (.NOT)
file. In this case, the PPM data for PPM 751991 is in error, so you
could create a PPM.NOT file and add the following three lines:

$751991
The PPM cross-index to CD -34 1866 is in error, and should read
CD -34 14866. (Pointed out 17 Jan 2000, by Carlos Lopez.)

(Replace the '$' with a '~'. My e-mail software objects to lines
beginning with a '~'.) When you next ask for 'more info' about this star,
the above lines will be added to the PPM section.

I'm reluctant to change original catalog data. It's better to leave the
original data, with a note indicating improved information and its source.
The .NOT files let you accomplish just that.

And I'm not totally sure this example really _is_ a PPM problem; it may
be a Guide problem. I'm looking into this.

GUIDE IN LINUX:

And finally, I just got another inquiry about a possible Linux version
of Guide. (There is already some text about this on my Web site, at

http://www.projectpluto.com/future.htm#Linux

This gent is suggesting that a port using the svgalib might be
preferable to an X-Window version (I'd been contemplating using GTK+
and GDK). An svgalib version would, unfortunately, have something of
the look-and-feel of DOS Guide. It would be a lot easier to do, though,
and would be good on older machines that don't handle X well.

I really lack time to do a Linux port all on my own; I'd be more
likely to post source code and have the Linux version of Guide fall
under the GNU Public Licence. Opinions regarding a Linux version, or
offers of help in the port <grin>, are welcome... it may be best to
address them to me, though, rather than to the list.

-- Bill