Comet mags/printed legend/listing user-added

Bill J. Gray Apr 18, 2001

Hi folks,

COMET MAGNITUDES:

These are indeed a real pain to deal with. You can click on "Extras",
"Edit Comet Data", and select the comet in question. The simplest thing
to do is to change the absolute magnitude, H. If the comet is, say,
five magnitudes brighter than expected, then decrease H by five. (H
is the magnitude at which you would see the comet if it were one AU from
the Sun, and if you were standing on the Sun.)

The alternative would be to play around with G, a parameter describing
how quickly the comet brightens as it approaches the sun. I've not seen
any real patterns in G; as a result, I've just stuck with the values
provided by MPC.

By adjusting these, you're basically doing what Bernd Brinkmann suggested:
altering the magnitude parameters that were originally supplied by MPC.

None of this will really handle the underlying problem: we're modelling
the very weird and unpredictable magnitude changes in a comet with only
two variables. One possibility I've contemplated is to make use of the
MPC page of current comet magnitude estimates,

http://cfa-www.harvard.edu/iau/icq/CometMags.html

so that Guide could say (under 'more info') something like "Joe Smith
observed this object two nights ago at mag X.XX, Janet Doe observed it
last night at mag Y.YY..."

MISSING LEGEND:

Ned, this one's a bit baffling; if the legend appears on-screen,
it should appear on the printer, too. The first thing I'd do is to go
to "Display... Printer Font". Perhaps that got corrupted somehow. If
it's okay (and text does appear elsewhere on the printed charts), I'd
suggest e-mailing me your STARTUP.MAR file privately. That will give
me your settings, and perhaps I can puzzle something out.

SHOWING A LIST OF OBJECTS FOR USER-ADDED DATASETS:

Sorry, no, there is no way (at present) to do this. If I do it,
it will work by allowing the user to generate and display a list of
objects on-screen than can be examined, printed, etc. If you click
on an object in the list, Guide will center on it.

-- Bill