Notes on Comet Finder & CFGS

[John_L._Graham@adbbs.antioch.edu (John L. Graham)]

With comets in the news recently I thought I'd post a few notes on using
Comet Finder and Comet Finder GS to track the current Comet Hyakutake and
next year's Comet Hale-Bopp. During my recent vacation trip I toted along
my IIc+ to start work on updating Comet Finder (which will also lead to an
update to Comet Finder GS). Jeesh, did I really write that hack? *B^) I
hate looking at old code, t'is embarrassing. Anyway, I'm looking to add
the code needed to track periodic comets like Hyakutake and Hale-Bopp.
After pounding on it for a while I discovered that for LONG period comets
like these (orbital periods of thousands of years) their trips near the
Sun may be approximated with the elliptical orbit model that the current
versions of Comet Finder use. Sooooo, until the new versions are out you
can just go ahead and use Comet Finder v4.0 and Comet Finder GS v1.1 with
satisfactory results. Use the periodic orbital elements and ignore the
eccentricity and orbital period terms. I'll post the elements for
Hyakutake as soon as I can. It's a tad late for this comet but it'll still
be fun to see what the orbit looks like. For Hale-Bopp I pulled the
following elements from the Observer's Handbook 1996;
 
     Date of Perihelion:              4/1.6416/1997
     Perihelion Distance:               0.913023 AU
     Eccentricity (ignore):             0.994441
     Argument of Perihelion:          130.6678 deg.
     Longitude of the Ascending Node: 282.4729 deg.
     Orbit Inclination:                89.4142 deg.
     Orbital Period (ignore):      ~2,000 yrs.
 
A quick look at the orbit suggests the comet will be on the far side of
the Sun at perihelion. Although this one's being talked up in the press I
fear it'll be another Halley. We'll see.
 
Have fun!
 
John