			CometPlt


Welcome to CometPlt. This utility program computes comet ephemerids from
orbital elements stored in the file Comet.DAT located in the current directory.

The ephemerids are output to the file CometOut.TXT as a standard text file
which can be viewed by your favourite editor, or printed out.

Dates are output are in the form YYYY/MM/DD which is closer to international
convention, so as not run into the confusion with US or Canadian forms.

The program also computes close encounters that the comet will have with a set
of bright better known deep sky objects.



2. Input Parameters

You will be prompted to enter the following info:
  1. Enter the start date of computation in form YYYY.MMDD
     ie. for July 28, 1996 you would enter 1996.0728

  2. Enter the number of positions to compute: ie. 10

  3. Enter the number of days between positions:
     You would enter 1 if you want every day computed.
     You would enter say 5 if you wanted ephemerids for every 5th day.

  4. If you want to compute possible close encounters with a list of
     bright deep sky objects you then answer 'y'. Any other character
     if not.

  5. If you selected to compute close encounters, you'll then be prompted
     to enter the field size around the comet to see if any of the objects
     pass within range.  You must enter a value between 1-10 degrees.




3. Output fields

   Program output looks like this:

Ephemeris for Comet: Machholz (1994r).   Perihelion: 1994/10/05

Date 0h UT   R.A.       Dec      Distance(AU)        SA Uran       arcsec pos  
YYYY/MM/DD       J2000.0        Earth    Sun    Mag  2K chrt Elong  min   angle
-------------------------------------------------------------------------------
1994/10/10   8h38.9m  +5518'   1.694   1.841  13.8   2   44   82
1994/10/11   8h37.0m  +5514'   1.675   1.841  13.8   2   44   83  1.216  261


Included is the comet's name followed by its designation and perihelion date.

The ephemerids are computed for 0h UT for the date in question, follwed by RA
& Dec computed for Epoch 2000.

Distances in AU for Comet-Earth and Comet-Sun distances.

Magnitude is computed using the H & G parameters. The magnitudes have the
tendency to be inaccurate. These parameters are updated as more observations
of the comet are sent to the CBAT and refinements made. Hence magnitudes
should not be regarded as absolute. You should update these as the refined
elements are made available.

The next two fields contain chart numbers for SA-2K (Tirion Sky Atlas 2000)
and Uran-chrt (Uranometria). These will help you find the current position
quickly in the appropriate atlas.

The next field shows the Elongation from the sun. (0-180 degrees).

The next two fields show the comet's daily motion in arcsec per minute and
the position angle of motion. These are useful when attempting to photograph
a moving comet by either using the step quiding method or a mechanical stepper.




4. Input Data file: Comet.DAT

All input is assumed to be for Epoch 2000 which is the current IAU standard.
If there is sufficient interest, I will add the flexibility of inputing
orbital elements from Epoch 1950 and conversion to current Epoch.

 ==============================================================
 Comet data is assumed to be in COMET.DAT in current directory
 in format:
	  a "//" before a Comet Designation, ignores this comet.(ie. //1994m)
	Comet Designation (ie. 1994m, or the new 1995D3 style designations)
	Comet Name (ie. Swift-Tuttle,  Sorrells  or  P/Machholz)
	Perihelion (T) in YYYY.MMDDnnn (ie. Oct 5.574, 1994 = 1994.1005574)
	Eccentricity (e)
	Perihelion Distance in AU (q)
	Inclination (i)
	Longitude of ascending node in degrees
	Longitude of perihelion in degrees
	magnitude parameter: H
	magnitude parameter: G

   for example:
1994r Machholz 1994.1005574 1.0 1.83977 102.027 249.603 144.449 7.8 7.4

   an example of an ignored comet: (notice the // in first two positions)
//1994f Takamizawa-Levy 1994.0522537 0.99955 1.35926 132.871 306.831 61.631 7.6 3.3
