
Orion, the Copernicus Planisphere (Version 0.11)
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If you want to do more than simply use this program
as it is, please read the copyright details and other
important information at the end of this help file.
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WHAT DOES THIS PROGRAM DO?

This software imitates a "planisphere" - a popular aid
to viewing the sky at night, which comes in the form
of two plastic disks. On the bottom disk is a map of the
heavens in polar coordinates; in the top disk is a
clear window which lets you see only that part of the
sky which is above the horizon. To get a view of the
stars at any particular time, one disk is rotated with
respect to the other until the required date and time
line up on scales which run around the circumference.
Only stars are shown - not planets.
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WHERE CAN I USE IT?

A planisphere can only be made to work accurately at
one geographic latitude. Orion is set to be accurate at
54 North, which is roughly the latitude of Lancaster,
Harrogate, Leeds or York. However it will still be
accurate enough throughout the UK and Ireland or in 
fact at any point on earth between say 5 of 54N.
If you live in New Zealand forget it! 

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HOW DO I USE IT?

When the program first starts the whole of the visible
sky is shown for 23:00 on the current date, the oval
window representing the horizon. The centre of this
window shows the region of the sky directly overhead.
The time and date can be altered using the adjuster 
arrows but alterations only come into effect after you
click the RESET icon.

NOTE: The program does not yet understand the concept
of summer time. 
During BST subtract 1 hour from clock time.  

SELECT mouse clicks...
Clicking on the map with "Select" brings up an
information box on the first star the software finds
at that location.  

ADJUST and MENU mouse clicks...
Clicking on a star with "Select" or "Menu" rotates and
magnifies the map in such a way that the region clicked 
upon appears enlarged in the centre of the screen with
north at the top.
After this "Select" and "Menu" can be used to zoom in
or out.

Clicking the RESET icon takes the program back out of
zoom mode.

Clicking the DISK icon brings up a standard save box.

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WHAT DOES ALL THE INFORMATION MEAN?

Example:
The star "Rigel" (Orion's left foot!) brings up
the following information:

HD 34085   (in the title bar)
19, beta Ori
"Rigel"
R. ascension: 5h 14m 32.3s
Declination: -8 12' 6"
Magnitude: 0.12
Spectrum: B8Ia
Parallax: 0.013"

      HD 34085
       the star's number in the Henry Draper catalogue
      
      19, beta Ori
       19 is the Flamsteed number
       alpha is the Bayer letter
       Ori is the constellation (Orionis) 
       
      R. ascension: 5h 14m 32.3s
       the star's right ascension
       (The celestial equivalent of latitude)
       
      Declination: -8 12' 6"
       the star's declination
       (The celestial equivalent of latitude)
       
      Magnitude: 0.12
       the star's visual magnitude
       (On a scale in which the brightest stars in the
        sky have a magnitude around 0 while the faintest
        stars visible with the unaided eye in perfect
        viewing conditions have a magnitude around 6)
       
      Spectrum: B8Ia
       the spectral classification of the star
        
      Parallax: 0.013"
       the parallax of the star in arc seconds
       

Q: WHAT IF I STILL HAVEN'T GOT A CLUE?
A: Find a book on astronomy!
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The program as a whole is freeware and may be passed
on without charge as long as none of the associated
files are used separately or are altered in any way. 
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ABOUT ORION 

This is a VERY early version of a program which may
or may not grow into something more substantial.
It was first written as a way of testing some fresh
data and evaluating a couple of new ideas for possible
inclusion in the next version of Copernicus. If it
does grow I intend to maintain it as Freeware.

Most of the data (on over 9000 stars) is extracted
from the Bright Star Catalogue 5th revised edition.
The next issue of Copernicus uses this data merged
with the next magnitude of fainter stars from the SAO
catalogue.

This little program is written entirely in BASIC and
gives a fairly sad perfomance on older machines. 
Until I get around to shifting at least the major 
number crunching routine into assembler I have
deliberately restricted Orion to Strong ARM users.
Life would be A LOT easier if Acorns had a floating
point accelerator!

Astro enthusiasts & PD authors:
Please get in touch. I would love to hear from others
interested in astronomy on the Acorn platform.
Despite what has been said above, if you do wish to 
write your own astronomy software for pleasure - ie
public domain software - I may be able to help.
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 Disclaimer
 ==========

 No guarantee is given as to the suitability of this
 program for any purpose whatsoever. 
 The author will take no responsibility for any loss,
 inconvenience, damage or injury caused as a direct
 or indirect consequence of using this software.
 
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Ray Middleton,  2 March 1997

Email:  ray@skymappert.co.uk

WWW     http://www.skymapper.co.uk

TTFN



