Re: [Celestia-developers] Light Travel Delay

[Chris L. <cl...@ww...>]

On Sun, 26 Jan 2003, Fridger Schrempp wrote:

> Christophe:
> 
> I attach what I have been doing yesterday, for anyone to play with. It is an
> OS-independent, handy, key-shortcut implementation of a light travel (LT) delay
> scheme: 
> 
> If the selection is not empty, 
> 
> '?' : displays the LT-delay in [hr:min:sec] (for hr > 0, LT-delay < 1day) 
>                             or    [min:sec] (for hr = 0, LT-delay < 1day) 
>                             or         [yr] (for LT-delay >= 1day)
> 
> from the /observer to the selection/, as a 2 sec /flash/ message.
> 
> If the selection is a 'body',
> 
> '-' : subtracts the LT-delay from the actual (JD) time. The modified time
> is        displayed as usual in  the top right corner. Moreover, a 2 sec
> flash          message displays again the LT-delay that has been subtracted.
> 
> 
> I have conducted extensive tests of the LT accuracy computed via the known
> distance in Celestia for bodies within the Solar system versus horizons and
> found it practically /perfect/. Given its simplicity and mnemnonical
> key-assignment ('?' (LT?), '-' (subtract)), I found this /very/ handy for doing
> quantitative work, e.g. like mutual satellite events etc. 
> 
> I am thinking of realizing the '-' operation as a toggle?  
> 
> Note: that my patch /includes/ the previous patch to 'lookback' ('*'-key)
> 
> Please, let me know what you think,

Nice work, Fridger . . .  I think that these additional keyboard commands
are a reasonable compromise between convenience when viewing celestial
phenomena and calculation time.  At some point, I would like to introduce 
an option to turn on light time delay, but your change solves a big part 
of the problem.  You should check in the light time addition.

--Chris