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On Thu, 30 Sep 2004, Brooke Clarke wrote:

> One way to determine star to star angles is with either Starry Night Pro
> or TheSky.

Are these commercial programs?
(I always prefer shareware when possible:-)

I am using a script I made myself, on a laptop,
the only disadvantage is
that I have to input the almanach data manually.
(I don't know whether I can generate my own almanach
as Frank Reed did; I am not a professional programmer)

This can be easily fixed, of course, just by
tabulating ALL mutual distances between the usual 57 navigational
stars. If there will be enough interest in this,
I may consider putting such table on the web:-)
Something similar to the Bruce Bauer list, expanded.

But this list will be useless without a refraction correction.

As Chauvenet and Frank Reed explain (see his postings on April 6),
measured star distances substantially depend on refraction
and thus from both stars altitudes.
And one need a separate simple computer program that takes care
of this correction.

This is where I find my Star Globe indispensable: I can measure
the distances and altitudes instantenously, simply by
applying a hand divider to the globe and then to the scale on one of the
globe's circles.

The preliminary distance estimate is needed to preset my sextant.
Otherwise catching two distant stars to the field of view
is very hard.

On Thu, 30 Sep 2004, Brooke Clarke wrote:

A> One way to determine star to star angles is with either Starry Night
Pro or TheSky.  Both of these astronomy programs move the star locations from 
the almanac date forward to account for earth precession and for proper 
motion of the stars.  Atmospheric refraction is also included so the 
elevation of the observation is needed.  A friend who uses Starry Night Pro 
got these separations on 29 Sep 2004:
>
> Vega sep to Altair reports 34d 11'42"
>
> The Vega -Eltanin sep reports as 14d 31'46"
>
> Have Fun,
>
> Brooke Clarke, N6GCE
>
> --
> w/Java http://www.PRC68.com
> w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
> http://www.precisionclock.com
>

   

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