[sac-board] Re: Board Meeting

On Wed, 12 Oct 2005 21:57:28 -0700, Rick Tejera wrote:

> We can discuss the 2006 schedule, See if we can solve the March problem.
> I'll bring a few copies of the proposal I put out.
> 
> Stan has posted it on the web at:
> 
> http://www.saguaroastro.org/content/db/SAC-Schedule-2006.pdf

On March 18, I show twilight ending (a sun dip of 15 degrees) at 19:50,
15 minutes earlier.  "Astronomical twilight", which is a sun dip of 18
degrees, is when instruments can no longer detect the twilight.  The
human eye can usually no longer detect the twilight when the sun is 15
degrees below the horizon.  Since these star parties do not usually
support CCD instruments, the sun dip of 15 degrees likely is best.

I figured this out by my own observations and it was later confirmed by
Brian Skiff, who uses this value too.

If your software doesn't support a 15 degree sun dip, just average
astronomical and nautical twilight times.

I have moon rise at 22:29.

So the question is:  is 2h 39m long enough to observe?

        -Paul

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