NavList:

Doug,

You will need to determine civil twilight from the Nautical Almanac then use your star finder to select the lower altitude stars/planets/Moon that are within 15* of meridian angle from due north or south. Usually there will be a body available. For example at my location here at 34N 119W civil twilight is at 17:20 showing Fomalhaut in a good ex-meridian position at Hc 25* Az 185*.

Greg Rudzinski

[NavList] Question: Ex-Meridian method for computing Latitude and azimuth limits around the Meridian
From: Doug MacPherson
Date: 19 Dec 2012 20:17
All:

I have been playing around with Hansen's simplex Ex-Meridian tables. I have normally just used the sun at around noon to get the Latitude via the ex-meridian tables, and Norie's ABC tables for an azimuth in case I needed an LOP.

Lately I've been working on other bodies that are close to the meridian at dawn or dusk. This got me to thinking.

Hansen's tables are good for a body that is about 60 minutes on either side of transiting the meridian (if I am using them correctly). If I were to be up at dawn, looking for bodies close to the meridian to shoot, what would be the azimuth limits that correspond to plus or minus 60 minutes of time? Ia this something that can be computed ahead of time? It would be handy.......any body within _____ degrees and _____ degrees would be fair game. You could determine the body later with the star finder.

Doug
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