NavList:

Byron,

Sky cover and horizon sharpness seem to set the rules for how many and how accurate a round of stars will be. More often than not the navigator doesn't get to choose the stars to shoot. You get what is given peeking between the clouds.

If given the chance I like to observe three bright stars on a sharply contrasted horizon that are separated 120* in azimuth at about the same altitude. Having one of the three exactly on the beam to indicate cross track error is desirable. Body altitudes and azimuths are pre-calculated. This aids in locating bodies and ensures the completion of the round within the twilight period.

If pressed for time then I take what ever is available. Venus and the Moon seen through thin clouds may have to suffice.

Greg Rudzinski

[NavList] Shooting Stars
From: Byron Franklin
Date: 8 Nov 2012 14:10
Byron: What is your experience and thoughts about shooting stars? I have read on navlist that many set the star height in the sextant than look in the direction of Azimuth. This makes me wonder how, and what is the best procedure for ensuring the best fix. Notice I said to ensure. I don’t go to sea anymore, but I often go out at about the right time and observe the stars as they pop out. As I have always noted the high stars are the first to appear, and away from the sunset/rise. Often I shot high stars because,
like the other night I would not have any other choice and I needed a position. It’s always a balance of good star, good horizon but take what is available.
I will talk about what I have observed personally. The time to get on the bridge to prepare for observing stars depends on sunrise/sunset. In the AM 30 to 40 minutes before sunrise. You want to accustom your eyes to the present light. You want to get the star/body as soon as the horizon is sharp to the east because the stars will start to fade. High stars away from the sun will normally pop out first & fade last. Don’t hurry, only get 3-5. Try to get a good spread. Soon the horizon to the west will sharpen and lower stars will be sharp for a while. For sunset be ready 15 minutes after sunset. First look to the east because that horizon will thicken first. Look high darker blue with less atmosphere to see through, and to the eastward for the first star to appear, but still, look everywhere. You should in both cases sunrise/set have information from a star finder. High stars should start to appear first and early, get them with a good horizon. Don’t hurry. Try to get 4 or 5 with good spread. As in visual compass bearings you need to plot at least 3 ,best if two is near 90 degrees spread, the third any other angle but not parallel to judge the fix accuracy. What is your take or method?

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