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From: Bill (no email)
Date: Sat Dec 10 2005 - 23:38:05 EST
> Bill, you wrote:
> " I did not try changing temperatures but will do. I did occur
> to me with Venus relatively low in the sky and high PB refraction could be
> playing with me."
>
> By the way, I'm not suggesting that this will eliminate your errors (they're
> insignificantly small anyway), but simply that it's interesting to see how
> much a temperature change of a few degrees at low altitudes *might* change
> the results of the clearing process.
>
> -FER
Looks like I was pretty close to a rounding point. Using one shot with a
-0.1 error, 2d F increase brought me from -0.1' to -0.2' error. It took a
10d F drop to go from -0.1' to -0.2' error.
As the shots were done between 6:35 and 6:45 EST, and temp was 11d at 6:00
and dropping, I can be sure that it was at least that cold when I did the
observations. Think it bottomed out at about 4d F.
I was surprised that both an increase and decrease of temperature increased
the bodies separation by 0.1' Simplistically, I would have thought that an
increase in temperature (BP constant) would reduce refraction and lift the
bodies less, hence a greater observed separation. A decrease in temperature
would increase refraction, lifting the bodies more, and observed separation
would be less. Back to the think tank on that subject.
If I had a strong suit, refraction would not be it. I have no clue as to how
pressure and temperature around St. Louis (maybe lower BP, higher temp?)
might affect the outcome. Could it lift the lower body (Venus) less than
predicted by local conditions, increasing the apparent separation as
calculated from local conditions? No idea.
Bill
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