[time-nuts] finding time astronomically.

J. Forster jfor at quikus.com
Mon Jan 23 23:59:32 EST 2012


At the solstices, the derivative of the declination goes through just
about to zero, just like a sine wave.

-John

==============


> It might be useful to determine the rate of the sun's movement at
> the ends of the analemma.
>
> There is a passage grave north of Dublin, Ireland, that has a long
> passage from a shadow box above the entrance to a spiral carving on
> the rear wall. Light shines on the carving at the winter solstice.
>
> The waiting list to see this event fills up with New Agers about a
> year before the event. I asked our guide if that wasn't very hard
> on people who could only see the event on one day if that day was
> cloudy. "Oh, no," she said. "The event happens for 3-4 days on
> either side of the solstice."
>
> Of course, a passage grave is not the same as a shadow cast by a
> fine wire on a microscope. It might take a few years to locate it
> properly.
>
> Are there any timenuts that want to be buried in a passage grave?
>
> Bill Hawkins
>
>
> -----Original Message-----
> From: Chris Albertson
> Sent: Monday, January 23, 2012 8:40 PM
>
> On Mon, Jan 23, 2012 at 6:07 PM, J. Forster <jfor at quikus.com> wrote:
>>> I think you'd want a slit, not a pin hole.  The pin hole would be
>>> better but it would only work one day a year.
>>
>> Actually two days per year, unless it was adjusted for the summer or
>> winter solstice, then it'd be one.
>
> I still think it is "one".  because there are not an integer number of
> days per year so you don't get and exact repeat in 6 months.   Maybe a
> pin hole would only work once ever?  I don't know.  To "work" the
> pinhole has to exactly line up with the detector at the exact same
> time of day.
>
> But I'm not liking slits either because I can't see how to adjust them
> to exact vertical.
>
> I'm back to the first thing I thought of,  a wire with a large weight.
>  Then you measure the light curve as shadow of the wire sweeps over
> the detector.
>
>
>
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