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(meteorobs) Re: Antihelion
Robert,
Due to the apex attraction (which appears to move radiants toward the
east) the actual antihelion would arrive at the meridian near 0100 local
mean solar time and not at midnight. An experienced observer would then
have no difficulty locating the radiant area since it lies on the
ecliptic. Those not familiar with the ecliptic or the zodiacal
constellations would not have any idea the elevation of this radiant.
Another guide to the antihelion area visible from very dark sites would
be the Gegenschein, a faint oval of light that appears like a detached
portion of the Milky Way. Since the Gegenschein lies precisely opposite
the sun the anthelion radiant would be located 15 degrees east of the
center of the Gegenschein.
At sunset the apex lies at its lowest point also known as its nadir. It
always lies 90 degrees west of the sun so it can rise as early as 2300
or as late as 0100 depending on the season.
Perhaps you were thinking of the antiapex, at point which lies 90
degrees east of the sun and is near the meridian at sunset.
Unfortunately it has been shown that this area is not a practical target
for observers. Although it encompasses a massive area of the sky, it
produces the lowest rates of the entire night.
I hope this helps!
Bob
Robert Gardner wrote:
>
> Robert;
> Can one, while observing, come close to estimating the location
> of the antihelion point by noting the point on the ecliptic at midnight
> local mean solar time? Similarly with some more difficulty, noting the
> local meridian at sunset for apex, if there are enough bright stars for
> reference? What I am calling "local mean solar time" is your standard
> time, not daylight savings, corrected for your distance east or west of
> the local prime meridian. That may be stated inaccurately but I hope
> you know what I mean; I do 8-)
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