Re: Moon - Aberration

"MET" <Marcel.E.Tschudin@xxxxxxxxx> wrote in message news:5d7e4e3b-c0d5-4dd7-8075-9b4d7f1e54e0@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Ok, I found it now myself. The "diurnal" aberration at the equator is
0".32. This is for my purposes sufficiently small to be neglected.

This effect shifts the apparent position of *everything*: Moon, background stars, etc in a particular direction and the maximum amount is equivalent to the ratio of equatorial rotation speed of around 0.46km/sec to c, about 300,000km/sec, when expressed as an angle:

0.46/300000 = .92/600000 radians = 0.32 arcsec.

So I don't think it is what you were looking for, unless you are concerned with extremely exact telescope pointing. See also the "annual aberration" of around 20 arcsec.

Do you have in mind the difference between the actual position of the Moon at some instant and the observed position which is shifted due to the finite time delay due to the speed of light? Approximation: the Moon moves about 1/2 deg/hour, or 1800 arcsec in 1800 seconds of time, so the calculated position and actual position will differ by about 1.3 arcsec.

See Bill Owen's answer for yesterday on J2000, which is closely related to this.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

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