posted on Oct, 3 2011 @ 08:53 PM
reply to post by Vamp333
Well I just observed and measured the moon's position and orientation last night. It's exactly as it should be. Hopefully you've seen my video
showing the effect field rotation has over time and how it's caused by observing the moon from a non-polar aligned perspective. Indeed, any
celestial object or constellation you watch in the sky will show this effect from an altitude-azimuth perspective.
I also performed astrometric measurement of the moon's position last night. Here's the astrometric solution showing that the moon was right where
it was supposed to be.
First I took a frame of the moon from the video right as I disengaged the drive system at 10:29:00 PM eastern time (00:58:03 on this recording from
last night: www.ustream.tv...
). I then determined where the center of the moon should was based on the curvature of the
moon's limb. In this particular image (having expanded the canvas size to 1100x960) the center was at 528x500:
I then took the frame immediately after re-engaging the drive system at 10:38:45 eastern time and put it in the same position. Since 585 seconds had
passed between drive disengagement and drive re-engagement (meaning the telescope was not moving at all during this time), we would expect the stars
to progress through the field of view by 586.6 arcseconds (a sidereal day is shorter than a solar day, making a solar day about 1.0027 times longer).
Given that the moon's coordinates at drive disengagement should have been 17h 41m 53.91s, -23d 05' 33.1", the previously determined center point of
the moon should now correspond to the following coordinates:
17h 51m 40.51s -23d 05' 33.1"
Overlaying the Palomar Sky Survey image corresponding to those coordinates centered on the 528x500 point corresponding to the previous position of the
moon's center point finds a match with the stars from the video at the moment the drives were re-engaged 585 seconds after disengagement:
In other words, the stars that were present at that point reveal that the moon was right where it should have been relative to the stars. In summary,
the moon was right where it should have been in the sky to within the resolution of the telescope (in this configuration, 2.24 arcseconds per pixel).