This is pretty amazing!
First of all, the clear and short question by Jack, could have been
answered with 12 words: "The camera positions should be the same as in
the HC drawing." I can't actually find an answer to Jack's question
in the 364 words that Allen just spent.
Second, the HC part of Allen's figure:
http://vatceo.phys.au.dk/horde/imp/message.php?index=7668
beautifully shows what Paul, Philip and I have been trying to say for
quite a while now, and I just can't figure out how Allen's words can
correspond to that figure.
It shows the camera, fixed w.r.t. the Earth, taking pictures at
midnight, at three different points in the orbit around the Sun.
The figure makes it clear to me, that the camera points towards Polaris
in all three cases, throughout the year, and also that it will do so at
any time during the day.
It is also clear that if the camera is mounted at another angle (still
fixed) the camera will point at great circles around the celestial poles,
both during the day and during the year (taking pictures every [tropical]
solar day).
No rotation around the ecliptic axis!
By the way - spin and rotation is the same, I have never said anything
to the contrary. An orbit, does however, not need to involve a rotation/
spin, but can be purely translational - as shown in Allen's figure.
Kind regards,
