PreCam Tilt/Rotation History

Photo of PreCam Looking Up Toward Tilt/Focus Box & Telescope

• • PreCam is at "zero rotation" -- i.e., the CCD columns and rows are aligned with RA, DEC

  • Compare with Tilt/Focus Box Diagram above.

  • The directions N, E, S, W come from the masking-tape labels on the corners of the Tilt/Focus Box; I think these are correct, but I am not 100% certain.

  • I am a little vague on the orientation of the CCDs within the dewar, but the on-sky observations indicate that, when the PreCam is rotated to this orientation, the PreCam CCDs are aligned such that their long axes point North-South and their short axes point East-West. (Larger row numbers are due North and larger column numbers are due West in ds9.)

[The last two items are degenerate: if I was sure that the masking-tape labels were accurate, I would know the orientation of the CCDs in the PreCam dewar, and, if I knew for certain the orientation of the CCDs in the PreCam dewar, I would know if the masking-tape labels were accurate.]

In the above photo, we have labeled the tip/tilt screws as TT1, TT2, TT3 ("TT" for "tip/tilt").

TT2 and the central bolt are behind the large folding flat support structure and are thus hidden from view.

Another view of the original secondary, taken by Oscar Saa. Note the central bolt (large brass-colored bolt) and the three tip/tilt screws TT1, TT2, and TT3.

This is a schematic diagram of the original folding flat (as seen from behind looking toward the primary).

I am not 100% sure of the orientation of the support structures. They are roughly accurate, but they did not seem to be at 90deg to each other.