Re: Two new Show-and-Tells

[Tom Droege <tdroege@veriomail.com>]

Michael and Mark,

Thank you for the show and tell notes.  It is great to see the 
progress.  Just in time to be buried in the snow.  I hope you can keep the 
snow plows away.

I am glad that you have a student involved.  Nothing like learning how 
science is really done.  I would suggest that the sign of the angular drift 
is needed in the table, otherwise it does not make sense.  One might also 
measure the shift in the tape marks and convert to degrees/radians to 
relate to the drift.  Then one could show angular change vs pixel drift in 
the table.  Then Mark might be able to derive a formula.

A question for Mark.  The CCD is mounted in the camera head on a printed 
circuit board.  This board is mounted to the cooling back on three 
screws.  The cooling back is mounted to the Mark IV frame on trombone 
slides.  There can be errors everywhere, so the CCD pixels may not be 
pointing NS - EW even though the Mark IV is.  How does this affect the 
alignment process?  Suppose we mounted the camera at 45 degrees to the 
present position.  How would you then do this alignment?  (Note, I worried 
about this in the design.  It would appear that the scheme does pretty 
well.  It relies on screw clearances, printed circuit boards, and machining 
of the trombone bearing holes and cooling back to work.  I estimate that 
these errors might total to a maximum of 20 minutes of arc.)

In the dome I have a piece of steel ruler nailed under the frame that holds 
the Mark IVs.  I can adjust the frame position to about 1/16"  This should 
be 8 minutes of arc with the 25" (with the angles) lever arm.  I cannot do 
so well with TOM1 since the slide out rails wiggle a little.  The last time 
I checked, I was drifting 24 pixels per hour NS.  The drift EW was measured 
as 0.  This with a 2.3 hour run looking at image shift.

Tom Droege

At 03:11 PM 12/8/01 -0500, you wrote:

>   One of my students at RIT, Mark Teseny, is helping me
>set up the Mark IV here.  We've put together some pictures
>showing our enclosure, and how we aligned the camera.
>Check out
>
>
>         http://a188-l009.rit.edu/tass/showtell/st0008.html
>         http://a188-l009.rit.edu/tass/showtell/st0007.html
>
>                                        Michael Richmond