Re: Dec Drive, etc.

[Tom Droege <tdroege@veriomail.com>]

Arne and all,

Fair enough, I want it better too.

Here is my program:

1) Work on the Stamp program so that the declination motor current can be 
kept on until the dec. clamp is on.  The present problem is that the dec 
motor current has to be turned off before the clamp motor can be turned 
on.  The present software only supports moves by one motor at a time.  If 
you try to leave two motors turned on then both move.

2) Work on the existing clamp mechanics.  I don't see any good design 
changes, just better execution.  Like brake pads that stay in place and are 
the right thickness.

3)  Try to make the focus flatter.  I know how to make a significant 
improvement, but it requires major rework.  The present focus bearings 
stick.  They are just nylon sleeve self adjusting bearings.  I could 
replace them with linear ball bearings.  This would take some doing.  I 
will probably order a set of parts to try and install them on MICHAEL at 
some slowdown in delivery time.

Tom Droege

At 08:54 AM 9/19/00 -0700, you wrote:
>The reason Tom keeps bringing up the subject of the
>Declination Drive with my name attached is that he and
>I are running the Mark IV in different modes.  Instead
>of just repeat scanning of a single declination zone, I tend
>to move all over the sky.  For example, here is what I am
>programming ARNE to do automatically this evening:
>     * turn on TEC cooling, move to RA/Dec limits
>     * when dark, take series of 90 second darks.
>     * at 0300 UT, move to BP Vul and take 90-second exposures
>       for 2.5hrs.
>     * when finished, take series of 90 second darks. (I don't
>       want interspersed darks during the BP Vul dataset because
>       the time series needs to be continuous.)
>     * go into survey mode: single RA, 150 second exposures moving
>       about 3.5 degrees in declination between exposures for about
>       8-10 moves; then move to new RA, move back to the starting
>       declination and repeating for the rest of the night. Darks
>       are interspersed, taken just before moving to the next RA.
>     * when finished, park the telescope and turn off TEC.
>The RA drive moves nicely and I have no problems with it.  The
>Dec drive depends on the Dec clamp, and that is where most of
>the repair activity is taking place.  I think it is working
>well enough to give the full schedule a shot.
>   The CCD and electronics are working really well.  I'm impressed
>with what Tom got from Loral for $1700.  Reading out two CCDs of
>this size in 48 seconds is faster than what we do with our
>scientific systems, and there is no obvious pattern noise.
>The image quality looks good, but I'm sure I'm not at the
>best focus yet.  Several problems still remain that I'm not
>sure I will have time to address before Europe; fixing these
>will make the difference between 0.03mag errors and 0.01mag errors,
>or in going another magnitude fainter.  The system works as-is,
>but I want it better!
>Arne