Time Stamp   Filename       File size	Description
----------------------------------------------------------------------------
   13:42:32    blocker1     	 38380	 Scan w/ just blocker and polarizer
   13:46:32    blocker2     	 38285    Unless otherwise noted ALL scans
   13:50:49    blocker3     	 38247    have blocker & polarizer.

   14:22:26    lyot_nowave1	 38323    Lyot without half-wave plate
   14:34:00    lyot_nowave2	 38342    (but w/ polarizer in place.)

   14:43:46    lyot_nowave_nopol 38418   Lyot w/o HW plate or polarizer

  Some amount of fiddling occurred in here.   It was decided that the Lyot
     actually cut about 90 - 95% of the light.  We increased the PMT bias
     from 780 to 1080V in order to get enough counts from PMT's 

   15:16:00    lyot_nowave3	 38361   Lyot without half-wave plate
   15:20:31    lyot_nowave4	 38361    (but w/ polarizer in place.)
   15:24:38    lyot_nowave5	 38399   


   15:35:39    lyot_hw-90  	 38361  Scans of Lyot with Half-wave plate
   15:39:52    lyot_hw-75  	 38361     Set at the designated rotation.
   15:45:11    lyot_hw-60  	 38418     Note that 0 degrees is arbitrary
   15:49:42    lyot_hw-45  	 38418     however, +90, 0, and -90 should
   15:54:13    lyot_hw-30  	 38304     show substantially the same
   15:58:21    lyot_hw-15  	 38342     spectrum.
   16:02:32    lyot_hw000  	 38361
   16:06:51    lyot_hw+15  	 38418
   16:10:58    lyot_hw+30  	 38323
   16:15:16    lyot_hw+45  	 38323
   16:19:27    lyot_hw+60  	 38304
   16:23:34    lyot_hw+75  	 38380
                                        *** WSO had an incident - it tried 
                                            to shutdown
   16:36:18    lyot_hw+90  	 38380   Scan appeared normal


   16:44:40    lyot_nowave6	 38361   Lyot w/o half-wave but w/ polarizer

   16:49:28    lyot_nowave_polrot 38399 Lyot w/ polarizer rotated 90 degs

   16:54:46    lyot_nowave_nopol2 38361 Lyot w/o HW & w/o polarizer

   17:05:43    blocker4     	 38323  Scan with only blocker & polarizer
   17:09:43    blocker5     	 38418    - we also used some polarizer to
                                          adjust the light level so as not
                                          to saturate the PMTs.

The conversion from encoder units to Angstroms is:

             Ang = enc/14982. + 6149.6

*
*
Detailed Notes:  

Distance from bottom of Lyot to the slit is 670 +/- 50 mm 
(why +/- 50 mm?  Because we have an image slicer which is 100 mm long
and is not confocal so it changes the light path length to the slit
along the slit.)

All scans were run using this arg list: scanspectrum 10000 40 2200

This should provide about 0.025A spectral resolution.

The first three scans (blocker1,2,3) were to set the baseline.


The next scans (Lyot_nowave1,2 and Lyot_nowave_nopol) showed that
there wasn't enough light getting through the Lyot to get a good
measurement.  After some back of the envelop calculations we decided
to up the PMT bias voltage to 1080V (at 2:55 pm) it remained at this
level for the remainder of the scans.

The next scans (lyot_nowave3,4,5) were taken, they showed that the
bias level was fine.

The next 13 scans were taken with the half-wave plate at orientations
from -90 to +90 degrees in 15 degree increments.  The zero point for
this is arbitary, but apparently close to tuned on the line.

Another scan was taken without the half-wave plate (lyot_nowave6)

A scan was taken with the polarizer rotated 90 degrees (set to 204
degrees - all the previous scans with the polarizer were set to 294
degrees. - as with the HW plate, the zero point is arbitrary).

Another scan without the half-wave plate and without the polarizer was
done - (lyot_nowave_nopol2).

Finally, two more scans without the lyot or the half-wave plate were
done (blocker4,5).  These had the polarizer plus another one to reduce
the light level to prevent the PMTs from saturating.