Date: Fri, 4 Jun 1999 07:59:58 -0600
From: long@apo.nmsu.edu (Dan Long)
Subject: 2.5m obslog 990603 ( MJD 51333 )
                          THURSDAY JUNE 3, 1999
                     APACHE POINT OBSERVATORY SDSS 2.5m
                              OBSERVING  LOG
    Observering team:   Dan Long                (APO)
                        Jeff Hayes              (APO)
                        Ellyne Kinney           (APO)
   After last night's poor model, the scraping sound when moving the
primary, and the conical baffle coming loose, we were looking for some good
news.  We got some!  The source of the scraping sound was found and
removed, and I took a 70 point model which had a sky rms of 1.4 arcseonds!
   Jeff and Ellyne mounted the spectrographic cartridge for FASTT field L
and got the fiducials set in the evening twilight.
        Az:     120:45:46.957
        Alt:     14:53:09.490
        Rot:      0:59:38.003
   French came back in around 22:30 and listened while I homed the primary.
He tracked the scraping sound to the number 2 astigmatism actuator.  When
it was removed, it was found that the piston was damaged, and was the
source of the scraping sound, rather than the primary.  The damaged
actuator was left out, but the astigmatism corrector was left on.
  At this point it was a little after 23:00.  Given the time and the
removal of the damaged actuator it was best to continue to improve or at
least characterize the pointing.  With Matt Newcomb's help, I switched to
the engineering camera ( including the swapping of kinematic mounts ).
Balance was at a counterweight setting of 330. I was on the sky by 00:30.
   The first thing I did was home and relax the primary.  Next, I took a
focus sweep consisting of -400, -50, 0, 50, and 400 units out of focus.  I
then homed the secondary and repeated the sweep.  The images are in
/data/spectro/guider on sdsshost, and are called 990603_*.  The ones called
990603_ah* are the sweep after homing the secondary.  There is considerably
less coma in these images compared to last night, but it is not entirely
absent.  I decided not to tweak the coma adjustment until the astigmatism
corrector is back to its full compliment of actuators.
                                MIRROR NUMBERS
   Primary:
   setmir:  0   3.9   -2.3   -128   -214
   galil:   4350 -1750   0 16300  -11550  -11450
The linear gauges after setting to above position and relaxing
   1.9325
   0.5555
   0.5575
   0.4220
   1.8850
   0.3845
   Secondary:
      SecOrient=-1400.0, -219.4, -100.0, -50.0, -44.8   El=58.0
homing secondary yielde the following errors.
-000020000, -000010000, -000010000,  000000350,  000000150 position error
   I then proceeded to repeat last night's 70 point grid collecting
pointing model data.  I also found a value for the change in piston of the
secondary versus elevation, by focusing on the first dozen points of the
model.  A number for the sin component of SecPistCoef of about -380 was
found, and I added that to DEFAULT.DAT.  I then observed the focus during
the rest of the model, and saw that it remained within about 25 microns of
the compensated value.
   The grid was completed at about 05:20. I closed up at that point, and
went to check the data set ( not without some trepidation ).  However, the
first fit to existing coefficients and removing no points yielded a 2.5
arcsecond rms.  By adding some terms and removing two outliers, I got the
fit down to 1.4 arcseconds.  I output the model listed below
       coeff       change     value    sigma
  1     IE       -179.119   -179.12    0.517
  2     IA       -232.665   -232.66    0.860
  3     PZZ1     -129.527   -129.53    0.658
  4     AN         -6.502     -6.50    0.371
  5     AW        -54.314    -54.31    0.351
  6     CA        +13.131    +13.13    0.588
  7     ACEC       -4.813     -4.81    0.715
  8     ACES       -0.904     -0.90    0.735
  9     HWSA2      +3.956     +3.96    0.780
 10     HWCA2      -2.271     -2.27    0.383
 11     HXSA2      -3.261     -3.26    0.606
 12     HNSA2      +0.628     +0.63    0.430
 13     HNCA2      +1.678     +1.68    0.409
 14     HZSA2      -1.027     -1.03    0.254
 15     HZCA2      +0.574     +0.57    0.241
Sky RMS =   1.43
Popn SD =   1.62
   I noticed during tonight's model as well as last night's, that the
windscreen azimuth is quite jittery, more so than I remember it being
recently, and _much_ more than when motor 3 was removed to power the
altitude.  Maybe we should run with just 1 and 2 all the time? :)
                                WEATHER
   Weather tonight was clear or mostly clear all night.  Winds were
southwesterly at 10 to 20 MPH, temperatures were 11 to 14 C, the dewpoint
depression was between 20 and 31 C, dust counts were less than 1000.
                                  Dan