August 2001 anneal report for program 8841.

There was an anneal of the CCD on August 21, 2001, 24 days after the
previous anneal on July 28, 2001.  A homogeneous set of data was obtained
from proposal 8841:  The CCD Hot Pixel Annealing.

Previous trends continue.  The growth rate of hot pixels continues within the
range seen for previous months.

1) The number of post-anneal hot pixels has decreased at all levels.

   > 0.1 e/s: 15093 pixels on Aug 21, 2001
   > 1.0 e/s:  3215
   > 10. e/s:   363
   
   > 0.1 e/s: 15140 pixels on Jul 28, 2001
   > 1.0 e/s:  3240
   > 10. e/s:   370
   
   > 0.1 e/s: 15866 pixels on Jul 11, 2001
   > 1.0 e/s:  3278
   > 10. e/s:   379
   
   > 0.1 e/s: 17012 pixels on May 1, 2001
   > 1.0 e/s:  3455
   > 10. e/s:   389


2) The *raw* post-anneal dark countrate for this anneal is 0.02430 cts/pixel.
   This compares with 0.02401 cts/pixel a month ago, and 0.02444 cts/pixel 
   a year ago.  The offset relative to last year is due to the safing in May.
   and subsequent operations of the CCD at lower temperatures.
   
3) The iterated median count rate (after iterating up to 30 times by
   eliminating pixels +/- 5*sigma) is 0.00389, up from last month.

4) The creation rates for hot pixels over this period were within the normal
   range of fluctuations.

   > 0.1 e/s:   4.3 pixels/day in Aug 2001
   > 1.0 e/s:  -2.1
   > 10  e/s:  -0.9

   > 0.1 e/s: -13.4 pixels/day on July 28, 2001
   > 1.0 e/s:   0.2
   > 10  e/s:  -0.4

   > 0.1 e/s: -205.8 pixels/day on July , 2001
   > 1.0 e/s: -53.0
   > 10  e/s: -10.6


   > 0.1 e/s:  40.5 pixels/day 1 year ago
   > 1.0 e/s:   4.5
   > 10  e/s:   0.3


5) The rate at which new hot pixels annealed out was within the normal range of
   fluctuations.

   > 0.1 e/s: 147.0% annealed away in the Aug 21, 2001 anneal
   > 1.0 e/s:  47.9%
   > 10  e/s:    65%
   
   > 0.1 e/s: -237.7% annealed away in the Jul 28, 2001 anneal
   > 1.0 e/s:   1366%
   > 10  e/s:    -50%
   
   > 0.1 e/s:  29.4% annealed away in the Jul 11, 2001 anneal
   > 1.0 e/s:  45.9%
   > 10  e/s:    53%


   The usual plots are attached.