December 2000 anneal report for program 8841.

There was an anneal of the CCD on December 17, 2000, 28 days after the previous
anneal on November 19, 2000.  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.  The flattening seen over the last several
months in the mean raw post-anneal dark count-rate is interupted this month, as
we see a slight increase.  As reported for the last couple months, this
flattening seemed to go to an average value of about 0.24.  In this anneal
period the growth rate of hot pixels was slightly higher than that in previous
months which results in a number of post-anneal hot pixels more than that of
the previous two anneal periods.

1) The number of post anneal hot pixels increased slightly compared to the last
   couple anneals.

   > 0.1 e/s: 16091 pixels on Dec 17, 2000
   > 1.0 e/s:  3226
   > 10. e/s:   355

   > 0.1 e/s: 15692 pixels on Nov 19, 2000
   > 1.0 e/s:  3175
   > 10. e/s:   346

   > 0.1 e/s: 15719 pixels on Oct 21, 2000
   > 1.0 e/s:  3175
   > 10. e/s:   344

   > 0.1 e/s: 15690 pixels on Sep 23, 2000
   > 1.0 e/s:  3181
   > 10. e/s:   353

2) The *raw* post-anneal dark countrate for this anneal is 0.02481 cts/pixel.
   This compares with 0.02434 cts/pixel on Nov 19, 2000, and 0.02256 cts/pixel 
   a year ago in Dec 1999. 
   
3) The iterated median count rate (after iterating up to 30 times by
   eliminating pixels +/- 5*sigma) is 0.00419, up by about 2% from last month.

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

   > 0.1 e/s:  37.2 pixels/day on Dec 17, 2000 
   > 1.0 e/s:   4.7
   > 10  e/s:   0.7

   > 0.1 e/s:  30.9 pixels/day on Nov 19, 2000 
   > 1.0 e/s:   3.4
   > 10  e/s:   0.1

   > 0.1 e/s:  20.7 pixels/day on Oct 21, 2000 
   > 1.0 e/s:   2.5
   > 10  e/s:  -0.2


   > 0.1 e/s:  39.1 pixels/day in Dec 1999 
   > 1.0 e/s:   4.5
   > 10  e/s:   0.2


5) The rate at which new hot pixels annealed out was within the normal range of
   fluctuations, perhaps a bit on the low side.

   > 0.1 e/s:  64.2% annealed away in the Dec 17, 2000 anneal.
   > 1.0 e/s:  64.1%
   > 10  e/s:  57.0%

   > 0.1 e/s: 103.1% annealed away in the Nov 19, 2000 anneal.
   > 1.0 e/s: 100.0%
   > 10  e/s:  50.0%

   > 0.1 e/s:  94.8% annealed away in the Oct 21, 2000 anneal.
   > 1.0 e/s: 108.8%
   > 10  e/s:  31.0%

   The usual plots are attached.