February 2001 anneal report for program 8841.

There was an anneal of the CCD on February 10, 2001, 27 days after the previous
anneal on January 14, 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.  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 previous anneal periods.

1) The number of post-anneal hot pixels has increased as expected.

   > 0.1 e/s: 16565 pixels on Feb 10, 2001
   > 1.0 e/s:  3372
   > 10. e/s:   382

   > 0.1 e/s: 16286 pixels on Jan 14, 2001
   > 1.0 e/s:  3364
   > 10. e/s:   371

   > 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

2) The *raw* post-anneal dark countrate for this anneal is 0.02591 cts/pixel.
   This compares with 0.02521 cts/pixel on Jan 14, 2000, and 0.02267 cts/pixel 
   a year ago in Feb 2000. 
   
3) The iterated median count rate (after iterating up to 30 times by
   eliminating pixels +/- 5*sigma) is 0.00429, up from last month but within
   the expected range.

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

   > 0.1 e/s:  41.3 pixels/day in Feb 2001 
   > 1.0 e/s:   4.5
   > 10  e/s:   0.3

   > 0.1 e/s:  49.6 pixels/day in Jan 2001 
   > 1.0 e/s:  13.2
   > 10  e/s:   2.1

   > 0.1 e/s:  41.3 pixels/day in Dec 2000 
   > 1.0 e/s:   5.3
   > 10  e/s:   0.8


   > 0.1 e/s:  27.8 pixels/day in Feb 2000 
   > 1.0 e/s:   2.7
   > 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:  74.0% annealed away in the Feb 10, 2001 anneal.
   > 1.0 e/s:  93.1%
   > 10  e/s: -22.0%

   > 0.1 e/s:  85.4% annealed away in the Jan 14, 2001 anneal.
   > 1.0 e/s:  61.3%
   > 10  e/s:  72.0%

   > 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%

   The usual plots are attached.