March 2001 anneal report for program 8841.

There was an anneal of the CCD on March 11, 2001, 29 days after the previous
anneal on February 10, 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 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: 17151 pixels on Mar 11, 2001
   > 1.0 e/s:  3452
   > 10. e/s:   397

   > 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


2) The *raw* post-anneal dark countrate for this anneal is 0.02685 cts/pixel.
   This compares with 0.02591 cts/pixel on Feb 10, 2000, and 0.02324 cts/pixel 
   a year ago in March 2000. 
   
3) The iterated median count rate (after iterating up to 30 times by
   eliminating pixels +/- 5*sigma) is 0.00485, up from last month and on the
   high end of th expected range.

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

   > 0.1 e/s:  53.0 pixels/day in Mar 2001 
   > 1.0 e/s:  10.2
   > 10  e/s:   1.1

   > 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:  44.5 pixels/day in Mar 2000 
   > 1.0 e/s:   5.1
   > 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:  60.5% annealed away in the Mar 11, 2001 anneal.
   > 1.0 e/s:  71.9%
   > 10  e/s:  50.0%

   > 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%

   The usual plots are attached.