April 2000 anneal report for program 8410.

There was an anneal of the CCD on April 6th, 2000, 28 days after the 
previous anneal on March 8, 2000.  A homogeneous set of data was obtained
from proposal 8410:  The Continuing Monthly Anneal Monitor.

For the most part, previous trends continue. The rate of hot pixel
growth, was within the average of previous months. A considerable number
of 1 e/s level hot pixels were annealed this period but there were more 10e/s 
level hot pixels after the anneal that there were before it. 


1) The number of post anneal hot pixels continue increasing consistent
   with the previously determined long term trends. 


   > 0.1 e/s: 14258 pixels on April 6
   > 1.0 e/s:  2936
   > 10. e/s:   318

   > 0.1 e/s: 14249 pixels on March 8
   > 1.0 e/s:  2890
   > 10. e/s:   287

   > 0.1 e/s: 14028 pixels on February 12
   > 1.0 e/s:  2861
   > 10. e/s:   304


2) The *raw* post-anneal dark countrate for this anneal is 0.0227 cts/pixel.
   This compares with 0.0220 cts/pixel in February 2000, and 0.0165 cts/pixel in
   March 99. 
   
3) The iterated median count rate (after iterating up to 30 times by
   eliminating pixels +/- 5*sigma) is 0.00424.
   
4) The creation rates for hot pixels over this period were within the normal
   range.
   
   > 0.1 e/s:  27.8 pixels/day in April 2000 
   > 1.0 e/s:   2.7
   > 10  e/s:   0.2

   > 0.1 e/s:  39.9 pixels/day in March 2000 
   > 1.0 e/s:   3.0
   > 10  e/s:   0.0

   > 0.1 e/s:  39.1 pixels/day in February 2000 
   > 1.0 e/s:   4.5
   > 10  e/s:   0.2

   > 0.1 e/s:  56.1 pixels/day in March 98
   > 1.0 e/s:   5.9
   > 10  e/s:   0.4

5) The number of 1 e/s level hot pixels annealed was larger than usual while
   the number of 10 e/s level hot pixels was larger after the anneal that 
   previous to it. The rate at which new hot pixels annealed out, however, was 
   within the normal range of fluctuations.

   > 0.1 e/s: 98.8% annealed away in the March 00 anneal.
   > 1.0 e/s: 37.8%
   > 10  e/s: -417%

   > 0.1 e/s: 74.8% annealed away in the February 00 anneal.
   > 1.0 e/s: 86.4%
   > 10  e/s: 300.%

   > 0.1 e/s: 60.0% annealed away in the January 00 anneal.
   > 1.0 e/s: 57.7%
   > 10  e/s: 43.0%

   The usual plots are attached.