October 1999 anneal report for program 8410.

There was an anneal of the CCD on October 24, 1999, 28 days after the previous
anneal on September 26.  The next anneal had been scheduled for November 20,
but obviously this will not now be done. 

The previous few months had shown a slight decrease in the rate of hot pixel
growth, however, this month there was a larger than average incrase in the
number of post anneal hot pixels, which negates much of that trend (see
post_plot_oct99.ps).  The number of new hot pixels formed during the month was
not unusally large, but the rate at which hot pixels were annealed away was
substantially lower than usual.  For the last two anneals at the 10 e/s level
there were actually MORE hot pixels  after the anneal than there were before
it.  

1) The number of post anneal hot pixels increased by a greater than usual
   amount this month, but the total number of hot pixels is still consistent
   with the previously determined long term trends.

   > 0.1 e/s: 13570 pixels on October 24
   > 1.0 e/s:  2658
   > 10. e/s:   613

   > 0.1 e/s: 12960 pixels on September 26
   > 1.0 e/s:  2587
   > 10. e/s:   595

2) The *raw* post-anneal dark countrate for this anneal is 0.0203 cnts/pixel.
   This compares with 0.0192 cts/pixel in September, and 0.014820 cts/pixel in
   Feb 99.
   
3) The iterated median count rate (after iterating up to 30 times by
   eliminating pixels +/- 5*sigma) is 0.00416.
   
4) the creation rates for hot pixels over this period were within
   the normal range.
   
   > 0.1 e/s:  53.8 pixels/day in October 99
   > 1.0 e/s:   6.0
   > 10  e/s:   0.2

   
   > 0.1 e/s:  32.8 pixels/day in September 99
   > 1.0 e/s:   3.0
   > 10  e/s:   0.2

   > 0.1 e/s:  52.2 pixels/day in August 99
   > 1.0 e/s:   5.2
   > 10  e/s:   0.5
   
   > 0.1 e/s:  57.5 pixels/day in September 97
   > 1.0 e/s:  11.8
   > 10  e/s:   5.4

5) The rate at which new hot pixels annealed out was significantly lower
   than average.  At the 10 e/s level there were actually MORE hot pixels
   after the last two anneals than there were before.

   > 0.1 e/s: 58.5% annealed away in the October 99 anneal.
   > 1.0 e/s: 39.0
   > 10  e/s:-37.5%
   
   > 0.1 e/s: 80.3% annealed away in the September 99 anneal.
   > 1.0 e/s: 99.0
   > 10  e/s:-29.6%

   > 0.1 e/s: 80.7% annealed away in the August 99 anneal
   > 1.0 e/s: 54.1%
   > 10  e/s: 89.9%  

   > 0.1 e/s: 83.7% annealed away in the early July 99 anneal
   > 1.0 e/s: 25.6%
   > 10  e/s:200.0%  

   The usual plots are attached.