August 1999 Anneal Report for 8410

There was an anneal of the CCD on August 23, 1999, 26 days after the
previous anneal of July 28. A homogeneous set of data was obtained from
proposal 8410: The Continuing Monthly Anneal Monitor.  

As shown in the attached plots, the usual trends continue. At the 0.1 e/s
level, the post-anneal dark now shows 11845 hot pixels.

1) the *raw* post-anneal dark countrate for this anneal is 0.018790
   cts/pixel. This compares to 0.01805 cts/pixel on 1 July and 0.014820
   cts/pixel in Feb 99, consistent with a growth rate of 0.0066
   cnts/pixel/year.  This continues past trends.

2) the iterated median count rate (after iterating up to 30 times by
   eliminating pixels +/- 5*sigma) is 0.00348 cts/pixel.  This is a 
   larger than usual jump in the median count rate, but is it not
   unprecedented.

3) the creation rates for hot pixels over this anneal period were within
   the normal range found in recent anneals.

   > 0.1 e/s: 52.2 pixels/day in August
   > 1.0 e/s:  5.2
   > 10  e/s:  0.5

   > 0.1 e/s: 52.4 pixels/day in late July
   > 1.0 e/s:  4.9
   > 10  e/s:  0.5 

   > 0.1 e/s: 47.5 pixels/day in early July
   > 1.0 e/s:  5.2
   > 10  e/s:  0.5

4) The rate at which new hot pixels annealed out was also within the normal
   range of fluctuations.

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

   > 0.1 e/s: 81.4% annealed away in late July anneal
   > 1.0 e/s: 92.4%
   > 10  e/s: 00.0%  
   
   > 0.1 e/s: 83.7% annealed away in early July anneal
   > 1.0 e/s: 25.6%
   > 10  e/s:200.0%  


   Cumulative plots of total post-anneal hot pixels, and the new pixel
   anneals are attached.