Late July 2001 anneal report for program 8841.

There was an anneal of the CCD on 28 July 2001, 17 days after the previous
anneal on 11 July 2001.  This half month between anneals was caused by the
safing of STIS which occured in May, and the subsequent turn-on of the
instrument in mid-July.  An anneal was done shortly after turn-on.  This anneal
is part of the regularly scheduled anneals done every 4 weeks.  A homogeneous
set of data was obtained from proposal 8841:  The CCD Hot Pixel Annealing.

1) The number of post-anneal hot pixels has decreased at all levels due to
   the extended period of being shut off, and due to the CCD operating at a
   lower temperature.

   > 0.1 e/s: 15140 pixels on Jul 28, 2001
   > 1.0 e/s:  3240
   > 10. e/s:   370
   
   > 0.1 e/s: 15866 pixels on Jul 11, 2001
   > 1.0 e/s:  3278
   > 10. e/s:   379
   
   > 0.1 e/s: 17012 pixels on May 1, 2001
   > 1.0 e/s:  3455
   > 10. e/s:   389
   
   > 0.1 e/s: 17042 pixels on Apr 7, 2001
   > 1.0 e/s:  3473
   > 10. e/s:   389
   
2) The *raw* post-anneal dark countrate for this anneal is 0.02401 cts/pixel.
   This compares with 0.02439 cts/pixel on Jul 11, 2001, and 0.02306 cts/pixel 
   a year ago.

3) The iterated median count rate (after iterating up to 30 times by
   eliminating pixels +/- 5*sigma) is 0.00359, down from earlier in the month.

4) The creation rates for hot pixels over this period are

   > 0.1 e/s: -13.4 pixels/day in late July 2001
   > 1.0 e/s:   0.2
   > 10  e/s:  -0.4

   > 0.1 e/s: -205.8 pixels/day in early Jul 2001 
   > 1.0 e/s:  -53.0
   > 10  e/s:  -10.6

   > 0.1 e/s:  37.3 pixels/day in May 2001 
   > 1.0 e/s:   6.9
   > 10  e/s:   0.2


   > 0.1 e/s:  40.2 pixels/day 1 year ago
   > 1.0 e/s:   4.4
   > 10  e/s:   0.2


5) The rate at which new hot pixels annealed out was odd given the creation
   rates being negative at some levels.

   > 0.1 e/s: -237.7% annealed away in the Jul 28, 2001 anneal
   > 1.0 e/s:   1366%
   > 10  e/s:    -50%
   
   > 0.1 e/s:  29.4% annealed away in the Jul 11, 2001 anneal
   > 1.0 e/s:  45.9%
   > 10  e/s:    53%
   
   > 0.1 e/s: 103.5% annealed away in the May 1, 2001 anneal.
   > 1.0 e/s: 111.4%
   > 10  e/s: 100.0%
   

   The usual plots are attached.