===============================================================
Investigation of the increase in the number of hot pixels
in the INGRID array - Hawaii-I

A. Zurita (November 2003)  
===============================================================


Darks taken on November 6th, showed an apparent increase in the number of hot 
pixels of INGRID.
It was then decided to investigate further and to find out when the increase took place.
The table below shows the percentage of hot pixels in each quadrant (being outside a 
+/-4-sigma range around the dark current level) and in each intensity interval.
It's clear that the increase took place between July 18th and August 16th 2003.
There was a warm up of the intrument just after the NAOMI+INGRID July run, and
it's not clear to us (sgr,awr,azurita) whether the power was kept on while 
colling down (which we have heard could increase the number of hot pixels).




				             Hot pixels (percentage)  Hot pixels with intensity 
					                              greater than...(%)
                                             ----------------------------- ---------------------- 
 date         file  BIAS   CCDTEMP  noise  total  l-t   r-t  r-b  l-b   >30  >50 >100  >1000 
(yyyymmdd)                          (adu)
-------------------------------------------------------------------------------------------------
20030327   r585921  ----   79.0    5.4       0.7   0.4  0.4  1.1  1.1   0.6   0.5  0.3  0.09
20030419   r589404  11868  76.6    6.6       0.5   0.2  0.2  0.8  0.8   0.4   0.4  0.2  0.07     
20030514   r593341  12410  79.8    2.6       1.0   0.6  0.5  1.5  1.5   0.6   0.4  0.3  0.08
20030614   r600181  20418  83.3    8.7       0.6   0.3  0.3  0.9  0.9   0.6   0.6  0.4  0.08  (*)
20030718   r606798  20128  82.1    2.1       1.1   0.6  0.5  1.5  1.6   0.6   0.4  0.3  0.07
20030816   r615933  19989  81.7    4.3       2.0   1.3  1.3  4.1  1.3   1.7   1.3  0.9  0.3
20030908   r621196  20662  82.1    5.7       2.1   1.4  1.4  4.1  1.4   1.4   1.5  1.1  0.3
20031106   r632054  -----  80.2    4.8       1.8   1.2  1.2  3.6  1.1   1.5   1.2  0.8  0.3

(*) Not valid, filter H in, light reaching detector

l-t = quadrant left-top
r-t = quadrant right-top
r-b = quadrant right-bottom
l-b = quadrant left-bottom

>30 = percentage of pixels with intensity
      greater than 30 adu