Dark Current.- 

 

 

These are the values obtained for gain and readout noise:
 

Up-Left Quad  Down-left Quad Up-Right Quad Down Right Quad Average
Gain (e per ADU) 4.18 4.25 4.16 4.15 4.18
Readout noise (e) 21.63 22.95 22.48 20.92 21.99

In figure 1, we plot the median for the four quadrants
and for the whole array.

These are the parameter obtained with  polyfit of IRAF to calculate the parameters of the fitting for each graph (in all the cases the correlation was over 0.999). The polynomial used for the fitting is of third order:

Statistic for up-left quadrant:
Integration time 
Mean
Median
StdDev
1
7.28
6.65
6.75
2
19.28
17.99
10.13
5
29.64
27.76
15.43
10
36.59
34.47
21.84
15
41.55
39.17
20.91

Statictic for down-left quadrant:
Integration time 
Mean
Median
StdDev
1
6.81
6.88
6.65
2
9.13
17.94
10.98
5
29.57
27.63
17.42
10
36.52
33.28
18.91
15
42.00
39.23
24.22

Statistic for up-right quadrant:
Integration time 
Mean
Median
StdDev
1
7.44
7.19
4.55
2
20.02
19.25
9.49
5
30.89
29.39
15.94
10
38.32
36.62
20.02
15
44.42
41.67
22.11

Statictic for down-right quadrant:
Integration time 
Mean
Median
StdDev
1
4.46
6.18
11.76
2
15.32
8.31
16.94
5
22.29
7.69
26.73
10
26.76
7.48
33.66
15
30.70
8.52
37.40

Statictic for whole frame:
Integration time 
Mean
Median
StdDev
1
7.19
7.22
7.46
2
19.55
17.84
11.87
5
29.95
26.74
18.77
10
36.84
33.39
23.44
15
42.14
39.10
25.93

In the next table are shown the coefficients of a third order polynomial fit to the dark median data for each quadrant and the full array (in all the cases the  correlation was over 0.999).
Quadrant
Median (x:=time)
Standard deviation (x:=time)
1
0.037x3-1.08x2+10.88x-1.01
-0.002x3-0.075x2+2.68x+4.47
2
0.0383-1.12x2+11.15x-1.64
0.025x3-0.67x2+5.94x+1.41
3
0.038x3-1.14x2+11.42x-1.24
0.015x3-0.47x2+5.20x+0.22
4
0.031x3-0.88x2+8.51x-0.71
0.014x3-0.50x2+6.27x+6.09
Frame
0.035x3-1.04x2+10.61x-0.64
0.013x3-0.42x2+4.94x+3.17

From the plots of the mean versus time, it's clear to see, that there is something striking in the down-right quadrant. The mean is much different to the other quadrants. A more detail study must be done to understand
what it's happening.