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The FEROS at the ESO-1.52m CCD Page

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General Information

The CCD camera is operated with the CCD controller developed by the Astronomical Instrument Centre at the AOC and identical to that in operation at the Danish 1.54-m telescope on La Silla. The controller is capable of delivering the full performance of the CCD in terms of readout noise, CTE, immunity from interference, crosstalk, etc., and provides the image files with the necessary header information. Readout times are of the order of 70 sec through two parallel signal chains.

CCD Characteristics
Op. temperature -1100 to -1200 C
RON 3 e- (for 50 kpix/sec/port)
Dark current 1.5 e-/h/pixel
CTE (par/ser) 0.99999/0.99999
Linearity < 1% deviation up to full well
Full well capacity 150.000 e-

The performance figures given above are based on experience at AOC and are typical measured figures, after optimising operational temperatures, clock waveforms, etc. They apply to CCDs operated at a pixel rate of 50 kpixels/sec and at a nominal temperature of -110°C. ``Full well'' is defined as the exposure limit to which no measurable departure from linearity occurs; the exposure level causing actual blooming is considerably higher.

The camera uses an EEV CCD detector of the design specified for FEROS, i.e., 2048x4096 pixels of 15x15microns, mounted in a continuous-flow cryostat. The CCD can only be mounted with the columns in the main dispersion direction.

The thinned 2kx4k CCD and the standard ESO-VLT continuous-flow cryostat are provided by ESO.

The CCD controller electronics (+ 1 spare) were built by the AOC; also the integration and testing of the complete CCD system were carried out at the AOC.

Note regarding the bias level from Peter Sinclair:

My experience with the Danish controller on DFOSC tells me that a change in 5 adu is rather normal... Actually, the bias level of DFOSC moves around a larger figure... within a single test. I have discussed this with Preben Norregard and he says that this should not be a problem provided the user takes the bias level from the overscan area...

* Derivatives
* Standard CCD Test
* Long CCD Test



Time Evolution

The below plot shows the variation of the bias level, standard light-source (note that often a beta-light is used which, due to radioactive decay, will fade. It is also possible that the phosphor can be poisoned, but our data show no evidence for such an effect), gain, read-out noise, shutter error, and linearity error as a function of time. The values for the bias, gain and read-out noise are plotted along with the associated measurement error. The blue dashed line in the plots shows the mean value of all the points, while the dotted blue line shows the standard deviation of this distribution. The blue and red points in the bottom plot show the maximum deviations in a positive and negative sense wrt the least-squares fit of the linearity data. Plotted vertically on the bottom of the graph is the date (dd/mm) on which the test was made.

[Click here to download ps file]

For printing, the above plot is also available in postscript format . The raw data can also be viewed in a tabular format.




Standard CCD Test

Below we show the most recent test.



  ***  MIDAS logfile (vers. 97NOV) *** Su, 08 Sep 2002   15:50:46   Page 1
 
 
  ***  MIDAS logfile (vers. 97NOV) *** Su, 08 Sep 2002   15:52:17   Page 2
 
     ========================================================== 
     SUMMARY STANDARD TEST CCD#60 TAKEN ON 020908 IN blow MODE 
     ========================================================== 
  
      BIAS 
      ==== 
  
      5 biases at start test: average = 210.50 stddev =   1.81 
  
      There were 1 hot pixels/columns detected 
  
  
      TRANSFER FUNCTION AND LINEARITY DATA 
      ==================================== 
  
  Table : Std_blow_60_020908 
 Sequence Exp_tim1  Med_cnt1  Med_cnt2  Variance  Frc_cnt1  Frc_cnt2  el_adu1  
 -------- --------- --------- --------- --------- --------- --------- ---------
        1      2.00     638.8     639.0     264.7      0.27      0.26      2.41
        2      4.00    1256.8    1256.5     509.5     -0.44     -0.47      2.47
        3      8.00    2509.4    2509.3    1037.0     -0.13     -0.14      2.42
        4     16.00    5007.5    5007.2    2048.1     -0.13     -0.13      2.44
        5     32.00   10015.1   10015.7    3999.1      0.00      0.01      2.50
        6     52.00   16287.2   16286.7    6372.8      0.12      0.12      2.56
        7     72.00   22549.7   22549.6    8691.2      0.13      0.14      2.59
        8     92.00   28806.8   28804.9   10951.7      0.12      0.12      2.63
        9    112.00   35056.6   35054.6   12819.1      0.09      0.10      2.73
       10    130.00   40641.4   40643.4   14868.7     -0.03     -0.01      2.73
 -------- --------- --------- --------- --------- --------- --------- ---------
  
      Dynamic range explored: from 1745 to 111025 e- 
      Average count rate measured: 313 ADU/sec. 
  
      CONV. FACTOR AND RON 
      ==================== 
  
      C.Fact =   2.73 +/-   0.03 e-/ADU 
  
      RON    =   4.94 +/-   0.06 e- RMS 
  
  
      SHUTTER ERROR 
      ============= 
  
 Average shutter error derived from fractional count rate =  0.038 sec 
  
  
      LINEARITY ERROR 
      =============== 
  
 Average linearity error after shutter correct. = + 0.26/-0.46 % 
  
 These errors represent maximum deviation in % from the average 
 count rate after correction for shutter delay 

In addition, the previous standard tests are available. Click in the table below to access these files.

Standard Tests 1 2 3 4 5 6
990606.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
990814.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
990901.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
990916.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
990928.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
991028.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
991110.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
991123.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
991208.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
991222.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
991229.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
000105.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
000124.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
000329.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
000404.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
000514.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
000525.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
000702.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
000730.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
001012.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
001120.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
010129.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
010323.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
010506.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
010516.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
010517.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
010716.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
010725.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
010925.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
011010.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
011023.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
011105.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
011119.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
011212.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
011217.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
011231.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
020308.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
020320.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
020326.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
020330.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
020422.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
020704.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
020728.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
020812.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
020825.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
020902.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps
020908.txt aver.ps cbias.ps hist.ps lin1.ps lin2.ps trans.ps

In the above table, the postscript files are:

Column
Number
Description
1 Average of the rows and cols. of the bias image
2 Combined bias frame of 5 bias images
3 Histogram of the bias image
4 Plots of exposure sequence, unedited transfer and raw linearity
5 Plots of filtered linearity and differential non-linearity in
6 Filtered transfer curves for both data sets

Note: filtered means that saturated images or deviating too much from the other data, if present, have been removed.




Long CCD Test

Below are the results of the long tests carried out by ODT. Be warned that these are large compressed tar files, and are of specialised interest. To download, press the shift key and click on the hypertext link with your middle mouse button.

Long Tests


Updated:
23/Oct/2002
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