FEROS at the MPG/ESO-2.20m :: Procedure: CCDTests

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FEROS on the MPG/ESO-2.20m

CCD Tests

Overview

During the Oct/Nov-2003 upgrades an LED CCDTest system was installed. This system was tested in parallel against the tried and trusted BetaLight system during Jan-Mar, 2004. The results from the two systems agree well and the LEDs are clearly seen to be at least as stable as the BetaLight source. Therefore the LED system is accepted and becomes the default source for regular monitoring of CCD performance.

CCD performace will thus now be executed according to the following strategy:LED tests therefore be carried out daily for standard readout mode in one set of LEDs + a complete set in all three readout modes and all three LED colours on a weekly basis) with BetaLight "checkups" every 6-12 months.
After extensive test during the period 2004-2006, it appeared that the 3 LEDs gave similar results. From 2006 Nov 27th on, the CCD tests in all modes will be done only with the green LED. However, we'll continue the monitoring tests with the Red and the Blue LEDs in the 225kHz,1,low,1x1 mode once per week.

As a daily maintenance task:
1. Wednesday : Green LED in 225kHz,1,low,1x1 mode
2. Thursday : Red LED in 225kHz,1,low,1x1 mode
3. Friday : Green LED in 60kHz,1,high,1x1 mode
4. Saturday : Green LED in 225kHz,1,low,1x1 mode
5. Sunday : Blue LED in 225kHz,1,low,1x1 mode
6. Monday : Green LED in 625kHz,1,med,1x1 mode
7. Tuesday : Green LED in 225kHz,1,low,1x1 mode
OBs to implement this plan have been created. OBs for the daily tests have the names linearity-<i>-<dayname>.obd where <i> is a number bewteen 1 and 7 and <dayname> is Wednesday to Tuesday. One OB for the BetaLight tests has the name linearity-Beta.obd. These OBs are archived in CMM module stdferos.

Below are procedural details for carrying out both BetaLight and LED CCD Tests.

BetaLight tests

At FEROS install the betalight into the LED ring and move into the light path.
Ensure the Dome is dark and that the M1 cover is closed.
On wferos at the RITZ insure that MIDAS PCO session is up and running, if not from the desktop menu select Users menu... --> FEROS --> MIDAS for pco.
In Bob on wferos at the RITZ:
- Load from file the linearity.obd OB.
- Skip the last 9 templates (which are the LED tests).
- Run the OB. This will acquire the BetaLight data, process in the MIDAS PCO session, transfer the reults to www.ls.eso.org and email the summary to the ls-feros maillist, Peter Sinclaire and Aldo Pizarro for the each of the three modes fast = 625kHz,1,med, norm = 225kHz,1,low and slow = 60kHz,1,high readout modes. Each data set comprises 28 images, the first is a dark to "clean" the CCD of any residual signal (e.g. Dark current) and is not used in the analysis, the second is a 5sec normal expsoure to determine the count rate in order to calculate the exposure times required to fully sample the CCDs dynamic range, the third is a BIAS image used to correct the previous image for the BIAS level, then follow the standard 25 CCDTest images of 5 BIAS frames and 10 pairs of flat fields of varying exposure times.
At FEROS Remove the Beta Light from the LED ring and then move the LED ring back into the light path.

LED tests

Ensure the Dome is dark and that the M1 cover is closed.
On wferos at the RITZ insure that MIDAS PCO session is up and running, if not from the desktop menu select Users menu... --> FEROS --> MIDAS for pco.
In Bob on wferos at the RITZ:
- Load from file the linearity.obd OB.
- Skip the first 3 templates (which are the BetaLight tests).
- Run the OB. This will acquire the LED data, process in the MIDAS PCO session, transfer the reults to www.ls.eso.org and email the summary to the ls-feros maillist, Peter Sinclaire and Aldo Pizarro for the each of the three modes fast = 625kHz,1,med, norm = 225kHz,1,low and slow = 60kHz,1,high readout modes for the Green LED and for the Red and Blue LED for the normal mode. Each data set comprises 28 images, the first is a dark to "clean" the CCD of any residual signal (e.g. Dark current) and is not used in the analysis, the second is a 5sec normal expsoure to determine the count rate in order to calculate the exposure times required to fully sample the CCDs dynamic range, the third is a BIAS image used to correct the previous image for the BIAS level, then follow the standard 25 CCDTest images of 5 BIAS frames and 10 pairs of flat fields of varying exposure times.

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