During October and November of 2003, the FEROS CCD Controller was
changed from the original Copenhagen University Astronomical
Observatory BIAS CCD Controller to an ESO-VLT Compliant FIERA
controller. Historical CCD performance information for the BIAS system
can be found here. The FIERA
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.
Five standard readout modes are available (the Conversion Factor (CF),
ReadOut Noise (RON) and ReadOut Time (ROT) figures given below in table
1 are representative)
| CCD Characteristics | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| ReadOut Mode | CF [e-/ADU] | RON [e-] | ROT [s] | Dark Curr [e-/pix/hr] | CTE [par/ser] | Linearity [%] | Full Well Cap. [e-] | Num Ports | Purpose |
| 225kHz,1,low,1x1 (norm) | 2.96 | 4.80 | 41 | 1.1 | TBD | TBD | 150,000 | 1 | For High S/N Observations |
| 60kHz,1,high,1x1 (slow) | 1.03 | 2.67 | 148 | 1.1 | TBD | TBD | 150,000 | 1 | For faint, RON-limited sources |
| 625kHz,1,med,1x1 (fast) | 2.56 | 6.48 | 21 | 1.1 | TBD | TBD | 150,000 | 1 | For fast-monitoring observations |
| 225kHz,1,low,2x2 (norm 2x2 binning) | TBD | TBD | TBD | TBD | TBD | TBD | 150,000 | 1 | For High S/N Observations |
| 60kHz,1,high,2x2 (slow 2x2 binning) | TBD | TBD | TBD | TBD | TBD | TBD | 150,000 | 1 | For faint, RON-limited sources |
The performance figures given in table 1 were updated on 2004-12-05. They were derived from the regular CCD tests carried out in during the period Nov-2003 -- Dec-2004.
Note: the 625kHz,1,med readout mode should be considered EXPERIMENTAL and should not be used for science data until it has been properly commissioned which will not happen unless there is a well defined and strong scientific case for doing so. It is definitely NOT offered in Service Mode. Visitor's wishing to use this readout mode must contact the FEROS instrument Scientist well in advance of preparing their Phase 1 proposal.
Regular CCD Tests in the three 1x1 binning readout modes began in Nov 2003.
They are carried out on a daily to weekly
basis using the remote controlled Stabilized LED sources permanently mounted
inside the spectrograph on a ring just in front of the camera, and on a two
to three times a year basis using a standard Beta-Light source since to use
the Beta-Light we must enter the FEROS Climate Controlled Room which we try
to do as infrequently as possible in order to maintain the temperature
stability of the instrument.
Regular CCD Tests in the 2x2 binning readout modes have not yet been started.
Due to time constraints it is no longer possible to check all LEDs in all
readout modes, while still all readouts are checked at least on a weekly
base.
| Source |
norm 1x1 binning |
slow 1x1 binning |
fast 1x1 binning |
norm 2x2 binning |
slow 2x2 binning |
| Beta light |
225kHz,1,low,1x1 (discontinued) |
60kHz,1,high,1x1 (discontinued) |
625kHz,1,med,1x1 (discontinued) |
N/A | N/A |
| Red LEDs |
225kHz,1,low,1x1 |
60kHz,1,high,1x1 (discontinued) |
625kHz,1,med,1x1 (discontinued) |
N/A | N/A |
| Green LEDs |
225kHz,1,low,1x1 | 60kHz,1,high,1x1 | 625kHz,1,med,1x1 | N/A | N/A |
| Blue LEDs |
225kHz,1,low,1x1 |
60kHz,1,high,1x1 (discontinued) |
625kHz,1,med,1x1 (discontinued) |
N/A | N/A |