Calibration Plan

Introduction

There are two components to the FEROS Calibration Plan:

  1. Daily Calibrations
  2. Long Term System Monitoring

Daily Calibrations

As the name suggests Daily Calibrations are carried out EACH and EVERY day that FEROS SCIENCE observations are made. As of 2005-Nov-19, they consist of:

  • Afternoon: A short set of Daily Heath Check calibrations in one readout mode (currently the default mode 225kHz,1,low) but in both 1x1 & 2x2 binning. These allow the DRS to be initialised for both 1x1 and 2x2 binning modes, i.e. All data will be reduced online.
  • Morning: A "Standard" set of calibrations are acquired in each readout mode used during the night using the CALOB tool.

Daily Health Check calibrations

One set of DHC calibrations consists of:

  1. 2 BIAS frames
  2. 2 FlatField frames with high signal to noise (S/N in extracted flats of 500-800 in the majority of the spectral orders).
  3. 1 WaveLength Calibration frame (either WLC lamp can be used, but only one is used, currently by default we use the ThAr+Ne lamp).

Standard Calibrations

One set of Standard calibrations consists of:

  1. 5 BIAS frames
  2. 10 FlatField frames with high signal to noise (S/N in extracted flats of 500-800 in the majority of the spectral orders).
  3. 6 ThArNe frames of three different exposure times in the ratio of 1:5:10 to give optimum S/N in different parts of the spectrum.
  4. 6 ThAr+Ne frames of three different exposure times in the ratio of 1:5:10 to give optimum S/N in different parts of the spectrum.
  5. One 1-hr DARK exposure for each readout mode used duirng the night, only once every TEN days basis.

Other Calibrations

  1. 2 x 120 sec exposures of the SolarSpectrum. Obtained approximately 1hr berfore sunset, pointing the telescope ~2hrs EAST of the meridian without tracking, at Declination -30 degrees.

Observers need only prepare calibration OBs if they require calibrations in addition to the above, in particular the spectrophotometric standards

Long Term System Monitoring

Philosophy

The objective of the Long Term System Monitoring programme of the FEROS Calibration Plan is to monitor the system performance. The main components are CCD performance and Instrument+Telescope performance.

CCD performance is monitored via standard CCD tests. Instrument+Telescope performance is monitored via observations of spectrophotmetric standard stars.

CCD tests are currently carried out using a BetaLight. In order to install the BetaLight it is necessay to enter into the FEROS Climate Controlled Room, which is rather undesirable, since it means in order to avoid disturbance to the system performance BetaLight CCD Tests can not be carried out during an ongoing observing run. Therefore we are currently testing a remotely controlled LED system which we hope will allow us to largely elliminate the need to enter the FEROS Climate Controlled Room. If and when the LED system has been accepted, LED CCD tests will likely be carried out on a daily basis, at least initially.

Instrument+Telescope performance is carried out on allocated Technical nights, though some information can be provided by the nightly SpectroPhotometric Standard star observations carried out under the Daily Calibrations plan.

Monitored Quantities

  1. CCD test: BIAS level, Read Out Noise, Conversion Factor, Linearity.
  2. Total System Efficiency [TSE].
  3. Relative Fibre Efficience [RFE].
  4. Response Curve [RC].
  5. Focus.

CCD Test

CCD tests are performed on a daily basis using a a green led to perform the following operations:

  1. Compute the bias level
  2. Compute the conversion factor
  3. Compute the Read out Noise
  4. Perform a lineary test

The results of these tests can be found here

Instrument+Telescope Performance

Execution

TBD

Reduction

In MIDAS...