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Quality Control and
Data Processing

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FORS2 ...
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FORS2: Spectral efficiency
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FITS key QC1 database: table, name definition class* HC_plot** more docu
QC.SPEC.EFFICIENCY1 fors2_response..efficiency_1 efficiency at 9300 A HC [docuSys coming]
QC.SPEC.EFFICIENCY2 fors2_response..efficiency_2 efficiency at 4100 A HC [docuSys coming]
QC.SPEC.EFFICIENCY3 fors2_response..efficiency_3 efficiency at 4500 A HC [docuSys coming]
QC.SPEC.EFFICIENCY4 fors2_response..efficiency_4 efficiency at 4900 A HC [docuSys coming]
QC.SPEC.EFFICIENCY5 fors2_response..efficiency_5 efficiency at 5300 A HC [docuSys coming]
QC.SPEC.EFFICIENCY6 fors2_response..efficiency_6 efficiency at 5700 A HC [docuSys coming]
QC.SPEC.EFFICIENCY7 fors2_response..efficiency_6 efficiency at 5700 A HC [docuSys coming]
QC.SPEC.EFFICIENCY8 fors2_response..efficiency_8 efficiency at 6500 A HC [docuSys coming]
QC.SPEC.EFFICIENCY9 fors2_response..efficiency_9 efficiency at 6900 A HC [docuSys coming]
QC.SPEC.EFFICIENCY10 fors2_response..efficiency_10 efficiency at 7300 A HC [docuSys coming]
QC.SPEC.EFFICIENCY11 fors2_response..efficiency_11 efficiency at 7700 A HC [docuSys coming]
QC.SPEC.EFFICIENCY12 fors2_response..efficiency_12 efficiency at 8100 A HC [docuSys coming]
QC.SPEC.EFFICIENCY13 fors2_response..efficiency_13 efficiency at 8500 A HC [docuSys coming]
QC.SPEC.EFFICIENCY14 fors2_response..efficiency_14 efficiency at 8900 A HC [docuSys coming]
QC.SPEC.EFFICIENCY15 fors2_response..efficiency_15 efficiency at 9300 A HC [docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter
**There might be more than one.


Efficiency in different grisms is trended. Only data obtained during photometric nights with binning 2x2 and standard resolution collimator are used. Only data points for the upper CCD are plotted. The lower CCD usually has no standard stars and no response curve.

Scoring&thresholds Efficiency

No threshold nor scoring applied.


Since 2011-01-17 we use the new Paranal extinction curve.

Algorithm Efficiency

The efficiency parameters are derived from MOS observations of spectrophotometric standard stars. These spectrophotometric standard stars are acquired with the MOS #10 slit with the slit width of 5 arcsec. MOS slit #10 is projected on the upper CCD of the FORS2 mosaic detector. The position of the MOS #10 slit is either in the center to calibrate MXU and MOS science observations or it is shifted to one of the seven positions of the LSS slits to calibrate LSS science spectra. (see Appendix E.2 of the FORS2 User Manual for the long slit positions).

The efficiency is taken from the efficiency curve at the given wavelength (starting at 3700Å and ending at 9300Å). The efficiency curve is derived by comparing observed flux values to tabulated ones and is then strongly smoothed. For more details see the FORS2 pipeline manual.

The spectrophotometric standard star observations are taken within three days of the corresponding science observations and are meant to provide a response curve for data reduction. They can also be used to determine the efficiency of the spectroscopic modes of FORS2, provided they have been taken under photometric conditions which however is not guaranteed.

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