[ESO Logo] B&C Spec. - Overall Efficiency [ESO152 Telescope]

The B&C overall efficiency curves shown below are the combination of the efficiencies of the telescope, the spectrograph, the grating and the detector. They also include the atmospheric extinction and to the obstruction of the secondary mirror. In other words the efficiencies shown in the curves are the ratio between the number of detected photons divided by the number of incident photons on the primary mirror area.

Here are the latest measurements (May 2000) for the grating #15, obtained with CCD#38. The global time evolution over almost 2 years is shown (Aug 1998 and Feb 1999 measurements were obtained with CCD#39).

[Efficiency evolution for gt#15]

Below are the previous measurements for other gratings, with the old CCD.

[*] February 1999 Gratings #15, #32, #33 and #34
[*] August 1998 Gratings #15, #33 and #34

Old Manual

For your information here are efficiencies for a number of gratings from old versions of B&C manual.



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