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Table 3.

ESPRESSO’s instrument modes and characteristics.

Observing configuration 1-UT
4-UT
Instrument mode UHR11 HR11 HR21 HR42 MR42 MR84
Simultaneous reference Available (no simultaneous sky background on fiber B)
Sky subtraction Available (no simultaneous reference on fiber B)
Wavelength range [nm] 378.2–788.7
Median resolving power R = λλ > 190 000 (a) 138 000 138 000 130 000 72 500 70 000
Aperture on sky [″] 0.5 dia. 1.0 dia. 1.0 dia. 1.0 dia. 4 × 1.0 dia. 4 × 1.0 dia.
Spectral sampling [physical pixels] 2.5 4.5 4.5 4.5 10 10
Spatial sampling [slices × physical pixels] 2 × 5 2 × 9 2 × 9 2 × 9 2 × 20 2 × 20
Detector readout speed [kpix s−1] 300 300 100 100 100 100
Detector binning, spatial × spectral [pixels] 1 × 1 1 × 1 2 × 1 4 × 2 4 × 2 8 × 4
Effective spectral sampling [extracted pixels] 2.5 4.5 4.5 2.25 5 2.5
Detector readout noise (RON) red/blue (b) [e] 5/8 5/8 2/3 2/4 2/4 2/5
Detector conversion factor red/blue [e/ADU] 1.15/1.1 1.15/1.1 1.13/1.09 1.13/1.09 1.13/1.09 1.13/1.09
Total peak efficiency 5% 10% 10% 10% 10% 10%

Notes.

(a)

To be considered as a lower limit since many thorium lines used for the analysis are partially resolved at this resolution.

(b)

The “FAST” readout modes (HR11 and UHR11) of the blue detector are still undergoing optimization.

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