The net throughput of WHT + WEAVE
is expected to be 0.25 - 0.33 in
low-resolution mode and 0.10 - 0.25 in high-resolution mode, depending on
wavelength.
The commissioning results so far are consistent with these predictions.
The
WEAVE signal-to-noise calculator
can be used to predict SNR per A as a function of apparent magnitude, band,
spectrograph mode, readout noise, airmass, seeing and sky brightness.
When using the calculator, bear in mind
that the apparent magnitude to be entered
is the surface brightness averaged over a 2-6-arcsec fibre. I.e. if the
targets are star-like, the mags need to be converted to surface brightness,
i.e. add Δ = 2.5log10(fibre-area).
The fibre area = 5.3 arcsec2, so Δ = 1.8 mag.
Useful tabulations of results from the calculator can be found on
this page provided by Scott Trager.
