The tables give the above-atmosphere AB apparent
magnitudes which yield 1 detected photon/sec/Å for a wide-slit
observation made at the zenith in clear conditions.
(Number of photons
= number of counts 
CCD gain; gain typically 
1.)
Table: WHT ISIS with the 158 lines/mm gratings and the TEK1 (blue arm) or TEK2 (red arm) CCDs
Table: WHT FOS first-order, with the GEC CCD
Table: WHT UES with the 79 lines/mm grating
and the TEK1 CCD and IPCS
Table: WHT LDSS with the TEK1 CCD
Table: INT IDS 235-mm camera with
the AgRed collimator, R300V grating, EEV5 CCD and with the AlWide collimator,
R150V grating and TEK3 CCD
The throughput of the IDS 500-mm camera has been measured only at 6700 Å; it is similar to that of the 235-mm camera.
Table: INT FOS with the GEC CCD