Flux standard data and empirical throughput
figure below shows the results from throughput measurements of flux standards using the
EEV12 and RED+ CCDs in the blue and red arm
respectively, and the new 5300 dichroic. The Y-axis is the apparent AB
magnitude of a star
at the zenith which gives one detected photon per second per Angstrom. The
lowest resolution grating was used (R158R) in the red arm (without any
order sorter filter) and the R300B grating was used in the blue arm.
Spectra were obtained with a wide slit (10
arcsec). The conditions were photometric, with negligible dust levels
present. This figure shows the response of the whole ISIS red and
blue arms (i.e. WHT primary + secondary + dichroic + ISIS optics + detector
~3200 to ~9300Å.