Here is the measured signal in electrons/sec/Angstrom for a 10th magnitude star with gratings BL181 (1st order, 2.78 Å/pixel) and KPC-18C (2nd. order, 1.14 Å/pixel). As more data becomes available, this plot will be updated. The upper curve represents the signal using a very large slit (~6-10") and the lower curve represents a typical signal with a 2" slit width. See the NOAO Newsletter, 43, September 1995 for more information.
Below are charts showing the grating efficiencies. The rulings with KPC designations were ruled in the NOAO Gratings Lab [C engine] and the BL designations are Bausch & Lomb rulings. The measurements were made by Mr. Ian Gordon of the Kitt Peak (NOAO) Gratings Laboratory in May 1985. All measurements are absolute efficiencies and were made at alpha+beta=46 degrees corresponding to the collimator-to-camera included angle of the R.C. Spectrograph.