# BENCH UPGRADE COMMISSIONING DATA: CCD ON-TELESCOPE COMPARISON MEASUREMENTS # # MAB 27 May 2008 # # Measurements of relative efficiency of Bench Spectrograph with T2KA # (Feb 2008) vs STA1 (Mar 2008). This is a double-differential # measurement: # # Bench aperture photometry was performed on un-dispersed, in-focus # images through narrow-band filters (fold-flat in grating turret) # with identical spectrograph configuration (camera angles and # distance). Photometry aperture radii of 25 pixels (24 microns) # enclose close to EE100 (except for large-angle scattering from # optics -- assumed to be the same amplitude for both detectors). # # Bench photometry is normalized to mean counts in dome-flats taken # with MiniMo at identical lamp settings in filters closely matching # Bench filter band-pass, and interleaved in time with Bench data # collection. Identical minimo image subections and processing were # used for both data sets. Lamp stability is 1,1.5, and 2% at 650 nm, # 550 nm, and 370 nm (R,V,U) respectively, with lamp-color varying by # less than 1% from U through R over 5 days across a 2-month period at # a fixed lamp setting. # # Filters used (and matching Minimo filters): # # X6 (U solid), X7.5 (U solid), X14 (W21), X19 (W15), X23 (W15). # # o X6 measured with high-lamp (3200) setting # o X14,X19,X23 measured with low-lamp (1500) setting # o X7.5 measurement excluded because different lamps-settings yield # uncorrectable color-terms # # Data columns: # (1) Filter central wavelength (X6,X14,X19,X23 - X7.5 excluded) # (2) Filter half-width half-maximum # (3) Measured throughput ratio of system STA1:T2KA # (4) Uncertainty in measurement # # wave dwave dQE sigma(dQE) # (nm) (nm) # (1) (2) (3) (4) 375.40 7.20 1.357 0.043 511.75 13.45 1.315 0.020 663.40 27.60 1.207 0.025 867.65 51.75 1.374 0.075