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The McMath-Pierce Facility Dual-Grating Spectrometer (1Dec92) (from NSO, NOAO Newsletter No. 32, 1 December 1992) A shutdown of solar observing at Kitt Peak in October gave us the opportunity to dismantle the spectrometer at the McMath-Pierce Solar Facility, with its original 10-inch Babcock grating, which has served us so well for 30 years, and to install a dual-grating system. Kurt Cramer successfully decoded the wiring of the old system and has wired the new grating's scan and slew drives prior to making the interconnections to electrical power, controls and computer. Ed Perkins, engineer, and Russ Cole, instrument maker, have nearly completed the design and construction of the flip- grating mount. Two gratings--visible and infrared--are nested in the wavelength drive-spool. Stainless steel tapes attached to a precision screw and to the rims of the drive-spool rotate the gratings to scan the spectrum. The visible grating, weighing 60 lbs., ruled with 632 grooves per millimeter, has dimensions 3.0 x 12.6 x 16.5 inches. The infrared grating, weighing 100 lbs., with 120 grooves per millimeter, has dimensions 4.0 x 14.5 x 18.5 inches. A test of the system began in mid-October in our Tucson shops prior to a planned careful move and installation at Kitt Peak by early November. The new system will permit observations from the UV cutoff at 2900 A to 15 um in the infrared. Keith Pierce
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