THE SANDIFORD 2.1-M CASSEGRAIN ECHELLE SPECTROGRAPH FOR MCDONALD OBSERVATORY - OPTICAL AND MECHANICAL DESIGN AND PERFORMANCE

被引:168
作者
MCCARTHY, JK
SANDIFORD, BA
BOYD, D
BOOTH, J
机构
关键词
D O I
10.1086/133250
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We describe the design, construction, and performance of an efficient new flexure-compensated Cassegrain echelle spectrograph for the 2.1-m (82-in.) Struve reflector at McDonald Observatory. The instrument has a resolving power R = lambda/DELTAlambda of 60,000 for two CCD pixels (for a reciprocal velocity dispersion of 2.5 km s-1 per pixel) and provides continuous wavelength coverage for lambda < 8000 angstrom using a thinned backside-illuminated Reticon 1200 X 400 CCD detector. Total wavelength coverage in a single exposure varies from roughly 500 angstrom at lambda = 4400 angstrom (range 4200-4700 angstrom) to 2500 angstrom at lambda = 7500 angstrom (range 6500-9000 angstrom), and the total system efficiency at lambda = 6000 angstrom from the top of the atmosphere through the telescope, spectrograph, and CCD detector is 10% or more. The mechanical design of the Cassegrain-mounted spectrograph incorporates a unique cantilevered counterweight system designed to drastically reduce the effects of gravitational flexure. In spite of the large physical size of the Cassegrain instrument, worst-case flexure shifts over 60-degrees (4 hr) of telescope motion are less than 2 pixel and are typically on the order of 0.2 pixels or less from all sources. A subsequent paper will describe the CCD and associated electronics in detail.
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页码:881 / 893
页数:13
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