FIRE: a near-infrared, cross-dispersed echellette spectrometer for theMagellan telescopes

摘要

FIRE (the Folded-port InfraRed Echellette) is a prism cross-dispersed infrared spectrometer, designed to deliver single-object R=6000 spectra over the 0.8-2.5 micron range, simultaneously. It will be installed at one of the auxiliary Nasmyth foci of the Magellan 6.5-meter telescopes. FIRE employs a network of ZnSe and Infrasil prisms, coupled with an R1 reflection grating, to image 21 diffraction orders onto a 2048 × 2048, HAWAII-2RG focal plane array. Optionally, a user-controlled turret may be rotated to replace the reflection grating with a mirror, resulting in a single-order, longslit spectrum with R ～1000. A separate, cold infrared sensor will be used for object acquisition and guiding. Both detectors will be controlled by cryogenically mounted SIDECAR ASICs. The availability of low-noise detectors motivates our choice of spectral resolution, which was expressly optimized for Magellan by balancing the scientific demand for increased R with practical limits on exposure times (taking into account statistics on seeing conditions). This contribution describes that analysis, as well as FIRE's optical and opto-mechanical design, and the design and implementation of cryogenic mechanisms. Finally, we will discuss our data-flow model, and outline strategies we are putting in place to facilitate data reduction and analysis.