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The Cambridge Infrared Panoramic Survey Spectrograph is being built at the Institute of Astronomy in Cambridge, UK.

CIRPASS is a near-infrared spectrograph with a 499 element integral field unit to collect the light from the target object. The optics deliver a high resolution spectrum on a mirror surface which is then reimaged on to the detector. This provides the option to block out, or suppress, the bright OH emission by making the mirror (or mask) non-reflective at the positions of the OH lines.

For use on Gemini we have defined a baseline instrument with the minimum acceptable capabilities. This baseline can be thought of a as a fall-back position should we enconter any unforeseen problems. However, we expect to provide the full instrument capabilities from first use on Gemini.

The table below outlines the capabilities of both the baseline and the complete instrument. The main differences are in the detector size and the operating temperature (and hence the accessible wavelength range). We are already using a HAWAII-I array and expect to receive a HAWAII-II array very soon.

Baseline Complete
Detector Type HAWAII-1 HAWAII-2
IFU # lenses 499
lens scale (arcsec) 0.36,0.25,0.12,0.05
Spectrograph Resolution (per spectral res. elem.) 4.4 Å
total wv range (micron) 0.85-1.35 0.85-1.8
wv range in 1 shot (micron) 0.23 0.45
Operating temp (C) ambient -40

The different parts of the instrument are discussed in more detail in the Operational concepts definition document.

Rachel Johnson <>
Last modified: Wed Nov 24 12:12:20 1999