The Infrared Spectrograph (IRS) is one of three science instruments on the Spitzer Space Telescope. The IRS comprises four separate spectrograph modules covering the wavelength range from 5.3 to 38 m with spectral resolutions, R ¼ k=Ák % 90 and 600, and it was optimized to take full advantage of the very low background in the space environment. The IRS is performing at or better than the prelaunch predictions. An autonomous target acquisition capability enables the IRS to locate the mid-infrared centroid of a source, providing the information so that the spacecraft can accurately offset that centroid to a selected slit. This feature is particularly useful when taking spectra of sources with poorly known coordinates. An automated data-reduction pipeline has been developed at the Spitzer Science Center.

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Surfaces of low reflectance are ubiquitous in animate systems. They form essential components of the visual appearance of most living species and can explicitly influence other biological functions such as thermoregulation. The blackness associated with all opaque surfaces of low reflectivity has until now been attributed to strongly absorbing pigmentation alone. Our present study challenges this assumption, demonstrating that in addition to the requirement of absorbing pigmentation, complex nano-structures contribute to the low reflectance of certain natural surfaces. We describe preliminary f indings of an investigation into the nature of the black regions observed on the dorsal wings of several Lepidoptera. Specifically, we quantify the optical absorption associated with black wing regions on the butterfly Papilio ulysses and f ind that the nanostructure of the wing scales of these regions contributes signif icantly to their black appearance.

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