Design and Operation of the NASA 91.5-cm Airborne Telescope

Infrared Observations of Planetary Nebulae and Related Objects

In this paper, I present how near and mid-infrared observations can be used for the study of planetary nebulae and related objects. I present the main observing techniques, from the ground and space, highlighting main differences and how they can be complementary. I also highlight some new observing facilities and present the infrared observatories of the future to show that the future of infrared observations of planetary nebulae is bright.

Lévy statistics of light scattering in turbulent mixing layers

Experimental evidence and computational evidence suggest that the distribution of random segment lengths defined by the intersections of ray paths with the contorted and folded interface between two fluids mixed by turbulence follows a probability distribution with a Lévy law tail. Assuming that the two fluids have different optical properties, one finds that the statistics of light scattered by the mixing interface reflect the probability distribution for the random distances between the intersection points of straight ray paths with the interface. Examples of light-scattering calculations for limiting cases, including the planetary albedo problem and imaging through a transparent mixing layer, are discussed.

Infrared Fourier spectrometer for airborne and ground-based astronomy

A unique high resolving power near-infrared, astronomical Fourier spectrometer has been constructed foruse at both ground-based and airborne telescopes. Its capabilities include a limiting resolution of 0.01 cm(-1) and spectral coverage over the InSb detector sensitivity region (0.8-5.6 microm). The instrument is optimized for operation in environments inaccessible to other high-resolution Fourier spectrometers, namely, the Cassegrain focuses of conventional telescopes and the NASA Kuiper Airborne Observatory's 91-cm telescope. Details of the spectrometer are discussed, and various astronomical and laboratory spectra are presented.

Airborne infrared astronomical observations by Fourier transform spectroscopy

Infrared spectroscopic observations from NASA-operated aircraft constitute a rapidly maturing application of FTS methods initially developed for ground-based telescopes. Coupled to airborne telescopes up to 36 in. in diameter, these experiments are now producing new astronomical results as exciting and unexpected as those derived from Connes's first high resolution planetary observations at mountain-top observatories. This review examines the special problems of the ir spectral region that led to aircraft observatories and includes a brief survey of the facilities themselves and their modes of operation. The special problems of operating FTS devices on aircraft and the scientific results achieved with current capabilities are discussed. Finally, airborne observations are compared to the ultimate in high-altitude observing platforms: earth-orbiting cooled and uncooled telescopes carried by the space shuttle vehicle.

High resolution Michelson interferometer for airborne infrared astronomical observations. 1: Concept and performance

A Michelson interferometer has been built for use with the 91-cm telescope on NASA's Gerard P. Kuiper Airborne Observatory primarily to measure ir line emission from H 11 regions. Operation is in the rapid scan mode, and the achievable resolution is 0.02 cm(-1) in the wavelength range from 10 micro to around 300 micro. A minicomputer is used to provide on-line spectrum displays and to control and monitor the instrument performance. The design and use of the instrument is discussed, and a comparison is made between the theoretical performance and that actually achieved on the first flights when measurements of line emission from the Orion nebula and from the atmosphere were made.

Visual modeling of laser Doppler anemometer signals by moiré fringes

This report describes the employment of moiré patterns to model visually interference phenomena in general and laser Doppler anemometer signals in particular. The modeling includes signals created in dual beam and reference beam anemometers by both single particles and particle pairs. The considerations are extended to visual modeling of multiparticle signals and the decay of signal quality in the presence of many particles. The fringe model of the laser Doppler anemometer is also considered, and moiré patterns are employed to demonstrate the interference fringes in the crossover region of two intersecting laser beams. Gaussian beam properties are taken into account to allow the effects of improperly designed optical systems to be studied. Instructions for using computer generated transparencies to produce the different moiré patterns are provided to allow the reader to study in detail the various interference phenomena described.

Infrared Fourier spectrometer for laboratory use and for astronomical studies from aircraft and ground-based telescopes

A portable, versatile, ir Fourier spectrometer is described that provides 0.5 cm(-1) spectral resolution in the 0.87-5.6-microm region. This spectrometer is employed in a varied program of astronomical observations from round-based telescopes and from the NASA 91.5-cm airborne ir telescope. A number of spectral results are presented to illustrate the performance of this spectrometer in astronomical applications.