For the past eight years, the small automated telescope Raven has been tested in detecting and tracking deep space objects. As the Raven has proven successful in tracking this regular and predictable orbit, its one arc-second accuracy made it a perfect candidate to attempt to accurately track the less predictable Highly Eccentric Orbit (HEO) objects. Ranging data was obtained from the Sirius satellite radio company for the Sirius3 satellite (Satellite Control Center (SCC) # 26626). This satellite was chosen for its long dwell time over the United States and for its favorable Raven tracking conditions. Angles-only data obtained from another Raven telescope located at the AMOS Remote Maui Experiment (RME) facility was used to track the satellite of interest. Then the Analytical Graphics, Inc. Satellite Tool Kit Orbit Determination (STK/OD) program was used to compare the accuracy of the orbit prediction using ranging tracking data from Sirius and angles-only tracking data from Raven. This paper shows the improvement in orbit determination uncertainty obtained by adding Raven observations to the ranging data. The Raven angles data improved the orbit plane uncertainty and eccentricity estimate differences by over 80% when used with the range observations.

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A 2.7-meter Liquid Mirror Telescope (LMT) is currently under construction at the University of British Columbia. The stationary, parabolic primary mirror is formed by uniformly rotating the highly reflective liquid, metallic mercury. Compensation for the lack of mechanical tracking will be accomplished by using the Time Delay and Integrate (TDI) readout technique with our Ford 2048 x 2048 CCD detector. The ability to produce large, diffraction-limited mirrors in the laboratory has been previously demonstrated; this project, the first of its kind, is an investigation into their potential for astronomical survey-work, in a working observatory environment. A set of 40 intermediate-band filters, one filter to be used per "photometric" night, will facilitate the collection of Spectral Energy Distributions (SEDs) of all objects, to a limiting stellar V[symbol omitted] ~21, in the 83.0 deg² strip (1/3 deg wide) available to this telescope. A catalog of >10⁵ galaxy and ~3,000 quasar SEDs is expected, providing the largest database of its type to date. A detailed stress-tensor analysis of the mercury-loaded mirror cell is given. The maximum flexure of the cell (at the mirror rim) was found to be ≲0.32 mm. The high resonant frequency of the cell was designed to minimise the excitement of both gravity and capillary waves, surface phenomena which can degrade image quality. An analysis of the support structure indicated that its maximum deflection under wind loading (≲0.3µm) would be significantly less than the Ford CCD's physical pixel size of 15 µm. Temperature-sensitive autofocussing was needed to ensure that thermal expansion/ contraction of the support structure did not lead to defocussing. Star-trail curvature at non-zero latitudes and the discrete nature of the TDI readout mode leads to elongation of north-south (NS) and east-west (EW) image structure, respectively. Convolving stellar Point Spread Functions (e.g. Gaussian) with the CCD's pixel width showed image broadening of ~5% (EW) and ~9% (NS). While these effects are expected to be negligible for our instrument, quantifying them under on-site testing will be imperative before proceeding with the development of larger LMTs. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Thesis (Ph. D., Electrical Engineering)--University of Idaho, April 2007. / Major professor: David Egolf. Includes bibliographical references (leaves 156-161). Also available online (PDF file) by subscription or by purchasing the individual file.

Research has been carried out on three major difficulties in designing efficient and economic telescopes with 8m f/1 lightweight mirrors. These problems are polishing f/1 aspherics, thermal distortion of borosilicate glass mirror and mirror seeing. Viable solutions to all three have been developed. Solving the fundamental problems allows future very large telescopes to use such mirrors as the basic elements in the design which will reduce the cost. Accurate mirror figure together with good pointing stability given by the short focal length will enable the telescope to form images as sharp as that permitted by nature on the ground. A new technology of polishing f/1 aspherics with a computer controlled stressed lap will give very accurate figure because the lap is changed accurately to adapt the desired figure. Design parameters and performance specifications for a 0.6m aluminum stressed lap for polishing a spun cast 1.8m f/1 borosilicate glass honeycomb mirror have been developed. These can be readily scaled up for polishing 8m f/1 mirrors. Stressed lap polishing also requires accurate material removal over the entire mirror surface. An optimization algorithm using the theory of material wear has been developed to search for the polishing strokes suited for uniform or other desired removal rates. Direct casting of lightweight mirrors requires that the glass be borosilicate. The figure distortion caused by the expansion of borosilicate glass requires the mirror be isothermal to less than 0.1°C for image degradation not to exceed 0.1 arcsecond. The problem of thermal interference by air and the environment has been investigated. A method of injecting well controlled air into the cells that forces the mirror to be isothermal to within 0.1°C has been discovered. Mirror seeing caused by temperature difference between the mirror and ambient air can degrade the telescope performance, but can be reduced by careful thermal design. A simple theoretical thermal model is used to select the glass thickness of a honeycomb structure mirror. Under air ventilation thermal control, the mirror responds to changing air temperature in less than an hour, reducing mirror seeing also to 0.1 arcsecond for telescopes at good seeing sites.

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A new radio telescope composed of an array of antennas is under development at the National Research Council. Each antenna includes a large scale multi-tethered aerostat system to hold the telescope receiver at the reflector focus. This receiver is located at the confluence point of the tethers. Starting from a previously developed dynamics simulation of the triple-tethered aerostat system, an existing statics model of the same system is incorporated into the simulation to provide an initial equilibrium condition for the dynamics. A spherical aerostat is used in both models. The two models show a very good match with each other after being merged together. This combined computer model is further developed to study the use of six tethers and the use of a streamlined aerostat instead of a spherical one. In the case of the six-tethered system, two topics were investigated: using the six tethers to control the position of the airborne receiver only; and using the six tethers to control the orientation of the receiver as well as its position. A streamlined aerostat is also modelled by a component breakdown method and incorporated into the triple-tethered system to replace the spherical one. The main findings from the simulation results are as follows: (1) the six-tethered system with reductions in the tether base radius and the tether diameter exhibited increased stiffness compared to the triple-tethered system when used to control the receiver position only; (2) the six-tethered system showed difficulty achieving satisfactory control for both the position and orientation of the receiver; (3) the streamlined aerostat showed no oscillations typical of a spherical one but the system requires more power to control in the presence of wind turbulence.