Engineering topics

Mcmillan, Robert S.

Publications and source records attributed to Mcmillan, Robert S..

5 records

NASA NTRS1991

The radial velocity search for extrasolar planets

Radial velocity measurements are being made to search for planets orbiting stars other than the Sun. The reflex acceleration induced on stars by planets can be sensed by measuring the small, slow changes in the line-of-site velocities of stars. To detect these planetary perturbations, the data series must be made on a uniform instrumental scale for as long as it takes a planet to orbit its star. A spectrometer of extreme stability and unprecedented sensitivity to changes in stellar radial velocities was operated.

Mcmillan, Robert S.↗

NASA NTRS1991

Discovery of near-Earth asteroids by CCD scanning

The found near-Earth asteroid are different objects with peculiar orbits. With the new technique of CCD scanning we entered the domain of the smallest, the fastest, and the closest near-Earth asteroids. The results are presented.

Gehrels, Tom↗

NASA NTRS1991

High accuracy image centroiding with a moving Ronchi ruling

A moving Ronchi ruling at the focal plane of a telescope has been employed to measure the relative motions of stars with great accuracy. The method has long-term stability and exceptional linearity over a relatively large field-of-view. This measurement technique may prove useful in other applications where such capabilities are required. This paper employs Fourier optics to describe the operation of the device, explore performance at very long and very short periods, and consider ruling profiles and other means of optimizing performance.

Lawrence, George N.↗

NASA NTRS1987

Nonvariability of the radial velocity of Eta Cassiopeiae A

Twenty-eight measurements of the radial velocity of the G0 V star Eta Cas A on 14 nights between December 11, 1986, and February 19, 1987 UT (inclusive) were made with an uncertainty per observation between + or - 10 and + or - 20 m/s. The velocity of the star never exceeded 30 m/s from the mean, even though the star was monitored on three occasions for three consecutive nights. The standard deviation of all 28 measurements is + or - 13.7 m/s.

Mcmillan, Robert S.↗

NASA NTRS1987

Performance analysis of the multichannel astrometric photometer

It has been proposed that extrasolar planetary systems may be observed if perturbations in star position due to the orbit of Jupiter-type planets could be detected. To see this motion, high accuracy measurements of 0.01 milliarcsecond are required over a relatively large field of view. Techniques using a moving Ronchi grating have been proposed for this application and have been successful in ground-based lower resolution tests. The method may have application to other precision angular measurement problems. This paper explores the theoretical description of the method, considers certain of the error sources, and presents a preliminary calculation of the performance which may be achieved.

Huang, Chunsheng↗