Engineering topics

Macqueen, Phillip J.

Publications and source records attributed to Macqueen, Phillip J..

2 records

NASA NTRS1995

The high-resolution cross-dispersed echelle white-pupil spectrometer of the McDonald Observatory 2.7-m telescope

A new high-resolution cross-dispersed echelle spectrometer has been installed at the coude focus of the McDonald Observatory 2.7-m telescope. Its primary goal was simultaneously to gather spectra over as much of the spectral range 3400 A to 1 micrometer as practical, at a resolution R identical with lambda/Delta lambda which approximately = 60,000 with signal-to-noise ratio of approximately 100 for stars down to magnitude 11, using 1-h exposures. In the instrument as built, two exposures are all that are needed to cover the full range. Featuring a white-pupil design, fused silica prism cross disperser, and folded Schmidt camera with a Tektronix 2048x2048 CCD used at either of two foci, it has been in regularly scheduled operation since 1992 April. Design details and performance are described.

Tull, Robert G.↗

NASA NTRS1994

Preimpact characterization of Comet P/Shoemaker-Levy 9

At McDonald Observatory, we have undertaken a major program of observation of Comet P/Shoemaker-Levy 9 in order to charcterize the dynamics and physical make-up of the fragments prior to their disappearance in July 1994 when they collide with Jupiter. Obserations have included astrometry, photometry, and spectroscopy. Our astrometric observations have been important for deriving accurate orbits for the individual fragments. With the photometry, we have derived (B-V) and (V-R) colors for a number of fragemnts. We show that they are slightly redder than the Sun in (B-V) and similar to the Sun in (V-R); they may show differences in colors for the individual fragments. We detected no gas with our spectroscopic observations and have derived sensitive upper limits on the quantity of gas. Our observations are consistent with the parent being a comet, as classified, but cannot rule out certain types of asteroids as progenitors.

Cochran, Anita L.↗