Stephen J. Ratcliff

The Measurement of Astronomical Parallaxes With CCD Imaging Cameras on Small Telescopes

Small telescopes equipped with charge‐coupled device (CCD) imaging cameras are well suited to introductory laboratory exercises in positional astronomy (astrometry). An elegant example is the determination of the parallax of extraterrestrial objects, such as asteroids. For laboratory exercises suitable for introductory students, the astronomical hardware needs are relatively modest, and, under the best circumstances, the analysis requires little more than arithmetic and a microcomputer with image display capabilities. Results from the first such coordinated parallax observations of asteroids ever made are presented. In addition, procedures for several related experiments, involving single‐site observations and/or parallaxes of earth‐orbiting artificial satellites, are outlined.

Modular spectrographs for undergraduate laboratories

The assembly of laboratory spectrographs from individual components is a valuable exercise in an undergraduate setting. We describe several different spectrograph configurations that we have implemented with electronic panoramic detectors and present the data acquired with each of them, concentrating on the detection and measurement of Doppler shifts of absorption features in the spectra of bright celestial objects.

High‐resolution solar spectroscopy in the undergraduate physics laboratory

The richness of the solar spectrum at visible wavelengths makes it ideally suited for many laboratory exercises in optical spectroscopy. A number of such experiments taking advantage of a high‐resolution scanning spectrometer are described as they have been performed by seniors at Middlebury College. Physical principles emphasized include optical depth, the nature of molecular spectra, the Doppler effect, and the Zeeman effect. These experiments are suitable for advanced undergraduate physics and astronomy majors.

Spectroscopic Observations of SRd and RV Tau Variables at Middlebury College

A program to collect time‐series spectra of pulsating variable stars was undertaken over a period of several months in 2004 with the 0.6−m reflecting telescope at the Middlebury College Observatory using a bench‐mounted, fiber‐fed CCD spectrograph. The spectra were obtained in the red region (5800–6800 A) at resolution approximately 2.5 A. Primarily, stars classified SRd or RV Tau were observed, although other targets (such as delta Scu variables) were included as well. The spectral coverage and resolution allow, for stars brighter than roughly R = 10, the study of Hα emission or absorption strength variation, as well as the determination of temperature spectral class. The spectrograph is also capable of radial velocity determinations (for brighter specimens) at the level of a few km/s. This program demonstrated the utility of a dedicated, modest‐aperture telescope in acquisition of useful spectroscopic time‐series observations for these variable stars.