The Use of Photographs in Astronomical Instruction

Summary

The Edinburgh Teaching Packages.

For many years, copies on film of photographs, both direct and through objective prisms, taken with the 1.2 m United Kingdom Schmidt Telescope, have provided teaching material suitable for universities and colleges (Brück and Tritton, 1988). Table 1 outlines the various types of application to which the photographs may be put. With additional data, some real physics can be injected into the exercises, allowing students to perform quite elaborate projects.

Uses for UK Schmidt Telescope Film Copies

Direct photographs

1. 1. Recognition of objects:

2. galaxies

3. minor planets

4. HII regions, SNRs (in external galaxies)

5. globular clusters (in the Magellanic Clouds)

6. 2. Statistics

7. star-counts, for various purposes

8. number-magnitude counts

9. star-galaxy counts

10. galaxies in clusters

11. 3. Changes in position (from more than one photograph)

12. precession

13. comet

Objective prism photographs

1. 1. Spectral classification:

2. coarse classification (of about 100 stars per film)

3. 2. Search for unusual objects:

4. emission-line stars

5. carbon stars

6. planetary nebulae

7. quasars

A limitation to such purely visual observations is in regard to photometry, where we have to make do with rather rough estimates of magnitude. Measuring the brightnesses or magnitudes of objects is a basic necessity in astronomy, but one that is, ironically, less easy to perform with students than it was ten or twenty years ago. Instruments that were once standard equipment and could be employed on the films – photographic photometers and microphotometers – have fallen into disuse as astronomers receive their data ready processed. For the brighter stars, down to magnitude 13 or 14, magnitudes may be estimated visually to about a fifth a magnitude. This is adequate, however, for our stellar statistics problems (e.g. Fig. 1).