9_7_4

4. Photometric measurements can be used for determining distance and comparing objects


 * define absolute and apparent magnitude
 * solve problems and analyse information using: and to calculate the absolute or apparent magnitude of stars using data and a reference star
 * perform an investigation to demonstrate the use of filters for photometric measurements
 * identify data sources, gather, process and present information to assess the impact of improvements in measurement technologies on our understanding of celestial objects
 * explain how the concept of magnitude can be used to determine the distance to a celestial object
 * outline spectroscopic parallax
 * explain how two-colour values (ie colour index, B-V) are obtained and why they are useful
 * describe the advantages of photoelectric technologies over photographic methods for photometry