An introduction to astronomical photometry

These notes are chosen (mostly) from a number of the lectures I give in classes. Don't forget that you can access the materials for all my classes.

What can one learn from measurements of starlight? Let me just just a very few of the MANY things we can learn ...

• Sizes and shapes and temperatures and separations of eclipsing binary stars
• The properties of gas in an accretion disk around a white dwarf in a cataclysmic variable stars
• The angular diameter of a star occulted by the edge of the Moon.
• Does a star have its own planets circling around it?

Okay ... but how do we measure starlight accurately? Are there any complications?

• Astronomical photometric systems and colors
• Complications caused by the atmosphere (extinction)
• Complications caused by the equipment (color terms)
• Just a tiny bit on all-sky photometry
  But this is a complicated subject. Once you are ready to tackle it, you should consult much more serious sources:
  • The "Photometry" section of the AAVSO CCD observing manual
  • "An Introduction to Astronomical Photometry Using CCDs" by Bill Romanishin is a complete book, available on-line!
  • "Astronomical Photometry, Text and Handbook for the Advanced Amateur and Professional Astronomer" by Henden and Kaitchuck must be purchased, alas.
  • A Guide to Minor Planet Photometry focuses on asteroids, but has lots of good basic information.
  • A collection of references to the photometric literature which I have encountered over the years.
• The basics of aperture photometry on digital images

We will then be ready to move on to measuring some real live (well, three-month-old, really) images of a variable star.

Copyright © Michael Richmond. This work is licensed under a Creative Commons License.