MEASURING THE SKY - a workshop on Observational Astronomy
by Rick Kang, Spring, 1999
Initial response, since we are so visually oriented, is normally
a survey in the form of a picture. What? Why?
We want to get a sense of what is there, but ultimately, to
discover what is going on, we need to measure.
The good news for astronomers is that there is a lot of radiation
generated by objects in space, some of which is directed toward Earth.
The bad news is that due to the extremely large distances involved,
this radiation is very thinned out. We must work hard to capture
enough radiation to begin to answer some of the above questions.
These days, we use mosaics of photo-electric grids, Charge Coupled
Device (CCD) Cameras, to store up the incoming photons and to
translate the data into digital form, so that we can see the image
on a computer monitor, make measurments on our data, and store our data.
There is a basic limitation, though. The image yields only two basic
1. Amount of light/Change in light over time (PHOTOMETRY)
2. Position of light source/Change in position over time (ASTROMETRY)
Yes, with appropriate additional instrumentation we can also measure
the variety (spectrum) of light, and how much of each portion of the
spectrum, which yields a great deal of information about the source,
but this is really just another exercise in photometry.
Students and teachers can use a basic CCD Camera to make some very
interesting measurements of the sky, just relying on the two basic
types of measurements outlined above:
Your class can engage in actual data acquistion via Pine Mountain
Observatory's CCDDOP project as outlined in the next link on this web
page, or from other observatories, from links further down in this page.
Here are some suggested projects for various grade levels:
Everyone should initially start by taking a series of exposures where
exposure time is progressively increased. I call this your Deep Field
Imaging project, similar to the Hubble Deep Field images, this gives
you an idea of how your instrument functions and what you can do with it.
For Elementary Level, you can count the visible stars and galaxies,
and/or survery the distribution of stars around the sky.
For Middle School, you can try to locate an asteroid.
For High School/JC, you can monitor a variable star.
I will add more information to this page in a few more weeks.
This is the paper that I initially wrote for and distributed at
the Teachers' Workshop at the AAS meeting in Austin, Texas,
this past January.
Let me know what you think.
Thanks! Rick Kang