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													      Center Sonoma State University
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Educator Materials

These pages outline how someone not familiar with telescopic observations might go about using the GTN site to gain a basic understanding of the methods and science underlying the project.


The GTN is not intended to be used in traditional classroom lessons, per se. In fact, it was not created strictly to be used in classrooms at all. Nonetheless, it can be a powerful resource for students and teachers (as well as others) to obtain an experience doing real astronomical observations as part of a real research project. While some teachers have used the Network as part of a high school or college astronomy class, the intention is more that it be used for semester (or longer) science projects or as part of a semester long observing class. This is because obtaining and then analyzing astroonomical data is a long process. It cannot always be done in a time frame shorter than several months. However, use of the network is limited only by the imagination, time and energy of those using it. Here we outline a few exercises and pages to bring you up to speed if you are not an experienced astronomer.

Background Material

We have created several web pages on this site that discuss the science of the GTN. These describe in general terms what active galaxies are and how we study them. You can find links to these pages on the Resources page of our site. In particular, if you read the sections on Normal Galaxies, Active Galaxies and AGN Variability you will gain some understanding of the types of objects we study and their relationship to one another.

In addition to active galaxies, the GTN does followup work on gamma ray bursts (GRB); when one of these extremely energetic and enigmatic objects goes off, many of the GTN telescopes automatically slew to observe it before it fades from view. If you would like to learn about GRB, you can check out the Imagine the Universe GRB web site from Goddard Space Flight Center, a NASA research center just outside Washington, DC. Gamma-ray bursts have only been known for a very short time. In fact, gamma-ray astronomy itself only goes back a few decades. To get an overview of its history, look over our page on the history of gamma-ray astronomy.

Several of our pages discuss topics directly related to observational astronomy. Probably the first of these to look at for someone new to the field is the page on Basic Photometry and Astrometry. On that page we define common terminology and introduce coordinate systems that are used to describe the locations of objects in the sky and to point telescopes.

To learn the basics of photometry, the process by which the brightness of a star or other astroonomical object is measured, you should go over the Cookie Cutter Photometry exercise in the GTN Guide. This exercise was developed here at the SSU NASA E/PO Group and was designed to be used in a classroom or workshop setting. It provides an activity in which participants model the measurement of an object's brightness. The camera on a telescope does this by using an electronic light detector called a charge coupled device (CCD); in the exercise participants use playdough and a kitchen scale instead of a CCD, but the basic notion is the same. The exercise does a nice job of showing how a CCD can be used to measure the brightness of a star. While a CCD is the light detector found in modern digital cameras, the ones used for astronomy are more sensitive and have certain modifications that allow them to image extremely faint objects.

A more involved discussion of CCD photometry can be found on our data reduction page. However, we do not suggest you tackle that until you have familiarized yourself with some of the concepts introduced by the Cookie Cutter exercise. Working with data from a CCD is computer intensive and requires special software packages, examples of which are given in the data reduction pages. We are available to provide mentoring for people who would like to work with data... see the section below on More Advanced Activities.

Classroom Materials

As we mentioned in the introduction, the GTN was not specifically set up to be used in traditional science classrooms. However, we have put together several exercises that are designed for the classroom. These introduce some of the science and methodology related to the GTN in a way that makes it (we hope) more understandable for students and teachers not already experienced making observations with a telescope.

  • Both of the first two exercises can be found in the GTN Guide.
  • Cookie Cutter Photometry - The same exercise mentioned in the previous section. Students use playdough to represent the stars and sky. A kitchen scale represents a light detector. Students are asked to devise a method by which they may determine the weight of each "star" (weight is a proxy for brightness in this exercise) without actually putting the star alone on the scale. The exercise includes some background material on CCD detectors and how they work.
  • Jelly Bean Spectroscopy - Like Cookie Cutter Photometry, the Jelly Bean Spectroscopy exercise uses a simple activity to model an astronomical measurement, in this case scpectroscopy, in the classroom. Jelly beans of different colors are used as a stand-in for light of different colors. Students make a histogram of jelly beans, based on their color, in order to learn how spectra are used in astronomy. The GTN does not do any spectroscopic observations, but we have included this exercise because spectroscopy is of fundamental importance in astrophysics and other branches of science.
  • AGN Flares - Finally, we have created an exercise (still under development) that asks students to look for relationships between flares seen in active galactic nuclei (AGN) by optical telescopes (like those in the GTN) and a gamma-ray telescope (the Fermi Gamma-ray Space Telescope, in this case). The exercise uses real observational data contained in a spreadsheet, so students must use a computer to complete it. Both Mac (iWork '09) and Windows versions are included. You can download the archive file (3.1 MB) containing the entire exercise, including written materials and spreadsheets. This exercise introduces one of the basic ways we learn about AGN, namely doing coordinated observations simultaneously in many wavelengths. These are called multiwavelength (MW) campaigns and involve many telescopes that span all the way from the radio through infra-red, optical, ultraviolet, x-ray and gamma-ray. In addition to day to day monitoring of AGN, MW campaigns are one of the primary observing activities of GTN telescopes.

More Advanced Activities

If you have made it through the materials described above and think you might be up for a bigger challenge, then we encourage you to sign up with us to be a GTN member. As an associate member we will show you how you can access GTN data, and we will help you (and your class) learn how to analyze it. If you decide this is what you want to do, you should definitely have a look at the data reduction page. You will need a computer on which to work with your data. You will also need some special astronomical software (described on the data reduction page). Most of the currently available software is quite expensive (more than $100). There is also free software that will do the job, but it has been written by and for professional astronomers and is not easy to learn to use. We are working on making a data handling system that circumvents these problems.

This page is meant to provide a guide to what you can find on this site and how you might go through it if you are an educator, not an astronomer, and are thinking astronomical imaging and measurement might be a fun activity for your students (and yourself). If you have questions, please direct them to Kevin McLin (email at the bottom of this page). We hope you and your students will join us as we learn about some of the most energetic and exciting objects in the universe.

If you have a question about the GTN, please contact one of the "Responsible SSU Personnel" below.

This page was last modified on Friday 01st September 2017 @ 09:17am

Science Mission Directorate Universe Division

Responsible SSU Personnel:

Dr. Kevin McLin (mclin at universe dot sonoma dot edu)

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