Author: Richard Beare, Jessica Barton

Introduction:

This is a straight forward project to image a number of galaxies in color and to identify the features visible in the images. Students can also attempt to fit each galaxy into the Hubble Classification of galaxies.

Planning

• Book an observing slot, preferably when the Moon is not visible.
• Once you know when you will be observing, you will need to choose a number of galaxies to observe that will generally be higher than 30 degrees. The higher in the sky you point the telescope, the less atmosphere you will be looking through and the clearer your image will be. To plan your session in advance, you can use sky charts or planetarium software. In a half-hour session you should be able to obtain about 5 images once you’ve taken slewing (moving the telescope) and exposure times into account.
• Select galaxies of a variety of different types, e.g. spirals, barred spirals, ellipticals and irregular.
• Background Information - You can read about the different types of galaxies using the Hubble Classification document

Obtaining Data

Use the telescope to get color images of each galaxy you chose to observe. Use an exposure time of 180 seconds. When your observing session is over, you will able to save your images to your computer. They will be zipped and in .fits format so you will need special software to open them.

Analysis

• If you wish, you can print the images out using the best print quality available to you. But do not worry if you cannot print the images out.
• Look carefully at each of your images and identify the different regions, e.g. spiral arms, galactic core, dust lanes, galactic halo. If you have printed your images, label these regions on your image.
• Decide on the type of galaxy you are looking at according to the Hubble Classification. Describe each galaxy in your own words, referring to the regions you have identified and compare them to galaxies of other types. You can also describe in scientific terms, what different regions and colors tell you about the galaxy, e.g. blue looking spiral arms are where hot, young stars are present.

Evaluation

• Are you happy with your images?
• What could you do to get better ones?
• What questions do you still have about galaxies?
• How could you find the information to answer your questions?
• What will you do with your next observing session?