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Galaxies Web Lab

In this lab, you will do an exercise written by the people at the Sloan Digital Sky Survey (SDSS), using data that has come out of that survey.

To complete this lab, do the following:

Do not read anything past the page with Exercise 1 until you have completed Exercise 1. Do Exercise 1 on your first own before you talk to anybody else in the class as described in Question 1.

The SDSS project can be found here: http://cas.sdss.org/dr3/en/proj/basic/galaxies/.

1. Do Exercise 1. Do not read the pages after this one until you've finished Exercise 1! Answer questions 1-3. You will need to compare your results with another person in the class, so make sure you plan ahead and will be able to do this. Do not talk to that other person about your results from exercise 1 until you've done it yourself

   What to turn in: List the galaxies (by run/camcol/field) in columns according to how you classified them. Briefly describe the classification scheme you came up with. After that, answer the questions. Be sure to state who you compared results with, and then list the joint classification scheme you came up with. (This latter joint classification scheme can and should be the same for the two people working together. For this lab only, a photocopy of the page describing the joint classification scheme may be turned in, provided that both student's names are on it.

2. Do Exercise 2. Once you have completed Exercise 1, you may go on and read the next pages. Read all of them up to Exercise 2. Do Exercise 2.

   What to turn in: List your classification for each of the galaxies based on the Hubble scheme. Answer Question 4.

3. Do the Galaxy Collisions Supplemental Exercise. Skip Exercise 3, and go on to "Galaxy Collisions" page. Click on the link "web-based simulation tool" at the bottom of this page, and do the Supplemental Exercisxe 1. This will require you to use a computer with a browser that has a functioning Java plug-in. Make sure you can get this working before the night before this is due, or you may be in trouble.

   What to turn in: Describe the galaxy collision parameters you use. Optional: print out a few screen-shots of cool galaxy messes you made to illustrate this. Answer Question 1, including how your observations from the simulation lead you to this conclusion.

   (Aside: your prof thinks that the Galaxy Crash applet is a very jolly toy, and has wasted some time playing around with it; he's also used it in a Dyer Observatory public talk. He's just jealous that he didn't write it....)

4. Stop there. You do not need to do Exercise 3 or 4. You may, of course, go on, and explore the rest of the SDSS website, if you are interested!