Measuring the speed of asteroids

Aug 14, 2001

Your goal in this project will be to measure the orbital speed of an asteroid. In order to do that, you will have to carry out the following steps:

  1. choose an asteroid to observe
  2. determine where it will be at a given time
  3. make a finding chart
  4. learn how to measure positions and brightnesses of objects in astronomical images
  5. take two pictures of the asteroid through a telescope, over an interval of 30-60 minutes
  6. reduce the pictures (remove instrumental defects)
  7. find the asteroid in the pictures
  8. measure the angular distance it moves
  9. measure its brightness in "magnitudes"
  10. find the distance of the asteroid from the Earth and Sun
  11. convert the angular motion into linear motion
Each pair of students will work on a different asteroid. After all groups have finished their work, you may compare the velocities you have calculated, and look for some pattern.

Day one: preparing for an observing run

During the first day, you must get everything ready for the night's work at the RIT Observatory. Without a good plan, you'll just waste time and energy. Here's what you need to do:

Night: observe your asteroid

At night, we'll go to the RIT Observatory and use the 10-inch telescope and CCD camera to take pictures of your asteroids. We will take one picture of each asteroid, then go back and take a second picture of each one. Each group should end up with two pictures of their chosen field, taken 30-60 minutes apart. The asteroid will move a perceptible distance from one image to the other, which should make it easy to find.

You must be ready to provide your field's Right Ascension and Declination, which we will use to point the telescope. You should also be ready to compare the image which will appear on the computer's screen with your finding chart, so that you can verify that we are indeed pointing at the proper spot in the sky.

We will save all the images in FITS format and transfer them back to computer on campus for processing on Day Two.

Day Two: reduce and analyze the images

On the second day, you must first process your images to remove several types of instrumental defects, and then analyze them to measure properties of your asteroid.

  1. Display your raw image

  2. Remove the dark current

  3. Correct for flat field variations

  4. Find your asteroid

  5. Measure your asteroid's magnitude

  6. Determine the angular distance your asteroid moved

  7. Calculate the linear distance your asteroid moved

  8. Calculate the speed of your asteroid in kilometers per second

At this point, different groups can compare the speeds of their asteroids. There might be some connection between the orbital speed of an asteroid and its distance from the Sun. Do your results show any obvious pattern?

Last modified by MWR Aug 15, 2001