You have seen a few of the features of a good introductory image
processing program. There are many more complex modifications you
can make to the images. For example, you can apply a variety of filters
to the image. The filters use mathematical algorithms to modify the image.
Some filters are easy to use, while others require a great deal of
technical knowledge. The software also will calculate the ra, dec,
and magnitude of all objects in the field if you have a star catalog such
as the Hubble Guide Star Catalog (although this feature requires the purchase of an
The standard tricolor images produced by the SDSS are very good
images. If you are looking for something specific, you can
frequently make a picture that brings out other details. The "best"
picture is a very relative term. A picture that is processed to show
faint asteroids may be useless to study the bright core of a galaxy in the
Try one or more of the following exercises. When you finish them,
us your images and interpretations. We'll look at all the results
we receive, and we'll put the best of them up on these pages!
Research Challenge 1.
Search for an object that is in both the SDSS database and the
2MASS database. Retrieve the images from 2MASS and the SDSS.
Make a tri-color image using the J, H, or K filters for 2MASS data and
filters of your choice for SDSS data. Compare and contrast your
images. What information do they give you about the object? What interpretations
can you make by studying the two images?
Research Challenge 2.
Scientists are very interested in distant quasars, objects that have
very red colors. Retrieve the i and z images for a
field. Use the blink command to look for objects that are
visible in the z filter but not visible in the i filter. These
objects might be distant quasars or very small, cool stars. Either
way, you will be finding something very interesting!
Look at these objects in detail, using these or other images. What
can you conclude about them? How could you tell if one of these objects
were a quasar or a cool star?
Research Challenge 3. Iris can
obtain images from a webcam. If you have access to a webcam and
a small telescope, mount the webcam looking into the eyepiece.
Click on the Webcam menu in Iris and click Image Acquisition.
Obtain and process an image of a bright object such as a moon or a
planet. Although you cannot see very faint objects with a webcam,
many amateur astronomers produce nice images of bright objects using webcams.