ImageJ
As scientists, astronomers do not only take pretty pictures, but also must produce quantitative (mathematical) analyses of these pictures. There are many different methods for analyzing astronomical images, and therefore many different software tools for doing this analysis.
During this workshop, you will be performing your own analysis of images of star clusters. We have selected a program called "ImageJ" for you to use. The advantages of this program are that it is Java-based (so it can run on any computer), it is free, and it is relatively user-friendly.
It will help you to become familiar with a few basic aspects of ImageJ before coming to the workshop. This webpage will step you through the installation of ImageJ and then provide you with a few, short activities to familiarize you with the program. Each activity only takes about 15 minutes, and you can work through them at your leisure.
Please try these activities before coming to the workshop. If you have trouble or get stuck, don't panic! Just give it you best shot, and we'll work with you at the workshop.
Table of Contents:
- Downloading and Installing ImageJ
- Downloading and Installing the Circle Tool
- Pre-workshop ImageJ Activities
Downloading and Installing ImageJ
To download and install ImageJ, do the following:
- Make sure your computer is connected to the Internet.
- Go to the ImageJ Download Page
- Click on the version appropriate for your computer.
- Follow the installation instructions.
Downloading and Installing the Circle Tool
In astronomical images, stars appear as circles. ImageJ doesn't come with a circle installed (it has ellipses/ovals), though they do provide a separate circle tool that you can install yourself. We've simplified the installation for you. The instructions below work for ImageJ version 1.40, the current version as of July 2008, but it may not work for other versions.
- Download this file (StartupMacros.txt) and save it somewhere you can find it (like your desktop).
- Find the ImageJ folder.
- On a Windows machine, this is probably under Program Files --> ImageJ
- On a Mac, it is wherever you put it (probably the Desktop or your home directory)
- Open the "macros" folder.
- Copy the StartupMacros.txt file you downloaded above into the ImageJ macros folder. This will overwrite a file of the same name in that directory. Probably this is okay.
- Open ImageJ and look for a circle on the right of the
toolbar. If you see it, you are done!
Pre-Workshop ImageJ Activities
NOTE: To save .fits files to your disk, either right-click (PC) or ctrl-click (Mac) on the file name. DO NOT just click on the image, as your browser will try to open it, and your browser will crash.
| Activity | Needed Online Materials |
|---|---|
| Worksheet 1 (PDF, 1.7 MB) | kermit.jpg |
| Worksheet 2 (PDF, 3.3 MB) | quintet.fits (4.1 MB) |
| Worksheet 3 (PDF, 5.6 MB) | m34_u.fits (4.1 MB) |
Workshop and Post-Workshop ImageJ Activities
The Observing Challenge details the creation of color magnitude diagrams and the open star cluster white dwarf search activity. Lesson 4 describes how to make pretty color pictures with ImageJ.
| Activity | Needed Online Materials |
|---|---|
| Observing Challenge | NGC6633B.fits NGC6633V.fits |
| Worksheet 4 (PDF, 3.0 MB) | M16B.fits M16V.fits M16R.fits |
