Activity

Before you start this activity, make sure you’ve followed our main guide on “How to create stunning color images” to find out where and how to get your observations to use in this activity.

Materials

• Computer with internet access
• Image files for observations taken in red (rp), green (V), and blue (B) colour filters

1. Once you have your observations, go to the JS9-4L website: https://waps.cfa.harvard.edu/eduportal/js9/software.php
2. Close the popup tutorial, and go to My List and clear any images that are pre-loaded in there.
3. Next, go to Image and select either Open (if you saved your image files to your computer), otherwise select Open URL, to load in your first image.
4. You may need to use the zoom tool to zoom out a few times once the image has loaded, to be able to see the full image.

5. When your image is open, you may notice the details are hard to see. To fix this you’ll need to adjust the levels in the side panel. You will want to first change the scale to log to help bring out the details in the image as you adjust the brightness limits.

6. The next step is to adjust your image so the background sky is as dark as possible without losing any of the detail from your image. First, you’ll need to set the Low Brightness Limit. Hover your mouse over the bottom left corner of your image and set the low brightness limit to be the same as the Pixel Value shown.

7. Then adjust the High Brightness Limit until you’re happy the image is showing as much detail as possible, and make further small adjustments using the Stretch and Shift sliders.

8. To colour the image go to the Color tab along the top and select either red, green or blue, depending on which colour image file you’ve opened.

9. Go to Image > Open or Image > Open URL and load in your next colour image file. Follow the same steps as you did for the first image.

10. Once you’ve done the above steps, click on Color > RGB mode to combine all 3 images into a color image.

11. You may have to make a couple of final adjustments for a perfect image, however. If your image layers are slightly misaligned this can be fixed by going to Tools > Shift and moving the image layer you have selected up, down, left or right to line it up with the other image layers. To see how well they’re lined up, you may want to zoom in and use Tools > Pan to pan to a region with easy to see stars.

Congratulations, you just created beautiful full colour astronomical images to share with your class!