Navigate to <https://afterglow.skynet.unc.edu/>

Open an image. You'll notice that it probably doesn't look great. That's why we're doing this!

Click on the eyeball icon on the upper right to open the "Display Settings" tab

There are three preset buttons: "Bright Target", "Default Preset", and "Faint Target." Click them to choose the one that makes your image the closest to what you need.

For planets, "Bright Target" is going to be close. In this example you can suddenly see the stripes on Jupiter, and the face of the planet!

This is the same image of Jupiter using the "Faint Target" preset.

You image may still not be quite as you need it to be. Click the up and down arrows inside "Saturation Level Percentiles" to adjust it to be exactly as you need.

If we are looking for moons around a planet, you'll want it to show the outlines of the moons clearly. If you're looking at a nebula, you want to see the gas filaments.

Also click the up and down arrows inside "Background Level Percentiles" to adjust the background to be exactly as you need.

This is an example of well-adjusted for taking moon measurements.

Click the eyeball icon to show more of the image.

Use your scroll wheel to zoom until your image fills the screen. 

You can also use the Zoom In/Zoom Out magnifying glasses in the lower right.

Click and drag the object itself to move it to the center of your field of view.

Once your image is adjusted and centered:

Click the camera icon to "Download Viewer Snapshot." (NOT the mountain image icon.)\
The image will download to your computer. This is the image you need for assignments.

Afterglow: Adjusting Brightness, Saturation Levels, and Zooming In