Note: use a mouse instead of a trackpad or touchscreen to limit frustration while using Afterglow. 

Click “Next” above to see the step-by-step instructions.

Alternate Format: Video Instructions

• Follow along with this tutorial video

Alternate Format: Written Instructions

1. Open the plotter tab
2. Choose “centroid clicks”
3. Click on the moon once (let go, do not click and drag)
4. Choose “planet centroiding”
5. Click on the planet once. Now you have a line connecting the planet and the moon. This is the angular separation between the two on our sky.
6. Read the length in arcsecs from the information provided at the bottom of the screen.
7. Record this length, to the nearest 0.1 in the spreadsheet next to the correct date.
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8. Repeat for each image.