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
• Note that Dr. Reichart uses some different vocabulary:
  • He says "Illuminated Angular Distance" where we say "Illuminated Width",
  • He says "Angular Diameter" where we say "Diameter."

Alternate Format: Written Instructions

1. You will use archival data for this. If you have your own Venus image you will also use that one.
   • Open each image in Afterglow using the "Open Files" icon in the upper left.
     • File path: Sample/Astro 101 Lab/Lab 3 - Galilean Revolution/Venus/[filename].fits
2. Measure the the illuminated angular distance  and the angular diameter on each Venus image.
   • Open each image and set the display to "Bright Target."
   • Open the plotter tab
   • For each image take two measurements, and record them in the Skynet 3 Observation Report.
     • Illuminated Width
     • Diameter
     • 
     • Illuminated widths will always be smaller than diameters.
   • For each image, calculate the phase:
     • The phase is the illuminated width divided by the diameter. It will be between 0 and 1.
     • [latex]phase=\frac{illuminated\: width}{diameter}[/latex]