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 (begin at 8:40)
• (begin at 8:40)

Alternate Format: Written Instructions

1. Open the archived images
   • One was taken in January.
   • One was taken in July.
   • Open each image in Afterglow using the “Open Files” icon in the upper left.
     • Sample
       • Astro 101 Lab
         • Lab 4 – Parallax
           • Alpha Centauri
             • 1 – Alpha Centauri January.fits
             • 2 – Alpha Centauri July.fits
2. Do exactly the same thing we just did for the two asteroid pictures to align and stack them. Once they are aligned and stacked, return to this point in the instructions. These two images were taken 6 months apart.
   • Be sure to deselect any other files that might be selected in the aligner and the stacker.
3. Adjust the image so you seem to see four stars
   • Don’t get fooled, this is a two-star system, so each of those stars will be in two places, making four.
     • This image is poorly adjusted, you can’t see all four images:
     • 
   • We will be measuring the shift in Alpha Centauri B.
     •  This image is more properly adjusted, and you can see all four:
     • 
4. Measure the angular distance between the star’s two positions
   • Plotter tool on the right
   • Centroid clicks OFF because the images overlap.
   • Click on one image of the asteroid, then the other.
   • Record the measurement in arcseconds in the Skynet 4-2 Observation Report
   • 
5. Save the image with the measured distance
   • Click the camera icon just below each of the two images to download the jpg files.
   • These files should have the markers visible.
   • Insert the images into your assignment.
   • 
6. Complete the calculations requested in the assignment.