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 (stop after he measures the asteroid)

Alternate Format: Written Instructions

1. Load our two images of the asteroid you have been directed to load.
   • One is from a telescope in Chile. One is from a different telescope.
   • Confirm that the two images were taken within 20 seconds of each other.
2. Align our two images of the asteroid (one from each telescope)
   • Click on the “Show Aligner” icon in the lower right.
     • Select Images to Align: select both images in the dropdown menu.
     • Reference Image File: select one image (either one, it doesn’t matter which).
     • Leave all the other settings on default.
     • Click Submit
     • 
3. Stack our two images.
   • Click on “Show Stacker” icon in the lower right.
     • Select Images to Stack: select both images in the dropdown menu
     • Mode: average
     • Rejection: none
     • Leave all the other settings on default.
     • Click Submit
     • 
4. Select the new image to display in Afterglow
   • Zoom in very close on the asteroid in the new image. It will look oblong.
   • Adjust the Display settings until you can see two points of light for the asteroid.
     • This is the same asteroid, but it shows up twice because it is seen from two different angles (telescopes).
5. Measure the angular distance between the asteroid’s two positions
   • Plotter tool on the right
   • Centroid clicks on
   • Click on one image of the asteroid, then the other.
   • Record the measurement in arcseconds in your assignment.
   • 
6. 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
   •