Using MIRA to do simple aperture photometry

You should first download the images to your computer's "Documents" directory (the default place to put downloaded files). Each one should appear as an icon with a large capital "M" surrounded at the upper right with red markings; this means that the image processing program MIRA can be used to open the image.

• double-click on the "MIRA" icon on the desktop to start running MIRA
• use the "File -> Open Image" menu to select one of your images; a window should appear displaying the image
• (if desired) zoom in on the image
  • View -> Magnify -> 2
• prepare the aperture photometry tool
  • Measure -> Aperture Photometry
  • a set of icons should appear at the left side of the image
  • click the "P" icon with no asterisk -- a crosshair cursor should appear and a new panel called "Aperture Photometry" will pop up, too
  • move the cursor to star A and left-click -- circles should appear
  • use the check-mark icon ("Options") to adjust the size of the "Object" aperture so it is a bit bigger than the visible extent of the star, and the "Inner bg" and "Outer bg" apertures so that they are clear of any starlight and 5-10 pixels apart
  • click on the calculator icon at left ("Calculate")
  • in the "Aperture Photometry" panel, you'll see position of star A and its instrumental magnitude through your aperture
• measure the instrumental magnitudes of stars A, B, IY
  • click on stars B and IY; a new entry in the list will appear for each
• repeat for all your images

Copyright © Michael Richmond. This work is licensed under a Creative Commons License.