Harvard University Astronomy Lab and Clay Telescope

Day Labs | Evening Labs | Cloudy Day Labs | MaximDL Help

CCD Field of View using Albireo

Let's determine the CCD field of view! Using the known separation of the double star, Albireo (34 arcsec, as you measured in the Visual Observations of Albireo lab), we can determine the size of the CCD in arcminutes.

Procedure:

• Slew the telescope to Albireo RA=19:30:43 DEC=+27:57:40
• Take a very short (0.1 sec) exposure, making sure not to saturate the image. If necessary, use the Aperture Mask to essentially make our telescope aperture smaller and allow a longer exposure on the CCD before it saturates.
• Load the image you took above in MaximDL
• Measure the X, Y pixel coordinates of each of the 2 stars by hovering the curser on the center of each star in turn and then recording the X,Y coordinates in the table (pdf or docx).

Analysis:

• Star 1 has coordinates (X₁, Y₁) and star 2 has coordinates (X₂, Y₂).
• Consider the difference between stars (in pixels) the distance, Z, where Z = ((X₁-X₂)² + (Y₁-Y₂)²) ^1/2 [Do you recognize this equation? The hypotenuse of a right triangle!]
• When you divide this by the separation between the stars (34 arcmin), this gives you the number of arcsec/pixel on your CCD image.
• Determine the number of pixels your CCD image contains in X, Y by roaming the curser from one side of the image to the other.
• Since you now have the conversion of arcsec/pixel, use this to find the corresponding size (in arcsec, and then convert to arcmin) of the full CCD.