Optical data was taken with the WIYN 0.9m telescope using the S2KB detector. The .9m telescope is located near the southern edge of Kitt Peak outside of Tucson Arizona. The magnitudes of the sources were measuered using photometery in order to determine their variability in the optical range. Both B and V filters were used. There are 5 different types of filters that are used to view different parts of the spectrum.
U = "ultraviolet" wavelengths in the violet and ultra violet
B = "blue" blueish light.
V = "visual" greenish/yellow light
R = "red" redish light
I = "infrared" wavelengths just longer then those visible by the human eye
For each day observations were made there are also 8 to 10 Bias frames and about 5 Dome flats for each filter used. The bias frames have an exposure time of zero seconds and are used to measure the electronic noise from the ccd camera. The Dome Flats are images taken of the inside of the dome when a light is uniformly shone on it. These are used to find dust rings on the telescope or filter.
This is a raw image of Markarian 501 taken with a B filter. Notice how the image is much lighter in the top left and darker at the bottom. There is also a white line from a line of bad pixels in the ccd. These things will be fixed when the image is reduced
Here's how I did the Data Reduction With IRAF.
This is the same image of Markarian 501 after reduction. The white line is now gone and the image has a uniform background. The image is now ready for photometry
Photometry is the technique used to measure the flux of stars. The star's magnitude was measured using IRAF.
Here's how I did the Photometry with IRAF.
WIYN 0.9m telescope
Kirsten Larson's REU Home Page