Spectrum Calibration Using Four Vega Spectrums
- These four images were used to calibrate the spectrum measurements for August 6, 2010.
The spectrum image was taken by the below
- The star Vega H-alpha absorption line was used to calibrate the x axis in
angstroms by measuring the distance of the grating to CCD.
- Images of Vega spectrum were taken at the beginning of each evening imaging session.
- Vega H-alpha absorption line distance was measured from the centroid of the spectral order zero.
- The below table shows the four images used and the calculated grating distance between the grating and the CCD.
- The grating distance mean is 18.3272 mm with a standard deviation of 0.01414 mm.
- The first calibration equation is Å =SIN (ATAN (0.0000068* pixel distance /.01832719265135))*0.000005*10000000000
- Å is light wavelength measured in angstroms.
- 0.0000068 m is QSI532ws pixel size (6.8 microns).
- Pixel distance is the horizontal pixel distance from the centroid of spectral order zero.
- .01832719265135 is the distance of the grating to CCD (18.3272 mm).
- 0.000005 m is the distance between the Rainbow Optics grating filter lines (200 lines/mm grating).
- 10000000000 converts the wavelength from meters to angstroms.
- The second calibration equation is a linear x=Ay+B between absorption lines to align the H-alpha, H-beta, H-delta and H-gamma absorption lines of image vega08062010-01605s to the CCD pixel distance to the centroid of the zero mode image.
The following test pattern is to help you adjust your monitor to best view the CCD astro images.
The test pattern is used for adjusting monitor brightness, and contrast.
Adjust monitor brightness and contrast to see all 16 gray scale levels.
The most important adjustment when viewing astro images is to see the differences in all of the black bands.
© 1998-2010 David Haworth