Specifications

AUTOSTAR CCD PHOTOMETRY 21
Figure 3-5. New Calibrated Image Files.
9. To organize the calibrated files, make a new folder within the
current folder. Call this folder “Cal Filter Name Data” (or “Cal
V” for the V filter calibrated images).
10. Repeat steps 3 through 9 for each of the other filters. You now
have sets of calibrated data ready to have the star magnitudes
determined.
3.3 Differential Magnitudes
The best and most accurate way to do photometry is to use
differential photometry, in which Program star magnitudes are
compared against known Comparison star magnitudes and then
normalized to produce a differential magnitude. This means you
must know the Comparison star Reference magnitude accurately
for each filter band.
3.3.1 Setting the Reference Magnitude
1. From within the Autostar Image Processing program, select File
and Open.
2. From within the Cal V folder (e.g., the Calibrated V filter
images) select the first image to be processed. Make sure the file
name has “Calibrated” in front of it.