Specifications

22 AUTOSTAR CCD PHOTOMETRY
Note: AutoStar automatically adjusts the monitor display contrast;
so even if the images look faint, the data should be okay. If the star
image is too faint to be easily seen, you can adjust the contrast
manually. The adjustment only affects the display. You can also
expand the image to full screen if it helps.
3. Start by drawing a small box around the Comparison star. There
will be a diagonal line across the (inner) box. The box should be
placed so that the line is approximately across the middle of the
star image. This is not very critical, as the software will find the
center of the star (the “centroid”). (See Fig. 3-6.) The direction
used to draw the box is up to you.
Figure 3-6. Photometry Cursor.
Note: The Photometry region cursor has three main components
(Fig. 3-6):
(a) Magnitude/Centroid Area
(b) Pixel List Area
(c) Profile Line
The Magnitude/Centroid rectangle bounds the entire area used in
the magnitude and/or centroiding calculations. This is a bit
confusing – to properly determine the magnitude of a star, only
draw the small box (shown to the lower left – the Pixel List Area)
around the star of interest. The Profile line delineates the pixels
that will be displayed when the Draw Profile function is selected.