Meade Autostar Software Manual page 29

The Utilities Box is displayed when the left button is released.
Now choose the Determine Magnitude function. You should pick a well defined object, such as a star,
whose values are below the maximum set by the size of the data format. A warning message will be
displayed if the selected region contains any pixels that are at the maximum. Erroneous values will result
if you use objects that contain these pixel values since the actual brightness of these pixels in unknown.
Using the previously set value of the reference magnitude, the Determine Magnitude calculates the total
energy as in the Set Reference Magnitude command, but displays the magnitude of the currently
selected region defined by the following equation:
Where,
RefMag is the previously set reference magnitude
RefTotal is the total energy in the reference aperture.
and Total is the total energy in the currently selected aperture.
After a moment the following dialog will appear:
Photometry Cursor
Pixel List
Area
(
+
RefMag 100
5
-29-
Profile Line
Mag/Centroid Area
(
RefTotal
∗
log
10
Total
Autostar IP
)
)