Greetings everybody!
Today we have released another update for all platforms, this time with an improved version of the DynamicPSF tool.
The improvement consists of a new process parameter:
signed angles. When this option is enabled, rotation angles are represented in the ]-90,+90] range (in degrees). When this option is disabled, rotation angles are shown unsigned in the [0,180[ range.
As we have discussed in recent threads on this forum, signed angles are necessary to prevent ambiguities introduced by small rotations close to zero degrees. Small rotations occur frequently due to uncertainty in fitting rotation angles for nearly circular stars. For example, imagine a set of PSF fits where we have two subsets with rotations around zero and 180 degrees. If we compute average PSF parameters, the resulting average rotation would be around 90 degrees. This may be incorrect if both subsets are actually due to dispersion caused by fitting uncertainty, in which case the correct average rotation would be close to zero degrees.
This option is enabled by default, so rotation angles are represented as signed quantities in the ]-90,+90] range in degrees by default.
This improvement is the result of some interesting discussions with Jeff Weiss and other forum members. For more information refer to the following threads:
http://pixinsight.com/forum/index.php?topic=3261.msg23168#msg23168http://pixinsight.com/forum/index.php?topic=3352.0
