Help updates for multi-star selection and profile migration

help/Basic_use.htm

@@ -563,7 +563,7 @@ <h4><a name="Simulators"></a>Simulators</h4>
 &nbsp;The settings to
 control
 Auto-exposure are on the <a href="Advanced_settings.htm#Camera_Tab">Camera Tab</a>
-of the Advanced Settings dialog. &nbsp;<br><h3><a name="Multi-star_Guiding"></a>Multi-Star Guiding</h3>Most guiding configurations can benefit from guiding on multiple stars
+of the Advanced Settings dialog. &nbsp;<br><h3><a name="Multi-star_Guiding"></a>Multi-Star Guiding and Star-Selection</h3>Most guiding configurations can benefit from guiding on multiple stars
 rather than just one. &nbsp;This results in using a
 weighted average centroid position of multiple stars rather than just the
 centroid of a single star. &nbsp;Multi-star guiding is enabled using a
@@ -591,7 +591,53 @@ <h4><a name="Simulators"></a>Simulators</h4>
 will depend on many factors including image scale, star and background
 sky brightness, star size, focus, tube currents, and camera noise. &nbsp;Because of the way the
 algorithm is implemented, your best option will be to try it and decide
-for yourself. &nbsp;<span style="font-weight: bold;">Note: if you don't use the auto-select function and instead choose a guide star manually, multi-star guiding will be inactive.</span>
+for yourself. &nbsp;<span style="font-weight: bold;">Note: if you don't use the auto-select function and instead choose a guide star manually, multi-star guiding will be inactive.<br><br></span>Since
+the multi-star selection and guiding feature was introduced, users have
+asked for a means to override guide star selection based on what they
+see on the display.&nbsp; These requests have not been acted upon
+because they would disrupt the underlying mathematics of the multi-star
+process. More importantly, they would lead to inferior results for
+reasons described below.&nbsp; The algorithm applies the basic
+principle that the accuracy of centroid calculation - the fundamental
+calculation of where a star is located on the sensor - it proportional
+to that star's SNR.&nbsp; It has nothing to do with the shape of the
+star, its location on the sensor, its proximity to the sensor edge, or
+any other visual characteristics of the star candidate. The algorithm
+will always choose the set of stars with the highest SNR values subject
+to user-controlled parameters that define what a star should look like
+on a particular system.&nbsp; Two parameters, Min-HFD and Max-HFD,
+define a range of star "sizes" that control whether a bright area on
+the sensor can be accepted as a star candidate rather than being
+rejected as sensor noise, internal reflections, or close pairs of
+stars.&nbsp; The third parameter, Saturation ADU, defines an upper
+limit to the peak brightness of a star candidate, usually defined as
+the maximum ADU value produced by the guide camera.&nbsp; The algorithm
+tries to avoid saturated stars and will accept one only if there are no
+other viable candidates.&nbsp; Setting these parameters correctly is
+the single most important thing for a user to do in order to get the
+best possible sets of guide stars.&nbsp; The "Min" and "Max" HFD values
+can be determined empirically by using the Star Profile tool or by
+examining the PHD2 guide logs to see the range of star sizes that are
+typical for the guiding system and its seeing conditions. Once set,
+they should rarely need to be changed unless something in the
+configuration or the atmospheric conditions has substantially changed.<br><br>Users
+are commonly fooled by what they see on the display and think they can
+do a better job of guide star selection.&nbsp; This is a mistaken
+impression.&nbsp; The single biggest reason is that many of the
+"attractive" guide stars on the display are saturated.&nbsp;
+Secondarily, they are often just sensor noise, e.g. hot or warm pixels,
+that look like stars once the image has been down-sampled and
+gamma-stretched for display.&nbsp; No dark library or bad-pixel map can
+completely eliminate these artifacts. In summary, simply squinting at
+the screen and clicking on bright spots will produce inferior results
+compared to the quantitative, systematic approach taken by the
+auto-select star-finding mechanism.&nbsp; Of course, die-hard users can
+still manually choose a guide star, but they won't then be able to use
+multi-star guiding. For people who are not convinced about the merits
+of the auto-select process, the debug log file contains a detailed
+list, for every auto-find, of the location and properties of every
+single candidate object in the guide frame and how these were included
+or excluded to compile the final list.<span style="font-weight: bold;"></span>
 <h3><a name="Automatic_Calibration"></a>Automatic
 Calibration</h3>
 <h4>Conventional Mounts</h4>

help/Supplemental_Info.htm

@@ -802,12 +802,21 @@ <h3><a name="Managing_Equipment_Profiles"></a>Managing
 during a <span style="font-style: italic;">PHD2</span>
 session. Finally, you can import and export
 profiles for purposes of debugging, backup, or&nbsp;exchange
-between computers. &nbsp;When you export a profile to a new computer,
-remember that the dark library and bad-pixel maps will not be migrated
-automatically because they are stored in the file system - in the
+between computers. &nbsp;<br><br><span style="font-weight: bold;">Migrating PHD2 Settings to a Different Computer</span><br><br>On
+Windows, the profile information is kept in the Windows registry, so
+you can't simply do file transfers to move your settings from one
+computer to another. &nbsp;Instead, you should 'export' your profiles
+into files on the old computer, copy those files to the new&nbsp;one,
+then 'import' them on the new system. &nbsp;This will transfer all the
+settings associated with the profile except for the dark libraries and
+bad-pixel maps. The dark and bad-pix map data are stored in the file
+system because of their size. They are located in the
 'AppData\Local\PHD2' logical directory used by your operating system.
 &nbsp;You will need to transfer that directory and all of its files to
-the new computer manually.<br>
+the new computer manually without changing the directory location or
+file names. &nbsp;That said, the best practice is to simply rebuild
+them on the new system in order to have data that reflects the current
+behavior of the guide camera sensor.<br>
 <br>
 <h3><a name="Ask_for_coordinates_aux_mount"></a>Aux-Mount
 Connection using "Ask for coordinates"</h3>