Overview

The Horizon Tab opens the Horizon Tracking Limits Window.  Horizon Tracking Limits are limits that you set to represent your actual horizon at your observing location.  With Horizon Limits activated, you can leave an imaging setup running unattended with the knowledge that the mount will take the action you have selected when the scope reaches your defined horizon.

The horizon limits act upon a mount that is tracking.  They do NOT prevent slews that will point the scope below your defined horizon.  However, a slew into an area below the defined horizon limit will cause the mount to take your chosen action once the slew is completed and tracking commences.  The horizon limits will NOT, however, save you from an errant slew command.  See Notes at bottom of this page.

Use the Horizon Tracking Limits in conjunction with the Meridian Tracking Limits to define all of the allowable sky at which your scope can be pointed.  Note that you should use the meridian limits to define the horizon in situations where the scope is past the meridian.  Because these counterweight-up / scope-past-the-meridian positions will have higher usable horizons, you will not want the same limits as you will when the scope is in a traditional position.  For users with the Pro version of APCC, the Horizon and Meridian Tracking Limits are also extremely useful in point mapping for the pointing and tracking correction functions.

Northern Hemisphere

 

 

Southern Hemisphere

 

 

Your particular horizon can be edited and saved in the Horizon Tracking Limits Editor.  Multiple horizons can be saved for different favorite locations and the particular horizon for a specific location can be associated with that location's full group of settings for ease of setup.

Operation

Enable Horizon Tracking Limits: This enables horizon tracking limits once you have a set of limits defined. Think of it as the On / Off switch for the horizon tracking limits.  When a limit is reached while tracking (not slewing) the mount will do the appropriate action as described in the next paragraph.  You will note that enabling the horizon limits causes the horizon to appear on the small sky map in the Telescope Position section at the lower right side of the main window.  The horizon will not appear on the sky map if the limits are disabled.

     

Action when limit is reached: Choices are Stop Tracking, Park Mount or Just Warn. If Park Mount is selected, APCC will park to the park position selected on the Park tab. When the limit is reached, the Horizon Limits Indicator in the Telescope Position section of the main window will begin to flash alternatively between the dark red and yellow

 

Time before limit reached: Shows the estimated time before the Horizon limit is reached.  This box is only active if the limits are enabled.  (See Operation Controls screen above).

Starting with version 1.5.1.0 the clock time at which the limit will be reached is also displayed.

 

Horizon Tracking Limits - Altitude/Azimuth

The Altitude / Azimuth box on the Horizon Tab gives you a graphical representation of the sky with your horizon limits.  It shows the telescope position, a rectangular Alt / Az grid, and the corresponding R.A. and Dec. lines.  

Useful Tip:  A very useful feature of both the main tab graph, and the Horizon Limits Editor graph is that you can double-click on a spot on the graph to slew to that position.

 

Note: You can double-click a point in the graph to slew to that position as shown in the northern hemisphere view above.