Getting Started
Step 6: Pointing Exposure Interval

At this point we're going to set up the "every target centered" feature of ACP, given your camera, telescope, and site. ACP has a system for assuring that every target is centered. This is in addition to any lower-level open-loop mount improvement system (including ACP's pointing corrector) that tries to make the system point better. ACP has a closed-loop feature that assures a centered target. After slewing to the target coordinates, it takes an image and plate-solves it to determine the true coordinates of where it is pointed, then either syncs the scope and re-slews, or jogs the scope, to remove the pointing error.

Our eventual goal is to find the length of the exposure needed to successfully plate solve and measure your scope's pointing error. ACP will bin the pointing images as highly as possible, increasing the sensitivity with insignificant loss of pointing accuracy. You will probably be surprised at how short a pointing exposure you can get away with. The factors that influence this are (a) your scope's aperture and focal length, (b) your camara's sensitivity, and (c) how deep your reference catalog goes. Rather than trying to come up with some complex formula or series of tests, let's just start with an exposure that's "plenty long" then shorten it as much as we can without losing solving reliability. This will take time and experience with your system.

  1. Click this button to display the ACP PinPoint & All-Sky preferences panel.
  2. Verify that the catalog type and path are set up.
  3. If your mount cannot be synced (maybe it has its own pointing model - TheSky with TPOINT is an example) you can turn off All-Sky solving, as it cannot be used with mounts that can't be synced.
  4. In the Pointing Updates area, set the Exp. Interval to 45 seconds. This is going to be too long, way too long for larger scopes (16" or larger).
  5. Click OK to close the Preferences window.
note Do not alter the other settings in the PinPoint & All-Sky tab at this time.

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