The pointing model window shows some of the physical properties for the Astro-Physics dual model. The properties are explained below.

To open a model select the menu File->Open and navigate to the APPM model that you want to load.

 

The pointing model window is broken up into several sections. The lower right section shows the pointing errors for the East and West models as a pair of scatter diagrams. In the upper left of the graph is the overall average pointing error for the model (in arc-seconds - RMS). This is the average expected pointing error of the model using the Root Mean Square. The maximum expected error is shown at the bottom.

Note that obtaining the average error stated assumes that the mount is ReCalibrated into the model and that the effects of refraction are properly being accounted for.

In the upper left section is the Model Properties Group Box.  These are are the most important model terms. You can check/uncheck them to see how well the model fits the data by looking at how the average and maximum errors (and graph points) change. Usually you will want all terms selected.

NOTE: in the terms the Index Dec Error, Non-perp (Dec,OTA), and Flex Cantilever Axis usually have inverted signs between the axes. Also, the quality of the Polar alignment numbers can be judged by how well they match in each of the dual models. If they are close you can be confident that the numbers are modeled well (the Azimuth is most important).

The last large section in the upper right, the table, simple shows the raw data points collected for the model. You can uncheck specific data points if they seem to be bad data points.

Model Properties and Terms

This group box shows some of the major terms extracted from the pointing model. It is not all-inclusive of all terms and properties used in the pointing model. The pointing model will also take into account refraction and interpolation of residual pointing terms to provide greater accuracy than just these major terms. With time refinements and additional terms may be made visible.

NOTE: All coordinates are in JNOW. In APPM plate solves involving catalogs with J2000.0 coordinates are precessed to JNOW for the purpose of creating pointing models.

This said, you may find these terms useful for evaluating certain mechanical aspects of your setup. There are two columns for the terms. The left column contains the East model's term values. The right column contains the West model's term values. HOWEVER, do not treat these values as absolute.  APCC's sophisticated modeling uses a "best fit" approach.  The values may tell you whether you have a problem with orthogonality or with your polar alignment, but the exact values from the model are not appropriate guides for making precise polar alignment adjustments, or for shimming an OTA.

All/None  clicking these buttons will enable or disable all or none of the model terms. This is a convenient way to select all or none rather than clicking each individually. You can of course refine your choices by individually enabling the checkbox for each term.

Points  Indicates the number of map points that are used/available. If you disable some model points the right number will be updated to reflect this. Here's an example of disabling one model point:

Index Error - Hour Angle

This is the index error in the Right Ascension axis. For instance in a perfect telescope system if the scope is pointing at exactly RA=10h 00m 00s but the telescope coordinates show RA=10h 02m 04s, then the error is 00h 02m 04s. This type of error can usually be fixed by syncing to a known RA/Dec coordinate (e.g. via a plate solve).

Index Error - Declination

This is an index error in declination. For instance in a perfect telescope system if the scope is pointing at exactly Dec=35d 00m 00s but the telescope coordinates show Dec=35h 04m 07s, then the error is 00h 04m 07s. This type of error can usually be fixed by syncing to a known RA/Dec coordinate (e.g. via a plate solve).

Non-perpendicularity (HA,Dec)

This is the non-perpendicularity between the Declination axis and the Right Ascension axis. There are RA and Dec components to this error but they are both combined in the value shown.

Non-perpendicularity (Dec,OTA)

This is the non-perpendicularity between the Declination axis and the OTA. There are RA and Dec components to this error but they are both combined in the value shown.

Polar Axis Elevation

This is the polar alignment error in Altitude. A positive value means the axis is pointing higher than the true pole. Refraction is not included.

Polar Axis Azimuth

This is the polar alignment error in Azimuth. A positive value means the axis is pointing to the West of the pole when facing the pole.

Tube Flexure

This is the amount of flexure in the tube. There are RA and Dec components to the flexure but the value shown combines both.

Flexure in Cantilever Axis

A cantilevered beam is one that is anchored at one end only. In the case of the telescope it is the flexure of the RA and Dec axes caused by gravity. There are RA and Dec components to the flexure but the value shown combines both.