Index

Alignment

Alignment is the process of building a pointing model, which is a description of how RA Dec coordinates correspond to axis positions. Pointing model determines pointing accuracy, which is how accurate GOTO, alt-azimuth tracking, and identify is.

Default Pointing Model

If alignment has not been done, the app uses default pointing model (location related), which allows roughly accurate GOTO and tracking. Accuracy of the default pointing model depends on how perfectly the mount was placed in [home position] before power on.

Comparing Alternatives To Alignment

Mount position before power on Procedure after power on Typical accuracy
Default pointing model In home position Nothing GOTO and AZ tracking: Satisfactory
Alignment (non-default pointing model) Home position not critical, but is helpful Perform alignment GOTO and AZ tracking: Good
[Point And Track] Mount is leveled Manually point the telescope at the target to track AZ Tracking: Satisfactory

Perform Alignment

You choose an alignment variation and choose one or more alignment stars. App will prompt you with instructions and will eventually ask you to center a star in the telescope field of view. An eyepiece with an illuminated reticle can help you do this accurately. Before you can confirm center, the last slewing buttons you press must be the RIGHT and UP buttons. The right and up buttons will blink to remind you of this.

Alignment has a few variations:

Name Stars required Alt-Azimuth Equatorial First action
1 Star Alignment 1 Yes Yes App starts rough GOTO to first star
Brightest Star Alignment 2 Yes Yes You manually point to first star
North Level Alignment 2 Yes You manually point the telescope level and to north
2 Star Alignment 2 Yes App starts rough GOTO to first star
3 Star Alignment 3 Yes Yes App starts rough GOTO to first star

Saving Pointing Model

When app has non-default pointing model, stars will be shown at the top of the alignment menu corresponding to how many stars were used in the alignment procedure. App will keep using the same pointing model when it reconnects to the same mount. App considers that it has connected to the same mount by comparing mount model and the mount mode (alt-azimuth or equatorial). As a result, you do not need to perform alignment in the following cases as long as the mount is not relocated:

App reverts to default pointing model when

On Windows platform, data of pointing model is stored in file “Settings.txt” in the SynScan Pro app’s folder. Users can make a copy of this file as a backup.

See [preserving pointing accuracy] for how to keep pointing model valid.

PM (Pointing Model) Sharing

Pointing model is stored in each individual app instance. This means if you performed alignment using one app instance, only it will have the newly created pointing model. If another app instance connects to the same mount, it will not have access to the new pointing model.

PM sharing (Utility > PM Sharing) allows one app instance to send a copy of its pointing model to another app instance. For it to work, the devices running the app instances must be on the same local area network (e.g. connect to the same Wi-Fi network). The sending instance turns on Share my pointing model, while the receiving instance turns off this option. The receiving instance should then see the shared pointing model appear in a list. Loading pointing model overwrites the previous pointing model.

PM sharing is pending patent.