This feature helps you align an equatorial mount to Earth's rotational axis. It will also work with other similar instruments such as equatorial platforms, barn-door mounts, etc.
Due to Earth's rotation around its axis, the objects in a telescope's or camera's field of view will appear
to move even though the telescope itself might be stationary. To compensate for this motion, a corresponding
movement needs to be made on the mount. This compensatory movement is called
To help with tracking, equatorial mounts and similar instruments have an axis that needs to be aligned with the Earth's axis of rotation. The lesser the alignment error, the lesser will be the tracking error.
RA axis of mount as the axis on which the mount is intended to rotate such that only the Right Ascension
of the target changes. This is the axis that needs to align with the Earth's rotational axis, which is marked by the two
Declination axis of mount is the axis on which the mount is intended to rotate such that only the Declination
of the target changes.
To Polar Align with this app, follow the steps below.
- Ensure the location in the app is set accurately.
- Ensure Plate solving is working. See this page for more details.
- Roughly align the mount. While not strictly necessary, it will help reduce ambiguities. An alignment within 45° of the celestial poles is good enough and should be easy to achieve by just eye-balling it.
- Physically attach the Android device to the OTA or mount. It can be attached in any convenient orientation, as long as the camera points towards the sky.
- In the live view screen, press pause, and bring up the
Start polar alignmentbutton
- You will be greeted by a screen such as the one shown below.
- You will be walked through a number of steps, including,
- Locking the declination axis
- Rotating on the RA axis
- Locking the RA axis as well
- And finally, the alignment screen shown below:
This screen indicates the degrees by which the mount needs to be adjusted, so that it is fully aligned. While you move the mount, the screen keeps updating with the latest measurements.
When you are happy with the alignment, you can click the
Done button to exit.