In astrophotography, a pier typically refers to a stable, fixed mount or platform that is used to support an equatorial mount and telescope. Piers are often constructed of sturdy materials such as steel, concrete, or wood, and are designed to provide a stable base for the telescope, minimizing vibration and movement during long exposures.

Piers are often used in permanent or semi-permanent observatories, where they can be anchored to a solid foundation and remain in place for extended periods. However, they can also be used in portable setups, such as in backyard astrophotography, where a pier can be temporarily set up on a stable surface such as concrete or decking.

Using a pier in astrophotography can have several benefits. The stable platform helps to minimize vibrations and movement, resulting in sharper and clearer images. Piers can also provide a consistent alignment for the equatorial mount, making it easier to polar align and track celestial objects accurately.

Piers can be purchased pre-made or custom-built to suit specific telescopes and mounts. They may also include features such as leveling adjustments, cable management systems, and vibration isolation materials to further improve stability and image quality.

You may also encounter the term “side of pier”. In astrophotography, “side of pier” refers to the position of an equatorial mount and telescope relative to the celestial meridian line. The meridian line is an imaginary line that runs directly overhead from north to south, passing through the zenith. The side of pier is determined by the position of the mount and telescope relative to this line.

When an equatorial mount is set up and polar aligned properly, it will track celestial objects as they move across the sky along a path that is parallel to the celestial meridian. As an object crosses the meridian line, the mount will need to perform a meridian flip, which involves slewing the telescope to the other side of the mount. The side of pier refers to which side of the mount the telescope is on before and after the meridian flip.

For example, if the telescope is on the east side of the mount before the meridian flip, it will be on the west side of the mount after the flip. This is known as the “east side of pier” or “west side of pier” respectively. The choice of which side of pier to start on will depend on factors such as the location of the object being imaged, the location of obstacles such as trees or buildings, and the preference of the astrophotographer.

Knowing the side of pier is important when setting up an imaging session, as it can affect the placement of the guide camera and other equipment, as well as the sequencing of exposures and meridian flips. Some astrophotography software and tools, such as PHD2 and N.I.N.A., provide options to control the side of pier during imaging sessions.