Alt/Az Mount: An altazimuth mount is a simple two-axis mount that controls the telescope's movement in altitude (up and down) and azimuth (left and right). It's easier to set up but requires additional techniques for long-exposure astrophotography due to field rotation.

Bias Frames: Extremely short exposures (typically the shortest possible) taken with the lens cap on or the telescope covered. Bias frames capture the read noise, a type of electronic noise that's independent of exposure time, and is present in all images.

Dark Frames: Images taken with the same exposure time and camera settings as your light frames, but with the lens cap on or the telescope covered. Dark frames capture the thermal noise and other electronic noise inherent in your camera's sensor, which can then be subtracted during image processing.

Dithering: A technique where the telescope's position is shifted slightly between exposures during image capture. This helps reduce fixed-pattern noise and other artifacts when the images are stacked.

Equatorial Mount: A type of telescope mount designed to counteract the Earth's rotation by aligning one of its axes with the Earth's rotational axis. This allows for easier tracking of celestial objects.

Field Rotation: The apparent rotation of the field of view in an image caused by the Earth's rotation when using an Alt-Az mount.

Flat Frames: Images taken of a uniformly illuminated surface, such as a flat-field panel or the twilight sky. Flat frames are used to correct for vignetting (darkening of the image corners) and dust spots on your camera sensor or optics.

Histogram: A graphical representation of the distribution of pixel brightness values in an image. In astrophotography, histograms are used to assess the exposure levels and dynamic range of an image and to guide adjustments during image processing.

Light Frames: The main images you take of your celestial target during an astrophotography session. These contain the light from the object you're photographing, along with various noise and artifacts.

Mask: A tool used in image processing software to selectively apply adjustments to specific areas of an image. Masks can be created based on brightness, color, or other criteria, allowing you to isolate and enhance specific parts of the image without affecting the rest.

Mosaic: A large image created by combining multiple overlapping smaller images, typically used to capture wide fields of view that wouldn't fit in a single frame.

OTA (Optical Tube Assembly): The main optical component of a telescope, including the lenses or mirrors, tube, and focuser, but excluding the mount and tripod.