Definitions

• 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: You don't need this with Seestar. They're 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.

• Bortle Scale: A measure of how dark your sky is ranging middle of no where to downtown Tokyo.

• Dark Frames: Seestar will automatically create these for you when you start Stargazing DSO imaging. They're images taken with the same exposure time and camera settings as your light frames, but with the path blocked by an opaque filter. 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: Seestar does this automatically for you. 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. Seestar moves 15 pixels every 10 exposures.

• DSO: Deep Sky Object such a nebulae and galaxies, but also comets, asteroids, quasars, etc.

• 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. Some people have adapted the Seestar so it can operate in equatorial mode (Google seestar_alp).

• 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: Not required with the Seestar. Images taken of a uniformly illuminated surface, such as a flat-field panel or the twilight sky are called flat frames. 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: Also known as subframes or just subs, these are 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. You can tell the Seestar to save these for you in the Settings page.

• 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. Use in post-processing, and not required to capture images with the Seestar.

• 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. The Seestar has a so-called framing mode that approximates the creation of a mosaic.

• OTA (Optical Tube Assembly): The main optical component of a telescope, including the lenses or mirrors, tube, and focuser, but usually excluding the camera, mount, tripod. The Seestar's camera is in the OTA.

• Sub frames: when the Seestar is enhancing stacking your images in Stargazing DSO Mode, the image is created from sub frames (also called subs). You can save those subs if you tell the Seestar to keep them by turning on the feature in Settings.

* YMMV: Your mileage may vary.