Astro abbrevations & Terms

Many accepted abbrevations are used in Astronomy, here are some of them:

ADU: Pixel Value (analog-to-digital unit)

APO: Apochromatic refractor

AAPOD: Amateur Astronomy Picture of the day

APOD: Astronomical picture of the day (website)

APT: Astrophotography tool (capture software)

AU: Astronomical Unit (distance from Earth to the sun)

Bahtinov mask: A patterned mask put in front of the aperture to aid focus. Invented by Pav Bahtinov who didn't patent it!!!

Bayer: Bayer is the name of the person who invented the Bayer pixel pattern that is in every DSLR. It has groups of four pixels in a square and is configured R,G,G,B so you get twice as many green as red or blue. The camera software decodes all this and you get a normal looking colour picture.

Bias: Very short image possibly 0.001 secs taken with the lens cap on. Used for calibrating certain noise in astro-images.

Binning: Binning is the combination of two or more CCD image sensor pixels to form a new “super-pixel” This improves signal to noise ratio SNR, allowing exceptional quality image recording, at extremely low light levels.

Bins: Binoculars

CCD: Charge-Coupled Device, generally referred to in Astro-imaging as dedicated cooled cameras.

CME: Coronal mass ejection

CMOS: Complementary metal–oxide–semiconductor (type of camera sensor). There are now cooled CMOS cameras available for Astrophotography of DSOs. These require shorter images but in total about the same amount of time spent as CCD camera images. But they run less risk of place trails ruining a long image, or guiding issues are reduced.

Dec: Declination, the astronomical equivalent to latitude

Differential Flexure: Slight movement between a guidescope and an imaging scope.

Dithering: A method of moving your image by a few pixels between exposures in order to reduce noise and hot pixels by overlapping. Normally operated on software which will speak to the guiding software.

Dob: Dobsonian telescope

Drizzle: Increases the resolution for small objects. It is memory hungry so select small area.

DSLR: Digital SLR camera (Single lens reflex)

DSO: Deep space object

DSS: Deep Sky Stacker, free stacking software

Ecliptic: The path that the Sun Moon and planets move along in the course of a 24 hour rotation. Also the plane of the solar system.

EFW: Electronic filter wheel

EP: Eyepiece

FF: Field Flattener. Optical lens for correcting curvature in an image and helps alleviate comet shaped stars in the corners provided the right spacing is used.

Flats: (Or flat fields). Images of the light train through the scope and camera.

Focal Ratio: The focal length divided by the aperture.

FOV: Field of view

FR: focal Reducer

GEM: German equatorial mount

GMT: Greenwich meantime

Guiding: Using a 2nd camera and scope to correct tracking during imaging.

Ha: Hydrogen alpha, often used to denote typed of filter used.

HaLRGB: Image using hydrogen alpha, Luminance, and RGB

Hartmann Mask: Another focusing tool, like a Bahtinov Mask using 3 holes

HDR: High Dynamic Range

HOO: Hydrogen Oxygen and Oxygen ( a combination in a bicolour narrowband image)

Hubble Palette: This is a term applied to narrowband imaging where Ha is used in the green channel, Sii is used in the Red Channel, and Oiii is used in the blue channel. This creates the blue and yellow images seen.

IR: Infrared

ISO: Sensitivity to light by an image sensor

ISS: International space station

LMG: Large Magellanic cloud

Looping: Repeated short images which give a sort of "live view" effect in CCD cameras.

LP: Light Pollution

LRGB: Luminance, Red, Green and Blue filters

LX: Long Exposure

Mak: Maksutov cassegrain telescope

Meridian: Imaginary line that runs north to south overhead

Mono: Black and white image or B&W camera

NEO: Near Earth object

NGC: New general catalogue

OAG: Off axis guiding

Oiii: Normally refers to Oxygen filter

OSC: One shot colour (camera)

OTA: Optical tube assembly

PA: Polar alignment

PE: Periodic error in a mount is caused by imperfections in the gear train

PEC: Periodic error correction

PHD: Guiding software (Push Hard Dummy)

PI: Pixinsight

PN: Planetary nebula

POD: Personal Observatory Dome

PS: Photoshop

PST: Personal Solar telescope

RA: Right ascension, the Astronomical equivalent to Longitude

RC: Ritchey-Chretien Telescope

RDF: Red dot finder

Register: Align the images so that they exactly match. Normally done by aligning the stars.

RGB: Red, Green, Blue

ROR: Roll off roof

SCT: Schmidt Cassegrain Telescope

Sii: Normally refers to Sulphur filter

SMG: Small Magellanic Cloud

SNR: Signal to noise ratio

UFO: Unidentified flying object

UT: Universal time