ACS

Attitude Control System

AIS

All-sky Imaging Survey [EXPTIME=100 s]

All-sky survey Tile

 A tile whose image center coordinate (RA, DEC J2000) and size is specifically selected for the all-sky survey.

ATS

Absolute Time Sequence

BFA

Back Focal Assembly

CAG

Calibration Grism

CAI

Calibration Imaging

CAO

Calibration Opaque

CRP

Count Rate Protection

DIB

Data Interface Box

DIS

Deep Imaging Survey [EXPTIME=30,000s]

Dither

A controlled motion of the satellite to move the telescope boresite in a tight, slow spiral pattern that moves outward to 1.5' diameter across the sky.

Dose

Number of detected photon counts in detector coordinates

DPU

(Instrument) Data Processing Unit

DSS

Deep Spectroscopic Survey [EXPTIME=

Eclipse

Time interval during which the Sun is occulted by the Earth during a particular orbit of the spacecraft. Typically 1800-2000 sec in length for GALEX.

EE

Encircled Energy

FEE

Front End Electronics

FSW

Flight software

FUV

Far Ultraviolet detector (1300-1750 Angstroms)

GALEX

Galaxy Evolution Explorer

GROW

Grism and Optical Wheel

HK

House Keeping (data)

IOC

In-Orbit Checkout

Leg

A time period during an eclipse when the instrument configuration is not changed and valid photon data is expected

MCP

Microchannel Plate

MIS

Medium-Imaging Survey [EXPTIME=1500 s]

MOC

Mission Operations Center

MPS

Mission Planning System

MSS

Medium Spectroscopic Survey [EXPTIME=100 ksec]

NGS

Nearby Galaxy Survey [EXPTIME=1500 s]

NUV

Near Ultraviolet detector (1750-3000 Angstroms)

Observation

The acquisition of photon data from a region of the sky during a single orbital night (eclipse).

ObsFile

Observation commands generated by the SOC to be sent to the spacecraft 

OOL

Out Of Limit

PA

Passive Analog (thermistor temperature)

PHA

Pulse Height Analyzer

PhotoObj

Extracted objects from direct images

Plan

 The requirements, constraints and priority for a series of observations of a single target.  Requirements might include minimum exposure time and predecessor targets.  Constraints may include start and end dates and South Atlantic Anomaly avoidance flags. Priority is used to create a hierarchy of plan based on a simple rank order scheme.

Primary Tile

 A tile whose image center coordinate (RA, DEC J2000) is matched to the center of a target.

Programs

 A collection of plans designed to accomplish a particular scientific goal.  This can include survey programs, calibration programs and targeted observation programs.

PSF

Point Spread Function

PTAG

Photon Tag (to deliminate raw photon data)

QDE

Quantum Detector Efficiency

Region

A pre-defined area on the sky where one or more targets (see list below) are clustered.  A region is used for planning purposes.

RTS

Relative Time Sequence

SAA

South Atlantic (Magnetic) Anomaly

SC

SpaceCraft

Scan

A single motion of the satellite at single commanded rate about the X and/or Y axes where the Z axis is aligned with the instrument telescope boresite.  Scans move the boresite axis of the telescope across the sky.

SDSS

Sloan Digital Sky Survey

Secondary Tile

 A tile whose image center coordinate (RA, DEC J2000) is not matched to the center of a target.

SOC

Science Operations Center

SODA

Science Operations and Data Analysis

SpecExtract

 Data describing each spectral extraction  (extraction type may be optimal (default) or simple boxcar)

SpecFlux

 Spectrum consisting of wavelengths, fluxes, & error  tables

SpecStrip

 2-D spectrum

SSR

Solid State Recorder (non-volatile memory on spacecraft)

Sub visit

A single pointing during an All-sky survey eclipse. Typically there are 10-12 subvisits in a single AIS eclipse.

Target

 An area of sky to be observed by the GALEX telescope as described by a series of attitude control dither and/or scan maneuvers of the satellite.  A target may have an arbitrary shape.  Targets may overlap one another.

TBD

To Be Determined

TDC

Time to Digital Converter (part of FEE detector electronics)

Tile

 An area of sky for which the pipeline has generated an image using GALEX photon data.  A tile may have an arbitrary shape, but in general tiles will be rectangular with north in the +Y direction.  Note that there can be primary, secondary and all-sky survey tiles. These are defined as follows

TLM

Telemetry

VC

Virtual Channel (VC18=spacecraft and VC32=instrument)

Visit

 The period during a single eclipse that the GALEX field of view actually overlapped a particular tile

VisitData

  Processed data from a single visit

WCS

World Coordinate System (FITS CRVAL1,CDELT2,CROTA2,etc.)

WSS

Wide Spectroscopic Survey [EXPTIME=30 ksec]