The following terms and acronyms are used in this Handbook.
2MASS: Two Micron All Sky Survey

A&A: Astronomy & Astrophysics journal.

ABMAG: –2.5 log (Fν) – 48.60 where Fν is the flux from the source in erg cm–2 sec–1 Hz–1.

ABν: Correction to ABMAG to account for the fact that the source spectrum is not constant in Fν (ABMAG=V+ABν).

ACS: Advanced Camera for Surveys.

ACS-R: Repaired ACS from SM4.

ADC: Analog to digital converter.

AJ: The Astronomical Journal

Aladin: Interactive sky atlas (

ApJ: The Astrophysical Journal

APT: Astronomer's Proposal Tool.

ASIC: Application-Specific Integrated Circuit in CEB-R.

aXe: Spectroscopic Data Extraction Software.

BOPBright Object Protection.

BOT: Bright Object Tools for SBC proposing.

CALACSACS calibration pipeline software.

CCD: Charge Coupled Device. Solid-state, light detecting device.

CDS: Correlated Double Sampling mode in CEB-R (dual-slope integration or clamp-and-sample).

CEB: CCD Electronics Box.

CEB-R: New CCD Electronics Box installed during SM4.

CMD: Color Magnitude Diagram.

CR: Cosmic ray.

CR-SPLITDivision of a CCD exposure into shorter exposures to be used for cosmic ray rejection.

CS: Contact Scientist for a HST proposal.

CTE: Charge transfer efficiency.

CVZ: Continuous viewing zone.

DN: Data number.

DQ: Data Quality

DSI: Dual-Slope Integrator.

DSS: Digital Sky Survey.

ETC: Exposure Time Calculator. ETCs are Web-based tools which can be accessed through the ACS webpages.

FGS: Fine Guidance Sensors.

FOS: Faint Object Spectrograph.

FOV: Field of view.

FUV: Far ultraviolet (~912 to 2000 Å).

FWHM: Full width at half maximum.

GALEX: Galaxy Evolution Explorer.

GHRS: Goddard High-Resolution Spectrograph.

GO: General Observer.

GSC: Guide Star Catalog.

GSC2: Guide Star Catalog II.

Help DeskSystem for getting help on HST-related topics are and

HRC: High Resolution Channel.

HST: Hubble Space Telescope.

IDT: Investigation Definition Team.

IR: Infrared.

IRAF: Image Reduction and Analysis Facility. The environment in which ­STSDAS operates.

ISR: Instrument Science Report

IUE: International Ultraviolet Explorer Satellite

K: Degree Kelvin.

LED: Light-emitting diode

L-flats: Low Frequency Variations Flats.

LMC: Large Magellanic Cloud.

LVPS-R: replacement Low Voltage Power Supply.

MAMA: Multi-Anode Microchannel Array.

MAST: Mikulski Archive for STScI Telescopes.

MCP: Microchannel Plate.

MNRAS: Monthly Notices of the Royal Astronomical Society

MPP: Multi Pinned Phased, a CCD mode that reduces dark current rate.

NICMOS: Near-Infrared Camera and Multi-Object Spectrograph.

NIR: Near infrared.

NUV: Near ultraviolet (~2000 to 4000 Å).

OTA: Optical Telescope Assembly.

PASP: Publications of the Astronomical Society of the Pacific.

PC: Program Coordinator.

Phase I proposal: A proposal for observing time on HST.

Phase II program: An approved HST program; includes precise detail of how program is to be executed.

P-flats: pixel-to-pixel high-frequency flats.

POS TARG: POSition TARGet is used to move the sky in the FOV of the camera.

PRF: Pixel Response Function.

Proc. SPIE: Proceedings of the SPIE, an international professional society for optics and photonics technology.

PSF: Point-spread function.

PyRAF: version of IRAF implemented in the Python language.

pysynphot: Python package for synthetic photometry.

QE: Quantum Efficiency.

QEH: Quantum Efficiency Hysteresis.

Quadrant: Section of detector that is read out by an amplifier. For WFC, there are 4 amplifiers, two for each detector, so each amplifier reads one 2048 x 2048 pixel quadrant.

reference file: data file containing ACS parameters or calibration information which is used by the calibration pipeline.

rms: Root mean square.

RQE: Responsive Quantum Efficiency.

SAASouth Atlantic anomaly.

SBC: Solar-Blind Channel.

SDSS: Sloan Digital Sky Survey.

SIDECAR: System Image, Digitizing, Enhancing, Controlling, And Retrieving.

SITe: Scientific Image Technologies; company that designed the ACS CCDs.

SM3B: Servicing Mission 3b to HST in March 2002.

SM4: Servicing Mission 4 to HST in May 2009.

SMOV: Servicing Mission Observatory Verification.

S/N: signal-to-noise ratio.

SNAPSHOT: Short exposures taken during unused blocks of telescope time.

SSDR: Solid state data recorders.

ST-ECF: Space Telescope European Coordinating Facility.

STIS: Space Telescope Imaging Spectrograph.

STScI: Space Telescope Science Institute.

TAC: Telescope Allocation Committee.

TEC: Thermal Electric Coolers.

Tiny Tim: PSF simulation software developed by John Krist & Richard Hook.

TIR: Technical Instrument Report.

UV: Ultraviolet.

UVIS: Ultraviolet and Visual (CCD channel of WFC3).

VEGAMAG: A magnitude system in which Vega has an apparent magnitude of 0 at all wavelengths

WFC: Wide-Field Channel.

WFC3: Wide Field Camera 3, new instrument installed during SM4.

WFPC2: Wide Field Planetary Camera-2. Replacement for WF/PC installed during first servicing mission of December 1993.