The following terms and acronyms are used in this Handbook.
ADC : Analog to digital
ABMAG : –2.5 log ( F cm
–2
sec
-1
Hz
) – 48.60 where F
ν
is the flux from the source in erg
AB
ν
: Correction to ABMAG to account for the fact that the source spectrum is not constant in F
ν
(ABMAG=V+AB
ν
)
ACS : Advanced Camera for Surveys
APT : Astronomer’s Proposal Tool aXe : Spectroscopic Data Extraction Software
BOP: Bright Object Protection calacs: ACS calibration pipeline software
CCD : Charge Coupled Device. Solid-state, light detecting device
CMD : Color Magnitude Diagram
CP : Call for Proposals
CR : Cosmic ray
CR-SPLIT: Division of a CCD exposure into shorter exposures to be used for cosmic ray rejection
CTE: Charge transfer efficiency
CVZ : Continuous viewing zone
DN : Data number
ETC : Exposure Time Calculator. ETCs are Web-based tools which can be accessed through the ACS Web pages.
ERO: Early release observations
FGS : Fine Guidance Sensors
FOS : Faint Object Spectrograph
FOV: Field of view
FTP : File Transfer Protocol. Basic tool used to retrieve files from a remote system. Ask your system manager for information about using FTP.
FUV : Far ultraviolet (~912 to 2000 Å)
255

256 Glossary
FWHM : Full width at half maximum
GALEX : Galaxy Evolution Explorer
GHRS : Goddard High-Resolution Spectrograph
GO : General Observer
GSC: Guide Star Catalog
GSCII : Guide Star Catalog II
GTO : Guaranteed Time Observer
Help Desk: Facility for getting help on HST related topics via email.
help@stsci.edu.
HRC : High Resolution Channel
HST : Hubble Space Telescope
IDT : Investigation Definition Team
IR : Infrared
IRAF : Image Reduction and Analysis System. The environment in which
STSDAS operates.
ISR : Instrument Science Report
IUE : International Ultraviolet Explorer Satellite
K : Degree Kelvin
L-flats : Low Frequency Variations Flats
LMC : Large Magellanic Cloud
MAMA : Multi-Anode Microchannel Array
MCP : Microchannel Plate
MPP : Multi Pinned Phased, a CCD mode that reduces dark current rate
NICMOS : Near-Infrared Camera and Multi-Object Spectrograph
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
PI : Principal investigator
P-flats : pixel-to-pixel high-frequency flats
PRF : Pixel Response Function
PSF : Point-spread function.
PyRAF : version of IRAF implemented in the Python language

Glossary 257
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.
RA : Right Ascension
RAS : HST simulator used in ground tests to accurately simulate the full field OTA illumination, and is used to calibrate HST instruments.
Also know as RAS/HOMS, the Refractive Aberrated Simulator/Hubble Opto-Mechanical Simulator.
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
SAA: South Atlantic anomaly
SBC : Solar-Blind Channel
SDSS : Sloan Digital Sky Survey
SITe : Scientific Image Technologies; company that designed the ACS
CCDs
SLIM : Slitless Spectroscopy Simulator
SMOV : Servicing Mission Observatory Verification
S/N : signal-to-noise ratio
SNAPSHOT : Short exposures taken during unused blocks of telescope time.
ST-ECF : Space Telescope European Coordinating Facility
STAN: Space Telescope Analysis Newsletter
STIS : Space Telescope Imaging Spectrograph
STScI : Space Telescope Science Institute
STSDAS : Space Telescope Science Data Analysis System. The complete suite of IRAF data analysis and calibration routines used to process
HST data.
synphot: STSDAS synthetic photometry (IRAF) software package
TAC : Telescope Allocation Committee
TECs : Thermal Electric Coolers
Tiny Tim : PSF simulation software developed by John Krist &
Richard Hook
URL : Uniform resource locator. Address for WWW.
UV : Ultraviolet

258 Glossary
WFC : Wide-Field Channel
WFPC2 : Wide Field Planetary Camera-2. Replacement for WF/PC installed during first servicing mission of December 1993.
WWW : World Wide Web. Hypertext-oriented method for finding and retrieving information over the Internet.