Chandra X-Ray Observatory
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Last modified: 19 May 2015

Chandra/CIAO Dictionary


Chandra and CIAO use a number of specialized terms, some of which are common in X-ray astronomy data analysis, but not used elsewhere, and some of which are specific to CIAO.

Here we provide a dictionary of these terms. We have provided links to more information in the CIAO website, on the CXC site in general, and in external webpages as appropriate. Help on the CIAO tools is available from the ahelp documentation page.



A
ACIS Background
ACIS: Advanced Camera for Imaging and Spectroscopy
ADU
Afterglow
Alternating Exposure Mode
APEC: Astrophysical Plasma Emission Code
APED: Astrophysical Plasma Emission Database
AREASCAL
ARF: Auxiliary Response File
asol
Aspect / Aspect Solution
Aspect Histogram
ATOMDB: Atomic Database
B
BACKSCAL
Bad Pixels
BI: Backside Illuminated
C
CALDB: Calibration Database
Chandra
ChaRT: The Chandra Ray Tracer
ChIPS: Chandra Image and Plotting System
CIAO: Chandra Interactive Analysis of Observations
Continuous Clocking (CC)-mode for ACIS
Coordinates
CP: Custom Processing
CSC: Chandra Source Catalog
CTI: Charge Transfer Inefficiency
CXC: Chandra X-ray Center
D
Dead Time
Dither
DM: Data Model
ds9
DTCOR
DTF
DTF: Data Text Format
DTF: the HRC Dead-Time Factor file
E
Effective Area
Energy
EPHIN: Electron Proton Helium Instrument
Event
evt
EXPOSURE and EXPOSURn
Exposure Maps
EXPTIME
F
FEF: FITS Embedded Function
FI: Frontside Illuminated
FITS: Flexible Image Transport System
FLSHTIME
flt
FOV: Field of View
FP_TEMP
G
Gain
Grade (Event Grade)
GTI: Good Time Interval
GUI
H
Hardness Ratio
HETG: High Energy Transmission Grating
HRC: High Resolution Camera
HRMA: High Resolution Mirror Assembly
I
img
Instrument Maps
Interleaved Mode
ISIS
L
LETG: Low Energy Transmission Grating
LIVTIMEn and LIVETIME
LSF: Line Spread Function
M
Marx
Mask File
MSC coordinate system: Theta and Phi
mtl / MTL: Mission Time Line
O
OBC: On-Board Computer
OBI: Observation Interval
Observation Times
ObsID: Observation Id
OGIP: Office for Guest Investigator Programs
OIF: Observation Index File
ONTIME and ONTIMEn
osol
P
PCAD: Pointing Control and Aspect Determination
PHA keywords
PHA: Pulse Height Amplitude
PI: Pulse Invariant
Pileup
Pitch
Pixlib
Platform
Prism
PSF: Point Spread Function
Python
Q
QE: Quantum Efficiency
QEU: Quantum Efficiency Uniformity
R
Regions
Repro, reprocessing, and reprocessed
RMF: Redistribution Matrix File
S
ACIS Sub-Pixel Event Repositioning
SDP: Standard Data Processing
Sherpa
SIM: Science Instrument Module
src
Stacks
Status Bits
Streak Events
Subspace / Data Subspace
T
TCD: Transforms, Convolutions and Deconvolutions
tg_part
TIMEDEL
V
V&V: Verification and Validation
Virtual Columns
VTP: Voronoi Tessalation and Percolation
W
WCS: World Coordinate System
WMAP: Weight Map
X
X-rays
Y
Yaw
Z
z
Zeroth Order

Last modified: 19 May 2015
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The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA.   Email:   cxchelp@head.cfa.harvard.edu Smithsonian Institution, Copyright © 1998-2017. All rights reserved.