ADP Aspect Data Processor
ATS Automatic Time Sequence - a set of spacecraft commands that execute at a specified time
Attenuator Two sets of aluminum disks that can be moved in front of the detectors to lower the count rate during large flares.  Attenuator state 0=both attenuators out; 1=thin in, thick out; 2=thick in, thin out; 3=both in.  Also referred to as  shutters.
Binary Microsecond 2.0^-20 seconds
Decimation Method of reducing volume of data to save space in the SSR.  Decimation level n means n out of (n+1) events below a specified decimation energy are deleted.  Front and back segments are decimated separately. 
Detector Event The recording of a photon in the detector. It has the attributes: time, a2d index, and channel.
DRM Detector Response Matrix for RHESSI spectral deconvolution.  Also referred to as SRM (Spectrometer Response Matrix).
Eventlist A list of detector events. The event list contains the background.
Filedb Database file containing a cross-reference between time intervals and the file names containing that interval.  Used for Level-0, obs summary, and other RHESSI file types.  Distributed with SSW  in the hessi dbase directory.
FITS Flexible Image Transport System.  Standard format for storing scientific data sets consisting of multi-dimensional arrays.  RHESSI uses FITS format for the Level-0 and Observing Summary files, as well as spectrum, image, and other output files.
GeD Germanium Detectors.  RHESSI has 9 segmented GeDs, one behind each RMC.
Grid Planar array of equally-spaced, X-ray-opaque slats separated by transparent slits.  Grid pitches range from 34 µm to 2.75 mm in steps of the square root of 3.
IDPU Instrument Data Processing Unit
Level-0 Raw telemetry data files.  ~15 files per day. Contain packed data and can only be interpreted with the SSW RHESSI software.
MOC Mission Operations Center at SSL, Berkeley
Observing Summary Daily files containing pre-binned data (from the Level-0 files) for quick access.
OSPEX An object-oriented spectral analysis package.  RHESSI spectra and imagecube, MESSENGER, SOXS, and XSM data input are implemented as of October 2008.
PLOTMAN Interactive plot package for images, spectra, time plots and spectrograms.
PMTRAS PhotoMultiplier Tube Roll Aspect System
QLP Quick Look Product
RAS Roll Angle System
RHESSI Reuven Ramaty High Energy Solar Spectroscopic Imager launched in February 2002.
RMC Rotating Modulation Collimator - a pair of widely separated grids mounted on a rotating spacecraft.  RHESSI has nine RMCs in front of a spectrometer with nine GeDs.
SAS Solar Aspect System
SHOW_SYNOP A data integration tool allowing selection and display of observations from numerous instruments.
SRM Spectrometer Response Matrix for RHESSI spectral deconvolution.  Also referred to as DRM (Detector Response Matrix).
SSR Solid State Recorder on board RHESSI.  Data are recorded on the SSR and dumped to ground-based computer during passes over ground stations.
Subcollimator A pair of identical pitch co-aligned grids separated by ~1.5m
TMS Twist Monitoring System - used to align the grid pair in the X-ray collimator
Tohban On-duty scientist monitoring daily spacecraft operations from the science perspective.

General Solar Physics / Computer Terms

CHIANTI Package consisting of an atomic database and IDL routines for analyzing the spectra from astrophysical plasmas.
CLI Command Line Interface
CME Coronal Mass Ejection
CoSec Collaborative Sun Earth Connector - an effort underway at the Lockheed Martin Solar and Astrophysics Lab to enable the integration and coordination of data analysis tasks across disparate data sources
DEM Differential Emission Measure
EGSO European Grid of Solar Observations
ETHZ Eidgenössische Technische Hochschule (Zentrum) in Zurich, Switzerland
FAQ Frequently Asked Questions
FHNW Fachhochschule Nordwestschweiz, University of Applied Sciences Northwestern Switzerland
GB Gigabytes
GDL GNU Data Language.  A freeware open-source alternative to IDL under development. (http://gnudatalanguage.sourceforge.net)
GIF Graphics Interchange Format.  One of several standard graphics formats.
GOES Geostationary Operational Environment Satellite.  Series of satellites in operation since ~1974 providing continuous measurements of the Sun in two channels, 1.0-8.0 and 0.5-4.0 Å.
GSFC Goddard Space Flight Center in Greenbelt, Maryland, USA
GUI Graphical User Interface
HEDC HESSI European Data Center
HXR Hard X-ray
I4DS Institute of 4D Technologies in Windisch, Switzerland
IDL Interactive Data Language.  Proprietary software purchased from ITT (www.itt.com).  Almost all the RHESSI data analysis software is written in IDL.
IHY International Heliophysical Year - 2007 & 2008
JAVA An object-oriented platform-independent programming language
Jython An implementation of the Python programming language written in Java
MB Megabytes
NSSDC National Space Science Data Center.  NSSDC provides deep archiving for RHESSI data archive, as well as access to other data sets.
PINTofALE Package for Interactive Analysis of Line Emission - Markov Chain Monte Carlo differential emission measure analysis package (Kashyap & Drake, 2000)
PNG Portable Network Graphics.  One of several standard graphics formats.
QLP Quick Look Product
RHESSI Reuven Ramaty High Energy Solar Spectroscopic Imager, launched February 5, 2002.
SAA South Atlantic Anomaly
SDAC Solar Data Analysis Center at GSFC.  Hosts SSW software, data repository for SOHO, TRACE and other solar missions, and science support staff.
SDO Solar Dynamics Observatory, launched February 11, 2010
SEP Solar Energetic Particles Event
SHOW_SYNOP A data integration tool allowing selection and display of observations from numerous instruments.
SOHO Solar & Heliospheric Observatory, launched December 2, 1995
SPASE Space Physics Archive Search and Extract.  Standard protocol under development for searching and retrieving data from VxOs.
SSL Space Sciences Lab at the University of California, Berkeley
SSW Solar SoftWare.  A collection of general and instrument-specific IDL routines for solar data analysis.  The SSW archive is hosted at the SDAC, and is freely available for download and automatic updates to local computers.  RHESSI software is distributed through SSW.
STEREO Solar Terrestrial Relations Observatory - twin spacecraft launched October 25, 2006
SXR Soft X-ray
TB Terabytes
TGF Terrestrial Gamm-ray Flashes
UTPLOT An collection of IDL routines that provide instrument-independent display utility for time-series data.
VCn Virtual Channel n
VSO Virtual Solar Observatory
VxO Generic term for any Heliophysics virtual observatory, including the EGSO, the VHO, the VIO, the VSO, the VSPO, and the VSTO
WCS World Coordinate System - standards for defining the relationship between pixel coordinates in an image and sky coordinates.