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Glossary & Acronyms

Acronyms and Glossary of terms used in the LSST project, Data Management, and Astronomy

Inclusion criterion: has to be in some way LSST-specific, not general terms used in astronomy. 

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Glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Accronyms

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


Glossary

Alert

Refers to the structured communication that is issued rapidly via the internet to the community during the Alert Production. It is intended to characterize the detection of one or more sources that are new, or have changed significantly in position or brightness, relative to the applicable image template.

Archive Center

Part of the LSST Data Management System, an archive center is a data center that hosts the LSST Archive, which includes released science data and metadata, observatory and engineering data, and supporting software such as the LSST Software Stack. 

AURA

The Association of Universities for Research in Astronomy (AURA) is a consortium of 44 US institutions and 4 international affiliates that operates world-class astronomical observatories. LSST construction project is an operating center under AURA management.

Auxiliary telescope (AuxTel)

LSST’s 1.2-meter Auxiliary Telescope will measure atmospheric transmission and will be used to calibrate LSST images.

Cadence

The sequence of pointings, visit exposures, and exposure durations performed over the course of a survey. 

Catsim

The catalog simulator simulates the properties and distributions of stars, galaxies, and asteroids that LSST expects to observe.

Co-add image

An image that is the combination of multiple input images. The inputs are aligned to a common projection and pixel grid, corrected to the same photometric scale and zero-point, with bad pixels and artifacts rejected. (Image PSFs may also be matched prior to co-addition.) Co-Add images have had non-astrophysical background removed. 

ComCam

The commissioning camera is a single-raft, 9-CCD camera that will be installed in LSST during commissioning, before the final camera is ready.

Corner Raft

Rafts in the four corners of the focal plane contain special CCsD, used for guiding and focusing.

Data Access Center (DAC)

DACs will provide users with LSST data rights access to LSST data products.

Deblend

Deblending is the act of inferring the intensity profiles of two or more overlapping sources from a single footprint within an image. Source footprints may overlap in crowded fields, or where the astrophysical phenomena intrinsically overlap (e.g., a supernova embedded in an external galaxy), or by spatial co-incidence (e.g., an asteroid passing in front of a star). Deblending may make use of a priori information from images (e.g., deep Co-Adds or visit images obtained in good seeing), from catalogs, or from models. 

DIA Object

A DIA object (often concatenated as DIAObject) is one that has been detected during difference image processing. It is distinguished from a regular object in that its brightness varies in time. 

DIA Source

A DIA source (often concatenated as DIASource) is one that has been detected during difference image processing. It is distinguished from a regular source by at least one of the following properties: its uniqueness (i.e., no association to known objects); its variability in brightness; or, if it is associated with a Solar System Object, a change in coordinates. 

Difference image

Refers to the result formed from the pixel-by-pixel difference of two images of the sky, after warping to the same pixel grid and scaling to the same photometric scale. The pixels in a difference thus formed should be zero (apart from noise) except for sources that are new, or have changed in brightness or position. In the LSST context, the difference is generally taken between a visit image and template. 

Difference image processing

A pipeline that constructs differences between two images (usually a recent visit exposure and a template image) in order to detect sources that are new or that have changed brightness. The input images are transformed to a common grid, scaled to the same photometric response, and matched to the same PSF. Sources are detected above a configurable threshold on the difference image. This pipeline feeds the Alert processing. 

Eups

ExtUPS (eups for short) is the software component management system that is used for the LSST Stack. It enables a choice of which versions of components should be used for a software build, and ensures that a consistent set is chosen. See the Eups Manual for details. 

Focal plane array

A focal plane array (FPA) is the arrangement of multiple sensors in the focal plane of a camera. For LSST, the FPA is divided into an array of continguous rafts, upon which 9 science sensors are mounted 3x3. Additional engineering sensors are mounted on rafts near the periphery to support wavefront sensing and telescope guiding. 

Forced photometry

A measurement of the photometric properties of a source, or expected source, with one or more parameters held fixed. Most often this means fixing the location of the center of the brightness profile (which may be known or predicted in advance), and measuring other properties such as total brightness, shape, and orientation. 

Four main science objectives:

Also referred to as science pillars, primary science themes. They are:

  • Constraining Dark Energy & Dark Matter
  • Taking an Inventory of the Solar System
  • Exploring the Transient Optical Sky
  • Mapping the Milky Way
Galsim

GalSim is open-source software for simulating images of astronomical objects (stars, galaxies) in a variety of ways.

LSSTC

LSST Corporation, the non-profit formed to initiate the LSST Project and advance the science of astronomy and physics. It will help provide the funding of LSST in its operational phase.

LSST Software Stack

Often referred to as the LSST Stack, or just Stack, the LSST Data Management System software stack is the collection of software written by the LSST Data Management Team to process, generate, and serve LSST images, transient alerts, and catalogs. It also includes software packages upon which the DM software depends. 

Main Survey

Also referrred to as Wide Fast Deep (WFD) is the portion of the LSST survey that will cover >=18,000 square degree of sky to achieve the four main science goal of LSST

Multifit

Multi-Fit performs a simultaneous fit of multi-component source models to multiple exposures of the same region, taken at different times and in different bands.  

Opsim

The Operations Simulator (OpSim) is an application that simulates the field selection and image acquisition process of the LSST over the 10-year life of the planned survey

Phosim

The Photon Simulator (PhoSim) simulate realistic astronomical images by tracing photons through the atmosphere and a telescope and camera into pixels.

Production, Data Release

A Data Release Production (DRP) is a highly controlled episode of processing all accumulated LSST images, in which all output products are generated. This includes generating Deep Co-Adds (various types), Object catalogs, Solar System Body catalogs, and related metadata. DRPs are planned annually during the LSST survey. 

QServ

The distributed database server to be used for collecting, storing, and serving LSST Catalogs and Project metadata. 

Raft

The sensors in the LSST camera are packaged into replaceable electronic assemblies, called rafts, consisting of 9 sensors in a 3x3 mosaic. 

Source

A single detection of an astrophysical object in an image, the characteristics for which are stored in the Source Catalog of the science database. The Data Management System attempts to associate multiple source detections to single objects, which may vary in brightness or position over time. 

Template image

Single-band, deep image of the sky composed of a co-add of images from a limited range of epochs. The co-add selection may additionally limited to a limited range of airmass, seeing, or other observation attributes. An image template is used in Difference Image Processing, as a reference for single-visit exposures when detecting transient sources. 

Visit

A sequence of one or more consecutive exposures at a given position, orientation, and filter within the LSST cadence. The baseline visit for the main survey consists of two snaps of 15 s duration. 

 
 

Accronyms

ADCO  

Associate Director for Chilean Operations

AOSS 

AURA Observatory Support Services

AMCL  

AURA Management Council for LSST

ANTARES 

Arizona-NOA Temporal Analysis and Response to Events System

AURA

Associated Universities for Research in Astronomy

AURA-O  

AURA Observatory in Chile

CACS  

calibration/auxiliary control system

CA-FATCS 

NSF Cooperative Agreement Financial & Administrative Terms and Conditions

CC-IN2P3

Centre de Calcul de Institut National de Physique Nucleaire et de Physique des Particules

CCB 

Change Control Board

CCS  

camera control system

ComCam

commissioning camera

DAC

data access center

DAF

data access framework

DAQ  

data acquisition

DC   

data challenges

DDS

data distribution system

DIMM 

Differential Image Motion Monitor

DM 

Data Management

DMO 

Data Management Operations

DMOC 

Data Management Operations Chile

DMOG

Data Management Operations Group

DMOG-AS  

Data Management Operations Group – Archive Site

DMS  

Data Management System

DP   

data products

DPDD  

Data Products Definition Document

DPP

Data Products Processing

DR   

data release

DR1

first or initial data release

DRB

Data Release Board

DRP

data release processing

EDR

early data release

FEC  

front-end cage

FEE  

front-end electronics

FITS

flexible image transport system (file format)

FPA 

focal plane array/assembly

FPSL  

forced-photometry sensitivity limit

GDS

guider data system

GIS  

global interlock system

I&T 

integration and test

ICD 

interface control document

ICoD 

interface compliance document

IDA 

interface design artifact

ImSim 

image simulation

ITIL 

information technology infrastructure library

L1

Lens 1

L2

Lens 2

L3

Lens 3

L1

L2

LCA 

archive handle format for LSST camera subsystem controlled documents

LDM  

archive handle format for LSST data management subsystem controlled documents

LOP

LSST Operations Plan

LOPT  

LSST Operations Planning Team

LPM  

archive handle format for LSST project management controlled documents

LSE  

archive handle format for LSST systems engineering controlled documents

LSR 

LSST System Requirements

LSST  

Large Synoptic Survey Telescope

LSSTC  

Large Synoptic Survey Telescope Corporation

LTS  

archive handle format for LSST telescope and site controlled documents

M1

primary mirror

M2

secondary mirror

M3

tertiary mirror

MASS

multi-aperture scintillation sensor

MCM 

master control module

MIE 

Major Item of Equipment (DOE)

MOA 

memorandum of agreement

MODTRAN 

MODerate resolution TRANsmission model

MOPS  

Moving Objects Processing System – a client of PanSTARRS’ image processing pipeline

MOU 

memorandum of understanding

MREFC

Major Research Equipment and Facilities Construction

NCOIRA

National Center for Optical and Infrared Astronomy

NCSA

National Center for Supercomputing Applications

NEA 

near-Earth asteroid

NEO

near-Earth object

NOAA

National Oceanic and Atmospheric Administration

NOAO  

National Optical Astronomy Observatory

NOC  

network operating center

NPCF

National Petascale Computing Facility

NSS 

NOAO Support Services

NVO/VAO

National Virtual Observatory/Virtual Astronomical Observatory

OAB

Outreach Advisory Board

OCDD  

operations concept definition document

OCS 

observatory control system

OMB 

Office of Management and Budget

OpSim 

operations simulator

ORR

operations readiness review

OSS 

Observatory System Specifications

OTS

observatory telemetry system

PMCS  

project management control system

PMO 

project management office

PST

project science team

QSERV 

LSST Query Services

RBSE  

Research-Based Science Education (AURA/NOAO)

RCI  

raft communication interface

RCC 

raft control crate

RCI  

raft communication interface

RCM  

raft communication module

REB 

raft electronics board

RSA  

raft sensor array

RTM  

raft tower module

SAC 

Science Advisory Committee

SAPP 

Science Algorithms

SCADA

supervisory control and data acquisition

SCIDAR

scintillation detection and ranging

SDS 

science array data acquisition subsystem

SDSS 

Sloan Digital Sky Survey

SE

systems engineering

SEMP

Systems Engineering Management Plan

SO   

scientific operations

SOCh

scientific operations in Chile

SOML  

Steward Observatory Mirror Lab (University of Arizona)

SRD

Science Requirements Document

SRT 

science raft tower

SSM

subsystem manager

T&S

Telescope and Site

TACABS 

absolute time-recording accuracy (millisecond)

TACREL

internal (relative) time-recording accuracy (millisecond)

TAI  

international atomic time

TBD

to be determined

TBR 

to be resolved

TCS 

Telescope Control System

TEA  

top-end assembly

TMA  

Telescope Mount Assembly

TOWG 

Technical Operations Working Group

VO   

virtual observatory

WBS  

work breakdown structure

WFS  

wavefront sensor or wide-field survey

WFD

Wide Fast Deep: the LSST main survey

 

Financial support for LSST comes from the National Science Foundation (NSF) through Cooperative Agreement No. 1258333, the Department of Energy (DOE) Office of Science under Contract No. DE-AC02-76SF00515, and private funding raised by the LSST Corporation. The NSF-funded LSST Project Office for construction was established as an operating center under management of the Association of Universities for Research in Astronomy (AURA).  The DOE-funded effort to build the LSST camera is managed by the SLAC National Accelerator Laboratory (SLAC).
The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 to promote the progress of science. NSF supports basic research and people to create knowledge that transforms the future.   




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