Glossary and Acronyms

Advanced Scientific Data Format or ASDF is a file format designed as a successor to the existing FITS format for astronomical data archiving. ASDF files are composed of human-readable, text-based metadata alongside binary data. ASDF was introduced by Greenfield, Droettboom, & Bray (2015). The format and its implications for Roman are discussed in the Introduction to ASDF article. 

Roman Coronagraph Instrument is a system of masks, prisms, detectors, and self-flexing mirrors built to block out the glare from distant stars and reveal the planets in orbit around them. The Coronograph will be used to demonstrate direct imaging technologies in space.  This instrument is officially referred to as "the Coronagraph", but the older acronym, CGI, persists in some contexts. 

Calibration Reference Data System (CRDS) is a metadata-based system that maps datasets to data using mapping rules that is used by HST and JWST. The calibration pipelines for Roman observations use CRDS to identify the best reference files for the data being processed. How CRDS is used for Roman is given in the CRDS for Reference Files article.

Exposure Time Calculator (ETC) is a tool that helps users make estimates about their observations to achieve their science goals. The ETC uses telescope and instrument characterizations with input source characteristics to perform simulations to explore the signal to noise in a given exposure time or vice versa. The ETC interfaces for Roman are described in the Roman WFI Exposure Time Calculator article. 

Element Wheel Assembly (EWA) is an opto-mechnical structure that holds the optical elements in the Wide Field Instrument (WFI). It was constructed by Ball Aerospace (now BAE Systems). The WFI Design section of the WFI Imaging Mode User Guide explains how the EWA works with other components of the WFI.

The record of the data from a detector over a period of time.

See the article on the WFI MultiAccum Tables for more context.

Focal Plane Array (FPA) is the term for the collection of eighteen sensor chip assemblies (SCAs) in a three by six configuration mounted into the Mosaic Plate Assembly (MPA), the Sensor Control Electronics Assembly (SCEA), and the Analog Flex Harnesses that ties the SCAs to their corresponding Sensor Control Electronics (SCEs). The MPA and SCEA are operated at different temperatures, with the MPA being the coldest system in the WFI. The Description of WFI article provides more information.

Focal Plane System (FPS) is the term for the Focal Plane Array (FPA) connected its associated Focal Plane Electronics (FPE) through a digital flex harness and a cable pass through assembly. The FPE operates at a higher temperature than either of the temperature zones in the FPA. The Description of WFI article provides more information.

Infrared Processing and Analysis Center (IPAC) is home to the Science Support Center (SSC) for Roman. 

JDox

JDox refers to the JWST Documentation.

Level 1 (L1) data products

Level 1 refers to the uncalibrated "raw" individual exposures for each detector, which consist of raw pixel information formatted into the shape of the detector. These data contain all instrumental effects. For more context, see the Data Levels and Products article.

Level 2 (L2) data products

Level 2 refers to the "calibrated" individual exposures for each detector that are corrected for instrument artifacts. Level 2 (L2) data have appropriate astrometric and geometric distortion information attached and, with the exception of Grism and Prism data, are transformed into units that have a known scaling with flux. Data arrays with both uncertainties and the data quality are provided. For more context, see the Data Levels and Products article.

MA Table

A multi-accum table, or MATable, is an incremental list of reads, grouped into resultant frames, which is used to define how an exposure is constructed. Only the resultant frames of an exposure are downlinked to ground and constitutes a Level-1 data product. 
For more on MATables, please see the Multi-Accum Table article.

Mikulski Archive for Space Telescopes (MAST) is a NASA funded project to support and provide to the astronomical community a variety of astronomical data archives, with the primary focus on scientifically related data sets in the optical, ultraviolet, and near-infrared parts of the spectrum. MAST is located at the Space Telescope Science Institute (STScI) and will host Roman data. The Accessing WFI Data article provides more information.

An observer-defined unit consisting of a series of one or more visits in the same general area of sky, which are contiguously schedulable within a single target visibility interval (though other science or engineering visits may be interleaved into the sequence). Observations are independent of one another except for observer-specified relationships.

The high-level, event-driven timeline that controls the execution of preplanned activities onboard the Observatory. An Observation Plan (OP) consists of an ordered sequence of visits with defined activities for each visit.

A time-ordered set of observations planned for execution.

Ramp refers to a three-dimensional data array containing the signal as a function of time that was measured using non-destructive reads of a detector.

Roman APT User's Guide (RAUG) is one of the components of the User Documentation for Roman hosted in RDox. The RAUG documents functions in the Astronomer's Proposal Tool (APT) that are used to design observations for Roman.

Relative Calibration System (RCS) is a subcomponent of the Wide Field Instrument (WFI) that is the light source for internal instrument calibrations and, due to innovate design of the optical elements, can also be used with external light as well. RCS refers the original design of the hardware (Wright et al. 2020), whereas a simplified design was ultimately adopted and called the simplified Roman Calibration System (sRCS). The sRCS is described in a subsection of the WFI Description article.

This is not a standard term for Roman, and this entry is provided for clarification only. Please see the entry for "resultant" to learn more. 

A science image output generated from one or more detector reads. Roman resultants are the final result of up-the-ramp sampling for a single or multiple reads. Resultants are analogous to groups for JWST and samples for the HST WFC3/IR instrument.

romancal is a python package that contains the calibration software for the WFI instrument. For more, see the Roman STScI Data Pipelines article.

S3 is Amazon Simple Storage Service. It is a scalable and cost-effective object storage service on the AWS cloud platform. Storage containers within S3 are known as "S3 buckets".

An S3 object is a file and any metadata that describes the file and an S3 bucket is a container for such objects.

Sensor Chip Assembly (SCA) refers to the combination of a photon-sensitive mercury cadmium telluride (HgCdTe) layer that is bonded to a silicon Read-out Integrated Circuit (ROIC) and then connected to a mechanical mount with electrical connections. More information is provided in the WFI Detectors section of the Instrument Handbook. For simplicity, the term "detectors" is often used in place of SCA. In other cases, the SCA at location in the Wide Field Instrument (WFI) focal plane is called WFI## where ## is the position from 01 to 18 (see the Figure of the Detectors and Focal Plane Array). In other cases, the SCA##### will refer to the specific identifier for a specific SCA; this was most common for detector characterization work performed before the final flight complement was selected. 

A computing environment hosted by the Science Operations Center (SOC) at STScI that allows users to customize science data analysis with Roman software, user custom software, user custom data, and local access to the data archived in the cloud.

The simplified Relative Calibration System (sRCS) is a subcomponent of the Wide Field Instrument (WFI) that is the light source for internal instrument calibrations and, due to innovate design of the optical elements, can also be used with external light as well. RCS refers the original design of the hardware (Wright et al. 2020), whereas a simplified design was ultimately adopted and called the simplified Roman Calibration System (sRCS). The sRCS is described in a subsection of the WFI Description article.

Space Telescope Imaging Product Simulator (STIPS) is the is used to simulate realistic astronomical scenes for WFI similar to Level 2 (L2) data products from the exposure level pipeline. STIPS is documented in the Simulation Tools Handbook. STIPS Development Team et al. (2024) also provides detailed information on the tool.

Space Telescope Science Institute (STScI) is home to the Science Operations Center (SOC) for Roman.

Wide Field Instrument (WFI) is the 300 megapixel camera for Roman and the workhorse instrument for its the large-area data collection. A quick, but comprehensive, over view of the WFI is provided in the WFI Quick Reference article. A more detailed description is given in the the WFI Design article.

An exposure with unevenly spaced resultants is one in which: 

1. the number of reads included within a resultant is not constant over the exposure and / or
2. the sequence of reads included within a resultant is not constant over the exposure and / or
3. the number of reads skipped between resultants is not constant over the exposure. (Note: Reads are taken at a fixed time interval and non-destructively sampled.)

Uniform Resource Identifier (URI) is a unique sequence of characters that identifies an abstract or physical resource, usually, but not always, connected to the internet. URL is a specific type of URIs  which is used to locate resources on a network, for example the internet.

YAML Ain't Markup Language (YAML) is a data-serialization language that is used to store meta data in ASDF files and to input configurations for some software. For more context, refer to the WFI Data Format section of the Data Handbook.