ALMA SSR Use Case Development Glossary

2000-July-28

This glossary defines those terms (single words or phrases) concerning the ALMA Software Science Requirements (SSR) Use Case development. This is a subset of the main ALMA Glossary.
 
 

Definitions

From observing program to correlator dump:

actor Actors are used when writing use cases. Actors are a role of an entity external to the system, and can be humans, machines, or devices. Actors are divided into primary and secondary. A primary actor is one having a goal requiring the assistance of the system, while a secondary actor is one from which the system needs assistance to satisfy its goal. (see The Unified Modeling Language Reference Manual, Rumbaugh, Jacobson, and Booch, p.144)
array The entire set of all ALMA antennas.
data set All data belonging to a particular observation block including UV data, astronomical information (sources, coordinates, frequencies, etc.), raw observing and reduction scripts, system data, logs, warnings, environmental data, etc.
engineer A person who uses scientific knowledge to solve practical problems. For ALMA an engineer's principle assignment will be to build and maintain the hardware.
observation A set of integrations while the antennas complete an elemental pattern across the source, and possibly while frequency switching, nutator switching, etc.
observation descriptor The hierarchical set of parameters that define the current observation.
observer The person who prepared, or is otherwise responsible for an approved observing program. The observer is usually an astronomer.
observing block A set of scans constituting an un-interruptible scheduling unit. The scans must be scheduled contiguously (synonymous with scheduling block).
observing program A set of observing sessions to fulfil a formalized astronomy proposal with a particular scientific goal. A synonym for observing project.
observing mode A recipe for obtaining data; includes instrument configuration, operating procedure, calibration and data reduction.
observing script An observing script defines a sequence of observations. It may contain loops and conditional tests using environmental parameters, pipeline results, and current scheduling status.
observing session  A time-contiguous set of observation blocks in the same observing program.
observing tool A GUI tool used by astronomers to prepare observations, usually from a template. The observing tool will produce an observing script, or may be used to directly control the instrument.
operator The person in immediate control of the array. The operator is not usually an astronomer.
scan A set of observations with a common goal, for example, a pointing scan, a focus scan, or atmospheric amplitude calibrations scan.
scheduler queue The prioritized list of observation blocks produced by the dynamic scheduler.
subarray A group of ALMA antennas sharing a common purpose.
target The central position being tracked by the antenna?s receiver beam. Normally this is a celestial object (AKA source), but it can be anything able to be specified to the AMS.
use case A specific way of using the system by performing some part of the functionality. Each use case constitutes a complete course of action initiated by an actor, and it specifies the interaction that takes place between an actor and the system. The collected use cases specify all the existing ways of using the system.