Superevents¶
Superevents are a new abstraction to unify gravitational-wave candidates from multiple search pipelines. Each superevent is intended to represent a single astrophysical event.
A superevent consists of one or more event candidates, possibly from different pipelines, that are neighbors in time. At any given time, one event belonging to the superevent is identified as the preferred event. The superevent inherits properties from the preferred event such as time, significance, localization, and classification.
The preferred event may change after a preliminary alert has been sent, but the name of the superevent will stay the same. The naming scheme is described in the alert contents section.
Selection of the Preferred Event¶
When multiple online searches report events at the same time, the preferred event is decided by applying the following rules, in order:
- Events that are detected in multiple interferometers are preferred over an events from a single interferometer.
- Events from modeled CBC searches are preferred over events from unmodeled Burst searches (see Searches for details on search pipelines).
- In the case of multiple CBC events, the event with the highest signal to noise ratio (SNR) is preferred. In the case of multiple Burst events, the event with the lowest false alarm rate (FAR) is preferred.
Note
A Preliminary GCN is automatically issued for superevents when the false alarm rate is lower than a threshold value.
Note
In case of an offline trigger upload from a pipeline, no preliminary GCN will be sent.