gwcelery.tasks.external_triggers module

This module listens to the GCNs from SNEWS and the Fermi, Swift, INTEGRAL, and AGILE missions. It is also responsible for carrying out tasks related to external trigger-gravitational wave coincidences, including looking for temporal coincidences, creating combined GRB-GW sky localization probability maps, and computing their joint temporal and spatio-temporal false alarm rates.

There are two GCN and two IGWN Alert message handlers in the ~gwcelery.tasks.external_triggers module:

• handle_snews_gcn() is called for each SNEWS GCN.

• handle_grb_gcn() is called for each GRB GCN such as Fermi, Swift, INTEGRAL, and AGILE MCAL.

• handle_snews_igwn_alert() is called for each SNEWS external trigger and superevent IGWN Alert.

• handle_grb_igwn_alert() is called for each Fermi and Swift external trigger and superevent IGWN Alert.

Flow Chart

Tasks

gwcelery.tasks.external_triggers.REQUIRED_LABELS_BY_TASK = {'combine': {'EXT_SKYMAP_READY', 'RAVEN_ALERT', 'SKYMAP_READY'}, 'compare': {'EM_COINC', 'EXT_SKYMAP_READY', 'SKYMAP_READY'}}

These labels should be present on an external event to consider it to be ready for sky map comparison.

gwcelery.tasks.external_triggers.FERMI_GRB_CLASS_VALUE = 4

This is the index that denote GRBs within Fermi’s Flight Position classification.

gwcelery.tasks.external_triggers.FERMI_GRB_CLASS_THRESH = 50

This values denotes the threshold of the most likely Fermi source classification, above which we will consider a Fermi Flight Position notice.

(task)gwcelery.tasks.external_triggers.handle_snews_gcn(payload)

Handles the payload from SNEWS alerts.

Prepares the alert to be sent to graceDB as ‘E’ events.

(task)gwcelery.tasks.external_triggers.handle_grb_gcn(payload)

Handles the payload from Fermi, Swift, INTEGRAL, and AGILE MCAL GCN notices.

Filters out candidates likely to be noise. Creates external events from the notice if new notice, otherwise updates existing event. Then creates and/or grabs external sky map to be uploaded to the external event.

More info for these notices can be found at: Fermi-GBM: https://gcn.gsfc.nasa.gov/fermi_grbs.html Fermi-GBM sub: https://gcn.gsfc.nasa.gov/fermi_gbm_subthresh_archive.html Swift: https://gcn.gsfc.nasa.gov/swift.html INTEGRAL: https://gcn.gsfc.nasa.gov/integral.html AGILE-MCAL: https://gcn.gsfc.nasa.gov/agile_mcal.html

(task)gwcelery.tasks.external_triggers.handle_grb_igwn_alert(alert)

Parse an IGWN alert message related to superevents/GRB external triggers and dispatch it to other tasks.

Notes

This IGWN alert message handler is triggered by creating a new superevent or GRB external trigger event, or a label associated with completeness of skymaps:

• Any new event triggers a coincidence search with gwcelery.tasks.raven.coincidence_search().

• When both a GW and GRB sky map are available during a coincidence, indicated by the labels SKYMAP_READY and EXT_SKYMAP_READY respectively on the external event, this triggers the spacetime coinc FAR to be calculated. If an alert is triggered with these same conditions, indicated by the RAVEN_ALERT label, a combined GW-GRB sky map is created using gwcelery.tasks.external_skymaps.create_combined_skymap().

(task)gwcelery.tasks.external_triggers.handle_snews_igwn_alert(alert)

Parse an IGWN alert message related to superevents/SN external triggers and dispatch it to other tasks.

Notes

This igwn_alert message handler is triggered by creating a new superevent or SN external trigger event:

• Any new event triggers a coincidence search with gwcelery.tasks.raven.coincidence_search().

(task)gwcelery.tasks.external_triggers._launch_external_detchar(event)

Proxy that evaluates object once.

Proxy will evaluate the object each time, while the promise will only evaluate it once.