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Introducing Einstein Probe, Astro Flavored Markdown, and Notices Schema v4.0.0. See news and announcements

Neil Gehrels Swift Observatory

Swift Observatory logo

Launch Date: November 20, 2004

Extended Mission Lifetime: 2025+ (Pending NASA Senior Review)

End of Operations: No specific requirement (no consumables, no significant degradation)

Data Archive: NASA

Swift is a MidEx class mission operated by NASA in partnership with agencies in Italy and the United Kingdom. BAT autonomously detects gamma-ray transients, and Swift autonomously begins a sequence of follow-up observations with XRT and UVOT. All three instruments provide alerts to GCN autonomously upon the detection of transients.

InstrumentsEnergy RangeField of ViewLocalization
Burst Alert Telescope (BAT)15-350 keV2 ster≤ 1–3′ radius (statistical, 90%)
X-ray Telescope (XRT)0.3–10 keV23.6′×23.6′1–3″
Ultraviolet/Optical Telescope UVOT170–650 nm17′×17′<1″

GCN Notice Types in GCN Classic and GCN Classic Over Kafka: Detailed Descriptions and Examples

TypeTypical Latency Since BurstLocation PrecisionDescription
Flight Generated:
SWIFT_BAT_GRB_ALERT~7 secondsN/AFirst Notice, Timestamp Alert
SWIFT_BAT_QL_POS13–30 seconds1–3′QuickLook Position Notice (subset of BAT_POS info)
SWIFT_BAT_GRB_POS_ACK13–30 seconds1–3′First Position Notice, the BAT Position
SWIFT_BAT_GRB_POS_NACK30–60 secondsN/AOnly if no position was found
SWIFT_BAT_SUB_THRESHOLD13–30 seconds1–4′Sub-threshold triggers (Position)
SWIFT_BAT_GRB_LC~220 seconds1–3′Lightcurve (also has the position)
SWIFT_FOM_OBS14–41 seconds1–3′FOM decision: Observe or Not
SWIFT_SC_SLEW14–41 seconds1–3′Spacecraft decision: Slew or Not
SWIFT_XRT_POSITION30–80 seconds<7″XRT afterglow location
SWIFT_XRT_CENTROID30–80 secondsN/ACould not find an XRT afterglow location
SWIFT_XRT_IMAGE31–81 seconds<7″2′×2′ FOV (5-30 s integration)
SWIFT_XRT_SPECTRUM40–81 secondsN/ASpectrum (few-to-100 s integration)
SWIFT_XRT_LC141–910 secondsN/AThe x-ray lightcurve (106–826 s)
SWIFT_UVOT_FCHART~260 secondsN/AThresholded pixel clusters
SWIFT_UVOT_DBURST~320 secondsN/AAll pixels from an 80×80 pixel subarray
SWIFT_UVOT_POS1–3 hours<2″UVOT afterglow location (Gnd-generated only)
SWIFT_UVOT_POS_NACK1–3 hoursN/ACould not find an UVOT afterglow location
Ground Processed:
SWIFT_BAT_GRB_LC_PROC~225 seconds1–3′Lightcurve (also has the position)
SWIFT_XRT_IMAGE_PROC40–70 seconds<6″2′×2′ FOV (~10 s integration)
SWIFT_XRT_SPECTRUM_PROC50–90 secondsN/AThe spectrum from that integration (~10 s)
SWIFT_UVOT_FCHART_PROC~280 secondsN/AThresholded pixel clusters
SWIFT_UVOT_DBURST_PROC~340 secondsN/AAll pixels from an 80×80 pixel subarray
SWIFT_BAT_SLEW_POS1–6 hours1–7′Bursts & Transient found in the slew data (BATSS)
SWIFT_BAT_MONITOR1–12 hours1–7′Flares from known sources
SWIFT_BAT_SUBSUB1–12 hours1–7′Sub-Sub-Threshold blips in all image produced on-board
SWIFT_BAT_KNOWN_SRC1–12 hours1–7′Peaks of known-sources found in all image produced on-board

JSON-Serialized GCN Notice Types in GCN Kafka

The GUANO system distributes alerts and localizations for sub-threshold detections of gamma-ray transients around the times of other triggers. These are bursts that did not result in any of the automatic GCN Notices described above, and is the result of analysis after the data arrives on the ground.

These notices are published on the GCN Kafka topic gcn.notices.swift.bat.guano.

The GCN schema and example JSON message files are available to use. See our Schema Browser for more information on the properties defined in the schema.

Detailed Description and Examples

AlertDetection of a burst5 min - 4 hours
LocalizationArcminute position or HEALPix map30 min - 5 hours
RetractionRetraction of an alert or localization4 hours - 1 day

Common GCN Circular Types:

Swift identification of a GRB30 minutesGRB 210517A
XRT enhanced GRB positionhoursGRB 210517A
UVOT follow-up of a GRBhoursGRB 210517A
BAT refined analysis of a GRB12 hoursGRB 210517A
XRT refined analysis of a GRB12 hoursGRB 210517A
BAT GUANO localization of a GRB6 hoursGRB 210827A
BAT GUANO recovery of a GRB6 hoursGRB 211105A
Swift ToO observations12 hoursGRB 210704A
Swift BAT observations of a GW trigger12 hoursLIGO/Virgo S200114f
Swift tiling of a GW trigger1 dayLIGO/Virgo S200114f

Annual Trigger Rates:

InstrumentLong GRBsShort GRBsDescription
BAT70–807–9On-board trigger rate
XRT60–656–8XRT follow-up detections
UVOT20–250–1UVOT follow-up detections
BAT8–102–4GUANO arcminute recovery rate

Trigger Rates determined from cataloged information including the Swift-BAT Third GRB Catalog and the Swift GRB Lookup Table. GUANO results are from the online summary table.

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