Neil Gehrels Swift Observatory
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.
| Instruments | Energy Range | Field of View | Localization |
|---|---|---|---|
| Burst Alert Telescope (BAT) | 15-350 keV | 2 ster | ≤ 1–3′ radius (statistical, 90%) |
| X-ray Telescope (XRT) | 0.3–10 keV | 23.6′×23.6′ | 1–3″ |
| Ultraviolet/Optical Telescope UVOT | 170–650 nm | 17′×17′ | <1″ |
GCN Notice Types in GCN Classic and GCN Classic Over Kafka: Detailed Descriptions and Examples
| Type | Typical Latency Since Burst | Location Precision | Description |
|---|---|---|---|
| Flight Generated: | |||
SWIFT_BAT_GRB_ALERT | ~7 seconds | N/A | First Notice, Timestamp Alert |
SWIFT_BAT_QL_POS | 13–30 seconds | 1–3′ | QuickLook Position Notice (subset of BAT_POS info) |
SWIFT_BAT_GRB_POS_ACK | 13–30 seconds | 1–3′ | First Position Notice, the BAT Position |
SWIFT_BAT_GRB_POS_NACK | 30–60 seconds | N/A | Only if no position was found |
SWIFT_BAT_SUB_THRESHOLD | 13–30 seconds | 1–4′ | Sub-threshold triggers (Position) |
SWIFT_BAT_GRB_LC | ~220 seconds | 1–3′ | Lightcurve (also has the position) |
SWIFT_FOM_OBS | 14–41 seconds | 1–3′ | FOM decision: Observe or Not |
SWIFT_SC_SLEW | 14–41 seconds | 1–3′ | Spacecraft decision: Slew or Not |
SWIFT_XRT_POSITION | 30–80 seconds | <7″ | XRT afterglow location |
SWIFT_XRT_CENTROID | 30–80 seconds | N/A | Could not find an XRT afterglow location |
SWIFT_XRT_IMAGE | 31–81 seconds | <7″ | 2′×2′ FOV (5-30 s integration) |
SWIFT_XRT_SPECTRUM | 40–81 seconds | N/A | Spectrum (few-to-100 s integration) |
SWIFT_XRT_LC | 141–910 seconds | N/A | The x-ray lightcurve (106–826 s) |
SWIFT_UVOT_FCHART | ~260 seconds | N/A | Thresholded pixel clusters |
SWIFT_UVOT_DBURST | ~320 seconds | N/A | All pixels from an 80×80 pixel subarray |
SWIFT_UVOT_POS | 1–3 hours | <2″ | UVOT afterglow location (Gnd-generated only) |
SWIFT_UVOT_POS_NACK | 1–3 hours | N/A | Could not find an UVOT afterglow location |
| Ground Processed: | |||
SWIFT_BAT_GRB_LC_PROC | ~225 seconds | 1–3′ | Lightcurve (also has the position) |
SWIFT_XRT_IMAGE_PROC | 40–70 seconds | <6″ | 2′×2′ FOV (~10 s integration) |
SWIFT_XRT_SPECTRUM_PROC | 50–90 seconds | N/A | The spectrum from that integration (~10 s) |
SWIFT_UVOT_FCHART_PROC | ~280 seconds | N/A | Thresholded pixel clusters |
SWIFT_UVOT_DBURST_PROC | ~340 seconds | N/A | All pixels from an 80×80 pixel subarray |
| Special: | |||
SWIFT_BAT_SLEW_POS | 1–6 hours | 1–7′ | Bursts & Transient found in the slew data (BATSS) |
SWIFT_BAT_MONITOR | 1–12 hours | 1–7′ | Flares from known sources |
SWIFT_BAT_SUBSUB | 1–12 hours | 1–7′ | Sub-Sub-Threshold blips in all image produced on-board |
SWIFT_BAT_KNOWN_SRC | 1–12 hours | 1–7′ | 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
| Type | Contents | Latency |
|---|---|---|
| Alert | Detection of a burst | 5 min - 4 hours |
| Localization | Arcminute position or HEALPix map | 30 min - 5 hours |
| Retraction | Retraction of an alert or localization | 4 hours - 1 day |
Common GCN Circular Types:
| Type | Latency | Example |
|---|---|---|
| Swift identification of a GRB | 30 minutes | GRB 210517A |
| XRT enhanced GRB position | hours | GRB 210517A |
| UVOT follow-up of a GRB | hours | GRB 210517A |
| BAT refined analysis of a GRB | 12 hours | GRB 210517A |
| XRT refined analysis of a GRB | 12 hours | GRB 210517A |
| BAT GUANO localization of a GRB | 6 hours | GRB 210827A |
| BAT GUANO recovery of a GRB | 6 hours | GRB 211105A |
| Swift ToO observations | 12 hours | GRB 210704A |
| Swift BAT observations of a GW trigger | 12 hours | LIGO/Virgo S200114f |
| Swift tiling of a GW trigger | 1 day | LIGO/Virgo S200114f |
Annual Trigger Rates:
| Instrument | Long GRBs | Short GRBs | Description |
|---|---|---|---|
| BAT | 70–80 | 7–9 | On-board trigger rate |
| XRT | 60–65 | 6–8 | XRT follow-up detections |
| UVOT | 20–25 | 0–1 | UVOT follow-up detections |
| BAT | 8–10 | 2–4 | GUANO 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.