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.