Swift hunts for gamma-ray bursts, the most powerful explosions in the universe. Its Burst Alert Telescope catches a burst somewhere on the sky roughly every two to three days; the spacecraft then autonomously slews within 90 seconds to point its X-ray and ultraviolet-optical telescopes at the location for follow-up. It has detected more than 2,000 GRBs since 2004.

Last updated: 22 September 2026 · live position refreshes every 10 seconds

Gamma-Ray Burst Hunter · Live

Swift Observatory Live Tracker

NASA's Neil Gehrels Swift Observatory, launched 20 November 2004 aboard a Delta II from Cape Canaveral. The world's most prolific gamma-ray burst hunter: three co-aligned telescopes catch a burst somewhere on the sky every two to three days, then autonomously slew within 90 seconds to point X-ray and UV/optical follow-up cameras. More than 2,000 GRBs detected in 22 years.

Operational · 21y in orbit NORAD 28485 COSPAR 2004-047A Type Payload Operator NASA GSFC

Live Tracker · Real-time Position

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Sub-satellite pointwhere Swift is over Earth

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Sub-satellite point

Trail

Ground track, current orbit

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Orbital positionon Swift's 96-min LEO orbit

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Currently Passing Over

the Indian Ocean

about 90 km from Agastinuagan, India · directly above at 18.77°N, 85.67°E

Ground-track heading

East · 6.91 km/s subpoint

Latitude

18.77°N

Longitude

85.67°E

Altitude

320km

Distance

325km

Speed

7.72km/s

Phase

In sunlight

Next Equator

28m 54s

GRBs Detected

2,038

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Latest Release Mission Instruments Milestones Discoveries vs Hubble & JWST FAQ Embed

GRB Alert

Latest GRB Caught by Swift · Detected 22h 56m ago

GRB 260921A: New Burst in Leo

Swift's Burst Alert Telescope caught a bright gamma-ray burst in the constellation Leo at 09:29:12 UTC. The spacecraft autonomously slewed within 88 seconds and both XRT and UVOT confirmed a bright X-ray and optical afterglow. Duration analysis is still in progress. Global follow-up is under way.

View the alert circular →

Updates on every burst detection · typically every 2, 3 days

The Mission

The Most Prolific GRB Hunter Ever Flown

Swift is a rapid-response gamma-ray burst observatory. Its Burst Alert Telescope stares at a quarter of the sky at all times; when it catches a GRB, the spacecraft autonomously slews the whole observatory within 90 seconds to point X-ray and UV/optical instruments at the burst location. In 22 years it has detected more than 2,000 GRBs and remains the only observatory in orbit capable of this rapid response.

Launched

20 Nov 2004

Delta II · Cape Canaveral SLC-17A

Named For

Neil Gehrels

original principal investigator

Wavebands

γ · X · UV / optical

three co-aligned telescopes

GRBs Detected

2,038

1 every 2, 3 days on average

The Instruments

Three Co-Aligned Telescopes

Swift catches gamma-ray bursts with its wide-field BAT and follows up seconds later with two narrow-field telescopes that autonomously slew to the burst location. The whole spacecraft is the pointing mount.

BAT · Burst Alert Telescope

Wide-field Detector

A 5,200-pixel coded-mask hard X-ray and gamma-ray detector covering a quarter of the sky at all times. Catches gamma-ray bursts with about 15-arcminute localisation, then commands the spacecraft to slew for follow-up within 90 seconds.

XRT · X-Ray Telescope

X-ray Imager

A focusing X-ray telescope with a 3.5-arcminute half-power radius. Refines the burst position to about 5 arcseconds within minutes of the alert, and captures the fast-fading X-ray afterglow of the GRB.

UVOT · UV / Optical Telescope

UV / Optical

A 30-cm Ritchey-Chretien telescope with six UV and optical filters. Provides the highest-resolution afterglow images and helps measure GRB redshifts, distinguishing nearby from cosmological events.

Milestones

22 Years of Rapid Response

20 Nov 2004

Launch aboard Delta II

Swift launched from Cape Canaveral SLC-17A on Delta II 7320-10C, reaching its 20.6-degree LEO orbit within an hour.

17 Dec 2004

First GRB detection

Swift caught GRB 041217, its first burst, then autonomously slewed and pointed the follow-up telescopes within 200 seconds, demonstrating the rapid-response concept.

2005

First short-GRB afterglow

Swift caught GRB 050509B, the first ever X-ray afterglow of a short gamma-ray burst, proving short bursts happen in old stellar populations, consistent with neutron star mergers.

2017

GW170817: multi-messenger astronomy

Swift followed up on the first neutron-star merger gravitational-wave detection, catching the ultraviolet counterpart within hours and confirming a whole new class of astronomical event.

2024

Commercial reboost contracted

NASA contracted a commercial partner to fly a rendezvous-and-reboost mission to raise Swift's decaying orbit. Without the boost, Swift would eventually re-enter in the 2030s.

Late 2020s

Continuing operations

Swift remains the only observatory capable of sub-minute autonomous response to gamma-ray bursts, feeding the global multi-messenger astronomy network.

The Science

What Swift Has Actually Caught

Twenty-two years of hair-trigger autonomous response has redefined what we know about the most violent moments in the universe.

2005

Short GRBs are neutron star mergers

Swift's afterglow of GRB 050509B was the first evidence that short gamma-ray bursts happen in old galaxies without star formation, ruling out collapsing massive stars and pointing to compact-object mergers.

2017

GW170817 kilonova follow-up

When LIGO caught the first gravitational-wave signal of two neutron stars merging, Swift's UVOT was among the first to catch the kilonova counterpart. It confirmed neutron-star mergers as the site of the universe's heavy elements.

2022

GRB 221009A: the brightest ever

Swift caught the brightest gamma-ray burst ever recorded, later shown to be the most energetic explosion humanity has observed. XRT and UVOT tracked the afterglow for months.

Ongoing

Comets, exoplanet transits, tidal disruptions

Beyond GRBs, Swift's wide-field UV coverage catches sun-approaching comets, extreme stellar flares, and tidal disruption events as supermassive black holes rip apart passing stars.

In Context

Swift vs Fermi, Chandra and XMM

Swift's speed is its superpower. Other X-ray and gamma-ray observatories have more area or higher resolution, but only Swift can autonomously slew to an unpredicted burst on the sky within 90 seconds.

Telescope	Waveband	Mirror	Orbit	Launched
Swift	γ / X-ray / UV-Optical	3 co-aligned (30 cm UVOT)	LEO ~335 km	Nov 2004
Fermi	Gamma-ray (30 MeV+)	LAT: 96 cm² area	LEO 550 km	Jun 2008
Chandra	X-ray (0.1, 10 keV)	1.2 m Wolter grazing	HEO 14k, 133k km	Jul 1999
XMM-Newton	X-ray (0.1, 12 keV)	3 co-aligned mirrors	HEO 6k, 100k km	Dec 1999

Long Form

Why Swift Is Still Unique 22 Years On

Gamma-ray bursts fade in seconds. To follow up a burst you need a telescope that already sees a big fraction of the sky, that can autonomously decide something interesting has happened, that can slew the whole spacecraft in tens of seconds, and that carries the follow-up instruments already aligned. Every one of those is hard. Swift is the only observatory ever built that does all four in one package.

Why the LEO orbit

Swift orbits at roughly 335 km altitude, low enough to reach easily and to stay clear of the outer Van Allen belts. The trade-off is that the orbit is decaying: atmospheric drag at this height slowly pulls Swift down. Without a boost, uncontrolled re-entry is expected before the end of this decade.

The commercial reboost

NASA has contracted a commercial rendezvous-and-reboost mission to fly to Swift and raise its orbit by hundreds of kilometres. This is the first time NASA has contracted a robotic servicing mission for a science observatory. If it works, Swift keeps flying for another decade.

What comes next

No proposed observatory matches Swift's combined wide-field alerting plus rapid slew capability. Its role in the multi-messenger astronomy network (following up gravitational-wave events, neutrino detections, and short-timescale transients) is unique. Every year Swift operates is a year of GRB and transient science that cannot happen any other way.

Swift Observatory, Frequently Asked

Where is Swift right now?

Swift is in low Earth orbit at roughly 335 km altitude, and falling, inclined 20.6 degrees to the equator. It completes one orbit every 91 minutes. Its current position updates every 10 seconds on this page.

Is Swift still operating in 2026?

Yes. Swift is fully operational in September 2026, 22 years after launch and more than 20 years past its 2-year design life. All three instruments (BAT, XRT and UVOT) continue to function, and a commercial reboost mission has been contracted to raise the decaying orbit.

When was Swift launched?

Swift was launched on 20 November 2004 aboard a Delta II rocket from Cape Canaveral Space Launch Complex 17A. It was renamed the Neil Gehrels Swift Observatory in 2018 in honour of the mission's original principal investigator.

What does Swift do?

Swift hunts for gamma-ray bursts, the most powerful explosions in the universe. Its Burst Alert Telescope catches a burst somewhere on the sky roughly every 2, 3 days; the spacecraft then autonomously slews within 90 seconds to point its X-ray and ultraviolet-optical telescopes at the location for follow-up. It has detected more than 2,000 GRBs since 2004.

What is a gamma-ray burst?

A gamma-ray burst (GRB) is a sudden, extremely intense flash of gamma-rays lasting from milliseconds to minutes. Long bursts come from the collapse of massive stars into black holes; short bursts come from neutron star mergers. Swift catches roughly one GRB every 2 to 3 days and autonomously points its follow-up instruments within 90 seconds.

What are Swift's three instruments?

Swift carries three co-aligned telescopes covering different wavebands: BAT (Burst Alert Telescope) is a wide-field gamma and hard X-ray detector that catches the initial burst; XRT (X-Ray Telescope) is a focusing X-ray telescope that follows up within seconds; UVOT (Ultra-Violet Optical Telescope) is a 30-cm optical and UV telescope for the afterglow.

Will Swift be reboosted?

Yes. NASA has contracted a commercial reboost mission to raise Swift's decaying orbit and extend the observatory's scientific life by several years. Without reboost, atmospheric drag would eventually cause an uncontrolled re-entry sometime in the 2030s.

Can I see Swift from Earth?

Swift is a small satellite at roughly 335 km altitude and generally too faint for naked-eye observation. With binoculars from a very dark site it becomes possible when the orbit takes it over you at the right sunlit angle. Our Satellite Pass Predictions tool will show any visible passes over your location.

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Last updated: 22 September 2026