Cosmic X-ray blast temporarily blinded NASA satellite!

By Phil Plait | July 14, 2010 10:58 am

On June 21, an intense blast of X-rays from a distant explosion slammed into NASA’s Swift satellite, and was so bright it actually temporarily blinded the observatory!

swift_grb100621ASwift is a satellite designed to look for gamma-ray bursts (GRBs); incredibly violent cosmic explosions that occur when black holes form. We think there are several ways this can happen, but the most common is when a massive star explodes at the end of its life. Forces in the star’s core can create unbelievably destructive power; essentially packing all the energy the Sun emits in its entire lifetime into two narrow beams that march across the Universe. A GRB beam can be so intense that from a hundred light years away it would blowtorch the Earth, and so bright it can be seen from clear across the observable Universe.

For once, I’m not exaggerating.

In the case of last month, the GRB was about 5 billion light years away. Called GRB 100621A (from right to left, the first GRB seen on the 21st of June in 2010), it was unusually, amazingly bright in X-rays. A lot of GRBs emit light across the spectrum, from radio to super-energetic gamma rays, but this one really overachieved in the X-ray department. Swift, normally easily able to handle the X-ray load from these explosions, was overwhelmed, and actually shut down temporarily when software detected that the cameras onboard might get damaged by the flood of light. That’s never happened before.

Artist's impression of a GRBThe burst was so bright in X-rays it put other GRBs to shame: slamming Swift with 143,000 X-ray photons per second, it was 5 times brighter than the previous record holder, and nearly 200 times as bright as a typical GRB! Weirdly, it didn’t look out of the ordinary in visible light.

So why was this burst such an overachiever? At the moment, that’s not clear. The good news is, GRBs don’t just blink on and off, they fade over time, allowing for long observations, and for other observatories to take a peek at other flavors of light (like radio, optical, and infrared). With a fleet of telescopes keeping their eyes on this prize, I expect the journals will soon see their own flood of papers being submitted to explain this extraordinary event.

I can’t help but add that for several years I worked on the Swift team, doing education and public outreach. Whenever we got an extraordinary burst like this one — and we did see a few whoppers! — everyone got very excited and the email and phone calls would fly. Neil Gehrels, the Principal Investigator of Swift (think of him as Big Daddy) was always particularly gung-ho about these, and was really supportive and willing to give time to talk to me about them. He was incredibly helpful to me when I wrote the GRB chapter of my book, and is just an all-around good guy. I’m really glad to see that Swift — one of NASA’s all-time most successful satellites — is still cranking out the hits, and the team is still jumping into action when it does.

Tip o’ the Cesium-iodide X-ray detector to my old pal Dan Vergano. Image credits: NASA/Swift/Stefan Immler, NASA

Related posts:

Anniversary of a cosmic blast
A Swift view of Andromeda
New burst vaporizes cosmic distance record
Swift bags the most distant cosmic explosion ever seen


Comments (46)

  1. So… just so I know…

    I’ve read that the difference between a GRB and a Type II supernova is that the GRB happens when a super massive star collapses directly into a black hole. Is that accurate?

  2. Cindy

    Was it a short burst or long burst GRB?

    Now I can’t get the song “Blinded by the Light” out of my head.

  3. Cz-David

    So… could there be a GRB that would fry Swifts sensors before any protection could be activated, but not strong enough to wipe out all the life on Earth

  4. Dave

    Earth has a lot of protection… any kind of short blast would fry all the satellites before it could blow off the entire atmosphere, which is about what it would take to wipe out (higher) life on the opposite side of the Earth.

  5. Allen

    I’m going to try out this doomsday hysteria thing.


    Nah, doesn’t feel right. Pretty cool and kinda scary that it overloaded Swift, but pretty cool!

  6. Interesting. From a quick run through of the data, this looks like a pretty long burst, over 200 seconds in gamma rays ( The X-rays had quite a long emission time as well (

    143,000/sec is off the charts for an X-Ray source. Chandra routinely is counting individual photons and has to wait a while for them. Even 1000 seconds after the trigger, they were still getting multiple photons per second. Impressive.

    It looks like this was an oddball primarily in the X-rays as optical afterglows have not been abnormally bright.

  7. Darrell E

    So why was this burst such an overachiever?

    One word …. er, acronym anyway.


    Trying to communicate. Or maybe manipulating the GRB to use it as a weapon against an enemy race. Sorta like the Ringworld system defense mechanism Larry Niven envisioned that lazed flares of the local star to destroy intruding objects.

    Nahhh. Would be really cool though.

  8. Rory Kent

    (Best Carl Sagan voice) 5 Billion light years away?

    But that’s almost 1/20th of the observable universe away! And it still blinded Swift…

    I’ve always believed you when you say they are powerful, Phil, but the figures you quoted never had quite that affect on me. I mean, freackin’ woah.

    I’m scared. Hold me please.

  9. You wrote a book?

    Moving right along…GRBs can be seen by us when they are pointed toward us and we have an idea of how often they occur in a manner that we spot them. But how often do they occur when they are not pointed toward us (the majority of the time I suppose).

  10. Roberta Dees

    What us your name? It is not at the top & not at the bottom

  11. slamming Swift with 143,000 X-ray photons per second

    Okay, I (and my guess is virtually everyone else here) have no way of putting that into context.

    How does that compare to, say, a typical X-ray machine? Or our Sun?

  12. Chris Winter

    According to my calculations, if this unusually bright GRB had been located 100LY from Earth, and its beam had struck us, the x-ray flux would be 3.6×10^20 photons per each area equivalent to the aperture of the Swift’s detector.

    That activity, is very roughly, 10 billion Curies over each square meter of Earth’s surface. The total yield from Chernobyl was estimated at less than 100 million Curies.

    Yes, this would be dangerous.

    See also:

    Will a Nearby Supernova Endanger Life on Earth?
    Michael Richmond
    [Last revised Dec 5, 2009]

  13. X-rays differ from gamma rays which differ from radio waves, etc. by their frequency. So when you say “X-ray photons” I get confused. What differs an X-ray photon from a gamma ray photon?

  14. Messier Tidy Upper

    Wow. :-)

    What A BLAST! 😉

    @ 2. Cindy Says:

    Now I can’t get the song “Blinded by the Light” out of my head.

    And now because you’ve mentioned it – neither can I! 😉


  15. Aaron

    @13. Mike: Same thing that differentiates between an X-ray and a gamma ray–frequency! Just as X-rays and gamma rays are both electromagnetic waves that oscillate at different frequencies, X-ray photons and gamma ray photons are both photons that have different frequencies (carry different amounts of energy).

  16. Chris

    @#9 Ken: An X1 solar flare from our sun puts out 10^-4 W/m^2. Assuming a 1 angstrom x- ray that would have 2 x 10^-15 J/photon. The detector has an area of 110 cm^2. Putting these together that would mean our sun would have 550 million photons per second reaching Swift’s detector with an X1 flare. That satellite is made for weak observations and if it looked at our sun it’d probably be blinded all the time.

  17. Chris

    @13 & @15. Technically x-rays come from inner shell electron transitions and gamma rays come from nuclear transitions. Although usually if the radiation comes from acceleration electrons (such as synchrotron radiation) it’s still considered x-ray. They are still photons and there is no way to determine the source so energies generally divide the regimes so below 120 keV are x-rays and above that is gamma rays.

  18. DrFlimmer

    @ Mike

    The energy of the photons! A gamma ray photon is the most energetic one, followed by X-rays, UV, optical, infrared, mm, radio, and so on. So X-rays are more powerful than optical photons, but gamma rays are even more powerful!
    NB: Higher energy means higher frequency / lower wavelength, since photons can be both particle and wave…. 😉

    @ PsyberDave

    Well, as guess more or less, a GRB can be pointed anywhere of course. The full solid angle is 4*pi. Since a GRB has two opposite jets, the chance that one is pointed at us is 2*1/(4*pi) = 1/(2*pi).
    In other words, assuming that we observe so and so much GRBs per day, one can multiply this number with 2*pi and one should get a rough estimate how many GRBs are blowing off in the universe per day.

  19. My friend Joanne was instrument scientist for the X-ray observatory on Swift. I’ll make sure she sees this!

  20. Tom Ames


    Doesn’t that calculation implicitly assume a detectable beam width of 1 steradian? That seems a little generous to me.

  21. Torbjörn Larsson, OM

    According to my calculations

    I’ve never gotten that. Assuming we don’t really know the jet mechanism, we don’t know the nature of the collimation of the beam. Or do we?

    Without knowing how narrow the beam is, what type of beam lobe we are observing, it would be impossible to calculate the flux equivalent at different distances I think.

  22. Adam English

    Just when you think you live on a peaceful planet in a calm universe. Science is so cool.

  23. Torbjörn Larsson, OM

    Errata to my #21 that never made the edit:

    The calculation is on an uncollimated beam (~ 100 vs 10^9 ly, so r^2 ~ 10^14; 1o^5 ph/s flux; total ~ 10^20 ph/s).

    Artistic license or not, some systems are thought to have near ideal jets.

    OT note: The research shows that stars heavier than 10 solar masses still develops the same, and still have a protoplanetary disk, with 1:1 disk to sun mass ratio. This is probably “BA” material and freaking awesome to boot!

  24. Sili

    Isn’t it just a matter of being more completely aligned with the centre of the beam? I’d imagine there’s a distribution to these things, and it should be easier to ‘hit’ somewhere along the perimeter of the beam, rather than dead centre. Presumably someone has done the stats on this.

  25. The question is what is the opening angle of the beams: how tightly focused are they. You don’t need to be right in the center to see it, but if you are too far off axis, you don’t see the gamma ray burst.

    Another question is are all types of radiation beamed equally. I admit I haven’t done as good a job keeping up with the research on these questions as I should have and would love to hear the current ideas on it.

  26. Jack Mitcham

    Reminds me of the “chargin’ mah lazor” meme. And this video:

  27. Chris Winter

    @Torbjörn Larsson, OM:

    I guess you were responding to my #12. Sure, it was a simplistic inverse-square-law calculation. But if the beam hits us (meaning Earth) dead on from 5 billion LY and gives 143,000 ph/s in a reference area, the same beam hit from 100LY should give just under 3.6 x 10^20 ph/s — unless I slipped a decimal place somewhere.

  28. Messier Tidy Upper

    In the case of last month, the GRB was about 5 billion light years away. Called GRB 100621A (from right to left, the first GRB seen on the 21st of June in 2010),

    That’s a catalogue listing not a name in my book. 😉

    5 billion years sounds familiar – that’s about the age of our solar system isn’t it? (Rounded up and approximate natch. 😉 ) So this explosion, this jet of high energy particles, happened back when our solar system was just forming and has been travelling ever since (near or at the speed of light) and has only reached us now. I find that thought pretty amazing.

    Given Einstein’s relativity and its effects on spacetime I wonder how long a time it would seem from the jet’s point of view since the supernova / hypernova that caused the GRB? (If the jet of particles could experience anything which (d’uh!) it can’t. Thought experiment in progress here.)

    @1. Chris Says:

    So… just so I know… I’ve read that the difference between a GRB and a Type II supernova is that the GRB happens when a super massive star collapses directly into a black hole. Is that accurate?

    I’m not sure. I thought Gamma Ray Bursts were produced by a couple of possible mechanisms one being the hypernova (bigger than just supernova)explosions of the most high mass stars of all such as Eta Carinae or the Pistol Star. Or perhaps I’m getting confused with something else?

    PS. Still got that “blinded by the light” song going through my head as I type this. 😉

  29. Wayne Robinson

    If it’s 5 billion light years away, wouldn’t the light be considerably red-shifted, so if it arrived as X-rays, wouldn’t the burst started as considerably more energetic gamma-rays? Was the spectrum recalculated to take into account of the red-shift?

  30. Nigel Depledge
  31. Kevin F.

    Superman needs to stop looking at Swift.

  32. So…I’m a little confused, too. The article mentions x-rays from gamma ray bursts, and several commenters have posted that x-rays differ from gamma rays by frequency…not so. While most gamma rays have energies above about 100 keV, gamma rays by definition are emitted from a nuclear interaction or decay. X-rays are emitted from outside the nucleus, generally from the transition of electrons between orbitals, or as energy given off from a change in direction of a charged particle (brehmsstrahlung, or braking radiation), the latter being the means of x-ray production by medical x-ray machines.

    Do GRBs produce x-rays or gamma rays?

  33. Robert Carnegie

    Superman doesn’t like Swift looking at him.

    You said this -was- a gamma ray burst, only it came with X-rays also… do these events happen in our near neighbourhood in spacetime, or only in the distant past and far away? What you prefer and what I do may differ. Even an event that vapourises only -one- hemisphere of the planet is, I suspect, a bad day. Think of the effect on the economy.

  34. amphiox

    I’ve read that the difference between a GRB and a Type II supernova is that the GRB happens when a super massive star collapses directly into a black hole.

    As far as I know, Type II supernova are the explosions of massive stars, the very biggest of which collapse into black holes (or blow themselves completely apart?) while the “smaller” ones produce neutron stars. GRB refers to an intense beam of high energy radiation, high in gamma rays, which can be produced by several known and/or hypothesized processes, including some of the biggest of the Type II supernovae, under certain circumstances.

    Do GRBs produce x-rays or gamma rays?

    The events that generate GRBs basically produce radiation of all wavelengths across the spectrum (including visible for example). They were so-named because when they were first observed they were mind-bogglingly and inexplicably intense in the gamma ray region of the spectrum. In other words, the name was descriptive and given before we actually knew what they were. (And since we can’t always know the source of a photon we observe, we can’t always know if it is a “true” gamma ray or an x-ray – we only know that the more powerful gamma rays are more energetic than the most energetic known X-rays, so if we observe a photon in that energy range, we know it must be a gamma ray, and below a certain energy range, we know it must be an X-ray because the nuclear processes producing gamma rays don’t produce energies that low. In the region of overlap, though, we can’t distinguish them without identifying the source process.

    This leads to the empirical argument to redefine gamma and X-rays based solely on an arbitrary energy/frequency cut-off. A name is just a name, after all. The photons themselves don’t care what we call them. (And, OT, neither does the object currently known as Pluto.)

  35. @ amphiox: Thanks! I work in a medical facility where x-ray energy routinely is higher than that of gamma ray sources…but these are artificially created x-rays. Considering only natural processes, I see how the division makes sense, and how it might lend a clue as to what might be going on.

  36. MikeS

    Phil, one point to clarify. I don’t think it’s accurate to say “Swift, normally easily able to handle the X-ray load from these explosions, was overwhelmed, and actually shut down temporarily when software detected that the cameras onboard might get damaged by the flood of light. ” That’s not an accurate reading of the article. The *software* shut down because it couldn’t believe the count rate.

    Interesting note. Swift got that bright data point while it was still settling from the initial slew. A few seconds later and it wouldn’t have been nearly as bright. Makes you wonder what we’re missing with other GRBs where we don’t get on them as fast.

  37. Gary Ansorge

    29. Wayne Robinson

    The red shift is also what I wondered about. The initially generated photons would be a considerably higher frequency than what we received. Still, a gamma ray at any frequency is still very “hot”(energetic).

    Gary 7

  38. It seems we’ve spotted this anomaly in a stroke of…

    [puts on sunglasses]

    … blinding luck.


  39. Has anyone seen the position information and visual magnitude estimates for the GRB involved?

  40. Neil S.

    @ E. Engel (39)

    @Marcum (35):
    The energy of a photon is related to the frequency by E = h*frequency. What you are thinking of is the flux of the source. It doesn’t matter how the photon is created, it will behave exactly as any other photon of the same frequency. The reason why you see your xray emitter depositing more energy than your gamma emitter is that your xray source is emitting enough photons to compensate for the energy difference in the gamma ray photons and then some.

  41. Eric

    I think it was an ETI that played with a big particle accelerator and discovered the Higgs boson. But, sadly, the same discovery made them (along with their solar system) evaporate in a cloud of very-high energy photons well before they managed to send a paper off for peer-review.

  42. Jim

    So for what I believe is the previous record holder (the one five times weaker) I tried to find some analogy that my human mind could comprehend to get a sense of the amount of energy involved.

    So I ran some rough numbers and came up with this:

    Turn off all the lights and appliances in your house, everything but a nice bright 150W light bulb. Turn off all the lights and everything in your whole city, too, and zoom out: the earth is s speck of dust outside the window, and the light bulb is our sun.

    On that scale, with the Sun putting out a nice quiet 150W, the previous record holder GRB was the Hiroshima bomb. Of course, on that scale, you’d actually have to turn out every other light on the continent: the closest lit bulb is over a thousand miles away, about the distance from Rome to Dublin, or Dallas to LA, or Hiroshima to Shanghai.

    The chances of a laser beam in Rome shot in an arbitrary direction hitting our particular speck of dust in Dublin are pretty remote, let alone this one 43000000000000000000000000000000 times farther away.

    And we’ve had that one and then this one five times larger in the last few decades. To get them that frequently against those odds … well, I guess that makes that a whole lotta stars out there.

  43. Vernon Nemitz

    Has anyone checked with the various gravitational-wave detection labs, about this event? While some gravitational waves are known/required to travel at light-speed (re: orbital decay of binary pulsars), events such as this might indicate that not all gravitational waves travel at light-speed.

  44. MikeS

    Vernon, it’s too far away to detect gravity waves.

    Engle, no visual detection was made. Only upper limits.

  45. ahmed

    great post mr plait, and the comments section was very informative!
    i cant help but compare the comments to some other sites…..a yahoo news comments section, which mostly consists of ill-informed bigoted people fighting each other :)


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