Brilliant GRB Blast with an Amateur Twist

The gamma-ray burst GRB 130427A erupted on April 27th with record-setting power. That made it an easy target for two of NASA's orbiting observatories, major ground-based telescopes, and even one lucky backyard observer. It reached visual magnitude 7.4.

Over the past four decades, orbiting observatories have recorded thousands of gamma-ray bursts (GRBs) coming from the depths of space. The lion's share of those have been snared by NASA's Swift, launched in 2004; and Fermi Gamma-ray Space Telescope, launched in 2008.

Brilliant gamma-ray burst
This animation compares the gamma-ray sky's appearance in two 3-hour-long exposures taken before and during the eruption of GRB 130427A on April 27, 2013. Fermi's Large Area Telescope recorded gamma rays with energies above 100 million electron volts (MeV). Click here for a larger view.
NASA / DOE / Fermi LAT Collaboration
But one that erupted at 7:47 Universal Time on April 27th turned out to be a record-setting blast. "We have waited a long time for a gamma-ray burst this shockingly, eye-wateringly bright," notes Julie McEnery, Fermi's project scientist, in a NASA press release. One of the blast's gamma rays had an energy at least 35 billion times that of a visible-light photon.

Moreover, this GRB, designated 130427A, lasted for hours — easily long enough for numerous ground-based telescopes to swing around to watch at visible-light and infrared wavelengths. Its location, in northeastern Leo, was right ascension 11h 32m 33s, declination +27° 41′ 56″.

Not many GRBs become bright enough in visible light to be within range of amateur observers. But this one was, and it caught the attention of Patrick Wiggins, who just happened to be awake — and imaging the night sky with his 14-inch telescope in Tooele, Utah. Wiggins was in the middle of snack break when notice arrived about Swift's detection. "I figured I was too late to catch anything, but I was currently working a spot on the sky just a few degrees from the predicted location," Wiggins told me via email, "so I slewed over and made a quick 60-second exposure."

Amateur record of GRB 130427A
Utah amateur Patrick Wiggins captured an image of GRB 130427A (upper panel) in the wee hours of April 27, 2013, despite interference from a nearly full Moon. He kept snapping away, as the blast dimmed in magnitude from 13.2 to 15.7 over the next three hours (lower panel).
Patrick Wiggins
There, clearly evident in the middle of his image, was a 13th-magnitude dot — too bright to be a GRB, Wiggins thought. So he slewed over a bit and took another image — and there it was again. He kept recording throughout the night, finally shutting down as dawn approached. At right are one of his images (made hazy by strong moonlight) and the light curve he derived. "It was my first GRB detection," exults Wiggins. "That it happened on my birthday made it even more special to me."

And that was just the afterglow. Three RAPTOR all-sky monitors recorded an optical counterpart at magnitude 7.4, 50 seconds before the Swift satellite trigger. Within a minute the optical glow was fainter than magnitude 10. Several other robotic telescopes were pointing to the spot within minutes; they caught the afterglow at about 11th magnitude. This compares to the visible-light record holder GRB 080319B, which reached magnitude 5.3 in 2008.

Gamma-ray bursts are typically short or long. Astronomers think that the latter type, which usually last no longer than a minute or so, herald the death of a supermassive star. The collapse of the star's core triggers jets of relativistic matter so powerful that they bore outward through the star and into the surrounding space. Interactions with shells of gas previously shed by the dying star creates dazzling outbursts of radiation — the most luminous explosions known.

GRB 130427A appeared so bright because it was relatively nearby, "just" 3.6 billion light-years away. This proximity ranks among the 5% closest GRBs recorded to date, and it gives observers hope that they'll be able to spot the star's shattered remains in the days and weeks ahead.

Ironically, gamma-ray scientists from around the world had just wrapped up a weeklong meeting to discuss their latest findings when the brilliant blast appeared.

15 thoughts on “Brilliant GRB Blast with an Amateur Twist

  1. Ag

    Are we looking at something that occurred some time ago given that we are 3bn light years distant? How far back in time are we seeing this?

  2. Ag

    Thanks for replying… probably a dumb question, but surely with the powerful telescopes being used we are seeing light that is closer to the event therefore it is more recent than 3 bn years…?

  3. Mike W. Herberich

    As far as I understand it, light always travels more or less at the same speed ("c", in vacuum). Therefore it would take light approximately 3.6 billion years to cover the distance of 3.6 billion "light years", which unit (of distance) was expressly dubbed and defined that way. Whether we’re looking at it with or without powerful scopes does not influence that. What do you mean exactly by "light that is closer to the event", Ag? If any (light) event were more recent than 3.6 billion years, it also were less distant than 3.6 billion light years away, by the same amount. Is what I’m saying clearing it up or rather confusing it more? Elaborate on your exact question a bit, Ag, please. Maybe we’d get to the ground of things that way.

  4. Tony Flanders

    Ag said "surely with the powerful telescopes being used we are seeing light that is closer to the event therefore it is more recent than 3 bn years." But the power of our telescopes is irrelevant; nobody can see light that isn’t here. When the GRB went off 3.6 billion years ago, it created a bubble of light that expanded outward from its source at a rate of one light-year per year. Two weeks ago this bubble of light swept past Earth, and we could see the flash. Now the bubble is two light-weeks bigger, the light from the GRB has passed on beyond Earth, and we can no longer see it.

  5. Bruce

    Ag, if Mike and/or Tony hadn’t answered myself or someone else would have. S&T’s newsblog in a way is like an informal classroom that anyone can sign up for and ask questions. Asking questions benefits both those who ask and those who provide answers, because to give a good answer (as both Mike and Tony have) you have to think about how best to explain the subject. Fear of looking dumb stifles some from asking questions, but not asking perpetuates ignorance. Welcome to class Ag.

  6. Ag

    Ok, so if the "bubble of light" has actually reached us then I understand. I thought that since what we were seeing was through telescopes, it meant the edge of the "bubble" is still distant i.e. closer to the event, and therefore what we are seeing is less than 3.6 bn light years away. Thank you for setting me right – obviously I need a lot more astronomy education.!

  7. Brad

    Light from any source (lightbulb, GRB) is made up of photons. Think of the photons as raindrops falling toward the ground from a set hight (the distance of the light source). If there was no air resistance, those raindrops would all fall at the same speed. The same is true of photons. If you put a dish on the ground to collect the rain, it takes the same amount of time for a raindrop to travel from the spot in the cloud it originated to that dish. This is true regardless of how large the dish is.

    Bigger/more advanced telescopes are like bigger dishes in this analogy. They collect more photons ‘or rain’, allowing for a ‘brighter’ picture, or more ‘rain drops’ to study, but they do not reduce the time the rain takes to arrive.

    I hope that analogy makes sense. The only way to see an event faster would be to be closer to it. From a technical standpoint, certain satellites may be closer than a ground based telescope, but only by tiny, tiny fractions of a second, given the tremendous speed of light (186,000 miles per second). As a side not, to give a sense of the speed, if the moon had been in the right position to be in a direct line and between this GRB than earth (instead of off to the side or behind), it still would have been seen on the moon only ~1 second sooner (if my lousy math is correct)

  8. Mike W. Herberich

    The bubble analogy of Tony’s is a very good one, used often in this context … and much more imaginative than my quirky statements. Also, Bruce, you are saying something extremely important and correct, I think, and -like always- in the most beautiful way possible. Then, Ag, you elaborated very well on your former problem; now I understand what you meant. You thought that telescopes actually take us closer to the objects observed, or the objects closer to us, simplified. It is always fascinating to experience how different our brains can work, within different persons, over different times. And, lastly, Brad, I also love your rain-dish analogy. It also directly goes to the heart of Ag’s question. All in all, this incident is a cozy little example of "swarm intelligence", I think. To make an easy thing complicated, though: considering that the bubble does not reach the stationary us from a stationary star through a stationary universe, things look different. Whereas relative velocities of the objects usually can not matter much versus the speed of light, the expanding space (over time) might (have). Adding possible (tight/ fast) orbits of objects might even change the latter.

  9. Paul Valleli

    Thanks Kelly for listing the coordinates.
    Darn ! I was trying to image RZ Leo, just 15 deg. away with a 100mm F/2 Lens- SBIG237A. The camera was mountrd on a 14-inch LX200R.
    Limiting mag was 13.0 due to faint moonglow and LP. LZ was fainter than that.
    Consolation prize was a cosmic ray hit.

  10. starffart

    I fondly remember attending a conference on high energy astrophysics at the very threshold of understanding what gamma ray bursts might be: it was at that time that a difference between short and long varieties was recognized in data, and that all of them were scattered randomly across the sky. It was positively electric. The ensuing informal discussions following the presentations were great fun – the chief hypotheses which we consider today of what could possibly produce such a terrific output of energy were worked out in principle that night. That meeting set the stage for our current theoretical understanding of GRB’s.

    After all these years its absolutely stupendous to read an account of AMATEURS having now contributed to what was back in 1998 considered to be the sole province and problem of the most sophisticated observing technology, necessarily requiring detectors in space and so on. I remember well when a member of the audience asked whether a visual observation might be obtained by amateur effort: the response was that it was "almost certainly impossible".

    They also used to say that about color astrophotography…the best examples of which are provided by the efforts of amateurs.

  11. Vince S

    SIMBAD reports a quasar near the location of this object

    SDSS J113233.55+273956.3

    but i couldn’t locate its distance.

    could it be the same object or something about the same distance?

All comments must follow the Sky & Telescope Terms of Use and will be moderated prior to posting. Please be civil in your comments. Sky & Telescope reserves the right to use the comments we receive, in whole or in part, and to use the commenter’s username, in any medium. See also the Terms of Use and Privacy Policy.


This site uses Akismet to reduce spam. Learn how your comment data is processed.