The Glitchy Gamma-Ray Burst
Adam Evans (Wikimedia Commons)
Andromeda is a spiral galaxy approximately 2.5 million light-years from the Milky Way.
Andrew Cooper/W. M. Keck Observatory
March 13, 2013, marks 20 years since the W. M. Keck Observatory began taking observations of the cosmos. Located in arguably one of the most extreme and beautiful places on the planet -- atop Mauna Kea, Hawai'i, 13,803 ft (4,207 m) above sea level -- the twin Keck domes have observed everything from asteroids, planets, exoplanets to dying stars, distant galaxies and nebulae. Seen in this photograph, the Keck I and Keck II telescopes dazzle the skies with their adaptive optics lasers -- a system that helps cancel out the turbulence of the Earth's atmosphere, bringing science some of the clearest views attainable by a ground-based observatory.
To celebrate the last two decades of incredible science, Discovery News has assembled some of the most impressive imagery to come from Keck.
William Merline, SWRI / W.M. Keck Observatory
Starting very close to home, the Keck II captured this infrared image of asteroid 2005 YU55 as it flew past Earth on Nov. 8, 2011.
Larry Sromovsky (University of Wisconsin)
Deeper into the solar system, the Keck NIRC2 near-infrared camera captured this beautiful observation of the oddball Uranus on July 11-12, 2004. The planet's north pole is at 4 o'clock.
W.M Keck Observatory/NASA/JPL-G.Orton
This is a mosaic false-color image of thermal heat emission from Saturn and its rings on Feb. 4, 2004, captured by the Keck I telescope at 17.65 micron wavelengths.
Antonin Bouchez (W. M. Keck Observatory)
A nice image of Saturn with Keck I telescope with the near infrared camera (NIRC) on Nov. 6, 1998. This is a composite of images taken in Z and J bands (1.05 and 1.3 microns), with the color scaling adjusted so it looks like Saturn is supposed to look to the naked eye.
Antonin Bouchez, W.M. Keck Observatory
This is Saturn's giant moon Titan -- a composite of three infrared bands captured by the Near Infrared Camera-2 on the 10-meter Keck II telescope. It was taken by astronomer Antonin Bouchez on June 7, 2011.
W. M. Keck Observatory/SRI/New Mexico State University
Another multicolored look at Titan -- a near-infrared color composite image taken with the Keck II adaptive optics system. Titan's surface appears red, while haze layers at progressively higher altitudes in the atmosphere appear green and blue.
Mike Brown, Caltech / W.M. Keck Observatory
This image of Neptune and its largest Tritan was captured by Caltech astronomer Mike Brown in September 2011. It shows the wind-whipped clouds, thought to exceed 1,200 miles per hour along the equator.
A color composite image of Jupiter in the near infrared and its moon Io. The callout at right shows a closeup of the two red spots through a filter which looks deep in the cloud layer to see thermal radiation.
Christian Marois, NRC and Bruce Macintosh, LLNL/W. M. Keck Observatory
HR 8799: Three exoplanets orbiting a young star 140 light years away are captured using Keck Observatory's near-infrared adaptive optics. This was the first direct observation by a ground-based observatory of worlds orbiting another star (2008).
Bob Goodrich, Mike Bolte, and the ESI team
Now to the extremes -- an image of Stephan's Quintet, a small compact group of galaxies.
W.M. Keck Observatory
The Egg Nebula: This Protoplanetary nebula is reflecting light from a dying star that is shedding its outer layers in the final stages of its life.
W. M. Keck Observatory
This is WR 104, a dying star. Known as a Wolf Rayet star, this massive stellar object will end its life in the most dramatic way -- possibly as a gamma-ray burst. The spiral is caused by gases blasting from the star as it orbits with another massive star.
W. M. Keck Observatory/UCLA
Narrow-field image of the center of the Milky Way. The arrow marks the location of radio source Sge A*, a supermassive black hole at the center of our galaxy.
Dr. Mark Morris (UCLA) Keck II, Mirlen instrument
A high resolution mid-infrared picture taken of the center of our Milky Way reveals details about dust swirling into the black hole that dominates the region.
Mansi Kasliwal, Caltech and Iair Arcavi, Weizmann Institute of Science/W. M. Keck Observatory
A false-color image of a spiral galaxy in the constellation Camelopardalis.
A scintillating square-shaped nebula nestled in the vast sea of stars. Combining infrared data from the Hale Telescope at Palomar Observatory and the Keck II telescope, researchers characterized the remarkably symmetrical “Red Square” nebula.
ESA, NASA, J.-P. Kneib (Caltech/Observatoire Midi-Pyrenees) and R. Ellis (Caltech)/W. M. Keck Observatory
Galaxy cluster Abell 2218 is acting as a powerful lens, magnifying all galaxies lying behind the cluster's core. The lensed galaxies are all stretched along the shear direction, and some of them are multiply imaged.
UC Berkeley/NASA/W. M. Keck Observatory
The central starburst region of the dwarf galaxy IC 10. In this composite color image, near infrared images obtained with the Keck II telescope have been combined with visible-light images taken with NASA’s Hubble Space Telescope.
On Tuesday night, the social web was whipped into a gamma ray burst frenzy. Had neighboring galaxy Andromeda just unleashed one of the most powerful explosions known in the universe? Unfortunately, the event turned out to be a false alarm, but the excitement it generated put the efforts of one space telescope and an entire community of astronomers in the spotlight.
So what happened? The source of the excitement can be narrowed down to a software glitch and a possibly interesting X-ray brightening.
NASA’s Swift telescope orbits Earth and is constantly on the lookout for bright transient events that could be generated by a gamma ray burst (GRB). GRBs are thought to be caused by two colliding neutron stars or by a collapsing massive star. Within seconds, a GRB will generate more energy that our sun will generate in its entire lifetime.
On board Swift is an instrument called the Burst Alert Telescope, or BAT, that will detect a distant flash, alert astronomers on the ground and command Swift’s main X-ray detecting optics to slew in the direction of the flash.
Time is of the essence. The whole process is fast and a community of GRB hunters around the world are on alert around the clock. So when they were notified of a GRB on Tuesday night, all eyes were on the Swift data. But when they realized that Swift had detected the flash in the nearest large galaxy to the Milky Way, there were hopes that this could be a historic moment.
Unfortunately, according to astronomer Phil Evans of the University of Leicester and a member of the real-time Swift data analysis team, it quickly became apparent that the transient brightening wasn’t a new X-ray event in Andromeda, but a known X-ray target.
“Just because the X-ray object was already known about, and was not something likely to go GRB doesn’t mean it’s boring,” Evans said in a blog update. “If the X-ray object was much brighter than normal, then it is almost certainly what triggered the BAT and is scientifically interesting.”
The known X-ray source appears to have triggered the automated software, which alerted the community and the news quickly spread across the social web, particularly Twitter.
Evans pointed out that the Swift team never announced a GRB discovery and that this was merely a preliminary alert that required urgent attention. GRBs are rare and still poorly understood, so immediate action is needed as soon as a candidate event is detected to ensure Swift and other telescopes can quickly measure the GRB’s afterglow that rapidly fades with time.
So in these cases a choice needs to be made: “Do we assume that these preliminary results are correct and chase the object, risking wasting telescope time? Or do we wait until we know for sure, and miss observing a one-in-a-century event?” Evans asks. Obviously, when time is of the essence, you need as many people looking at that patch of sky to avoid missing astromical history unfolding.
But this was one of those times where an X-ray source fooled the BAT software into thinking a GRB was underway.
Although it is a shame that Andromeda isn’t the site of a nearby (but not too nearby) GRB, this is a fine example of science and astronomy at work where cutting edge technology is making real-time observational data available to scientists on the ground. But sometimes on the leading edge of astronomical discovery, there’s the occasional false alarm.