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Dark Energy Survey @TheDESurvey
Almost 30 years ago, Frank Valdes (left) was the first to detect the weak lensing effect of galaxy clusters in imag… https://t.co/GfoHHFeLZO

21h reply retweet favorite 21 hours ago

Dark Energy Survey @TheDESurvey
I retired to my mountain stronghold for December, and helped prepare the world’s largest camera for science verific… https://t.co/HbxEWWuqHg

Dec 12 reply retweet favorite 2 days ago

Dark Energy Survey @TheDESurvey
The weather can sometimes be unpredictable on the mountain, blizzard conditions meant no data collection, but there… https://t.co/yraZoPdLUl

Dec 11 reply retweet favorite 3 days ago

Dark Energy Survey @TheDESurvey
One of the perks of being at the top of a mountain in Chile is watching the sunset. Some optical phenomena are very… https://t.co/Og7B7q3d9P

Dec 10 reply retweet favorite 4 days ago

Dark Energy Survey @TheDESurvey
We (K. Grabowski, A. Elliott, and H. Spinka) had finished preparations for observing and were awaiting sunset. We w… https://t.co/uWoyRYzFHU

Dec 09 reply retweet favorite 5 days ago

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The Dark Energy Survey is with Gilbert Akham.
21 hours ago
Almost 30 years ago, Frank Valdes (left) was the first to detect the weak gravitational lensing effect of galaxy clusters in images taken with the Blanco Telescope. Today, we're still using Blanco, with DECam, for the most accurate and precise cluster weak lensing studies to date. #DESendofnights ... See MoreSee Less
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The Dark Energy Survey
2 days ago
December 12th, 2012 was the turning of the Mayan Baktun. I retired to my mountain stronghold for the whole month, and helped prepare the world’s largest camera for science verification data taking. At the end of the month, the telescope was mostly working, the beautiful camera was mostly working, and science verification was on-going. Submitted by James Annis, Fermilab. #DESendofnights ... See MoreSee Less
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The Dark Energy Survey added 2 new photos.
3 days ago
The weather can be unpredictable on the desert mountaintop. In mid-Oct 2015, blizzard conditions made for a few days with clouds and no data collection. Life goes on. One of the best parts of observing is meeting and working with the Chilean staff at the observatory. Occasionally, there is a little fun and I got to enjoy making this snowman!

Natural critters like the Culpeo (South American Fox) remind us that we are only scientific visitors to this wonderful remote place on earth where the skies provide some of the best conditions on the planet for observing. It should be of no surprise that this fox was seen rather close to our dormitory and, of course, the kitchen where some food might be more easily found than out in the snow. His footprints next day were also found around our snowman who had some missing shirt buttons! Submitted by William Wester, Fermilab. #DESendofnights ... See MoreSee Less
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The Dark Energy Survey
4 days ago
One of the perks of being at the top of a mountain in Chile is watching the sunset. Some optical phenomena are very clear there; in this timelapse of the sky opposite to the sun during sunset, we can clearly see the Venus belt (pink band) followed by the Earth’s shadow (blue band on the horizon). Submitted by Agnès Ferté, a postdoc at NASA JPL. #DESendofnights ... See MoreSee Less
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The Dark Energy Survey
5 days ago
We (K. Grabowski, A. Elliott, and myself) had finished preparations for observing and were awaiting sunset. We went outside, and this photo was taken. We saw the color of the sun change as it went below the horizon, and another photo recorded a green flash! It was a fantastic moment.
Submitted by Hal Spinka, Argonne National Laboratory. #DESendofnights ... See MoreSee Less
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News

Dark Energy May Be Incompatible With String Theory

August 9, 2018 12:00 am

Since 1998, telescope observations have indicated that the cosmos is expanding ever-so-slightly faster all the time, implying that the vacuum of empty space must be infused with a dose of gravitationally repulsive “dark energy.” In addition, it looks like the amount of dark energy infused in empty space stays constant over time (as best anyone can tell). But the new conjecture asserts that the vacuum energy of the universe must be decreasing. Paul Steinhardt, a cosmologist at Princeton University and one of Vafa’s co-authors, said that over the next few years, “all eyes should be on” measurements by the Dark Energy Survey, WFIRST and Euclid telescopes of whether the density of dark energy is changing. “If you find it’s not consistent with quintessence,” Steinhardt said, “it means either the swampland idea is wrong, or string theory is wrong, or both are wrong or — something’s wrong.”

The dark-energy deniers

June 19, 2018 12:00 am

Make no mistake, dark energy – be it the cosmological constant or quintessence – is the leading theory with plenty of observational evidence to support it. The alternatives remain highly controversial. Yet those nagging questions just won’t go away. Upcoming surveys will either solidify dark energy theory’s position further, or produce a surprise by pulling the rug out from under it. With the Dark Energy Survey – an international collaboration using a 570-million-pixel camera called DECam on the Blanco 4 m telescope at the Cerro Tololo Inter-American Observatory in Chile – releasing its first data from a survey of 300 million galaxies, these are exciting times. “What makes this a really fun field to be in is that I don’t know what the next big step will be,” concludes Riess. “We’re just in the middle of our initial reconnaissance, and I don’t think we should be surprised by surprises.”

Simon Samuroff receives URA Thesis Award for Dark Energy Survey image analysis

June 1, 2018 12:00 am

The Dark Energy Survey captures images of galaxies billions of light-years away to help our understanding of the evolution of the cosmos. Assessing these galaxies’ properties, such as their size, shape and distance from each other, is a painstaking process, one that involves not only collecting massive amounts of data, but also correcting for potential miscues that challenge the very act of assessing the data. The Fermilab-led Dark Energy Survey aims to make unprecedented measurements of a phenomenon known as gravitational lensing. Gravity bends light produced by faraway galaxies, so images of galaxies are subtly distorted by the time they reach Earth. The degree of distortion itself can provide information about those galaxies, galaxy clusters and the universe around them. An important step in making accurate measurements of the universe is by successfully isolating these tiny distortions. Simon Samuroff is the recipient of the 2017 URA Thesis Award, presented annually for outstanding work by a graduate student working at or in collaboration with Fermilab. In his thesis, titled “Systematic Biases in Weak Lensing Cosmology with the Dark Energy Survey,” Samuroff built computer simulations to model the shapes of galaxies captured by the Dark Energy Camera, which was built by Fermilab and is located at an observatory on a Chilean mountaintop. He closely compared thousands of the simulations to actual images to determine the amount by which scientists’ initial estimates of these distortions are incorrect. He singled out miscues so the Dark Energy Camera could make improved measurements and be more sensitive to subtle effects of phenomena such as dark matter. “The committee was impressed by both the quality of writing and the magnitude of his study — cataloging millions of galaxies or clusters and taking very small effects into account,” said Fermilab scientist Lenny Spiegel, chair of the URA Thesis Award Committee. “His work is invaluable to scientists studying mysteries regarding astrophysics, which may ultimately point the direction for future progress in particle physics.” One of Samuroff’s major results showed that interactions between the images of neighboring galaxies that overlapped affected scientists’ measurements more severely than they realized. By identifying where and to what degree distortions like this cause inaccuracies, Samuroff helps scientists create a more reliable system of measurement.

KBO could be evidence for a giant planet in the outer solar system

May 31, 2018 12:00 am

The discovery of a distant Kuiper Belt Object (KBO) with an extremely eccentric orbit could be evidence that a giant planet is waiting to be discovered in the outer solar system. KBO BP519 was discovered by scientists analyzing data collected by the Dark Energy Survey, which observes a region far above the orbital plane of most of the solar system’s planets as part of a project to measure acceleration of the universe’s expansion. It orbits the Sun at a tilt of some 54 degrees from the plane of the inner solar system planets’ orbits. Like several other KBOs found in 2016, which all orbit at the same unique angle to the plane of the inner planets, 2015 BP519’s position suggests it is being influenced by the gravitational pull of a much larger object, sometimes referred to as “Planet X” or “Planet Nine,” which may be shepherding it and the other above KBOs into this strange orbit. Since the 2016 discovery of these KBOs orbiting at the same distinct angle, scientists have been searching for a hypothesized large planet influencing their orbits, which could be either a super-Earth or a gas giant. One possibility is 2015 BP519, described as “the most extreme Trans-Neptunian Object discovered to date,” is actually a moon of the large planet, which some astronomers estimate to be ten times as massive as the Earth.

‘Nova Wonders’ Asks ‘What’s the Universe Made Of’ Tonight

May 30, 2018 12:00 am

When gravitational-wave detectors recorded a distant collision of two neutron stars, astronomers around the world got the call and began to search for visible evidence of the crash. A team in Chile from the Dark Energy Survey — as well as other groups — was able to detect the so-called kilonova's light, providing the first-ever observations of both light and gravitational waves from the same cosmic explosion. For the Dark Energy Survey crew, these observations will help gauge the universe's expansion rate, aiding their investigation into the mysterious dark energy pushing the universe apart. "What's the Universe Made Of" digs deep into two cosmic mysteries — dark matter and dark energy — showing how researchers know those entities exist, but also revealing that they are still trying to learn what they're made of and how they work.

© 2018 The Dark Energy Survey