QUEST Community Science Blog

Infrared image of a zebra from the London Zoo.
Credit: Steve Lowe

Right now I am very excited about the possibility of working on a new small telescope in southern Utah. This telescope was funded by a private donation and will be run by the University of Utah. We even found a mountain top in the middle of nowhere that this telescope will call home.

Why this particular mountain? There are essentially three reasons:

It’s dark
It’s clear
It doesn’t make the stars twinkle

The first two reasons are so obvious that I am almost embarrassed. The last reason is not quite so intuitive. What makes a star twinkle and why do we care? This goes back to a post I made a few months ago.

The basic idea here is that the churning atmosphere blurs your astronomical image. Local geography and weather patterns can either mitigate or exaggerate this effect. It is difficult to predict and many measurements need to be done to determine what is actually happening. Cameras were placed all around southern Utah on various mountain tops to observe the North Star over the course of the year. The mountain top that produced the highest resolution image of the star won the competition. That was Frisco Peak.

The telescope that will be placed on Frisco Peak was built by a very specialized company. This is quite rare–more typical are either large custom-made telescopes or small amateur telescopes. This telescope falls in the middle. It is bought off the shelf but is far superior to the commercially made amateur telescopes.

We are now discussing plans for this telescope, like the type of cameras that should be used. There is a strong interest in building an infrared camera. This allows us to see through large clouds of dust and allows us to see very distant galaxies.

Like most people, I am much more experienced with cameras in the visible spectrum. I work on CCDs in Berkeley and have barely used anything in the infrared. CCDs are made of silicon which is sensitive to light that can be seen with the naked eye (plus a little more red than what can be seen).

However, there is a lot of information in the sky that is too red to be seen with the naked eye and too red to be detected with a silicon detector. New materials are required for detectors in this wavelength range. One of the major new materials for infrared detectors is a blend of mercury, cadmium and telluride, usually called Mer-Cad-Tell in the astro community. The wavelength range of the detector can be tuned by changing the amount of mercury in the blend.

Clearly, a lot of the legwork has been done for this new telescope. We have the funding, we have a vendor, and we have a location. Now all that’s left is to prioritize our science goals and to figure out how to get our hands on some mer-cad-tell.

Kyle S. Dawson is engaged in post-doctorate studies of distant supernovae and development of a proposed space-based telescope at Lawrence Berkeley National Laboratory.

Making Every Photon Count

Last week I went to a talk given by the leader of the Supernova Factory collaboration at LBNL. What is SN factory? This is an ambitious project to study supernovae like never before. I mentioned this project briefly in a previous post , now that they are so close to releasing their results I want to discuss it a bit more.

The main idea of this project is to study several hundred nearby supernovae using an instrument known as the Supernova Integral Field Spectrograph, or SNIFS. This type of instrument is essentially a blend between a traditional imaging camera and a spectrograph.

The resolution in an integral field spectrograph is defined in spaxels instead of the pixels that have become all too familiar with the advent of digital cameras. A spaxel is quite similar to a pixel, there aren’t nearly as many and each one carries at least a 1000 times as much information.

In your digital camera, the light passes through the lens and directly onto the CCD. Each pixel on the CCD counts the number of photons in the red, the blue, and the green. Typically, there are millions of pixels, each counting photons from a slightly different region of the subject of your photograph.

Now imagine that instead of just counting red, green, and blue, that each pixel counts the entire rainbow of light from your subject. Now you have a spaxel. In an intregral field unit, the light passes through an array of microlenses and prisms before landing on the detector. We would call each set of microlenses and prisms a spaxel. The resulting image carries information about every wavelength of light from every region of your target.

Spectrum of the first SN observed with SNIFSThe advantage to an integral field spectrograph like SNIFS is that you gain a lot more information than either an imager or spectrograph alone. With an integral field spectrograph you can basically identify and organize every photon that reaches the telescope.

Specifically designed to observe supernovae, SNIFS is being operated at the 88-inch telescope on Mauna Kea. Spaxels are quite expensive - this particular instrument has only 225. However, this is more than enough to observe the entirety of a galaxy, a supernova, and the background.

The members of the SN Factory have now observed over 100 SNe using this new camera. Last Thursday, I saw the data from the first 25 well-calibrated supernovae and was very impressed. The data showed the evolution of each supernova and the properties of the host galaxy in great detail. I’m sure the supernova community will be equally impressed when they first see these new results.

Kyle S. Dawson is engaged in post-doctorate studies of distant supernovae and development of a proposed space-based telescope at Lawrence Berkeley National Laboratory.

Last night we completed our observations for the Supernova Legacy Survey. This was a five year program to study supernovae using a 4-meter telescope in Hawaii in combination with several of the largest optical telescopes in the world.

The project was headed by a group at a university in Toronto and a group at a university in Paris. Canada and France sponsor the 4-meter telescope that is used to discover and observe the supernovae from the point of explosion to the final days when the supernova fades from view. We call this the imaging part of the program. This data constrains the apparent brightness and life cycle of the supernova, and eventually the absolute distance to the supernova.

Our contribution to the project was primarily through our affiliation with Keck Observatory. We were typically awarded four nights a year to observe recently discovered supernovae spectroscopically. The data is used to determine the redshift and the kind of supernova explosion.

The supernovae are used to study the rate of expansion of the universe. It was this type of experiment that was first used to discover that the universe is actually dominated by dark energy.

No one really suspected the presence of dark energy for almost the entirety of the 20^th century. Now, we not only know it exists but are actually trying to understand it in the same way we understand gravity, protons, and electrons. That is where projects like the Supernova Legacy Survey come in. With projects like this, we work to collect enormous samples of well-studied supernovae that can improve our understanding of dark energy.

We use a certain type of supernova as yardsticks to measure distances in the universe. We then model the affects of dark energy on the expansion history of the universe by comparing distances and rates of expansion. This comparison is typically represented in a Hubble Diagram.

The Supernova Legacy Survey has been very successful in its attempts thus far. On the right, I show the Hubble Diagram from the first year of data. This is less than 20% of the full sample. The dotted line outlines the expectations of the 1990’s cosmology crowd. The solid line shows the prediction from the more sophisticated cosmologists of the 21^st century. As you can see, the original expectations were pretty far off the mark - the supernovae just don’t lie on top of the dotted line.

Now that this program is finishing up, we should be seeing similar figures that are teeming with supernovae. Future programs should do an even better job of making these measurements. Someday we may actually understand this dark energy thing, it may turn out to be something else completely new and unexpected!

Kyle S. Dawson is engaged in post-doctorate studies of distant supernovae and development of a proposed space-based telescope at Lawrence Berkeley National Laboratory.

The Allen Telescope Array.When I first began to work on Quest’s SETI: The Search for ET segment, I have to admit that my initial reaction was “are we still looking for ET?” Of course, humans have been gazing up to the heavens for millennia, asking ourselves that interminable question “are we alone?” And of course, there’s been a long line of increasingly sophisticated radio telescopes searching the skies for cosmic signs of intelligence. But hey, don’t we at some point have to call it a day? Though I think most of us don’t actually believe we’re alone, the universe is really, really big. What chance do we have of finding ET?

Well, it turns out our chances are much better than I thought. Grote Reber began conducting sky surveys in the radio frequencies with his newly invented radio telescope in 1937, and detected the first signals from outer space in 1938. In the seven decades since then, we’ve seen a multitude of radio telescope designs pop up all over the world, but we still haven’t gotten signals from any little green men. What I didn’t understand, until I spoke to Jill Tarter and Seth Shostak at the SETI Institute, is that in all that time, we’ve hardly looked at any space at all.

Since SETI’s first experiment in 1960 by Dr. Frank Drake, and until very recently, they’ve only looked at a thousand stars out of about 400 billion stars in our galaxy, and there are 100 billion other galaxies to look at! There are two reasons for this: 1) The radio telescopes they’ve been using can only look at narrow swaths of the sky, and 2) they’ve had to RENT time on other people’s telescopes, which constrains their search and budget. Now, the new Allen Telescope Array is being built just for them, and with it they’ll be able to capture millions of frequencies from multiple star systems simultaneously. It will be the biggest and fastest tool in the world for seeking signs of ET!

To learn why scientists use radio frequencies in the hunt for intelligent life, and to learn more about the history & future of the search, watch our story SETI: The Search for ET. You can also watch our extended interview with Astronomer Jill Tarter. And hey folks, the SETI Institute is a non-profit organization, so if you’d like to help them out with the search, consider adopting a scientist like Jill Tarter or Seth Shostak. Go to Adopt-a-Scientist, or join Jill’s team and become a TeamSETI member at Join TeamSETI.
Also, check out U.C. Berkeley’s SETI@home page and turn your home computer into a tool that downloads and analyzes radio telescope data.

Watch SETI: The New Search for ET story online, as well as find additional links and resources.
Joan Johnson is an Associate Producer for QUEST on KQED Television.

The original Oakland Observatory in the 1880’s,
at Lafayette Square in Oakland. Credit: Chabot Space
& Science Center archives.This year marks an anniversary for the astronomical heritage of Oakland and the San Francisco Bay Area: Chabot Observatory turns 125!

Originally established as the Oakland Observatory in 1883, the facility was a unique creature from the very beginning. Conceived by then Oakland Public Schools Superintendent Jewett Gilson, who was inspired by a school observatory he saw in Philadelphia, the observatory was created for use by Oakland schools and the general public at large.

Gilson looked for, and eventually found, a donor to fund the observatory project: Anthony Chabot, a wealthy entrepreneur and philanthropist who made his fortune building municipal water systems in the Bay Area– including Lake Temescal and Lake Chabot. Anthony Chabot stipulated as part of his original $3,000 gift that the telescope shall forever be available for public observation at not cost– a tradition that continues today.

Chabot didn’t want the observatory to be named for him, so in its earliest years it was called the Oakland Observatory. The public, as the story goes, insisted on calling it Chabot Observatory in gratitude for the gift– and eventually the name was made official.

The original location for the observatory and its 8-inch Alvan Clarke and Sons telescope (”Leah”) was close to downtown Oakland in Lafayette Square– which today remains a square block of parkland, at 10th and 11th Streets and Martin Luther King Junior Way and Jefferson Street. In those days, 10 or so visitors on any given night would climb the tower-like structure to the telescope dome and peer at the heavens through the high quality instrument. Reservations had to be made in advance– sometimes as long as a month or two.

As Oakland grew, and particularly as it converted its street lighting from gas-powered lamps to electric lights, the necessity of moving the observatory to a darker spot grew. The observatory’s first director, Charles Burckhalter (who is said to have been the first person in Oakland with an astronomical telescope, set up in a backyard observatory at his home on Chester Street), arranged for the relocation. A number of different sites were considered– including a spot near Redwood Peak, the current location of the observatory– but a small hill next to the Mills College campus was finally adopted.

In 1915, Chabot Observatory opened at its new site, along with a new 20-inch Warner and Swasey telescope (”Rachel”), and continued to wow the public with the astronomical vistas it conveyed. In 1923 the directorship passed to Earle Linsley, a Mills College professor, who expanded the reach of the observatory to the public through outreach to schools and the establishment of an amateur astronomy group (today the Eastbay Astronomical Society).

Having visited this Chabot Observatory as a child in the 1960s, I now appreciate how long and distinguished a career those two telescopes spanned. At the time, I had no idea that Leah, even in 1968, was 85 years old-older than my grandparents! Then the observatory was run by the beloved Kingsley Wightman — “Mr. Science” to a generation or two.

It took the moving Earth to relocate the observatory a second time– literally. Because of Chabot Observatory’s location almost directly on top of the Hayward Fault, and the fact that the aging buildings were not quake– safe in the first place, another site had to be found: the present location of Chabot Space & Science Center, adjacent to Redwood Peak.

Happy 125th to Oakland’s special connection with the stars!

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.

Extreme close-up of the Sun’s visible surface,
showing ‘bubbling’ cells of convecting gas–each the size of
Northern California. credit: Hinode JAXA/NASA/PPARCBy all accounts, a new cycle-Cycle 24-in solar activity has begun… something you probably didn’t notice since the beginning of a solar cycle is quite subtle….

First things first: what is a solar cycle, and why is this one number 24? You’ve probably heard of sunspots and solar flares and disturbances in radio communications caused by solar activity, but had you noticed NOT hearing much about these things in the last two or three years?

The Sun exhibits a cyclic rise and fall in its level of magnetic activity. Being an enormous ball of roiling, circulating plasma (electrically charged gas), the Sun generates powerful magnetic fields in a way similar to how the circulating electricity in an electromagnet creates one.

Over the course of a solar cycle, the intensity and amount of magnetism generated by the Sun increases, like soup warming up on the stove, reaching a violent climax in which twisting, tangling magnetic fields break loose and release their energy in the form of solar flare explosions, coronal mass ejections, and tremendous heating of the solar atmosphere.

Sunspots are surface features formed by the presence of strong magnetic fields, and in general the number of sunspots that can be seen and counted indicate the level of magnetic activity on the Sun. For 400 years, since Galileo first started counting sunspots through his telescope, observers have kept track of sunspot counts, and over time a pattern in their number emerged. On average, the number of sunspot activity peaks every 11 years at a time called solar maximum.

I remember when I first started working at Chabot Space & Science Center, back in 1999/2000, during the last solar maximum. Using our Sunspotter telescopes on public observing days, in teacher workshops, and in my solar summer camp, we could easily count many sunspots-sometimes as many as 20 or more! Those were the days!

In the past two or three summers, however, it’s a lucky week to spot just a single sunspot! Most of the time, the Sun’s face has been a bland disk with few discernible surface features.

That status quo should start to change, now that we have allegedly reached solar minimum and are stepping onto the uphill slope toward the next maximum, which should happen sometime around 2011 or 2012. If you want to keep tabs on the rising solar activity, and you like lots of graphs and numbers and stuff like that, check out the Solar Cycle 24 website.

Oh, why is this Cycle 24? A 19^th Century astronomer who studied the then newly discovered sunspot cycle, Rudolf Wolf, established the cycle that spanned 1755 to 1766 as Cycle 1…and they’ve been counting up ever since.

But even in this “nap time” of the Sun, today’s modern solar observatories and spacecraft, with their arrays of high-tech cameras and sensors, see plenty on the Sun to keep them busy.

Japan’s Hinode spacecraft, launched in 2006, has returned libraries of amazing pictures and movies of solar flares, activity around sunspots, circulating hot gases, fine details of the life and times of magnetic fields…and all of this during solar minimum! I can’t wait until the Sun really gets going and Hinode becomes like a camera-happy tourist in Tahiti….

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.

More than meets the eye: The constellation Orion
in visible light (left) and infrared (right)
Visible light image: Akira Fujii;
Infrared image: Infrared Astronomical SatelliteSome months ago my blog, “SOFIA: Fly By Night,” talked about the up-and-coming astronomy ace of the night skies, SOFIA: the Stratospheric Observatory for Infrared Astronomy–a 2.5 meter infrared telescope built into a Boeing 747 airplane.

SOFIA’s been flying, and is gearing up to begin its first science flights in the not so distant future. SOFIA even put in an appearance in Bay Area skies a couple of weeks ago with a quick visit to NASA/Ames Research Center in Mountain View–then it was off again to its base of operations in the Mojave Desert.

Having worked on SOFIA’s predecessor, the Gerard P. Kuiper Airborne Observatory (KAO), in the last seven years of its operation, I thought I’d focus a bit on the science of airborne infrared astronomy, touching a bit on science done on the KAO over its 21-year career at NASA/Ames.

Why put a telescope on an airplane? Earth’s atmosphere, while transparent to the visible light the human eye can detect, is less so to many other wavelengths of light, including most infrared light. In fact, the water vapor in our atmosphere is pretty much opaque to a wide range of infrared wavelengths.

KAO flew at and altitude of 41,000 feet to get above as much as 99% of Earth’s atmospheric water vapor, giving astronomers a view of the infrared emissions from objects in space almost as if the telescope was out in space.

What’s so interesting about looking at infrared light? Aren’t visible light images taken from ground-based observatories enough?

Apparently not. Visible light is only a tiny fraction of the overall spectrum of electromagnetic radiation (the general term for “light” of all types–including gamma rays, X-rays, ultraviolet light, infrared light, microwaves and radio waves). There is a wealth of information contained in the entire electromagnetic spectrum that is only hinted at in the visible portion.

Visible light in our universe comes mostly from the photospheres of stars, either directly or by being reflected by objects such as dust, planets, comets, and the like; all of the light you see in the sky is starlight, either first hand or second hand.

Infrared light, however, is a lower energy form of electromagnetic radiation, and is emitted by any object or substance that is even slightly warm. So, interstellar clouds of molecules, rings of dust surrounding stars, atmospheres of planets–just about anything, in fact–emits its own infrared light, and observing the infrared emissions from these objects reveals a great deal about them: their chemical composition, their temperatures and densities, their velocities and structure–and a lot more.

One KAO astronomer observed the atmosphere of Venus to measure the relative abundance of hydrogen and deuterium (heavy hydrogen), looking for evidence of past oceans. Another observed Mars, looking for telltales of limestone (a mineral left behind by marine organisms) as evidence of past life on Mars. Others created detailed maps of clouds of complex molecules, probing the composition of the cooler material in our galaxy, as well as other galaxies.

The list goes on, as there’s plenty more cold matter in the universe than hot matter. Cooler matter can be more interesting, too, since complex molecules, like organic compounds and even life, don’t form in the sterile heat of stars.

So where KAO blazed an infrared contrail in the night skies, SOFIA may now follow and carry on the torch of astronomy, on the wing….
Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.

latitude: 37.8768, longitude: -122.251