We took off during the day to hunt down the shadow of a Kuiper Belt object, MU69, as it passed in front of a star. To get in its projected shadow path on Earth, we flew north from Christchurch, New Zealand toward Tahiti.
SOFIA flight path for the MU69 occultation flight. The occultation location is marked by an anchor.Catching SOFIA’s shadow on the clouds after a rare daytime takeoff.Flying north over New Zealand’s North Island before sunset.
We had to fly with the telescope door closed until the sun had set. During this time, the NASA New Horizons team went over the plan, rechecked all the computations, and did some time tests to reconcile differences between Coordinated Universal Time (UTC) and GPS time. The usually adjust their timing using the GPS clock, but all the mission and science planning used UTC. GPS is not perturbed by leap seconds so it slowly drifts ahead of UTC. However, GPS timing receivers put in the conversion factor to convert GPS time to UTC, but we had to double check. We also consulted the U.S. National Institute of Standards and Technology’s shortwave radio time signal station in Hawaii.
Manuel Wiedemann (left) and Enrico Pfueller (right), the instrument scientists who operated the high-speed camera, setting up their equipment.
Before the occultation, the flight plan had a short leg planned when we set up the telescope and instruments and then a time holder leg to give the pilots time to get the plane flying at exactly the right speed (adjust for winds etc.).
Sunset from the stratosphere.
After the sun had set we opened the telescope cavity door. Then it was time for the pilots and the mission director, Karina Leppik , to coordinate the plane’s position to intercept the shadow at 16 degrees south latitude, and 175 degrees west longitude at exactly 07:49:11.
Expectant Astronomers. This picture was taken minutes just before the event.
Don’t Blink!
We were exactly where the center of the shadow was predicted to be, at exactly the right time. But our eyes could not see the event in real time.
We used our high-speed camera to take images at a rate of 20 frames per second, so the dip in the star’s light as MU69 crossed it would only appear in 8-32 images out of the 60,000 we took over 50 minutes.
These observations should enable us to better understand the size of MU69, which is currently not well known. The Hubble Space Telescope images only provide a visual magnitude measurement. So, it’s unclear if MU69 is large and dark, or small and highly reflective because both combinations can provide the equivalent magnitude.
The occultation star is in the bottom middle, marked with the bulls-eye concentric circles. All eyes were on this star during this flight.
We landed back in Christchurch just after midnight. With data in hand, the scientists deplaned SOFIA, took a short nap, and then headed to South America to start preparing for the third of three occultations event by this MU69 on July 17.
Now we wait…
….to learn what the New Horizons team finds as they analyze the data.
We’ve teamed up with NASA’s New Horizons mission to observe an astronomical event known as an occultation, when an object passes in front of a background star.
Illustration of SOFIA’s observations of the MU69 occultation on July 10.
An occultation is not the same as an eclipse or a transit. It occurs only when one body completely hides another. For this event, on July 10, a Kuiper Belt object, MU69, is going to block out a background star.
A transit occurs when the body passing in front of the other body only partially blocks it (like Mercury transiting the sun and all those transiting exoplanets that Kepler has been discovering).
Finally, an eclipse occurs when one body passes into the shadow of another body and disappears, at least partially. During the solar eclipse that will occur on August 21 across North America, the moon will eclipse the sun relative to Earth. The moonhas occulted, or passed in front of, the sun. Thus, a solar eclipse could perhaps be called a type of solar occultation.
On July 10 we studied MU69 as it occulted a distant star. Two experts aboard SOFIA, Marc Buie and Simon Porter, of the Southwest Research Institute, used measurements from the Hubble Space Telescope to compute exactly where the shadow of MU69 would fall on Earth’s surface.
Scientists Simon Porter, Marc Buie, and Eliot Young will fly on SOFIA as Guest Observers to catch MU69’s shadow.
Based on these calculations, SOFIA needed to be at 16 degrees south latitude, and 175 degrees west longitude at exactly 07:49:11 UTC to catch MU69’s shadow. MU69 and the star lined up for less than 2 seconds because this Kuiper Belt Object is a very tiny (estimated to be between 12-25-miles (20-40-kilometer) across) and approximately 4.1 billion miles from Earth (well past Pluto), so this was a very challenging occultation to capture. But the flight planners and navigators on board can position SOFIA with the precision needed for this brief measurement. We’ve studied occultations of Pluto twice in the past.
The occultation on July 10th predicted ground path.
The event of July 10th had a predicted ground path as described here.
Studying the solar system and beyond using multi-wavelengths of light, including visible, x-ray, and infrared, reveals many different views of the same object. Check out the Milky Way’s Galactic Center in the visible, infrared and x-rays.
A Composite image of the turbulent heart of our Milky Way galaxy, in the visible, infrared and x-ray. courtesy of Hubble, Spitzer and Chandra.
Two recent Guest Observers were aboard to study the infrared universe- Dr. Monica Rubio from the University of Santiago Chile, and Dr. James Jackson, from the University of New Castle, north of Sydney, Australia.
Jackson is a veteran observer on the Kuiper Airborne Observatory (KAO), the predecessor to SOFIA which carried a 36-inch telescope in a converted C-141 military cargo plane. His first remarks about SOFIA were, “It’s big. The instruments are 10x larger than on the KAO. And there is more room for more people and space to walk.” He called the mapping feature of the GREAT instrument on the SOFIA telescope, “phenomenal.” This feature, aptly called “The Translator,” enables efficient communication between the science instrument and the telescope, so that this airborne observatory uses every minute in the sky to its fullest potential.
Panorama image as observations were underway.
The object that Jackson is studying is the Nessie Nebula, named because it looks quite serpentine across the sky. It is a large gas cloud in the spiral arm of our Milky Way, and is a fascinating home to some wacky star-forming regions. Jackson is looking for gas infalling on the cores, which are thought to be forming massive stars. With the data gathered on SOFIA, he hopes to be put together a clearer picture how stars form from collapsing clouds.
James Jackson (standing) talking strategy with Ed Chambers (seated), instrument scientist.
Rubio is studying the Small Magellanic Cloud, or SMC, a neighboring galaxy to ours that is 200,000 light years away. The SMC is very different from our own galaxy, in terms of its chemical makeup. SOFIA is in a prime location to observe this galaxy high in the sky when flying in the Southern Hemisphere. Over multiple nights, Rubio is observing seven different star formation regions in the SMC. She’s studying emission from ionized carbon, which is used as a tracer to measure the star-forming gases in the SMC and better explain the chemistry of the universe. These SOFIA observations give her the infrared view of the chemistry she needs to complete her research, which also includes observations from ground-based, sub-millimeter telescopes.
Monica Rubio discussing her science with GREAT instrument team members Anna Parikka and Denise Riquelme Vasquez.
This flight took us down to 64 degrees south, which also provided a nice glimpse of the Aurora Australis, also known as the southern lights. Aurora are a chemistry of a different kind, a result of Earth’s atmosphere interacting with solar winds.
Southern Lights or Tagu-Nui-A-Rangi, the great burning in the sky.
Last week aboard SOFIA, our observations included studying star formation regions in the Small Magellanic Cloud, a neighboring galaxy to our own Milky Way, a super-massive black hole, and the center of our Milky Way Galaxy. The method we used for these studies is called spectroscopy, and in more particular, high-resolution spectroscopy. The instrument onboard can isolate the wavelength, or frequency, of a particular atomic or molecular transition, allowing scientists to measure how fast and in which direction the molecule is moving.
When observing on SOFIA, the time spent on each celestial target is planned in advance, taking into account the position of the object in the sky, the direction of the aircraft, and the motion of the sky throughout the observation. When you add in the constraints that the airplane must take off and land at Christchurch International Airport and that the telescope only looks out the left (port) side of the plane, it makes for unique flight plans each night. Often the same targets are observed on multiple flights to get all the data we need.
Updated flight plan.
We, as humans, cannot see infrared light with our eyes. So, we are thankful to have SOFIA’s telescope and instruments which enable us to study the infrared solar system and beyond.
During the June 28 flight, we observed a target called Sagittarius A, or SgrA (pronounced ‘Sag A-Star’), which when viewed from Earth is in the constellation Sagittarius. Evidence has been mounting that SgrA is a supermassive black hole, as telescopes have measured the speeds of stars orbiting that point in space at much higher speeds than any other star in the galaxy.
Using the powerful instruments on SOFIA, we are studying atomic oxygen in the gas surrounding the black hole, which can only be studied with far-infrared wavelengths of light that do not reach Earth’s surface. The researchers onboard are trying to measure the amount of neutral (not ionized) gas that is falling into the black hole. With SOFIA they can actually determine how fast the gas is moving and its direction of motion using the high-resolution instrument onboard. Combining measurements of both the gas’s velocity and mass will help us understand how the black hole at the center of our galaxy is accumulating mass from its surroundings, due to its large gravitational pull.
Image from the visible light guide camera on SOFIA. SgrA is in the center.
What’s up tonight for this flying observatory? We’re looking at the Central Molecular Zone, the region around the center of our Milky Way Galaxy, young protostars, massive young stellar objects, and the “stuff between the stars,” called the Diffuse Interstellar Medium.
The Center of the Milky Way Galaxy as seen while flying at 40,000 feet.
As with any SOFIA flight, there is a timeline of preparation activities that must be followed to prepare the plane for an observing mission: the aircraft items refuel and coordinate transferring the onboard instruments from ground-based power to the aircraft’s power; the pilots meet to go over departure and arrival options; the scientists discuss the observations planned for the flight. Everyone flying has to be present for the head count at the final mission meeting.
The team meeting before the flight.
Soon it’s time to board and the clock is ticking. I sat in the cockpit for takeoff, this time for departure, and pilots Paul & Dean with flight engineer Moose (Marty) certainly were kept busy with air traffic control. For SOFIA, taking off within a narrow time window is crucial for the flight’s success in because each turn of the flight is planned to the minute to facilitate our scientific observations. If there are delays with takeoff, the mission directors need to work with the pilots to alter our path to get back on schedule. It was a fine balance and Paul & Dean handled it smoothly.
The flight plan showing where we flew during our observations.
This flight plan took us very south — we reached 64.534 degrees south latitude and were delighted to see a show of the southern lights, the Aurora Australis!
Southern Lights, seen from SOFIA while flying at 63 degrees south and 170 degrees east. (Kimberly Ennico Smith)
At the end of the 10+ hour flight, the science team disembarked with high-quality data thanks to the very low water vapor at 43,000 feet. Water vapor blocks infrared light from reaching the ground, but SOFIA flies above 99% of it. This data should provide new insights into the role of atomic gas in extreme conditions, like those at our galactic center, in jets and outflows of protostars, and in the regions of massive young stellar objects.
Dr. Kimberly Ennico Smith, SOFIA Project Scientist
SOFIA, the world’s only flying observatory, is in Christchurch, New Zealand for the next few weeks, to enable unique infrared observations from the Southern Hemisphere. From here, we can study our galaxy’s center and nearby galaxies, the Magellanic Clouds, which will feature prominently in our observations in the weeks to come.
I flew onboard SOFIA on the journey south from its home base at NASA’s Armstrong Flight Research Center, in southern California. We stopped in Honolulu, Hawaii, to refuel and change crews on the way to New Zealand.
During the flight, I got a chance to hang out in the cockpit and spend time with the flight engineer. He explained what all the dials and buttons do — some monitor the temperature of the engines and control the engine heaters, others monitor the airplane’s elevation.
The pilots and flight engineer aboard SOFIA. (NASA Photo)
The rest of my fellow passengers were a mixture of mechanics, software engineers, telescope operators, and avionics technicians. We got to chatting about all sorts of avionics systems and swapped stories. They know the world of aircraft inside and out and it was truly a pleasure to pick their brains over the two long flights down south.
SOFIA landing at Christchurch International Airport.
We are ready to observe the solar system and beyond from the National Science Foundation’s Antarctic Program Facility at Christchurch Airport!
Editor’s note:NASA research test pilot and aerospace engineer Troy Asher is the Armstrong Senior Representative for the second half of the deployment.
We have completed the first phase of the final portion of the New Zealand deployment, with the first three flights with the GREAT Instrument (the German REceiver for Astronomy at Terahertz Frequencies). The aircraft has been behaving well, and we have gotten all planned data, except for one leg on the first flight (see below).
The GREAT instrument installed on SOFIA’s telescope. Photo: NASA/USRA/SOFIA/Greg Perryman.
Weather has not been overly challenging although it is certainly wintertime here. Takeoff times have been on time every night due to the wonderful help we have received from the Christchurch Tower control professionals. Despite poor connectivity via high frequency (HF) radio communications and the Iridium (satellite) phone while flying in the extreme southerly latitudes, Auckland Control has worked with us and we have received virtually every flight path change we have requested.
Two nights ago, we used our new in-flight Internet system (lovingly known as “Skynet”) to do our coordination with Auckland Control when no other means would work. They would launch search and rescue efforts if they lose contact with an aircraft for 15 minutes beyond the planned contact time, but due to timely calls from us over Skype at 62-degrees South over the southern Pacific, all was well. This new capability will certainly continue to be a benefit for us in the future.
SOFIA’s flight path on July 13, 2015. SOFIA flew as far south as 62 degrees.
Flight 228, July 12, 2015
The first mission of the deployment for the GREAT instrument team was a very successful flight for four of the flight’s five science legs. Unfortunately, on one of the science legs we experienced a computer system crash, which eventually led to a complete loss of that observing leg. The other four legs collected 100 percent of the planned science. The airplane came home healthy and was ready for the following night.
SOFIA’s flight path on July 12, 2015. Each turn of the aircraft is called a new “leg” of the flight.
Flight 229, July 13, 2015
The second flight for GREAT was an extremely successful one. We collected all planned data on each leg, and even a bit more on some. Also, we had incredibly bright and very long lasting aurorae. The mission was enhanced by the use of Skynet to accomplish position reports with Auckland Control over Skype. The HF radio and Iridium phone were both not receiving any signal, but Skynet was working well.
Aurora Australis spotted by the SOFIA team. Photo: NASA/USRA/SOFIA/Carla Thomas.
Flight 230, July 14, 2015
Another very good flight with more than 100 percent of the planned data gathered on every leg. There were some challenges along the way, but the efficiency of the mission crew allowed them to quickly breeze through issues with no loss of science observations. The GREAT science team reports they are very happy with the results they have gotten with extremely low water vapor levels, as was also seen on the 2013 deployment to Christchurch.
SOFIA concluded research flights from Christchurch, New Zealand, on July 22, and returned to its home base of Palmdale, California, on July 24, 2015.
SOFIA taking off from Christchurch International Airport. Photo: NASA/USRA/SOFIA/Charlie Kaminski.
This is the final post.
All the flight paths SOFIA flew from Christchurch, New Zealand this year.
There are 60 busy scientists and support specialists in Christchurch, New Zealand, but everyone paused on Monday evening, June 29. That’s when the mission briefing room was packed to capacity with everyone anticipating the night’s flight. There was a buzz in the air; as the briefing went on, more and more people were caught up in it.
The night’s mission was to observe Pluto as it passed in front of a star. The event, known as an occultation, would cast Pluto’s faint shadow across the Earth’s surface, and the center of that shadow would pass somewhere off the southern coast of New Zealand. Many ground-based observatories and research teams would be observing the occultation as well, but SOFIA, NASA’s largest airborne observatory, would attempt to fly exactly in the center of the shadow to observe the occultation from the ideal vantage point.
Image: NASA/SOFIA/L. Proudfit
Should SOFIA capture the occultation, the research teams would be able to determine the detailed pressure and temperature profile of Pluto’s atmosphere, and verify if there are aerosol particles or dust in the dwarf planet’s atmosphere. If SOFIA were to hit the shadow in the exact mid-point, researchers could even determine whether there are winds in Pluto’s atmosphere and learn how they behave.
As the briefing went on, Mission Director Nancy McKown reminded everyone that this was only one of 14 science missions planned during the deployment, which includes observations of more than 40 celestial objects, each just as important as the next. Her attempt at calming the excitement in the room lasted for a few short minutes as people reflected on SOFIA’s overall mission, but the excitement was soon back in full force.
Research Scientist Michael Person from the Massachusetts Institute of Technology (MIT) also spoke about the night’s mission. Person’s area of research focuses on the techniques needed to observe stellar occultations, eclipses, and transits. He has a special interest in Triton, Pluto, and a number of objects that reside in the Kuiper Belt that stretches from Neptune out past Pluto. As Principal Investigator for this flight’s Pluto occultation observations, Person would be responsible for coordinating the work of all of the instrument teams on board.
A Little Bit of Back Story
An entire room full of science specialists, led by Jeff VanCleve and Ken Bower, had been working on where to fly SOFIA for the night’s observations. They looked at the weather forecast and developed a number of flight plans for a variety of possibilities, depending upon where the shadow would fall. Some predictions called for the center of Pluto’s shadow to fall north of Wellington, New Zealand, while others put it between the island nation and Antarctica. Working with observers at the U.S. Naval Observatory and Lowell Observatory’s Discovery Channel Telescope, both in Flagstaff, Arizona, with additional support from telescopes in Australia and Chile, Pluto observations were made and the data was provided to astronomers at MIT. They in turn made calculations to generate predictions for Pluto’s path that were provided to the SOFIA team, who generated a flight plan that would put the observatory in the shadow’s track.
Once the science flight plan was generated, it was turned over to SOFIA’s navigator for the flight, Jeff Wilson, who then converted it for use by air traffic controllers.
The observations would be made at 39,000 feet, an altitude that did not require maximum thrust from SOFIA’s four 50,000 pound thrust JT-9D-7J engines. The air at 39,000 feet was predicted to be very clear of infrared-blocking water vapor, and flying at the lower observation altitude provided more reserve power to the pilots in case they needed to make up a minute or two on the flight plan to intercept the shadow at the precise point.
Below the cockpit, on SOFIA’s main science deck, teams coordinated by Instrument Scientist Maureen Savage would monitor the three instruments used together to capture the occultation:
The First Light Infrared TEst CAMera (FLITECAM), an infrared camera collecting data between wavelengths of 1 and 5.5 microns.
The High Speed Imaging Photometer for Occultations, HIPO – Principal Investigator Ted Dunham, a visible light camera that was co-mounted with FLITECAM.
Fun fact: When FLITECAM and HIPO are mounted together, they are known as “FLIPO.”
The third instrument in use was the Focal Plane Imager-Plus (FPI+), a highly sensitive tracking camera on board SOFIA that can also be used as a photometer collecting data at visible and near-infrared wavelengths between 0.36 and 1.1 microns. FPI+ is managed by a team from the German SOFIA Institute at the University of Stuttgart, with Principal Investigator Jürgen Wolf heading the team.
All three-instrument teams would work together on this flight to ensure the success of their observations both individually and as a group.
SOFIA’s FLITECAM and HIPO Instruments, “FLIPO.” HIPO is getting cooled with liquid helium before flight. Photo: NASA/SOFIA/Carla Thomas
The SOFIA team’s Pluto fever was being fed by the anticipated success as well as a keen awareness of NASA’s New Horizons spacecraft, which will pass by the distant celestial body on July 14. Data from SOFIA’s observations will be an important part of a decades-long study of Pluto’s atmosphere that provides a baseline and context for New Horizon’s fly-by observations. Studying a target with as wide a variety of sensors as possible results in the most complete understanding of an object. That’s why NASA will often observe a celestial object with sensors that cover the entire electromagnetic spectrum. In Pluto’s case, New Horizons provides ultraviolet, radio, and visible wavelength coverage while SOFIA collects data in both the visible and infrared bands.
SOFIA is a GO!
As the mission briefing continued, each of the responsible team leads presented the status of their part of the mission.
The command pilot for the flight would be Clayton “Ace” Beale. Ace briefed the weather, fuel load, alternate landing fields, in case Christchurch’s notorious fog rolled in, and discussed flight timing for the mission.
SOFIA’s flight crew during the Pluto occultation flight, Ace Beale, Dean Neeley, and Tom Speer. Photo: NASA/SOFIA/Carla Thomas
Navigator Jeff Wilson, call sign “Elvis,” presented the night’s flight plan with the caveat that it might change depending upon the information received during the flight on Pluto’s estimated track. In flight, Wilson would collaborate with Jeff VanCleve and co-Mission Director Karina Leppik as updated Pluto shadow position forecasts were received from MIT.
Aircraft Operations Engineer Andrew Fischer said, “All aircraft systems are ready.” Fischer’s words captured the work of Aircraft Crew Chiefs Jerry Dobbins and Sal Ramirez and their crew of more than 20 technicians and engineers who worked in often cold and wet conditions to prepare the aircraft and its airborne systems for the flight.
Oliver Ziele, representing the telescope team from the German SOFIA Institute, reported: “The telescope is balanced and the telescope bearing temperature is within limits.”
Matt Enga, whose group is responsible for all of the mission communication systems on board the observatory – computers that interface between the telescope to the instruments – reported all systems were ready for the night’s mission.
Shawn Granen from SOFIA’s information technology group talked about computer protocols on the flight and then announced: “The celestial map overlays have been uploaded.”
SOFIA is a GO!
With all systems reporting as ready for the flight, Mission Director McKown reviewed the mission timing – when the crew had to board, when the door would close, taxi and takeoff times. With that, the excited crew grabbed their gear and headed for the plane.
Once on board, last minute details were attended to and the main cabin door was closed. On-board, in-flight safety technicians Mike Moore and Steve Laney gave the safety briefing and everyone took their seats. The engines were brought to life, and with clearance from the tower SOFIA headed out to the runway.
Having received permission from the control tower to take the runway and take off, Ace Beale positioned SOFIA facing south on Christchurch International Airport’s Runway 20. Beale, co-pilot Dean Neeley, and flight engineer Tom Speer completed their checklists and with the brakes holding SOFIA back, all four engine throttles were pushed forward as the flying observatory began to shake, building up thrust. At 10:07 p.m., local time, SOFIA thundered down the runway lifting off into the cold New Zealand night sky.
SOFIA taking off from Christchurch International Airport. Photo; NASA/SOFIA/Greg Perryman.
SOFIA flew to the south to set-up and test all systems. There were a couple of rough patches as systems were synchronized, but nothing the experienced group on board could not handle.
As the instrument teams were watching Pluto’s movements across the night sky, an updated prediction of the shadow’s path was received on board. Jeff Van Cleve’s pencil was processing the data and converting the prediction into a flight path. He then went upstairs to the cockpit to confirm his numbers, calling MIT on the aircraft’s satellite phone.
Having replanned the flight with navigator Wilson to intercept the shadow everything was set. Then another further updated position prediction came in. This one required the aircraft to be positioned 227 km (141 miles) north of the current flight path.
The race was on. SOFIA was trying to reposition itself before the Pluto’s shadow passed in front of it.
On the screen, everyone on board could see Pluto begin to approach the occulting star. Then it got closer. Then closer. The excitement was building on the science deck.
Memers of the German SOFIA Institute (DSI) monitoring the Pluto occultation. Photo: NASA/SOFIA/Carla Thomas
At a point approximately -44.8 latitude by 171.0 longitude SOFIA’s instruments captured Pluto’s shadow. As SOFIA reached the precise center of Pluto’s shadow, viewing Pluto exactly centered in front of the star, the star’s light brightened, which was reflected on the light curve as an obvious spike in the center. That momentary “central flash” held a wealth of data about Pluto’s atmosphere. As Pluto completed its pass in front of the star, there was loud shouting, clapping, handshaking, and congratulating all around!
Members of SOFIA’s science team react to the successful observations. Photo; NASA/SOFIA/Carla Thomas.
“In this single flight we were able to obtain observations covering four different wavelengths as close to the predicted center of the occultation as possible, which shows the power and flexibility of SOFIA to go wherever is required for events like these,” said Ryan Hamilton of SOFIA’s FLITECAM team. “We faced challenges at every point and overcame them all, and we’re all excited as can be for the next part of these observations: the science and interpretation!”
Shortly after the mission, occultation principal investigator Michael Person said, “All of the instrument teams worked together very well to get us the best possible result. The HIPO team, based at Lowell Observatory, the UCLA-based FLITECAM team, and the German FPI team all came together to help each other overcome challenges during the mission, resulting in successful observations of the event from all cameras. I couldn’t be more pleased with the cooperation from the instrument teams, the aircraft, and observatory personnel with our efforts to observe this historic occultation.
SOFIA’s flight path for June 29, 2015 indicating where the Pluto occultation observations were made. Image:NASA/SOFIA/L. Proudfit
Two reporters, Nadia Drake and Govert Schilling were on board this flight and documented the experience. Their articles can be found below.
Conducting SOFIA science operations more than 6,900 miles (11,100 km) from our home base in Palmdale, California, requires a great deal of planning and calls for a diverse group of researchers, aircraft technicians, facility managers, and outside vendors to work as a team. Should any one group stumble, the entire mission could be in jeopardy.
My team consists of staff from the German Aerospace Agency and the German SOFIA Institute from the University of Stuttgart. We have a huge responsibility: the care and operation of SOFIA’s 2.5-meter telescope and its subsystems. We will also support the German consortium team obtaining scientific data with the GREAT spectrometer (the German Receiver for Astronomy at Terahertz frequencies) when they arrive in Christchurch next week.
SOFIA’s 2.5 meter telescope, with the NASA logo reflecting in the primary mirror. Photo: NASA
SOFIA’s deployment this year has us supporting four instruments plus the needs of the Focal Plane Imager (FPI) team. The FPI is an added asset to SOFIA that is used as a standard tracking camera for observations and also serves as a fast frame-rate imaging photometer. The four instruments are the GREAT spectrometer, the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST) camera/spectrometer, plus the First Light Infrared TEst CAMera (FLITECAM) and High Speed Imaging Photometer for Occultations (HIPO), both of which were used for studies of Pluto’s atmosphere on June 28 and 29.
The FLITECAM and HIPO instruments getting installed on SOFIA’s telescope. Photo: NASA/Carla Thomas
Our first task upon arrival in Christchurch was to set up a working area and do an inventory of all the necessary tools, and confirm that the electrostatic discharge bench was working properly to ensure we could repair any electronic components if necessary. This sounds simple enough, but we have to rely on the logistics companies that handled and shipped our equipment from Palmdale, cleared it through New Zealand Customs, and then delivered it here to the airfield. For our operations at Christchurch, the National Science Foundation’s U.S. Antarctic Program has generously afforded us workspace, and we were able to set-up shop to support SOFIA in a matter of days.
SOFIA in front of the U.S. Antartic Program hangar at Christchurch International Airport. Photo: NASA/SOFIA/Carla Thomas
We have an excellent working relationship with the U.S. Antarctic Program. Aside from using their shops and facility, their IT staff helped us get up and running. Air New Zealand provides our airfield infrastructure (tow tugs, airstairs, etc.), MetService of Christchurch delivers our daily weather forecast, Anglo Pacific International provides logistics services for getting our equipment to Christchurch, and BOC Gas provides cryogens, which are used to cool our instruments, for the mission.
SOFIA’s instruments are cooled with liquid helium. Photo: NASA/Carla Thomas
Many groups of people support our mission to observe the southern skies, and it takes the work of an international team to achieve success. We have completed four successful observing flights, including observing a challenging Pluto occultation, and look forward to even more as we continue to observe from Christchurch.
Many thanks to the telescope operators for helping us through these complicated observations. The instrument for tonight’s and tomorrow night’s flights is the Cornell University developed Faint Object infrared CAmera for the SOFIA Telescope (FORCAST), a dual-channel mid-infrared camera and spectrograph sensitive from 5 to 40 microns.. SOFIA flies above 99% of the water vapor in Earth’s atmosphere that blocks infrared radiation from reaching the ground. The super dry atmosphere over the southern ocean was exceptionally good for the duration of the flight, which enabled the team to get better results.
The FORCAST Instrument installed on SOFIA’s telescope. Photo: Photo: NASA/USRA/SOFIA/Greg Perryman.
During the first science leg we observed V1309 Scorpii. At first this object was thought to be a “classical nova,” where a white dwarf star accretes material onto its surface from a companion star until the material ignites, causing a surface explosion. But it was later determined to be an explosion resulting from the merger of a binary star system, where the two stars spiral in toward one another until they finally collide. This is a very faint source that proved to be exceptionally challenging to get set up to observe. Once the observations were under way, however, the data looked to be acceptable. Luckily most of the effort was front-loaded, since soon after we began observing in earnest, the flight crew notified us that we could see the aurora outside. And it was just stunning, brighter and more active than anyone on the main deck had ever seen.
Aurora Australis as seen from SOFIA. Photo: NASA/USRA/SOFIA/Charlie Kaminski
The following science leg included observations of Eta Carinae, a system of two stars that are five million times brighter than our Sun. Eta Carinae can only be seen from the Southern Hemisphere, and this observation was the focus of our guest investigator, Pat Morris, from the California Institute of Technology, who was on board to assist with data collection. These observations proved to be challenging. The goal was to observe the faint emission surrounding Eta Carinae that originated in an earlier period of mass loss. To see this emission, we had to very carefully position the observation field next to Eta Carinae itself, the brightest IR stellar source in the sky. Unfortunately, besides the difficult setup, there were some technical issues on this leg that resulted in some lost observing time. Nevertheless, the data obtained looked very good. We are well positioned to optimize our observations of Eta Carinae on upcoming flights.
SOFIA’s flight path on June 23, 2015.
The last object we observed this evening was Westerlund 1 – one of the most massive star clusters in the Milky Way Galaxy. These observations were straightforward and rewarded us with some beautiful images of the most densely populated field observed by the FORCAST team to date.
