CTIO & Gemini South

I first heard of Cerro Tololo when I was in college.  My astronomy professor, Dr. Carlson Chambliss, had the opportunity to do some photoelectric photometry on the 16" telescope.  I remember writing the name, "Cerro Tololo" in my astronomy notebook- it was a place I would love to visit.  The Cerro Tololo Inter-American Observatory (CTIO) would be the backdrop of two amazing nights on the mountain.  You can see the results of that work under Southern Skies.  Here I want to talk about the instruments that dot the landscape  here and on nearby Cerro Pachon and the amazing research they perform. These instruments are brought together under AURA which comprises some 40 institutions in the United States as well as 4-6 international (2 of them in Chile).  Centered around CTIO is 90,000 acres with 35 telescopes and 2 mountaintops (a third mountaintop is possible).

The only thing better than one great telescope is two, especially if the second one is located in the opposite hemisphere.  This is the story of the Gemini twins, Gemini North on Mauna Kea in Hawaii and the twin we visited, Gemini South on Cerro Pachon in Chile.  As we walked around the cavernous dome that houses the 8.1 meter telescope we were immediately impressed with the magnitude of the instrument and the cutting edge technology it employs.  Huge segments of the walls can open up to help stabilize the mirror with the outside air temperature.  It uses the most advanced adaptive optics system of any telescope in the world.  There are 120 hydraulic actuators changing the shape of the 20 cm thick mirror to cancel out the effects of air turbulence. The adjustments to the mirror made by the actuators can be as fine as 1/1000th the thickness of a human hair providing razor sharp images.

The 15 story Gemini dome

Check out the size of the mirror compared to our group.
Photo courtesy of Gemini South

Three different camera systems are utilized on the telescope with the Gemini Multi-Object Spectrograph (GMOS) being the workhorse.  The Gemini Planet Imager (GPI) which is an adaptive-optics imaging spectrometer, and FLAMINGOS-2 a wide field imager and multi-object spectrometer complete the instrument package.  Notice the word “spectrometer” in all of the cameras.  This is because Gemini South sees the universe a bit differently than we do by looking at heat signatures in the near infrared rather than visible light.  The mirror has a coating of silver which gives it a much better sensitivity to heat,  but there is more of this precious metal in two silver dollars than what is coating the massive Gemini mirror.  The universe in these wavelengths allows us to see what is hiding behind those curtains of gas in star forming regions or revealing black holes at the center of galaxies, but that is just the beginning.  Observations with the Gemini telescopes can give us key insights into the history, structure and evolution of the universe.  Gemini telescopes are primarily used for the following scientific investigations:
  • Solar System- Near Earth Objects, Kuiper Belt Objects, Asteroids, and Exoplanets
  • Astrophysics- star clusters and star forming regions
  • Galaxies- active galaxies and dwarf galaxies
  • Galaxy Clusters- morphology of these galaxy groups
  • Redshift Universe- galactic formation and evolution
photos courtesy of Gemini South

If you want to use the telescope it goes through several phases.

PHASE ONE: Submit an online application detailing your scientific work.  Indicate whether you will need adaptive optics, and how much time you'll need to complete your project.  The National Time Allocation Committee (NTAC) will rank your research with a number from 1-3 (1 being the highest priority).

PHASE TWO: Your observation targets and observing sequences are now taken into consideration; when accepted you are placed into the queue.

QUEUE PLANNING TOOL: This is essentially a night plan template on who's observing when ranked according to your number priority from phase one. However, it is subject to change due to clouds or high winds.  No longer does an astronomer go to the telescope with a set observing time to discover his evening is ruined by clouds or a malfunctioning camera.  You simply stay at home and wait.  When the conditions are optimal for your research the Gemini staff takes your data.

The observations then go through a "data integrity" process and if acceptable are sent to the archive which is in Canada.  Gemini prides itself on its observing flexibility, and rapid access to data for observers.

Here I am in the control room.  Photo courtesy of Ryan Hannahoe

It stands for the SOuthern Astrophysical Research telescope.  At 4.1 m it is half the size of Gemini South, but is also a narrow field f/16 system.  It also uses adaptive optics and has instruments for viewing in visual and near infrared wavelengths, as well as a spectrograph.  Astronomers who get time on the telescope typically use the instrument remotely.

Photo courtesy of Tim Spuck                                                                                    

SOAR is well known for its incredible image quality as seen in this research taken through the telescope.

photo courtesy of SOAR

On the other mountaintop, amongst a lot of observatory domes, this is the primary telescope.  The main camera is 64 megapixels and there are only three of them in the world (the other two are in Hawaii).  It incorporates the use of 4 guide cameras to keep things on target and also utilizes a very special "dark energy camera".

 Astronomy Ambassador Jim O'Leary is standing next to it for scale.

Unlike the telescopes on Cerro Pachon, The astronomers typically go to Cerro Tololo to do their observing in person.  Astronomer Chris Smith was kind enough to invite us in for part of his observing session.  Chris is also the administrator in charge of Cerro Tololo.  The telescope operator is next to him and monitors screens dedicated to the health of the telescope, weather, and positioning.  Chris gave an hour of the early evening to an astronomer colleague who he communicates with via teleconference.  He's doing work on a supernova that is quickly setting into the western twilight and would love just one more data point.  Chris is happy to oblige and chats with him to make certain everything is set to his specifications.  As Chris begins his own research he monitors the screen to make certain all of the filters are properly working as the camera goes through its sequence.  He can see the CCD images on other screens but won't really see the results of his data until the next day.  The winds are high tonight, with gusts getting as high as 36 mph.  The telescope operator will close the instrument if it reaches 40 mph.  Neither astronomer or telescope operator is very concerned however.  The weather indicates that the winds will decrease rather than increase through the night.  The evening comes to an early close for another reason however.  The main camera develops a problem and won't work properly.  It will go in for repairs, but tonight the observing is done before midnight.  

                                                                                 Astronomer Chris Smith at the helm

Not much is really known about dark energy.  The $40 million dark energy camera is designed to look for patterns of galaxy clusters and lensing that occurs among them.  The deal with Cerro Tololo was to mount the camera on the Blanco 4M and run it 105 nights/ year for five years.  This would allow it to map about a quarter of the sky and give us the impact of dark energy over time.

There are a lot of observatories here!  We couldn't possibly get to all of them.  Some are used remotely and others require a human presence.  Here's a short list of some of the ones we saw:

GONG: looking for vibrations on the Sun.
Curtis Schmidt Telescope: space debris study
WHAM: studying hydrogen in the galaxy
SARA: remote observatories for university students
SMARTS: 1 m+ telescopes used by universities.
SKYNET: University of North Carolina at Chapel Hill remote telescopes

                                 If it happens in the universe, its a petty good bet someone is watching it at Cerro Tololo!

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