Living the ‘Magellan’ life : Observing at a Chilean masterpiece



You are driving up a mountain. In the middle of nowhere. In a part of the globe that’s too remote to imagine. On a road that could give way anytime. There’s an alpaca chilling by the hills, looking at you with interest. Well, almost.

You’ve seen textbooks of the Atacama Desert as a kid, but never actually believed that people live here, let alone work for science. I welcome you to Las Campanas, a mountain in one of the driest areas of the world – 2500m above sea level – and home to one of the world’s modern wonders, the Magellan Telescopes.

When I was asked of my aspirations growing up, it was becoming obvious that I loved the cosmos. After all, what could be more exciting than studying the galaxies and attempting to understand the physics of the universe! Unfortunately, in India, where I am from, astrophysicists are still thought of as ‘just stargazers’, and not being an ‘encyclopedias of constellations’ means that you are as far from an astronomer as astrology is from real science. What most people don’t realize is that the idea of actual observing at a telescope (that is classically called, well, ‘classical observing’) is almost a dying art in astrophysics, with the advent of modern day telescopes and algorithmic pipelines that let you observe and reduce data while sitting in the comfort of a coffee shop. You submit a queue of astrophysical objects (and hence the name ‘queue-observing’) that you wish to observe, and voila, thy job will be done! Space telescopes like Hubble and Spitzer, and even modern-day ground based observatories like ALMA, work like this. Hence, it is almost ironic that I root for more astronomers on telescopes today. This article shall tell you why.


The massive 6.5m mirror at the Clay telescope that I used.

The Magellan telescopes are run by the Carnegie Institution of Washington in collaboration with several major universities across the US. At the University of Chicago, I work with the South Pole Telescope collaboration on high-redshift galaxy clusters that were detected by the Sunyaev-Zeldovich effect. To lock down on how far these clusters exactly are and how massive they are, spectroscopic data and, subsequently, Doppler shifts of spectral lines are needed. This is why I left my cozy office chair in Hyde Park for a 20-hour long journey to another cozy chair in the control room of the Clay 6.5m telescope. This majestic structure houses LDSS3, one of the world’s best spectroscopic and imaging instruments in the optical and near-infrared wavelength bands (read Ian Czekala’s post on the same instrument, but with different science goals!). I was co-observing with Mike McDonald, an assistant professor at MIT and a boss at observing and handling data.

With photo opportunities like this, a wide grin is justified.

With photo opportunities like this, a wide grin is justified.

Everything about the Magellan telescopes is classical, and almost poetic. The first sight of the metallic domes bathed in sunlight gets you pumped up for the nights to come. The staff at the lodge is very friendly, and the cooks make sure that you have the best Chilean food that you can possibly get. You meet other astronomers working on other telescopes or instruments, and you see them recognizing each other from previous runs. It is this ‘inner circle’ that I hope to be a part of someday.


The control room at Baade, Clay’s twin 6.5m telescope. This is where the real action is.

We were allotted the nights of 31st January and 1st February, and were rewarded with the best weather we could possibly hope for. With The Beatles playing in the control room and delicious empanadas ready to be devoured, we started the night by calibrating our spectral slits – taking images of the grism, measuring the ambient light in the dome, and measuring the sky background for that night. We planned to use the 4000 Angstrom break (a super cool tracker to measure Doppler shifts in galaxies), which falls in the red part of the electromagnetic spectrum because of the distance of these clusters.  Once twilight was past, we attacked the first cluster with 3-hour long exposures – yes, it takes that long for us to get a sizeable signal-to-noise ratio for a cluster that far! By the end of two nights, all five cluster targets were spectrally conquered.

What did I learn from this past week? That it is computationally challenging to detect faint emission lines from a redshift 1.2 galaxy cluster hidden behind the glowing sky background. That it is important to consider all potential sources of error while dealing with data reduction of clusters. But what did I learn that I wouldn’t have sitting in my cozy office chair in Chicago?

Magellan against the backdrop of the Milky Way. The word 'surreal' comes to mind.

Magellan against the backdrop of the Milky Way. The word ‘surreal’ comes to mind.

That there is something amazingly profound about looking up in the sky and seeing the Milky Way with its stellar population and diffuse gas structures. The Magellanic Clouds give you good company, and the alignment of four planets in the sky (go figure!) adds the right touch to my story – that Mike and I upheld the spirit of astronomy and astrophysics by being there and looking at those clusters with our own eyes, while they were being studied on the grand canvas of the universe. We utilized our intuition, not an algorithm, to determine how long is good enough to see a cluster, or whether our time was better spent studying another cluster. I believe that part of what makes us astronomers is this very intuition. It is in the same spirit of the field that we should consider what we miss by moving to an automated version of astrophysics.

If and when astronomy moves in that direction, I for one, will miss the empanadas, the alpacas and this great opportunity to take some clicks of my own. It is beautiful up there.

About Gourav Khullar

Second year astro grad student at UChicago. Currently working on galaxy clusters and gravitational lensing statistics of sky surveys. Outside work, I love to play basketball, talk science and travel.


  1. ” We utilized our intuition, not an algorithm, to determine how long is good enough to see a cluster, or whether our time was better spent studying another cluster.”
    Good thing that the next task wasn’t to search for a safe and warm place for the herd. 🙂

    Awesome read and clicks!

  2. The more observation with telescopes like this the better. That’s what astronomy is all about despite the importance of theory and simulation . And want a place to do it at the top of the world. I’m very jealous I’m not a professional Astronomer. Just a pity there aren’t many more such telescopes . Congrulations and thanks for sharing your experience.

  3. Wow.. Great article Gourav bhaiya…i loved the way you’ve shared your experience…n so great pics n interesting work you’ve being doing.. :-D…. Nd in India… Tends are changing… I have a few friends of mine who are planning to pursue astrophysics..n their parents are supporting !!.. So people here have started seeing the cosmos science as a major field…they’ve started giving it importance.. It had caught some attention…As for me.. Even i have found in myself a great interest for the study of our universe…. Still confused for following it as a career yet.. But hope you’ll be there to help me 😉 … Nyways… Great article!!!… Congrats for your new experience..! 😉


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