Entries by Elizabeth George

It's early November--the start of summer at the South Pole, which means a large crew of SPTpol folks are headed down to the pole to start upgrade work on the camera. In fact, our first wave of summer folks arrived at the South Pole yesterday to finish up polarization calibration of the current receiver configuration before we take it apart for upgrades. Special thanks to winterovers Cynthia Chang and Nicholas Huang, who have spent the last 9 months at the South Pole running the telescope, taking data, and fixing any unexpected problems that cropped up. In the next few days (after they hand off telescope duties to the summer crew), they will be headed home for a well-deserved vacation.

We have several upgrades slated for this season. We are changing our observing bands slightly and replacing a subset of detectors to optimize sensitivity, improving the hold time of our cryogenic refrigerator, adding more co-moving ground shields to the telescope, and updating some of our readout so that we have the option of using digital active nulling (DAN) for readout if we want. A group of SPTpol students and post-docs attended SPIE this summer, and we published proceedings discussing the current state of the instrument, as well as the planned instrument upgrades for this summer. If you are interested in the more technical aspects of the receiver (and this summer's upgrades), check out the proceedings below.

Austermann, et al. 2012 - SPTpol: an instrument for CMB polarization measurements with the South Pole Telescope
de Haan, et al. 2012 - Improved Performance of TES Bolometers using Digital Feedback
George, et al. 2012 - Performance and on-sky optical characterization of the SPTpol instrument
Henning, et al. 2012 - Feedhorn-coupled TES polarimeter camera modules at 150 GHz for CMB polarization measurements with SPTpol
Sayre, et al. 2012 - Design and characterization of 90 GHz feedhorn-coupled TES polarimeter pixels in the SPTpol camera
Story, et al. 2012 - South Pole Telescope Software Systems: Control, Monitoring, and Data Acquisition

It's going to be a busy season, but we're all excited about the instrument and the tasks ahead for the summer.

The American Museum of Natural History has created a nice video about the South Pole Telescope. The video was filmed in November 2011, during the Antarctic season in which we deployed the new camera, SPTpol, on the telescope. It features SPT scientists John Ruhl, James T Sayre, Keith Vanderlinde, J. Dana Hrubes, and Daniel Luong-Van.

"The icy South Pole desert is a harsh and desolate landscape in which few life-forms can flourish. But the extreme cold and isolation are perfect for astronomical observations. Taking advantage of the severe conditions, scientists are using the new South Pole Telescope—the largest ever deployed in Antarctica—to observe the oldest light in the Universe, the cosmic microwave background (CMB)."

We started hoisting the optics/receiver cryostats into the telescope cabin at 9am on Jan 25, 2012. A mere 39 hours later at 11pm on Jan 26th we achieved first light with SPTpol! Below are detector timestreams as we scan across RCW38, one of the many calibration sources we use. In the next few weeks, we'll be working hard to characterize our instrument. We will make maps of calibration sources, characterize detector response and time constants, map our beams, get the telescope in really good focus for the winter, and measure our detector polarization angles. There is a lot to do to get ready for the observing season, but we're all really excited that we can see astrophysical objects with our new instrument! Congratulations and thanks to everyone who worked so hard to make this instrument possible. Stay tuned for updates!

Putting a new camera on the telescope means taking the old one off. The SPTsze camera was on the telescope for 5 years, and with it we were able to make an excellent CMB temperature map of 2500 square degrees of the southern sky. Using that data, we've discovered many galaxy clusters, published power spectrum results, and generally accomplished a lot of science. It is an amazing camera, and as excited as we are about the new polarization camera, we're sad to see it go. Thanks to everyone who worked on SPT and the SPTsze camera for 5 great years of observations. Hopefully the new camera will be just as awesome.

The Prime Minister of Norway is visiting the South Pole this week to celebrate the centennial of Amundsen reaching the South Pole on Dec. 14, 1911. Last night the Prime Minister gave a speech in the galley, highlighting how the international science that occurs at the South Pole is an inspiration to the world. He thanked the South Pole community for hosting him, and commented that though a warm welcome and hospitality are always appreciated, it is especially nice at the South Pole.

Today, the Prime Minister and his delegation toured around all the science sectors on cross country skis. They stopped by SPT and toured the Dark Sector Lab, where Brad Benson and Jamie Bock gave tours of SPT and BICEP2.

SPT is getting a new guard ring around the primary mirror to allow a cleaner view of the sky for the new polarization camera. Work has been going on for awhile now, and today the heavy welders started welding the support structure to the telescope. The guard ring will extend the primary mirror so that it measures 12m in diameter, though the illuminated area of the primary will remain on the precision inner part of the primary.

This season we are installing a new camera on the south pole telescope. Summer work at SPT has been going on for the last month, with teams deployed for installing a new guard ring around the primary, modifying the radiation shields in the optics cryostat to accept new filters, and setting up our new DfMUX readout system. They've accomplished a lot so far this summer, and hopefully you'll see some posts from them soon. I arrived at the south pole 2 days ago with the rest of the receiver team (Abby, Brad, and Jason), and our job for this summer is to assemble and test the new receiver. The new receiver is called SPTpol, and it is a polarization sensitive camera with 588 150GHz pixels (1176 TES bolometers) and 192 90 GHz pixels (384 TES bolometers).

The first thing we did upon arriving (after a good night's sleep of course) was head out to the telescope and unpack the focal plane parts that we had hand-carried to pole. Abby, Jason, and I each had a pelican case full of delicate detectors that we hadn't let out of our sight for 5 days. It was a relief to finally get them to the receiver lab where they would be safe. Once unpacked, we decided to test-assemble the focal plane parts that we had with us to ensure that everything fit as expected.





Even though all of the parts had been tested individually, and we had a test cooldown in the states with most of the focal plane parts, this was the first time that we had put all of the final focal plane parts together. Luckily, everything fits as designed and the focal plane looks great so far.





We are due to get the rest of the receiver parts through the cargo system in the next few days, at which point we can start assembling the cryostat and put the focal plane inside. In the meantime, the entire SPT crew continues to work hard on the many other tasks required to deploy the new camera.