The receiver team arrived earlier this week! Within in the next few days we'll shut down our calibration observations so that they can take instrument out of the telescope and do some maintenance and upgrade work on the detectors inside. As an added bonus, the station celebrates American Thanksgiving this weekend. That means an extra nice dinner on Saturday and some down time. There has been talk of going sledding on some of the large snow piles around the station. We've had some nicer weather this week and could actually see the telescope and the station from calibration source. It's still cold enough to freeze your breath though!There is one obvious question about SPT that I haven't answered yet: Why the South Pole? There are definitely easier places to build and work at a telescope. SPT observes the light from the CMB at millimeter wavelengths. At these wavelengths, any water in the atmosphere will absorb light, preventing much of it from reaching a telescope. Places at higher altitudes (like the South Pole) have less atmosphere and therefore more of the CMB light reaches the ground. Also, because it is so cold outside all of the water vapor in the atmosphere is frozen into ice crystals, which don't absorb millimeter light. On a sunny day, the air here actually sparkles! Combining the altitude and the cold, the South
And we thought Colorado had low relative humidity!
ReplyDeleteI love the photos!
Best,
Quyen
Hello Dr. Bender!
ReplyDeleteI appreciate the fact that you are sharing your experience with us from the South Pole. In this specific entry you addressed the location of the telescope which I found to be especially helpful. I understand now why this would be the best location to make observations of the CMB at millimeter wavelengths. Your explanation about the cold seems to be the most important factor when choosing the South Pole over places with equally high altitudes. What I mean by this is, I would assume that there are many places at high altitudes that would make a suitable site but one would not have the advantage of frozen water vapor to enable a clearer signal when collecting. Again, your explanation was extremely helpful and thank you for all of your hard work down there!
Sincerely,
Chandler Oley
Hi Chandler. There are other sites in the world that are suitable for millimeter wavelength observations, but the South Pole is one of the best. One other notable site is the Atacama Plateau in Northern Chile, which is one of the world's driest deserts. Another is Mauna Kea in Hawaii, but the number of days with the best atmospheric conditions is less. The South Pole has another advantage that I didn't mention before. There is only one sunrise and sunset a year. Whenever the sun rises, it stirs up atmospheric turbulence which adds noise to the data. At the South Pole, the atmosphere during the winter is not subject to these daily stirrings.
DeleteIf you were there when there was a dark night sky how would this affect your observations? JOEL
ReplyDelete