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Solar Observing at South Pole (1Mar95) (from NSO, NOAO Newsletter No. 41, 1 March 1995) South Pole has unique advantages for many types of astrophysical observations. This was recognized and advocated long ago by Martin Pomerantz of the Bartol Research Foundation and quickly exploited by solar astronomers starting in 1979. Other astronomers eventually appreciated the advantages, and the site is now a beehive of astrophysical activity. Helioseismology has been the main solar work done at South Pole. A group of researchers from NSO, Bartol, and NASA mounted their fifth helioseismology observing campaign during the current austral summer. The advantages of the site for helioseismology include a very slowly changing solar altitude, freedom from diurnal interruptions, exceptionally clean air, and a high duty cycle (weather permitting). The main disadvantages are the cold temperature and fairly poor seeing quality. Observing started on November 20 and will continue until the end of January. This season the weather has been unusually good. To date, more than 50 days of data have been obtained with a usable image duty cycle of more than 70%. A 35-day sequence has a duty cycle of nearly 80%. The area around South Pole is divided into various use sectors. For example, air sampling is done in the clean air sector up wind of all other activity. Most astrophysical work is done in the 'dark sector.' We set up an observing site, shown in the figure, on the other side of the pole from the light dark sector about 2.1 miles from the Amundsen-Scott station. This distance is as close as one can get and still be free from pollution from the station and especially aircraft contrails generated near the ground. To the right in the figure is our 10-cm telescope set up on top of a mound of snow and protected by a wind screen. About 20 meters downwind, to the left of Andrew Jones in the figure, is a small building that is buried under a half meter of snow in a trench. The building contains electronics for controlling the experiment and space for a small kitchen and emergency shelter. A further 130 meters downwind is a generator for power. The goals of our observing project included exploring the spectrum of solar oscillations in ways that will not be done by the upcoming two major helioseismology projects (the GONG project, expected to start network operations in mid-1995, and the Solar Oscillations Imager, to be launched on SOHO late in 1995). In particular, we are exploring the high frequency end of the spectrum of solar oscillations by recording an image every 42 seconds. We are also trying to make localized inferences about the structure beneath activity such as sunspots and to detect activity before it emerges. In this regard, the Sun favored us by producing a nice active region in a good position several days after we started observing. The instrument has a 1K 1K ccd and thus provides four times the resolution of GONG and is comparable with SOI, an important feature for localized helioseismology. (However, seeing at South Pole is rather poor and limits resolution to a few arc seconds.) The spectrum of solar oscillations changes slightly during the course of the solar cycle. We are interested in characterizing the spectrum changes at this phase of the solar cycle and also prior to the start of the two big projects. A pleasant event that occurred in early December was the dedication of the nighttime astrophysical facility to Martin Pomerantz in recognition of his pioneering role in almost all fields of Antarctic astrophysics. A large crowd braved the -25x outside weather to listen to brief (!) remarks by John Lynch, Aeronomy and Astrophysics Program Manager at the NSF, Neal Lane, Director of the NSF, Neal Sullivan, Director of the Office of Polar Programs, Jack Harvey, representing Martin's co-workers and colleagues, and Martin Pomerantz. By my watch, all the remarks were completed in 12 minutes. This must be a record for an observatory dedication. The reception at the station galley afterward was much more extended. The NSO-Bartol-NASA team is gearing up for a rapid reduction of the 1/4 terabyte of raw data obtained during this campaign. We expect to continue to find new things about the Sun from this data as has been the case for our previous four campaigns. We were also excited by the other astrophysical programs underway at South Pole, but that is another story. [Photo not included] NSO/Bartol/NASA solar observing site 2.1 miles from the South Pole. The telescope is mounted on an alt/az (= RA/dec) tracking platform atop a mound of snow to the right in the photo. The control electronics and observing room are in a building buried under the snow to the left. The Amundsen- Scott Station is on the horizon behind Andrew Jones. Jack Harvey
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