The TopHat experiment: A balloon-borne instrument for mapping millimeter and submillimeter emission

• Main Authors: Silverberg, R.F., Cheng, E.S., Aguirre, J.E., Bezaire, J.J., Crawford, T.M., Meyer, S.S., Bier, A., Campano, B., Chen, T.C., Cottingham, D.A., Sharp, E.H., Christensen, P.R., Cordone, S., Timbie, P.T., Dame, R.E., Fixsen, D.J., Kristensen, R.J.K., Nørgaard-Nielsen, Hans Ulrik, Wilson, G.W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2005
• Subjects: cosmic microwave background; cosmology : observations; galaxies : general; balloons; Antarc*; Antarctica
• Online Access: https://orbit.dtu.dk/en/publications/88dcfbd0-28dc-4de3-b704-781c31992c4c; https://backend.orbit.dtu.dk/ws/files/126662462/Silverberg_2005_ApJS_160_59.pdf

The TopHat experiment was designed to measure the anisotropy in the cosmic microwave background radiation on angular scales from 0.degrees 3 to 30 degrees and the thermal emission from both Galactic and extragalactic dust. The balloon-borne instrument had five spectral bands spanning frequencies from 175 to 630 GHz. The telescope was a compact, 1 m, on-axis Cassegrain telescope designed to scan the sky at a fixed elevation of 78 degrees. The radiometer used cryogenic bolometers coupled to a single feed horn via a dichroic filter system. The observing strategy was intended to efficiently cover a region 48 degrees in diameter centered on the south polar cap with a highly cross-linked and redundant pattern with nearly uniform sky coverage. The Long Duration Balloon flight over Antarctica in 2001 January surveyed about 6% of the sky. Here we describe the design of the instrument and the achieved in-flight performance and provide a brief discussion of the data analysis.