TOP HAT

The instrument was designed to operate on the top of a high altitude balloon, hence it's name. From this location, the experiment could efficiently observe using a clean beam with extremely low contamination from the far side lobes of the instrument beam. The experiment was designed to scan a large portion of the sky directly above it and to map the anisotropy of the Cosmic Microwave Background (CMB) and thermal emission from galactic dust. The instrument used a one-meter class telescope with a five-band single pixel radiometer spanning the frequency range from 150-600 GHz. The radiometer used bolometric detectors operating at ~250mK.

Balloon launched on: 1/4/2001 at 7:08 utc
Launch site: Williams Field, McMurdo Station, Antarctica  
Balloon launched by: National Scientific Balloon Facility (NSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon 800.000 m3 - SF3-29.47-.8/.8/.8-NA-TP
Balloon serial number: W29.47-2X-41
Flight identification number: 494N
End of flight (L for landing time, W for last contact, otherwise termination time): 1/31/2001 at 2:26 utc
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): ~ 27 d
Landing site: Bottom payload impact at 85º 5.66' S 164º 52.15' W. Balloon and telescope impact 85º 8' 54" S, 164º 26' 31" W. Antarctica
Payload weight: 2934 lbs
Overall weight: 4071 lbs

• TOP HAT website NASA - Goddard Space Flight Center
• The long duration flight of the TopHat experiment Proc. of SPIE Vol. 4857
• The MSAM/TopHat Program of Anisotropy Measurements Astrophysical Letters and Communications, Vol. 32, p.273