In:
Review of Scientific Instruments, AIP Publishing, Vol. 49, No. 4 ( 1978-04-01), p. 440-448
Abstract:
We have developed a 33-GHz airborne radiometer system to map large angular scale variations in the temperature of the 3 K cosmic background radiation. A ferrite circulator switches a room-temperature mixer between two antennas pointing 60° apart in the sky. In 40 min of observing, the radiometer can measure the anisotropy of the microwave background with an accuracy of ±1 mK rms, or about 1 part in 3000 of 3 K. The apparatus is flown in a U-2 jet to 20 km altitude where 33-GHz thermal microwave emission from the atmosphere is at a low level. A second radiometer, tuned to 54 GHz near oxygen emission lines, monitors spurious signals from residual atmospheric radiation. The antennas, which have an extremely low side-lobe response of less than -65 dB past 60°, reject anisotropic radiation from the earth’s surface. Periodic interchange of the antenna positions and reversal of the aircraft’s flight direction cancel equipment-based imbalances. The system has been operated successfully in U-2 aircraft flown from NASA-Ames at Moffett Field, CA.
Type of Medium:
Online Resource
ISSN:
0034-6748
,
1089-7623
Language:
English
Publisher:
AIP Publishing
Publication Date:
1978
detail.hit.zdb_id:
209865-9
detail.hit.zdb_id:
1472905-2
SSG:
11
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