[asac][almanews] ALMA Memo 461 Released

[Stacy Oliver]

ALMA MEMO #461 

The Amplitude Calibration System revisited 

S.Guilloteau (IRAM / ESO) 
A.Bacmann (ESO)

2003-09-16

Keywords: Amplitude Calibration, Receiver Saturation 

Different strategies of use of a semi-transparent device combined with
two temperature
loads for calibration are explored. It is shown that a system with an
ambient load, a hot
(100 Celsius or so) load, and a semi-transparent grid with 50 %
transmission allows to 
reach a 1 % accuracy on the receiver gain even in presence of
saturation. The best precision
requires a device which offers the 5 major combinations: Sky,
Sky+Ambient, Sky+Hot, Ambient,
Hot. If saturation is negligible, the system can be used as a standard
dual load calibration
device, with better accuracy. 

View a pdf version of ALMA Memo #461. 
http://www.alma.nrao.edu/memos/html-memos/alma461/memo461.pdf

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