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3mm amplitude test. by Cheng-Jiun Ma. Observation. Source : Orion SiO Frequency: 86.243GHz 256 channels within 64MHz bandwidth Ant 3 & Ant 4 no Tsys correction fixed attenuations. off source. Cross correlation of ant 3 and ant 4. Possible reason. System temperature fluctuation
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3mm amplitude test by Cheng-Jiun Ma
Observation • Source : Orion SiO • Frequency: 86.243GHz • 256 channels within 64MHz bandwidth • Ant 3 & Ant 4 • no Tsys correction • fixed attenuations
off source Cross correlation of ant 3 and ant 4
Possible reason • System temperature fluctuation • Variation of gain in receivers/antenna • Inteferometry phase fluctuation • Pointing accuracy
central band on source central band off source autocorrelation signal and noise
Compare the product of autocorrelation amplitude of ant3 & ant4 with the cross correlation amplitude. The amplitude variation comes from the single dishes, and not because of the inteferometry phase.
Second observation • High time resolution (0.3 sec) • cross correlation only • 32 channels with 128MHz bandwidth
Third observation • after adjust the pointing • do bore sight track and ½ power track alternatively • 10 sec averaging
The rms of the normalized amplitude is higher when the source is at 1/2 power.
Observation on 3.14 • Source: Orion SiO • Frequency: 86.243GHz • With 32 channel in 128MHz band • Ant 4 autocorrelation only
Autocorrelation data The autocorrelation amplitude rms is also higher when source is at half-power