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3mm amplitude test

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

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  1. 3mm amplitude test by Cheng-Jiun Ma

  2. Observation • Source : Orion SiO • Frequency: 86.243GHz • 256 channels within 64MHz bandwidth • Ant 3 & Ant 4 • no Tsys correction • fixed attenuations

  3. off source Cross correlation of ant 3 and ant 4

  4. Possible reason • System temperature fluctuation • Variation of gain in receivers/antenna • Inteferometry phase fluctuation • Pointing accuracy

  5. central band on source central band off source autocorrelation signal and noise

  6. 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.

  7. Second observation • High time resolution (0.3 sec) • cross correlation only • 32 channels with 128MHz bandwidth

  8. Third observation • after adjust the pointing • do bore sight track and ½ power track alternatively • 10 sec averaging

  9. The rms of the normalized amplitude is higher when the source is at 1/2 power.

  10. Observation on 3.14 • Source: Orion SiO • Frequency: 86.243GHz • With 32 channel in 128MHz band • Ant 4 autocorrelation only

  11. normalized amplitude v.s. time

  12. rms of normalized amplitude v.s. time

  13. Autocorrelation data The autocorrelation amplitude rms is also higher when source is at half-power

  14. The main reason for the variation

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