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 off source central band on 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

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

11. ca34 Bore sight½ power 12312 AVG8.907.576.714.234.04 N_RMS0.070.060.070.220.14 The rms of the normalized amplitude is higher when the source is at 1/2 power.

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

13. normalized amplitude v.s. time

14. rms of normalized amplitude v.s. time

15. aa44 3.14off source bore sight½ power 1212 avg551.1814.0511.706.615.83 n_rms0.080.140.300.43 Autocorrelation data The autocorrelation amplitude rms is also higher when source is at half-power

16. The main reason for the variation System temperature The variance of the off-source-channel amplitude is much smaller than that of the on-source amplitude. gain receiver antennae The variance of the amplitude of the source on the peak is different from that of the source on the half power, which should not happen if the variation is caused by the antennae gain. phase 1.The product of the autocorrelation data is highly consistent with the cross correlation data. 2.Sometimes, the phase is quite stable but the amplitude still oscillates a lot. pointing tracking error 1.The error showed on the ACC system is not larger than 3 arcsec. 2.We are going to check this by mounting the optical telescope on the antennae. drift caused by the atmosphere There is a small time scale, about 10 seconds, for variation of the autocorrelation amplitude. The spatial scale of the random motion is about 10 arcsec.