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lbaops:lbamar2008:vx014a [2008/07/23 15:22]
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lbaops:lbamar2008:vx014a [2015/12/18 16:38] (current)
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 Parkes, Mopra, Ceduna, Hobart, ATCA observed. ​ Parkes, Mopra, Ceduna, Hobart, ATCA observed. ​
  
-ATCA has a pecular pattern in the rates. See figure [[http://venice.atnf.csiro.au/​~dod052/​RATES.VX014.PS|RATES.VX014.PS]] Is has an amplitude of about 2mHz and a cycle of 1 hour. I wonder if it is to do with the array calibration?​ Is that on that time scale?+ATCA has a pecular pattern in the rates. See figure [[ftp://ftp.atnf.csiro.au/​pub/​people/​vlbi/​incoming/​vx014a/​RATES.VX014.PS|RATES.VX014.PS]] Is has an amplitude of about 2mHz and a cycle of 1 hour. I wonder if it is to do with the array calibration?​ Is that on that time scale?
  
-CEDUNA has awful phases and poor SNR. The delays are higher and more changeable. The changes in the phase and delay difference between the IFs and the polarisations are significant with times scales of about 1 hour.  See [[http://venice.atnf.csiro.au/​~dod052/​DELAYS.VX014.PS|DELAYS.VX014.PS]]. There was some data loss. There is no Tsys data. +CEDUNA has awful phases and poor SNR. The delays are higher and more changeable. The changes in the phase and delay difference between the IFs and the polarisations are significant with times scales of about 1 hour.  See [[ftp://ftp.atnf.csiro.au/​pub/​people/​vlbi/​incoming/​vx014a/​DELAYS.VX014.PS|DELAYS.VX014.PS]]. There was some data loss. There is no Tsys data. 
  
 MOPRA polarisation was reported as very unstable. However it seems to be stable, but it is very high at 40%! (this will break the linear solution model used by AIPS.) The default tsys data has an incorrect index. Furthermore the values in the log file (100 for R and 30 for L) are not reflected in the data (as R and L are the same amplitudes). ​ MOPRA polarisation was reported as very unstable. However it seems to be stable, but it is very high at 40%! (this will break the linear solution model used by AIPS.) The default tsys data has an incorrect index. Furthermore the values in the log file (100 for R and 30 for L) are not reflected in the data (as R and L are the same amplitudes). ​
  
-PARKES is has, at times, a relatively high phase between RR and LL. See [[http://venice.atnf.csiro.au/​~dod052/​RRLL.VX014.PS|RRLL.VX014.PS]]+PARKES is has, at times, a relatively high phase between RR and LL. See [[ftp://ftp.atnf.csiro.au/​pub/​people/​vlbi/​incoming/​vx014a/​RRLL.VX014.PS|RRLL.VX014.PS]]
  
 HOBART ... no problems! E-W Solutions worked. HOBART ... no problems! E-W Solutions worked.
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 ATLOD forces the AN table to be mount type 0, Polarisation Types X and Y (for ATCA). This needs fixing. It can be corrected inside AIPS with TABED. ​ ATLOD forces the AN table to be mount type 0, Polarisation Types X and Y (for ATCA). This needs fixing. It can be corrected inside AIPS with TABED. ​
  
-After parallel delay, phase and rate solutions, & the left to right delay and phase solutions, the bandpasses look reasonably sensible. The parallel hand phases and amplitudes are flat with zero phase, the cross hand phases are also flat and the phases are to be solved in the polarisation calibration. It would be reasonable, if Ceduna was not such a mess, and if Mopra was not so large. See [[http://venice.atnf.csiro.au/​~dod052/​POSSM.POL.PS|POSSM.POL.PS]]+After parallel delay, phase and rate solutions, & the left to right delay and phase solutions, the bandpasses look reasonably sensible. The parallel hand phases and amplitudes are flat with zero phase, the cross hand phases are also flat and the phases are to be solved in the polarisation calibration. It would be reasonable, if Ceduna was not such a mess, and if Mopra was not so large. See [[ftp://ftp.atnf.csiro.au/​pub/​people/​vlbi/​incoming/​vx014a/​POSSM.POL.PS|POSSM.POL.PS]]
  
  
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 All images match what would be expected. All images match what would be expected.
  
-Calibration of the polarisation D-terms, based on the Stokes I images, with LPCAL. See [[http://venice.atnf.csiro.au/​~dod052/​Mopra_D-Term_resid.ps|Mopra_D-Term_resid.ps]] for the pre and post fit of the D-terms to be Mopra data (on the complex plane). Ratio comes from ~0.5 to 0.05. Still not very good, not surprisingly,​ but better than I expected.+Calibration of the polarisation D-terms, based on the Stokes I images, with LPCAL. See [[ftp://ftp.atnf.csiro.au/​pub/​people/​vlbi/​incoming/​vx014a/​Mopra_D-Term_resid.ps|Mopra_D-Term_resid.ps]] for the pre and post fit of the D-terms to be Mopra data (on the complex plane). Ratio comes from ~0.5 to 0.05. Still not very good, not surprisingly,​ but better than I expected.
  
-LPCAL works fine, although the residuals will be large. ​ [[http://venice.atnf.csiro.au/​~dod052/D-term_Solutions.eps|D-term_Solutions.eps]] is the IF1 and 2 (connected line) for R and L for each antenna (based on 3C273, but they are a few percent from each other based on each source, and polarised/​unpolarised). ​+LPCAL works fine, although the residuals will be large. ​ [[ftp://ftp.atnf.csiro.au/​pub/​people/​vlbi/​incoming/​vx014a/D-Term_Solutions.eps|D-Term_Solutions.eps]] is the IF1 and 2 (connected line) for R and L for each antenna (based on 3C273, but they are a few percent from each other based on each source, and polarised/​unpolarised). ​
  
 Conclusions:​ Conclusions:​
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 -  Ceduna L, IF 1 and 2 are quite different (4%), which relates to the awful Cross-Pol bandpass. ​ -  Ceduna L, IF 1 and 2 are quite different (4%), which relates to the awful Cross-Pol bandpass. ​
  
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 +PCAL, which is not recommended for VLBI, does not work very well. Further work required. ​
 +
 +Finally the results are presented in [[ftp://​ftp.atnf.csiro.au/​pub/​people/​vlbi/​incoming/​vx014a/​pcln.eps|pcln.eps]],​ which shows 3C273, 3C279 and 1921-293 & 1934-638, which has no detectable polarised flux.  Shown are the LBA results (B&W) and the MOJAVE results at similar epochs, where they exist. The same regions are showing polarised flux.
  
  
  
lbaops/lbamar2008/vx014a.txt · Last modified: 2015/12/18 16:38 (external edit)