2006-07-13 ALMA Calibration Group Examples Document Review


Table of Contents:


Attendees

  1. EdFomalont
  2. JeffMangum
  3. Shigehisa Takakuwa
  4. Dick Sramek
  5. BaltasarVilaVilaro
  6. AlWootten


Review of Location Calibration Example

  • Baltasar Vila Vilaro :
    • Current version required reorganization. See CalExamples wiki for detailed comments.
    • Where does 71 micron come from? Mark aludes to an ALMA memo where the minimum baseline stability is stated as less than 100 micron. Apparently the 65 micron spec is a bit less than 100/sqrt(2).
  • Ed Fomalont :
    • Does one want to do baseline measurements with the WVR corrections enabled? Note that zero-point stability over 10s of minutes is required for WVR correction to not corrupt baseline measurements. Consensus was that WVRs should not be used during baseline observations. This then means that good weather is required for baseline measurements. From the current STI measurements, a 10 km baseline has a 400 micron path fluctuation during best quartile weather conditions on Chajnantor (175 micron for a 1km baseline) on timescales of 1000sec (100sec).
    • Note the need to do the K-term determination.
    • Antenna position stability requirement of 65 micron is over a timescale of 2 weeks (a fortnight). Therefore, to zeroth order, baseline runs will be required at least every two weeks in the beginning.
    • Note that this calibration interacts strongly with the antenna and electronic delay calibration.
    • It should be possible to couple pointing and baseline measurements done following an antenna move.


Review of Antenna and Electronic Delay Calibration Example

  • Baltasar Vila Vilaro :
    • Text following table in point 3 of section 1 needs clarification. Not clear what is being said.
    • Perhaps "Goals" section parts 2 onward should be made into a "Technique" section.
    • See comments on CalExamples wiki page.
  • Ed Fomalont :
  • Jeff Mangum :
    • Do the instrumental delays described implicitly include antenna-based (mechanical) delay contributions? If so, this should be mentioned early in the document.
    • The measurements required to make this calibration are a modification of a general phase calibration measurement. Can this example document be subsumed into the Phase Calibration example document? Concensus was no. It is sufficiently different as to be able to stand on its own.


Next Review

On 2006/08/03 we will review the beam and total power calibration example documents.


-- JeffMangum - 13 Jul 2006

This topic: ALMA > WebHome > AlmaSci > AlmaCal > CalExamples > CalExampleReview20060713
Topic revision: 2006-07-13, BaltasarVilaVilaro
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