2005-05-12 ALMA Calibration Group Telecon Agenda and Minutes
ALMA Calibration Group Telecon
  • Date: May 12, 2005 (Thursday)
  • Time: 15:00 UT
  • Duration: 1.0 hr
  • USA Toll Free Number: 1-877-919-7148
  • International: +1-203-566-1039
  • Passcode: 5 1 0 4 6 8
  • Leader: JeffMangum

Table of Contents:

Complete List of Action Items

Action Items from Last Telecon

Assigned To Due Date Description State Notify  

Agenda and Minutes

NOTE: Discussion from the telecon is shown in italic.


  1. BaltasarVilaVilaro
  2. Matt Carter
  3. EdFomalont
  4. JimGibson
  5. Richard Hills
  6. MarkHoldaway
  7. Ryohe Kawabe
  8. RobertLucas
  9. JeffMangum
  10. JohnRicher
  11. AlisonStirling
  12. ThomasWilson
  13. AlWootten

Calibration Plan

Thanks to those who contributed to the recent significant revision to the Calibration Plan. More work needs to be done on this document before it can be considered "done". Recall that we have organized ourselves into small groups concentrate on specific sections of the plan. I list below these groups, with the "lead volunteer" denoted in bold:

  1. Amplitude and Flux Calibration (Welch, Butler, Carter, Gibson, Holdaway, Mangum, Martin-Pintado, Kawabe, Wilson)
  2. Phase Calibration (Hills, Holdaway, Mundy, Richer, Stirling, Wootten)
  3. Bandpass Calibration (Guilloteau, Bacmann)
  4. Polarization Calibration (Myers, Holdaway, Laing)
  5. Pointing Calibration (Mangum, Lucas, Holdaway)
  6. Antenna Location Calibration (Conway, Wright, Morita)
  7. Antenna and Electronic Delay Calibration (Lucas)
  8. Optics Calibration (Butler, Saito)
  9. Total Power Calibration (Holdaway, Mangum, Mundy, Kawabe)
  10. Primary Beam Calibration (Holdaway, Wilson)
  11. Archiving and Accessing Calibration Quantities (Lucas, Mangum)

With regards the updates to the individual Calibration Plan chapters, with the exception of the changes identified through the Action Items, the Calibration Plan appears to be in pretty good shape.

All group members should read through the current version of the plan and suggest changes.

Calibration Category Issues

The following is a list of "calibration categories" which JeffMangum suggests we should discuss on a regular basis (note the similarity to the Calibration Plan sections). Please suggest additions/deletions to the following list.

  1. Amplitude and Flux Calibration
  2. Phase Calibration
  3. Bandpass Calibration
  4. Polarization Calibration
  5. Pointing Calibration
  6. Antenna Location Calibration
  7. Antenna and Electronic Delay Calibration
  8. Optics Calibration
  9. Total Power Calibration
  10. Primary Beam Calibration
  11. Archiving and Accessing Calibration Quantities

Please suggest topics of discussion for the next telecon.

Report from WVR PDR (Hills)

  • Review went well.
  • Radiometer passed all tests.
  • Minor problem with beam quality in Dicke radiometer design that will be fixed.
  • Recommendation to go with single-channel Dicke switched radiometer design.
  • No facility for sideband separation.
  • Will test Dicke switched system on an existing array.
  • Wootten asked if the use of these devices to measure anomolous refraction correction was addressed.
    • Hills: Yes, but management suggested that since it is not part of the specification, it is not relevant to this design.
    • Holdaway: Crossing time of antenna is about 1 second. Must make measurement over timescales much less than 1 second (like 0.1 second or smaller).
    • Hills: Since anomolous refraction correction must be fed-forward into drive, this is a complication. It is not clear on what timescale these corrections will need to be applied.
    • Holdaway: There are post-measurement corrections being developed.

Amplitude Calibration Subsystem Development Reports

  • Berkeley Absolute Flux Calibration System (JimGibson)
    • _Continue to work on data analysis of measurements made at BIMA last fall.
    • Manufacturing equipment to aid with waveguide loss measurements at CU. Hope to finish in next month or two.
  • Semi-Transparent Vane (STV) Calibration System (ThomasWilson)
  • Multi-Load (ML) Calibration System (Matt Carter)
    • Finished lab measurements of RAL load, writing report (done in a few weeks).
    • +-1% (+-0.5 C) accuracy on temperature up to 90C (83, 103, 300, 350 GHz).
    • Report available early next week.
    • Will be difficult to design a multi-load system that meets spec due to the use of a grid.
    • Two load system will meet spec.

Weather (Ancilliary) Measurement Devices

At the 2004-11-09 telecon AlWootten started a discussion of the state of the "ancilliary" measurement devices (generally, weather measurement devices). AlWootten pointed out that the Project will soon go through a "rebaselining" exercise, which will involve a reorganization of the scope of the Project. Since ancilliary devices are not currently funded, we need to make the case for the necessary ancilliary devices now. Jack Welch suggested that an oxygen sounder would be very useful to have. AlisonStirling has posted her review of oxygen sounders to the CalAncillary wiki.

A revised version of the "ancilliary" measurement devices specifications and requirements document has been posted by JohnRicher for comment. Final version will be submitted by 2005/05/20.

Date of Next Phone Meeting

The next ALMA Calibration Group telecon will be 2005, June 9th 15:00 UT. This is our "normal" meeting time (15:00 UT on the second thursday of each month).

-- JeffMangum - 12 May 2005
Topic revision: r4 - 2005-06-07, JeffMangum
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