2009-02-12 ALMA Calibration Group Telecon Agenda and Minutes

ALMA Calibration Group Telecon
  • Date: February 12, 2009 (Thursday)
  • Time: 16:00 UT (NOTE: Non-standard time)
  • Duration: 1.0 hr
  • USA Toll Free Number: 877-940-1273
  • International: +1-517-466-6602
  • Passcode: 5 6 6 4 7 9 4
  • Leader: JeffMangum

Table of Contents:

Agenda and Minutes

NOTE: Discussion from the telecon is shown in italic.


  1. Denis Barkats
  2. Fabio Biancat Marchet
  3. Stuartt Corder
  4. Bill Dent
  5. Darrel Emerson
  6. Antonio Hales
  7. Richard Hills
  8. RobertLucas
  9. JeffMangum
  10. Bojan Nikolic
  11. Dick Sramek
  12. Gie Han Tan
  13. BaltasarVilaVilaro
  14. Nick Whyborn
  15. Pavel Yagoubov

Amplitude Calibration Device Development Status

Richard will lead a discussion on the status of the amplitude calibration device (ACD). There have been three areas of progress over the past couple of months:

  1. Additional hot loads of the prototype design have been ordered from RAL so that the first 7 calibration devices will have these on them when they are delivered to Chile.
  2. A draft of the preliminary report from Bern on the shroud plus pyramid design was received. The shroud does improve the thermal but does not have much effect on the backscatter which remains higher than we require at frequencies of order 100 GHz and below.
  3. Pavel has provided a plan for the development of the production loads and an initial design proposal.
    • RH: Note that use of this load below 85 GHz was removed as a requirement. Plan allows for use down to Band 1. Are there any compromises in the design with allowing for operation down to Band 1?
    • PY: Perhaps. Will need to test/simulate this.
    • RH: Concerned about air flow and use at low elevations. Are we concerned about this?
    • PY: Simulations due by mid-April should shed some light on what can be accomplished.
    • JM: Would rather not set a low-elevation limit at this time. Wait for simulation results.
    • RH: Why can't an actual measurement be made, rather than relying on simulations?
    • GHT: Can do IR camera measurements of a prototype.
    • PY: Would like to have a meeting/workshop at the end of phase 1 so that we can decide on a design. Phase 1 should be done in May 2009. Is this a good thing to do?
    • RH: Yes, as long as information on design/testing results are distributed before the meeting.

RH brought up the issue of non-linearity in receiver response and how we deal with it (which is follow-on to some questions asked by Pavel on this subject). Suggests that someone revisit past analyses of this aspect of amplitude calibration (i.e. memos by Stephane Guilloteau). Volunteers Stuartt Corder to take on this task.

Ancilliary Measurement Devices

Weather Station (P,T,RH,Ws,Wd) Instrumentation

The first production weather station has recently been installed on holography tower 2 and is undergoing tests at the OSF by AIV.

Date of Next Phone Meeting

Tentative date for next ALMA Calibration Group telecon will be 2009, March 12th 15:00 UT.

-- JeffMangum - 09 February 2009
Topic revision: r2 - 2009-02-12, JeffMangum
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