MMA Imaging and Calibration Group

Agenda/Minutes for meeting Tuesday, 3 Dec 2002 at 4:00pm EDT.

Date: 3 Dec 2002

Time: 4:00 pm EST (2:00 pm Socorro, 2:00 pm Tucson)

Phone: (434)296-7082 (CV SoundStation Premier Conference phone 3rd floor).

Past minutes, etc on MMA Imaging and Calibration Division Page
 
 

Agenda


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Science IPT News - Wootten

News from my point of view.
  Draft Level 3 Milestones were enhanced and revised during the face to face meeting 21 October in Tucson.
 
 The VertexRSI antenna is up! Photogrammetry is scheduled.
 
  • Project News - 
  • ASAC
    • Telecon 4 Dec
     ALMA Project Office moves to Old Ivy Road 18 December.
     Carla Beaudet and Galen Watts of NRAO/GB conduct RFI tests at Chajnantor 3 - 20 December 2002
     Software IPT Internal Design Review to be held in Garching 9-12 Dec 2002.
    Al will be at Caltech 9-12 Dec; WVR status is one item of interest.
      European ALMA workshop in Leiden 18-20 December 
  • AMAC Meering 22-23 Jan Socorro
  • ALMA Week 28 April Victoria (TBC)
  •  May 26/27 ALMA Board face-to-face (Europe)
    •  The NRAO Director is forming a Science Advisory Group, which will formulate an ALMA Science Workshop in conjunction with the Spring NRAO Users Committee Meeting. I have suggested an agenda but the details will be entirely up to the SAG.
     November 3/4 ALMA Board face-to-face (N.A.?)
     
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    Proposed correlator upgrade -- Wootten


    Please review memo 441 by Escoffier and Webber and be prepared with your comments  
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    Calibration - All


     See a summary of the meeting held Friday 15 November. Next meeting 13 December.
      Front End Issues for FrontEnd Review in Charlottesville
  • Cartridge Specifications  

    •                iv.       Stability

                               (1)       1e-4 rms over 0.1 sec interval

                               (2)       1e-4 rms over 1 sec interval

                                                                                           i)         Singledish 1 10-4 1s

                                                                                           ii)        Interferometer 3 10-3 1min

                                                                                           iii)       Diff 5 10-4 1 min meaning between two mixers same cartridge.

    In practice this spec for total power will be hard (impossible?) to achieve, but all studies have shown that it is important that it be met for ALMA to work as advertised, that is, to include the total power flux in its images.
    From the MAP experience, the CDL estimates that the IF contribution to this, from 1/f noise in the 4-12 GHz amplifier, is 10-4 1 sec alone. There will also be contributions from the effect of the cooling cycle in the dewar, affecting the gain of the mixer, and from the effect of the variation of LO power to the mixer, also affecting its gain. One alternative might be to temperature stabilize the mixer, applying heat to thermally stabilize it. This approach has been used for years, by centimeter wave receiver engineers in the 60s, and recently by BIMA (ALMA Memo No. 131). However, the cartridge space is limited, as is the cooling capacity of the dewar and this alternative only addresses one of the sources of gain variation in the front end. One alternative, used for the MAP receivers, might be to construct special purpose receivers for the total power antennas. In these receivers, which could be correlation receivers such as will be employed on the GBT, the signal is electrically switched at a rate of 1 kHz or so between two feeds. This would mean special receivers, not compatible with the rest of the array, for the total power antennas. One drawback is that this makes demands on dewar real estate; this might be acceptable for dedicated total power antennas if some bands were not deployed on those special purpose antennas. The feed separation is of course fixed, presumably at the same elevation; in this configuration the receiver samples a different set of spatial frequencies than in a nutating mode, or in a non-switched total power mode. What is the optimum separation for these two feeds? What are the effects of this receiver design on the images ALMA will make? If all bands will be deployed in this manner, there may need to be more than one set of total power dedicated antennas--is this acceptable, or are there some bands which are more critical than others? For spectral line on-the-fly mapping, we may wish to use four antennas from the interferometer array--is this acceptable?


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      See a summary of our MMAImCal discussion of 5 November on this topic.
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      Telecon minutes from last telecon. Next telecon 13 December 2002.
      List of the status of the reviews/reviewers. The key is: "C" - already submitted a review; "U" = submitted an unsolicited review; "Y" = agreed to review the memo; "N" - declined to review the memo; "NR" - no response. Links are provided to reviews; please consult the archive for subsequent discussions.
      1 - Memo 423 - Steve Myers (Y), Matt Carter (N), Geoff Blake (Y)
      2 - Memo 422 - Douglas Bock (Y), Lee Mundy (NR), Jeff Mangum (C) , Dave Woody (U) (Memo withdrawn)
      3 - Memo 427 - Robert Lucas (C) , Ed Fomalont (NR), Craig Walker (C)
      4 - Memo 372 - Jeff Mangum (C) , Larry D'Addario (C) , Mark Gurwell (N), Bryan Butler (U)
      5 - Memo 415 - Jose Cernicharo (NR), Mark Holdaway (C) , John Richer (Y)
      6 - Memo 404 & 403 - Mel Wright (N), Dave Woody (Y&C) , John Richer (Y)
      8 - Memo 402 - Richard Hills (Y), Peter Napier (NR)
      9 - Memo 352 - Dave Woody (C) , Chris Wilson (C) , Dick Plambeck (N)
      10 - Memo 434 - Stephane Guilloteau (C)
      so, as yet no response from:
      Lee Mundy - 422
      Ed Fomalont - 427
      Jose Cernicharo - 415
      Peter Napier - 402
     
      and awaiting agreed upon reviews from:
      Steve Myers - 423
      Geoff Blake - 423
      Douglas Bock - 422
      John Richer - 415, 404, 403
      Richard Hills - 402
     
     
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    AIPS++ -

     
    There has been a great deal of email discussion on this point. it has been suggested that Miriad, Gildas and Gypsy also be subjected to an audit similar to that which Steve has led for aips++.
     
     
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    Configuration - Holdaway

     
      Conway has
      developed the antenna pad specifications. Coincidentally John gave birth on the same day as Min and Jessica Yun had twins--congratulations Min and Jessica!
     

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    Other


      The JAO has decided to compile reports on a quarterly basis, rather than monthly.
     A NA monthly report for November will be due to the Science IPT tomorrow. Please comment on this draft. This will be combined with the October report to submit to the NA Project Office for the NSF bimonthly report. Please send materials to HAW for NA.
    The next one will be for Dec-Jan.
     
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     SMA News...
     
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    Upcoming Meetings - Wootten

    JAN 5/9, 2003 201st Meeting of the American Astronomical Society

    JUL 13-26, 2003 Twenty-Fifth General Assembly of the IAU

    JUL 22/25, 2003 IAU Symposium (221): Star Formation at High Angular Resolution, Sydney, Australia. Tyler Bourke is a co-chair of the scientific organizing committee. Good opportunity to show ALMA capabilities.

    SEP 22-26, 2003 4th Cologne-Bonn-Zermatt-Symposium on The Dense Interstellar Medium in Galaxies

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    Travel

     Oh, always

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