ALMA Configuration Group

Date: JAN-31-2001 (Wednesday) 31 January 2001.

Time: 12:00 EST (10:00 MST, 1700UT)

USA Toll Free Number: 1-888-323-9872

International Number: 1-630-395-0180

Passcode: ALMA

Conference leader: Al Wootten

Past minutes, etc on ALMA Configuration Group Page

Minutes

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Attendance

Conway, Sakamoto, Woody, Radford, Guilloteau, Heddle, Morita, Webster, Wootten, Butler, Kogan, Holdaway, Yun, Wright

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Old Business

Al's updated minutes of the last teleconference are available . There was no discussion of these.

New Business

Action Items

Attendees to the meeting are asked to send their talk proposals, time estimates, and attendance details to Stephane and to Al so that the agenda may be assembled and documents supporting it corralled.

Conway and Heddle will work on producing two metrics for the images for the meeting. Heddle reports (2/7/01) having replaced the existing situation on his pages of two side by side fidelity histograms with 1) a histogram showing both the previous plots on one graph, next to 2) a histogram showing the 'cumulative' curves. The cumulative curves show fidelity on the x axis, with the y value showing log10(number of pixels with a fidelity greater than x).

In another plot, the rms in the fractional error maps will be compared, probably by blanking several times over intensity steps, calculating the rms each time.

PDR Plans.

Details for the Configuration PDR

1) Date and Place

Date: February 26 and 27

Location: IRAM, Grenoble

2) Attendant List (Plausible attendees only)

  • Leo Bronfman
  • Jaap Baars?
  • Bryan Butler
  • John Conway
  • Pierre Cox
  • Darrel Emerson
  • Frederic Gueth?
  • Stephane Guilloteau
  • Steven Heddle
  • D. Hofstadt
  • Mark Holdaway
  • Masato Ishiguro
  • Ryohei Kawabe?
  • Leonia Kogan
  • Angel Otarola?
  • Jerome Pety?
  • Koh-Ichiro Morita
  • Simon Radford
  • Seiichi Sakamoto
  • Francois Viallefond
  • Adrian Webster
  • Al Wootten
  • Min Yun
  • Lee Mundy
  • Eric Anterrieu
  • Mel Wright
    Lee Mundy (lgm@astro.umd.edu) of the University of Maryland BIMA Group, Eric Anterrieu (Eric.Anterrieu@cerfacs.fr) of (Signal & Image Processing Team), CERFACS, at Toulouse, and Mel Wright have agreed to serve as external referees.
    Review Committee
  • S. Guilloteau
  • A. Wootten
  • D. Hoffstadt
  • S. Radford
  • Jaap Baars?
  • Darrel Emerson
  • Lee Mundy
  • Eric Anterrieu
  • Mel Wright

    3) Documents

    To be ready 2 weeks in advance for distribution, specially to the outside members. We already have a lot, but are weak on operation issues. Links to most material are available at the ALMA Configuration Development WWW pages at The ALMA WWW Site. A good summary is given in the Project Book Chapter on Configurations.

    - Nested Ring concept (Yun / Butler) Summary and ALMA Memo No. 320 Strawperson Donut/Doubling-Ring Configurations by M.S. Yun & L. Kogan.

    - Spiral concept (Conway) See Conway's WWW site and specifically his Protomemo A Preliminary ALMA Zoom Array Design for the Chanjnantor Site by J. Conway.

    - Simulations (Heddle) The guidelines from the meeting in March 2000 led to the creation of the Image Library . These images were then run through a set of AIPS simulations by Heddle, with these results.

    - Multi-configuration aspects (Viallefond) Document??

    - Compact array issues (Morita / Guilloteau) The summary may be seen at my site.

    - Site issues (Radford / Butler)

    - Operation concepts (Wootten / Guilloteau)

    - Cost issues (Hofstadt / ? )

    Goal of the meeting: select a baseline design to continue with detailed implementation work ...

    Simulations


    Steven has been working down the list arrived at at the early January meeting. Some simulations have been done for the most compact array. A start has been made on the combination of B and D configurations in consultation with Conway on the weighting to use. The different array styles have differing short spacings. Other deconvolution methods have not yet been attempted and the newest AIPS distribution is not yet being used. Simulations of the new DOTS image, to determine whether the arrays respond well to compact sources, have commenced; these are in units of Jy/pixel after the restoration step.

    John asked that UVCON which currently employs 100 stations, couldn't be increased to 2017.

    Metrics

    Bryan's useful memo, wih comment by Woody and Wright was discussed. Stephane pointed out that residual errors in the maps seem proportional to the original sidelobe levels; though not proven this appears to be true from examination of the images. There was some agreement that among the uv metrics a beam metric was a useful tool for evaluation.

    Action Items

    Attendees to the meeting are asked to send their talk proposals, time estimates, and attendance details to Stephane and to Al so that the agenda may be assembled and documents supporting it corralled.

    Conway and Heddle will work on producing two metrics for the images for the meeting. Heddle reports (2/7/01) having replaced the existing situation on his pages of two side by side fidelity histograms with 1) a histogram showing both the previous plots on one graph, next to 2) a histogram showing the 'cumulative' curves. The cumulative curves show fidelity on the x axis, with the y value showing log10(number of pixels with a fidelity greater than x). In another plot, the rms in the error maps will be compared, probably by blanking several times over intensity steps, calculating the rms each time.