MMA Imaging and Calibration Group

Minutes for meeting Mon, 17 January 2000 at 4pm EST.

Date: 17 January 2000

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

Phone: (804)296-7082 (CV SoundStation Premier Conference phone).

Past minutes, etc on MMA Imaging and Calibration Division Page

Minutes

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News - Wootten

From the Division Heads meeting.

Vertex Antenna Systems, Santa Clara, CA will discuss the contract at the AOC on Weds.

FY2000 Budget is tight--very little travel/contingency.

Shaver, Contini and Warmels phone call on WWW site today.

Upcoming science meetings (IAU).

Correlator enhancement: Webber estimates that for $1M the correlator can have twice the currently planned number of channels. This will benefit spectral surveys, for example, and permit oversampling over wider bandwidths.

Project book updates on track--Test Interferometer by 7 Feb, ALMA by 31 Mar.

Change of meeting time.

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ALMA SW-SSR Group and Exploder - Glendenning, Yun, Butler

A review of highlights. --------

ASAC Meeting report

Third Joint ALMA Science Advisory Committee Meeting 10 Jan 2000.

Minutes will be posted.

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Configuration WG - Min, Butler, Wootten, Radford, Kogan

A meeting of the configuration working group was held on 22 Dec 1999. The next meeting will occur on 19 Jan 1999.

Min has set up a mailing list, alma-config, whose members are: myun@nrao.edu

awootten@nrao.edu

bbutler@nrao.edu

lkogan@nrao.edu

sradford@nrao.edu

dshepher@nrao.edu

efomalon@nrao.edu

mholdawa@nrao.edu

mgordon@nrao.edu

dpw@ovro.caltech.edu

thelfer@musca.as.arizona.edu

mwright@astro.berkeley.edu

lgm@astro.umd.edu

guillote@iram.fr

asw@roe.ac.uk

Francois.Viallefond@obspm.fr

jconway@oso.chalmers.se

jsr@mrao.cam.ac.uk

seiichi@nao.ac.jp

morita@nro.nao.ac.jp

The ASAC would like a report from this group at its 10-11 March 2000 meeting. A face-to-face review is being planned for 20-21 March 2000 in Tucson.

A basic decision to be made is the style of the array. This will affect the imaging performance of the array, as measured by several parameters, which we call metrics. Among these, Stephane proposed:

  • a) dynamic range
  • b) image fidelity
  • c) sidelobe level; effects of uv plane holes
  • d) noise degradation with tapering
  • e) noise degradation in intermediate configurations

    There was considerable discussion over these points. Both operational/economical considerations should also be considered. Overall, the array design must be suitable for the science it is to do.

    Image assessment can be most effectively measured by employing a standard image or visibility dataset of some sort. At the discussion, it was thought that a standard visibility dataset made much sense, perhaps with pointing errors as built-in corruptors. Autocorrelation data can be a separate dataset. A favored way to do this was to have a captive account, probably on an NRAO machine, running AIPS++ with user-defined station coordinates, on the standard dataset. Whether this is consonant with the NRAO computing policy will be examined.

    Bryan made a list of known simulation programs, and their capacities, which I will eventually place here, along with updates.

    Compact configurations are an integral element of most array styles. Accordingly, the siting of the compact configuration will depend upon the style chosen. Inasmuch as the topography limits siting, it will impact style. On the other hand, the detailed design of the most compact array depends less upon style than the extended arrays, and its design may be split off.

    Radford has posted new topographic images in various formats at the ALMA maps site. Included are coordinates of known things, with varying degrees of accuracy. Butler has produced a new mask set. Iteration will ensure that the criteria he used are acceptable. Consultation with VLA civil engineering experts will be sought.

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    WVR Discussions - Butler, Wootten

    The receiver group plus plus had an email discussion on the WVR recently. We have managed to get copies of these, which were not addressed to us. Bryan has summarized these here . Lamb apologized for missing us out on this list. He appreciated Bryan's summary, which summarized more of the messages than Lamb had seen.

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    Action Items 17Jan2000

    DECISION: Configurations--where are we? March meeting plans...

    DECISION: Implementation of 183 GHz WVR?

    DECISION: Is a nutating secondary necessary?

    DECISION: What is the total power specification on the ALMA?

    DECISION: What is the effect of 1/f noise in the HEMT amplifiers of SIS receivers upon our ability to combine total power and interferometric images into a faithful representation of the sky?

    MEETINGS: SW-SSR meeting at AOC 13-14 Jan 2000. AOC.

    AIPS++ Pipeline meeting 18-19 Jan 2000. AOC.

    Configuration phone meeting 19 Jan 2000.

    System/Test Interferometer PDR Garching 28-29 Feb 99.

    SAC phone meeting 14 February 2000 for members only.

    AGL meeting 16 Feb 2000, followed by general meeting 17-19 Feb 2000, Tokyo.

    MOC meeting 2-3 March 2000. D. C.

    ASAC face-to-face meeting 10-11 March 2000. Leiden.

    Configuration face-to-face meeting 20-21 March 2000. Tucson.

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    Travel

    AW -> AAS 12-16 Jan 2000. AW -> Tokyo 16-21 Feb 2000. AW -> Leiden 8 - 13 March 2000. ------