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Contact Information

* 2009-8-19 14:30 UT
* Note: C. Wilson points out line noise may be muted by pressing *6 which works thru the call center.
* Duration: 1 hr
* USA Toll Free Number: 877-874-1919
* Toll Number: +1-203-320-9891
* Passcode: 185064
* Leader: Hills, Wootten, Testi, Morita
* Attendees: Nikolic, OSF: Barkats/Dent, Laing, Wootten, Hills, Peck, Remijan, Liszt, Emerson, Hogerheijde, Morita, T. Wilson, S-Y Liu, Lonsdale


1 Old Business The enhanced Agenda from last meeting is available. Science IPT notes from last month's telecon are not available.

Dynamic OSF Fringes A major technical challenge for ALMA has been the provision of a stable Local Oscillator (LO) signal over ALMA’s wide range of operating frequencies, keeping the relative phase sufficiently stable after delivery of the signal to different antennas that may be separated by several km—the specification for phase drift is to keep within 2 parts in 1010. This is the job of the Central LO, the first unit of which, capable of providing signals to 16 antennas, has been installed at the 5000m ALMA site now. For the LO, a reference frequency is generated as the difference between two laser signals generated in the infrared portion of the spectrum at 1.5 microns. The frequency of one laser, the slave, is varied to produce the desired frequency at the antenna when mixed with the frequency of a master laser, both of which are located in the Array Operations Site Technical Building. The phase stable laser difference signal is used to phase-lock a signal generated locally at the antenna which in turn drives the signal for the mixers in the Front End. The phase drift and phase noise must be kept within stringent limits. The phase stability at the antenna is guaranteed by phase locking on the optical fringe, so the number of optical wavelengths must be kept constant over the round trip in the optical fiber. This effectively keeps the electrical length of the fibers, laid underground from the central building to each distant antenna, constant, and so guarantees a constant propagation delay and stable phase at each antenna even at the highest wavelength (0.32mm) used by ALMA. The first racks of the ALMA Central LO, which handle sixteen antennas, successfully underwent its Provisional Acceptance In-House (PAI) at the NRAO Technology Center on 2009 June 24. The performance of the first unit was verified and it was packed and shipped to the ALMA site. Once it arrived, the racks were assembled and cabled by W. Grammer, J. Meadows, J. Shelton, and J. Castillo, working in the oxygenated atmosphere of the AOS TB. Bill Shillue, JF Cliche, Jason Castro, and Yoshi Masui have conducted on-site testing. Rodrigo Brito has provided invaluable logistical and technical assistance on-site to both teams. Recently the testing team verified passage of an 84 GHz LO signal between the newly installed racks and antenna pad No. 106, just outside the building, onto which an antenna will be moved during September. The lasers have tuned and locked reliably and the phase correction system is working well.

Integration into the ALMA computing system is also going well, allowing monitoring of phase drift data from the OSF (and eventually worldwide). The system will next undergo Provisional acceptance on Site (PAS) and will be used for interferometry at the AOS in the coming months.

See other images and animations. See other images.

  1. New Business--Project news/updates.(Hills, Peck)
    1. R. Hills
      • For lots more details see Bi-weekly Reports and for the slightly bigger picture Monthly Reports
      • Interferometry at the OSF: Continues to progress. Baseline measurement now accurate and phase generally stable. Some fine delay fringe errors persisted.
      • Single Dish testing - pointing, focus, beams, etc also continuing and generally going well although slower than we would like. See Test Reports where we are starting to accumulate the results.
      • A hysteretic pointing behaviour was found in DV02 and the coupling to the encoder is being investigated as the most likely cause. The cause of the offset pointing errors seen on PM03 has not been established - a campaign to study this is being planned.
      • The refurbished test correlator, which was the one used at the ATF, is basically working but is not yet fully operational.
      • Nikolic tested WVRs at AOS; two are mounted on ALMA antennas at the OSF now.
      • System: AIV tests continue; preparations at the AOS for the first antenna (PM03) in September.
      • Site: Pad 106, near the AOS TB and to receive the first antenna in Sept, has fiber and power and has been connected to the CLO (see photo).
      • Antennas: Elements of more than 16 antennas from all vendors are at the OSF--necessary for early science (but not sufficient). Next antenna acceptance in Sept. Both the Vertex and MELCO types have been the subject of intense holography measurement campaigns to quantify their thermal deformations.
      • ASAC Matters. Next f2f meeting in Garching in October. Regional meetings begin next month. Sci IPT supports these meetings.
        1. Discussion of Board Charges. These are the current (draft) charges:
          1. Continue to monitor the readiness of the ALMA software system. The archive, the interface between the observing tool and the archive, and the capture of necessary proposal information by the observing tool, in the context of ALMA operations planning, are of special interest at present.
          2. Continue to review the progress and schedule of the AIV/CSV process, especially with respect to Early Science. The Board would appreciate a report on the plans and procedures set up by the Project Scientists for `Demonstration Science', and on the revised specifications for science requirements.
          3. Review the status of the plans for the proposal review process, in particular whether all the necessary software and procedures will be established and tested in readiness for the Call for Proposals for Early Science.
          4. Review the preparedness of the ARCs to support early science proposals and the ALMA helpdesk, and review the materials they have prepared to reach out to their communities to encourage early science proposals, and to inform their communities about realistic capabilities and performance.
        2. Other ASAC activities which are not formal charges from the Board.
          1. Community sounding on expectations for early science, and ALMA information resources for the general community.
          2. Continuing discussion and analysis of future ALMA developments.
          3. ASAC will continue to look for ways in which ALMA construction and operations might be more environmentally friendly, especially in terms of energy use (without compromising science). (Issues of energy use are discussed in the Marshall et al. Decadal Survey white paper at
    2. Review (mostly internal) of Commissioning Plans Early Sept OSF; R. Wilson Chair
    3. Employment
    4. ALMA Science IPT wiki page
    5. Astronomer Outreach: JAO ALMA Webpages. JAONews. ESO Newsletter No 16 NRAO eNews ALMA News. NAOJ News. NRAO ALMA Calendar
    6. Current ALMA System Block Diagram Vers P.
  2. Directories

Science IPT Group Activity Reports

Please include your Group Activity Report here (How to Enter Your Report), or email it to AlWootten

Project Scientists

  1. Science IPT
    • New CASA Beta release in June--feedback?
      • New features include total power developments (Appendix A of cookbook)
      • Simulator (name changed to simdata) developments (Appendix B of cookbook)
    • OSF (Peck)
    • A problem about the Generator_Location has come up. Comments welcome.

Richard Hills, Alison Peck, Robert Laing -- Commissioning and Science Verification

  • Commissioning and Science Verification Review, OSF, 2009 September 2-3. Bob Wilson, review Chair.

Jeff Mangum -- Calibration

  • Temporary weather station installation on roof of AOS TB.

Bojan Nikolic/John Richer -- WVRs

  • As people are probably aware, the work in Cambridge on phase corrections/WVRs is funded through an European Union Framework Programme 6 grant. European Union recently held a mid-term review of the whole ALMA enhancement under FP6, including the phase correction, and have informed that the review was passed.

  • Two WVRs installed on antennas at the OSF.

Lars-Ake Nyman -- eSSR

  • ALMA SciOps Implementation Plan Review, SCO 2009 September 29-30.

Testi, Klaassen-- Design Reference Science Plan

  • DRSP updates have been completed
  • Spreadsheet describing the details of each is up to date
  • Website has not yet been updated, but that will happen within the next two weeks (with a link to the excel spreadsheet).

Wootten -- Site Characterization

Remijan, Markwick -- Splatalogue

  • Andrew Markwick has been working with Stewart Williams and the ALMA OT group on accessing Splatalogue. Below is a screenshot of a current gui interface that has been developed for querying Splatalogue.
  • OT Select Spectral Line
  • Meeting in Koln in October. Remijan, Wootten, Markwick, Brogan will be attending. Any others?
  • Remijan received new laboratory data from Frank DeLucia from the Ohio State University to include into Splatalogue. Updates and edits continue on the internal Splatalogue website. Splatalogue Internal Testing Version

Science Corner:

1 A special issue of the Proceedings of the IEEE on radiotelescopes has just been published, with articles on SKA prototypes, SKA, ALMA, GBT, EVLA and other instruments.


1 Next meeting is on Sep 16th (14:30 UT). Oct 21st for the following month.

Events of Interest

(see also Al's ALMA Biweekly Calendar)

Day Date Time Event location details
Aug 19
Sep 2-3
CSV Review
Sep 16
Sep 29-30
SciOps IPT
ALMA SciOps Implementation Plan Review
Oct 13-14
ASAC f2f
ESO Garching
Oct 21
Nov 16

Upcoming Meetings

Science at Q Band Sep 14-15, Manchester

Mass Assembly and Star Formation History of Galaxies Sep 21-24, Charlottesville, Virginia

To the Edge of the Universe: 30 years of IRAM Sep 28-30, Grenoble

From circumstellar disks to planetary systems Nov 3-6 Garching

-- AlWootten - 2009-08-17
Topic revision: r11 - 2010-08-02, ToddHunter
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