ALMA Update

1  Recent Construction Progress

One of the major technical challenges for ALMA has been to provide a stable Local Oscillator (LO) signal across the wide range of frequencies at which ALMA will operate. The phase of this LO signal must be stable even when delivered to antennas that can be separated by several kilometers. The first unit of the central LO, which is capable of providing this signal to 16 antennas, has now been installed at the 5000 m Array Operations Site (AOS) in the Technical Building. An 84 GHz LO signal has been sent between the newly installed racks and the nearby antenna pad No. 106 and the system appears to be working well. Pad 106 will be the first pad to receive an ALMA antenna when it is moved to the AOS site on 17 September 2009. For more details on the LO installation, see the August 2009 issue of NRAO eNews.

Figure 1: The ALMA Central Local Oscillator installed at 5000m AOS technical building. Image from NRAO eNews August 2009; photo W. Grammar.

 

Interferometry testing continues at Operations Support Facility (OSF) at 2900 m, now using the second and third accepted antennas as the first antenna is moving to the AOS site. The water vapour radiometers have measured some exceptionally good weather at the OSF (pwv as low as 0.45 mm), which suggests that observations in the high frequency ALMA bands will be possible occasionally from the OSF. Indeed, the first Band 9 (450 micron) observations were made during 3-4 July, 2009 with a detection of the Moon and a scan of Jupiter. During this period the first successful interferometric observation in Band 6 (1.3 mm) was made from the OSF. As this is the first southern hemisphere winter since we have started having antennas in Chile, testers are taking advantage of the cooler night temperatures to investigate the surface performance of some of the antennas which are still in the contractor camps.

Figure 2: Two ALMA antennas being carried by the two ALMA transporters. Image from NRAO eNews August 2009.

 

In total, there are 16 antennas in various stages of construction and testing at the OSF as well as portions of various other antennas. 16 antennas is the magic number for early science with ALMA! At the AEM antenna area, preparation is continuing for foundations for removable shelters to be installed around pads during the assembly of the antennas. The first two BUS halves for the AEM antenna have been glued together. Integration of its legs, apex and subreflector mechanism has been completed. Lightning protection was installed on the BUS and work on panels and adjusters has been started The yoke arms were also installed.
The second quadrant of ALMA correlator in the AOS technical building and progress is being made towards on-site acceptance.
If my quarterly ALMA updates are not frequent enough for you, a good source for monthly updates on the ALMA project is the new electronic NRAO newsletter
http://www.nrao.edu/news/newsletters/

And don't forget the ALMA observatory web site
http://www.almaobservatory.org/

which contains wide range of information about the observatory, including details about science and technology, infrastructure, geographical location, etc. From there, you can also check out and subscribe to the new ALMA electronic newsletter (go to Newsroom and click on Newsletter), which comes out every few months and contains longer articles on various aspects of ALMA as well as recent updates.

1.1  Committees and Reviews

There have been at least two major reviews of ALMA in the last three months. The National Science Foundation held a review of the North America ALMA Project in July, 2009, in which HIA participated. ALMA held a Commissioning and Science Verification review 2-3 September 2009. The panel was chaired by Bob Wilson and the other panel members were Nario Kuno, Peter Schilke and Melvyn Wright, with Claire Chandler serving as an external advisor. The report from this review is expected by the end of the month. A third major review of Science Operations will take place in Santiago 29-30 September 2009.

2  ALMA Meetings

2.1  Upcoming ALMA Science Meetings

The next NRAO workshop on "Assembly, Gas Content, and Star Formation History of Galaxies", will be held 21-24 September 2009 in Charlottesville, Virginia. Keys issues to be addressed are: The web site for the meeting is
http://www.nrao.edu/meetings/galaxies09/

For those of us (like me) who cannot attend the meeting, it is likely that most of the talks will be posted on the conference web site.
The next ESO-MPE-MPA-USM Joint Workshop, "From circumstellar disks to planetary systems", will be held November 3-6, 2009 in Garching, Germany. The goals of the workshop will be to review the status of the field and to discuss transformational programs that will be made possible with the upcoming facilities, and especially by the combined use of the ESO present and future facilities. To achieve this, the workshop will bring together the communities working with ground based infrared large telescopes and interferometers, with space observatories and millimeter interferometers as well as theorists. The web site for the meeting is
http://www.eso.org/sci/meetings/disks2009/index.html

Based on the success of the McMaster workshop and the timeline for Early Science observations with ALMA, we plan to hold a half-day meeting in May 2010 to inform the community about Early Science opportunities with ALMA. This meeting will be held in conjunction with the 2010 CASCA Annual Meeting at Saint Mary's University in Halifax. Stay tuned!

2.2  ALMA Science Advisory Committee (ASAC)

The next face-to-face meeting of the ASAC will be 13-14 October 2009 in Garching, Germany. Doug Johnstone is Canada's representative on the ASAC. The current charges from the ALMA Board are
  1. Continue to monitor the readiness of the ALMA software system. Of special interest at present are: 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.

  2. Continue to review the progress and schedule of the AIV/CSV process, especially with respect to readiness for Early Science. The Board would appreciate a report on the status of plans for Commissioning and Science Verification and for obtaining “ALMA Public Images”, and commentary on the outcome of the Review of CSV plans which will take place in September.

  3. Discuss the revisions to Scientific Requirements and Specifications, which are in preparation, and make a recommendation to the Board on approval.

  4. Report on the status of the plans for the proposal review process and on what is being done to ensure that all the necessary software and procedures will be established and tested in readiness for the Call for Proposals for Early Science.

  5. Report on the readiness of the ARC’s to support early science proposals and the ALMA helpdesk, and on the plans to reach out to the communities to encourage early science proposals, and to inform the communities about realistic capabilities and performance.

  6. Provide further commentary on the prioritization of the items that are being considered for funding from the Development Budget, in particular those that might be considered for the first call for proposals.

Other ASAC activities include sounding the community on expectations for early science, and ALMA information resources for the general community, as well as looking for ways in which ALMA construction and operations might be more environmentally friendly, especially in terms of energy use (without compromising science).

2.3   ALMA North American Science Advisory Committee (ANASAC)

The ANASAC is holding a face-to-face meeting on 25 September 2009 in Charlottesville. Topics include plans for ALMA development, the role of the North American ALMA Science Center in ALMA Operations, and discussion of some of the ASAC charges. Doug Johnstone is Canada's representative on the ANASAC.

3  ALMA Developments in Canada

3.1  Band 3 Receivers and Development

HIA participate in the National Science Foundation review of the North America ALMA Project in July, 2009. The review committee was very pleased with the progress of the Band 3 production. It found the production schedule presented is realistic and achievable, and the project management team maintains time margins that are reasonable to very conservative. The Review Panel ranked the Band 3 risk contributions to ALMA performance and NA-ALMA schedule as very low.
Six more band 3 cartridges are scheduled to be delivered to the Front End Integration centers in late September for a total delivery of 18 cartridges to the project so far.

3.2  Software

The next version of CASA, beta 2.4.0, was released in Jun 2009. This software, along with example scripts and data sets, can be downloaded from the NRAO web site at
http://my.nrao.edu

ALMA commissioning work in Chile now regularly uses CASA. CASA supports direct import of data in ALMA, VLA, and EVLA formats, and almost any data set that can be written in uv-fits format can also be imported into CASA.
The Pipeline team continues to prepare for the next User Test which will focus on improvements to the calibration algorithms for single field interferometry and also the first implementation of mosaics with interferometric data. This User Test is now anticipated to start in November.
Chris Wilson wilson@physics.mcmaster.ca
Canadian ALMA Project Scientist
(with input from Gerald Schieven, as well as material from Al Wootten and the NRAO and ALMA newsletters)



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On 21 Sep 2009, 16:29.