ALMA Update

1  Recent News

By 8 August 2010, the array at ALMA's high-elevation site had grown to a total of seven antennas. Having seven antennas means we have twenty-one independent baselines, which greatly improves our ability to calibrate and to begin to make images from real ALMA data. Having more antennas makes a number of commissioning projects much quicker and easier as well. The array is expected to reach 8 antennas (half the number planned for Early Science) sometime later this month.

Figure 1: Seven antennas at the 5000m elevation Array Operations Site (AOS) on 10 August 2010. Image courtesy ALMA (ESO/NAOJ/NRAO).

ALMA plans to begin Early Science when the interferometer becomes the "best" instrument in the world for millimetre/submillimetre observations. This is expected to occur when the interferometer reaches sixteen antennas with at least three receiver bands available on all antennas, including the Canadian-made (Band 3) 3 millimetre receiver. The present schedule has the ALMA Early Science Decision Point in late November, with a Call for Proposals at the start of December. It is expected that the Call will provide two months for proposal submission placing a deadline at the end of January 2011. Now is the time to start thinking about Early Science proposals!

2  Construction Progress

At the Operations Support Facility (OSF), two MELCO 12 m antennas are close to meeting ALMA's strict technical specifications, at which point they will begin the acceptance review process. A 7 m MELCO antenna destined for the ALMA Compact Array has been measured to have very good surface accuracy, with the best test results indicating a surface accuracy of better than 6 microns rms. Seven Vertex antennas are at the OSF in various stages of construction and testing on their way to being accepted, further tested, and integrated into the ALMA array. The first ALCATEL antenna is currently undergoing acceptance testing at the OSF while five additiona antennas are in different stages of assembly, ranging from final commissioning to just starting to be assembled.
The Joint ALMA Office (JAO) has moved into their new central office in Santiago, which is located in Vitacura next to the ESO compound. The ALMA archive will also be hosted in this building, which includes office space for visitors as well as ALMA staff. Preparations have increased at the ALMA Regional Centers (ARCs) as ALMA moves closer to the key decision point on the timing of the Call for Early Science. A number of tests of user software packages are being held in late August and September, in preparation for reviews that will occur in October.

The month of June saw the arrival of some spectacularly good observing conditions. On the evening of June 30, the precipitable water vapour (PWV) in the atmosphere above the site fell to a low of 0.13 mm! Atmospheric transparency at ALMA's highest frequencies is a strong function of PWV; for reference, the weather conditions on the summit of Mauna are usually considered to be excellent if the PWV is 1 mm PWV or less.

Figure 2: Precipitable water vapour (PWV) versus time on the evening of June 30, 2010 shows extremely dry and transparent conditions. Figure from ALMA September 2010 newsletter.

There has been a lot of work over the last few months to test and implement ALMA's water vapor radiometers (WVRs). Ground-based millimeter images are blurred by water in the Earth's atmosphere, in a similar way that optical images are blurred by the atmospheric fluctuations commonly referred to as seeing. ALMA has recently made a big step towards its goal of using WVRs to measure the amount of atmospheric water vapour in the line of sight to each antenna. These measurements are used to provide a correction to the astronomical data which not only improves the image quality but is essential for using ALMA at its shortest wavelengths and on baselines exceeding several kilometers. The data shown in Figure 3 would be virtually useless for wavelengths shorter than about one millimeter without correction, but with the correction we should be able to obtain sharp images at all ALMA wavelengths.

Figure 3: Phase Correction on a mm source. In the upper plot the red line is the raw phase of the astronomical signals (converted into a path difference), and the blue line is the difference as measured by the radiometer, while the lower plot is the residual after applying the correction. (Credit Bojan Nikolic; from the September 2010 ALMA newsletter)

2.1  Personnel news

In September 2010, Dr. Lewis Ball will join ALMA as the Deputy Director of the Joint ALMA Observatory. Lewis began his career working on the application of the theory of shocks, particle acceleration, synchrotron emission, and inverse Compton scattering to supernovae, supernova remnants, pulsar winds and radio/X-ray transients. He later moved into research management at Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO), where he recently integrated the Australia Telescope National Facility (ATNF) and the Canberra Deep Space Communication Complex (CDSCC) into a new CSIRO division, Astronomy and Space Science. We welcome Lewis to the ALMA project, where his extensive management expertise should serve to strengthen the leadership in ALMA.

3  ALMA Meetings

3.1  Upcoming ALMA Science Meetings

Registration is now open for "ALMA: Extending the Limits of Astrophysical Spectroscopy", a conference to be held 15-17 January 2011 in Victoria, and will remain open until the maximum number of participants has been reached. An optional workshop on the following day (18 January) will provide participants an opportunity to get hands-on experience with the ALMA Observing Tool and related software. This workshop is a joint initiative of NRAO and HIA and will be the 5th NAASC workshop focusing on ALMA science. For information and registration go to

ESO will host a workshop on "The impact of Herschel Surveys on ALMA Early Science" 16-19 November 2010 in Garching, Germany. The workshop is designed to explore the powerful combination between Herschel and ALMA, taking advantage of the Herschel's first results to best exploit the ALMA Early Science call for proposals expected towards the end of 2010. ESO hopes also to foster collaborations among Herschel users and between the Herschel and ALMA communities. The conference web site is

Finally, there will be a special session on "Observing with ALMA" at the 217th AAS meeting in Seattle, Washington on 12 January 2011.

3.2  Early Science workshops in Canada

Want to get a head start on proposing to ALMA during the Early Science phase (deadline expected Q1 2011)? Members of the Millimetre Astronomy Group at HIA are willing to travel to your area to conduct mini-workshops on the use of the ALMA proposal tool and software, and/or give related science seminars. Please consult with Gerald Schieven (Gerald.Schieven(at) if you'd be interested in hosting a mini-workshop in your area this fall or winter.

3.3  ALMA Science Advisory Committee (ASAC)

Doug Johnstone will be attending three ALMA meetings in Chile in October 2010. The ALMA Commissioning and Science Verification Review will consider whether ALMA is ready to start Early Science on schedule, while the ALMA Science Operations Review will determine if sufficient infrastructure is in place to handle Early Science. Finally, the ALMA Science Advisory Committee has been charged with reviewing the status of the Proposal Review Process and consider the overall readiness of the Project for Early Science.

3.4   ALMA North American Science Advisory Committee (ANASAC)

Doug Johnstone attended the ALMA North American Science Advisory Committee (ANASAC) yearly face-to-face in Charlottesville in mid-September. At this meeting the steady advance toward Early Science with ALMA was clearly demonstrated, including commissioning results from seven antennas working together. The readiness of the North American ALMA Science Centre (NAASC) to handle both Early Science and Full Operations was provided, with the ANASAC asked to help prioritize the many tasks required by the NAASC over the coming year. The January tutorial on "Preparing for ALMA Early Science", to take place in Victoria on January 18th directly after the Spectroscopy Workshop (see above) was seen as a model for ALMA outreach to the science community.

4   ALMA Developments in Canada

4.1  Band 3 Receivers and Development

It has been a very hectic but productive summer. The second cartridge test set was completed in the beginning of this year, increasing the production rate to two cartridges a month. Nine cartridges have been delivered since the beginning of April, and five more cartridges are at various stages of the acceptance process waiting to be shipped to the Front End Integration Centers. As of the end of August, a total of thirty-five cartridges have been delivered to the ALMA project. The production is expected to be completed at the beginning of 2012.

4.2  Software

The sixth Pipeline User Test was completed and the report submitted in August. With 9 testers evaluating 15 data sets, including interferometry mosaics, this was the most ambitious pipeline test to date. The testing went well, with most of the functions working well and good feedback from the testers on items such as how to improve the use of clean boxes and the need for smoothed spline or polynomial fits to the bandpass calibration. The User documentation needs some additional improvement, and in particular the large number of plots presented to the testers (and eventually the PIs) needs to be reduced and organized better. The pipeline team is already hard at work on these improvements. The next test is tentatively planned for spring 2011 and should include the combination of single dish and interferometric data.

4.3  Canadian ALMA email list

An email list has been created for Canadian astronomers interested in ALMA. This moderated list will periodically send out updates on ALMA's status, news of software releases, notices of upcoming ALMA science meetings and workshops, etc., which would be of interest to Canadian astronomers. Those who wish to be subscribe to the alma-users list are encouraged to visit the web page

or send an email to Gerald.Schieven(at)

5  Further Information

With my new position as chair of my department for one year, these ALMA updates may be somewhat shorter than usual. A good source for monthly updates on the ALMA project is the new electronic NRAO newsletter

And don't forget the ALMA observatory web site

which contains wide range of information about the observatory, including details about science and technology, infrastructure, geographical location, etc. A new ALMA newsletter in September 2010 contains a wealth of detail on the project, including an in-depth discussion of how ALMA will correct for the effects of the atmosphere to obtain the sharpest possible images (AO for the submillimetre) and a detailed description of how ALMA's receivers work entitled "Sense and Sensitivity", as well as an update on construction
Chris Wilson
Canadian ALMA Project Scientist
(with input from Doug Johnstone, Gerald Schieven and Keith Yeung, as well as material from Al Wootten and the NRAO and ALMA newsletters)

File translated from TEX by TTH, version 3.40.
On 30 Sep 2010, 07:17.