ALMA Matters


By / par Gerald Schieven (ALMA)
(Cassiopeia – Winter / hivers 2019)

Continued Canadian Participation in ALMA

Canada participates in the ALMA consortium through an agreement between the National Research Council Canada and the US National Science Foundation. This ten-year contribution agreement is scheduled to end on 31 December 2020. To determine whether this agreement should be continued, and at what level, the NRC struck a review panel consisting of Erik Rosolowsky (chair; U Alberta), Sarah Sadavoy (Queen’s U), Nienke van der Marel (U Victoria) and Christine Wilson (McMaster U). The panel reviewed the participation of the Canadian community and the impact of ALMA on the broader study of astronomy, and conducted a survey of the community. The committee found that Canadians are receiving observing time and publishing high impact ALMA publications at rates commensurate with our investment in the facility, with approximately half of Canadian ALMA publications being led by Highly Qualified Personnel (HQP) trainees. Furthermore, the general public has shown great interest in ALMA’s participation in the results from the Event Horizon Telescope. The committee recommended that NRC should therefore negotiate with the NSF for continued Canadian partnership in the North American executive of the ALMA observatory.

Cycle 6/7 Update

Observing in the last few months of Cycle 6 was affected by a few episodes of high winds and/or snow. Adding to some delays earlier in the observing cycle, this resulted in Cycle 6 completing 88% of the target of 4000 hours of observations. The observatory delivered 90% of pipeline-processed observations within 65 days of completion and 90% of non-standard observations within 118 days. Cycle 7 began successfully on 01 October 2019, with a smooth transition in both hardware and software. Observations have been going largely smoothly, but access to the telescope and normal operations have been impacted by the political unrest in Chile. Due to advisories from the JAO, NAASC and MAG member Gerald Schieven did not travel to Chile for a schedule AoD shift in November.

ALMA received 1773 proposals for Cycle 7, a 3.6% decrease from the record number set in Cycle 6. It is possible that some of this decrease may have been due to the advertised supplemental call for the ALMA Compact Array scheduled for the fall (see next paragraph). All proposals were ranked by the Proposal Review Committee in Atlanta, Georgia in June. Forty-three of these proposals had a Canadian PI and 247 had a Canadian PI or co-I. The global oversubscription rates were 4.4 and 4.2 for the 12m array and the ACA, respectively, indicating a continuing high demand for ALMA time. A/B grades were awarded to 398 proposals and C grades to a further 236 proposals. Of these proposals, Canadian PIs led 10 A/B and 4 C-graded proposals and Canadians were PIs or co-Is on 57 A/B and 36 C-graded proposals. In terms of allocated A+B time, Canadian PIs received 10.1% of the North American share, 5.7% from the 12m array and 16.7% from the ACA. Overall, 18.4% and 15.6% of 12m array and ACA time, respectively, was awarded to proposals with a Canadian PI or co-I. Of special note is the award of the first Canadian-led large program, VERTICO (Virgo Environment traced in CO), an ACA-standalone program to map 51 spiral galaxies in the Virgo Cluster led by postdoc Toby Brown at McMaster University. The number of unique Canadian PIs was 25 and there were 92 individuals on submitted ALMA proposals from 18 institutions in Canada.

The observatory held its second supplemental call for ACA-only proposals in fall 2019. Unlike in Cycle 4, when the deadline was approximately a month after the main ALMA call, this proposal deadline was set to October 1 and was advertised well in advance of the normal April proposal deadline. A total of 249 proposals requesting 8000 hours were submitted, giving an oversubscription rate of 3.2. This proposal call also served as a test of a new review model called Distributed Peer Review (DPR). Each PI (or designated co-I) received 10 proposals to review and rank, with the final observing queue built using the average of the received grades. Anecdotal evidence suggests this review model worked quite smoothly. The observatory anticipates holding another supplemental ACA-only call in fall 2020 for Cycle 8. In the long term, the observatory is considering using Distributed Peer Review for the main ALMA call in the spring starting in Cycle 9, although the details remain to be worked out.

ESO hosted a very successful pan-ALMA meeting, “Science and Synergies” in Cagliari in Sardinia, Italy. Scientific highlights included invited presentations from the 10 ALMA Large Programs from Cycles 4-6, spanning science topics from protostellar disks to evolved stars to nearby galaxies to the high redshift universe. The meeting was highly oversubscribed, with selection required both for attendees and for poster presentations. Unfortunately, a typhoon in Tokyo the weekend before the meeting meant that many Japanese astronomers were unable to get to the meeting.

ALMA North American Development Studies Cycle 7 / FY2020

In order to assure ALMA’s continued role at the forefront of science and technology, each ARC periodically awards funding for ALMA development studies and projects. Studies are funded for 1-2 years to assess the feasibility of software or hardware upgrades to the array, while projects are funded for 2-3 years to develop the technology. The results of the latest North American call for development studies has recently been announced. (See here for more details.) Eight proposals, two of which were from Canadian institutions, were awarded funding. Of these, five were hardware studies, and three software/archive. The two Canadian proposals are described below. For a discussion of the eight successful studies, see here.

ARCADE: ALMA Reduction in the CANFAR Data Environment (Kirk/ NRC)

NRC’s Millimetre Astronomy Group and the Canadian Astronomical Data Centre, in collaboration with McMaster University, are pleased to announce that they were recently awarded funding for the ALMA North American Cycle 7 Development Study program for their proposal entitled “ARCADE: ALMA Reduction in the CANFAR Data Environment”. One year of funding is provided for our group to further develop and scale-up our prototype system, ARCADE. The vision for ARCADE is to provide a stable cloud-based computing environment designed to handle ALMA data for all Canadian researchers. ARCADE will have ample storage space and processing power, and will come pre-loaded with all versions of CASA. Through its intuitive web-based interface, both new and expert users will be able to access the computing resources required for all of their ALMA data reduction and imaging needs. At present, we have been working on an early prototype of the ARCADE system with a small number of alpha testers. The development study funding will allow us to learn how to best scale up the system to handle many simultaneous users with independent resource allocations and to improve the system’s general usability through extensive beta testing. For more information, please contact the PI, Helen Kirk.

High-level Design and Integration of NRC TALON based Correlator for Increased Channels, Bandwidth and Baselines (Pleasance/ NRC)

The National Research Council of Canada (NRC) Herzberg Astronomy and Astrophysics Research Center (HAA) has designed a Frequency Slice Architecture (FSA) Correlator/Beamformer (CBF) based on the NRC’s TALON technology for the Square Kilometer Array (SKA) Mid Frequency Correlator/Beamformer (Mid.CBF). The TALON FSA CBF design is flexible in nature and easily adapted to other radio interferometers. This has been demonstrated with the inclusion of a TALON FSA CBF in the ngVLA reference design. The NRC was recently awarded a Cycle 7 ALMA Development study to investigate the potential of integrating a TALON FSA CBF into the ALMA observatory. The scope of the study includes several activities. The first activity is to studying existing ALMA interfaces to the CBF and understand current capabilities and the roadmap for future capabilities. The second activity is to document a high-level design for a suitable TALON FSA CBF including a detailed description of the capabilities, rack space, and power estimates for a CBF that handles the existing bandwidth and number of antennas. A key focus will be on minimizing the impact to other ALMA systems surrounding the CBF. The final activity is to describe how the presented architecture could be expanded to handle additional antennas and provide increased bandwidth and channels. There is the potential for follow on studies to present a detailed design and project plan for deploying a TALON FSA CBF at the ALMA observatory. The principle investigator for this study, titled “High level design and integration of NRC TALON based correlator for increased channels, bandwidth and baselines”, is Sonja Vrcic located at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton, BC, Canada.

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