Radio Astronomy Interest Group

Third Virtual Meeting 2021, May 6th via zoom

Telecon Agenda:

• proposed changes to ObsCore to support radio data
• status of the implementation note
• agenda for the radio interest group session at the interop
• Any other business

Minutes

ObsCore extension:

Francois presented the proposal for the ObsCore extension that had been developed by him and the ESCAPE team. It allows for ranges in resolution and field-of-view for wide-band observations, includes the concept of largest angular scale, and also other uv-plane and instrumental characterizations (longest/shortest baselines, number of antennas, uv-plane filling factor). It also includes time resolution ranges, and spectral ranges expressed as frequencies instead of wavelengths. The proposal will be placed on GitHub for comments, and discussed in the DM session in the Interop.

In meeting 1, most of the discussion revolved around how a row in the ObsCore table should be defined, especially in terms of what common key could be used to link the ObsCore extension to the primary ObsCore Table (although the desirability of adding some of these new fields to ObsCore was also discussed), and how DataLink services could be implemented to fetch the relevant data.

For ALMA, Felix Stoehr broke out target+spw combinations into separate rows. Mark Kettenis said that JIVE takes the path of assigning a single obs_publisher_did to an observation (which can contain many sources and calibrators, and multiple bands). James Dempsey said that ASKAP is relatively straightforward (one band), but ATCA data has similar issues (multiple sources and bands in a single observation).

It may be that datalink services could be used to download what the user will need, e.g. a whole raw observation including calibrators in some cases, or a calibrated dataset or image of a single source in others.

Frequency for specifying spectral range was widely supported.

In meeting 2, the discussion was more focussed on what should be in the ObsCore extension - Severin Gaudet pointed out that obscore was designed to focus on the core properties of an observation for data discovery, and perhaps some of the uv-plane and instrumental characteristics might not be searched on much. Baptiste Cecconi wondered whether frequencies need be added as they are redundant given the wavelength ranges already in obscore, and a tool on the search front end could be used to do the conversion. He also suggested that we should work on mapping keywords from common data formats ((A)SDM/SDFITS/PSRFITS etc) to ObsCore and the proposed extension.

Implementation note:

Stories from CASDA (JD), ASTRON (Yan?), MERLIN (PH) missing, JIVE story needs an update (MK) ML will try to tidy it up in time for the Interop.

Interop schedule:

A 1hr session is tentatively scheduled for May 25th 22:00-23:00 UT.

Speakers who’ve volunteered already: Mark Kettenis (VO implementation at JIVE and uv-plane characterization) Yan Grange (FRBs) Hendrik Heinl (LoFAR DR1) Peter Teuben (Single dish radio data in the VO and SDFITS) Ricardo Rizzo

Other possible contributions: Susana Sanchez - provenance for radio data (may be scheduled in the DM session, also dependent on approval from company working on the problem) Arecibo/CI CoE (may be scheduled in CSP)