WP-A5.3 Focus Meeting @ Jodrell Bank (2002-05-24)

Present: Ant Holloway (AH), Anita Richards (AMSR), Bob Mann (BM), Simon Garrington (SG), Tony Linde (TL).

Time: 08:30-13:00

Actions: listed at the end of this report.

1. Introduction:

BM noted that the recent AstroGrid architecture meeting (see WPA1Focus20020517) had agreed that the optical and X-ray pilots (WP-A5.1 and WP-A5.2, respectively) should be terminated, but that the remaining three pilots should proceed to the end of Phase A, as planned. He explained that this was the first of two meetings (see WPA5Focus20020527 for the other) reviewing the progress on the three remaining pilots and scheduling the work for Q4. Another goal was to identify material that BM could include in his talk on the Pilot Programme at the Garching VO conference.

2. WP-A5.3 progress and plans:

The progress to date on WP-A5.3, and plans for Q4 work, were discussed by means of running through the WP-A5.3 deliverables for Q3 listed in the WP-A5 Q3 Forecast and the tasks remaining for Q4, as listed in the WP-A5.3 Project Description, as follows:

• 5.3.0 Design and requirements

Pretty much complete: the prioritisation of datasets for inclusion in the pilots is in hand (see note on 5.3.4 below); aips++ has been installed on COBRA; and some scientific requirements have been derived by AMSR's consulting colleagues at Jodrell Bank.

• 5.3.1 Evaluate aips++ for remote/distributed access to visibility data

Work to date has centred on producing a cgi wrapper to AIPS, not aips++, because the behaviour of AIPS is well understood, while aips++ retains some oddities. This cgi wrapper allows a user to launch AIPS with a particular set of inputs (data set, reduction parameters, etc) and it will go away and reduce the specified dataset. About 50% of the work on this has been done, and it should be complete by the end of Q3: remaining work basically just sorting out various problems with file permissions and cgi.

• 5.3.2 Develop prototype environment for access to visibilty data

This is likely to be a simple HTML form, although it is possible that it may be integrated with the JBO archive software. Either way, it will hide from the user all the oddities of AIPS user accounts, etc. Work on this can proceed in parallel with the other tasks of this pilot, and it should be complete by mid-August: a mock-up of the HTML front-end, and some information on the workflow run by users of this prototype will be provided to BM for inclusion in his Garching talk.

• 5.3.3 Develop metadata standards for interferometric data

This task is an important part of AMSR's work for AVO's Interoperability work area, as well as a core component of this pilot. To date, thoughts have centred on the inclusion of interferometry metadata within the UCD (Unified Column Descriptors) framework developed by CDS. Very little radio data is included in the CDS system at the moment, so not much thought has gone into defining UCDs relevant to radio astronomy, and those radio surveys that are included have been pretty minimalist in their approach to providing metadata, so we aspire to something more comprehensive now.

To a large extent, it is expected that the required metadata can be fit into the UCD system - it's just a case of defining the new terms needed for radio interferometry. For example, data near the edge of the field of an interferometry observation are degraded in a variety of ways, and one needs metadata to describe that, so that a user can decide whether it is possible to generate a postage stamp image of sufficient quality at such a sky position.

In some situations, however, the meaning of terms is different in interferometry than in other areas of astronomy. For example, the duration of an interferometric observations sets its field of view, rather than its depth, as in optical astronomy, say, so that one must be careful that, if one uses existing UCDs it is clear which of a possible multiplicity of interpretations is intended, lest a naive user be misled. One way of handling this would be to set up a number of "ontology namespaces" for the VO, so that differences in the meaning of terms in different communities could be handled clearly.

AMSR will produce a short note on the discussions on image data metadata she has had with CDS by the end of the quarter, while an initial draft of a fuller report on interferometry metadata will be delivered by mid-August, in time for inclusion in the WP-A5 report.

• 5.3.4 Select and prepare radio data for use in pilot

The full set of options are listed in the WP-A5.3 Project Description, but the priorities within them are becoming settled, with the Hubble Deep Field (HDF) as top priority, followed by a subset of the MERLIN archive: a one page note on the final choice, and the rationale behind it, will be posted in the Wiki by the end of Q3.

• 5.3.5 Trial of remote processing on JBO CORBA (aips++ pimager)

The pimager task is a parallelised interferometric imaging tool being pushed by the BIMA millimetric interferometer team in the US. It has its own message passing sysem (Glish), while individual pimager tasks use MPI.

The source code has been made available to JBO, and it has been installed on CORBA, but has proven difficult to compile, as it has a number of system dependencies. SG and AH are fairly confident that they can get these sorted in the next few weeks, but, if they can't get pimager running by the start of August, the fallback position is to use the non-parallelised version. This will allow some scalability experiments, but not as full a range as initially anticipated.

• 5.3.6 Investigate tools for multi-wavelength comparisons

This is to take a lower priority than the pimager stuff, probably only receiving a week or so's effort later in Q4. One suggested thing to look into is the generation of radio interferometric postage stamp images for Chandra AGN candidates in the HDF for which these do not yet exist and their overlaying on other HDF image data using GAIA and/or ds9.

• 5.3.7 Evaluate test bed implementation

Two JBO staff (Tom Muxlow and Andy McDonald) have been lined up as beta-testers, and efforts will be made to identify at least one external guinea pig. It is intended that the prototype system will be delivered by the end of July, allowing the test users to have a couple of weeks to play with them, before the delivery of a report on their experiences by mid-August.

3. Actions:

The short-term Actions are as follows:

• By the end of May:
  • finish cgi wrapper to AIPS (AH, SG)
  • post short note on dataset selection into Wiki (SG)

• Before Garching:
  • SG to send BM ppt file on radio astronomy and the VO
  • AMSR to produce interim report on image metadata
  • SG to send BM image of HTML form mock-up
  • BM to liase with SG over contents of Garching talk

A fuller list of Actions will be included in the Q4 forecast for WP-A5.

-- BobMann - 28 May 2002