Meetings/20081212

Warwick has gotten things to a point where ​images can be made from CABB data. We need to get ready to start making changes to code and testing them.

Agenda

change of project scientist

Emil steps in for Naomi

what role for Jamie Stevens?

Jamie starts ... January 12th?

state of MIRIAD code changes

We have a simple python script, is it

• still working?
• in RCS yet?

availability of test versions of programs

Vince to report

plan for January

There'll be pressure to get code ready. Who's away, when?

---

Minutes

Warwick gave a report on the status of CABB, which has advanced a lot now. The system has produced images (from simultaneous observations) that look very close to the old system.

• polarisation images differ. It may be just the error response that differs, i.e. it could be that the differences are not significant.
• relative amplitudes and phases (of the antennae?) appear to be wrong.
  • needs a change to Tsys output formatting (right data being written to wrong record)
  • need to investigate how the XY phase is being formed and how it is being recorded
• continuum output available only (no zooms)
• already writing autocorrelation data, though in a potentially wasteful way.
  • the data are being written as two fake 'timing bins'. ugh.
  • the way they are being written means there is a lot of redundant data.
    MarkW suggested 'packing' the correlations in some way, after discussion this was judged not worth the effort.
• Coping with hardware failures: if a module dies, lots of channels will disappear from the bandpass. However these will not be in a contiguous chunk. We'll need a way to deal with this. The discussion suggested the 'channel weight' flags can be used for the continuum case at least.
  • In the case of zoom nodes, each central frequency is a separate (FITS binary) table with all baselines in it (including the n-n "autocorrelation baselines"). The spectral weights feature is in the RPFITS library already, but it writes all baselines for every visibility; this leads to a 50% overhead in the raw data files. It's unclear how to deal with this.

Warwick sees two main issues for the software side:

1. using information in the autocorrelations to calibrate on a per-channel basis
2. dealing with the spectral weights issue.

Xmas absences:

Who	Last Day	Back In
Dave	19 Dec	05 Jan
Dave	? Jan	?+4 weeks
Emil	19 Dec	12 Jan
Jamie	N/A	12 Jan
MarkC	24 Dec	12 Jan
MarkW	?	?
Naomi	19 Dec	late 2009
Vince	24 Dec	05 Jan
Warwick	24 Dec	05 Jan

Actions

• Emil becomes PS as of today.
• Jamie will be dealing with "CABB issues" from day 1. He will be doing calibrator observations and reductions, for example, which may well turn up problems.
• Emil, in collaboration with Jim Caswell, to select some test fields - for repeated observations as the system implementation goes forward.
• Vince to work with MarkC on implementing a 'test version' of all the programs.
• Next meeting 2009-01-09.

Participants

• Dave
• MarkC
• MarkW
• Emil
• Naomi
• Warwick

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