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BDFITS Working Group

As of 3/31/04, GBT data is available as SDFITS and Arecibo data is available as bdfits as described in this document. We all want to converge to the same data format by the end of 2004, and both sides are willing to iterate to the desired shared solution. At this time, we need to decide between the "Other Options" presented below, and identify if there are any more critical issues to resolve.

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At present, the Arecibo data is written in variable length arrays, following the guidelines of the "proposed binary table extensions", in Section 5 of the 1997 NASA fits documentation (available online at http://archive.stsci.edu/fits/users_guide/). The data is written such that each individual dump, or integration, is given its own row in the array, as is each polarization.

Other Options (Community Involvement Required!)

Option 1: Variable Length vs. Non-Variable Length Arrays. Other options for the data layout in bdfits include not using variable length arrays, but instead starting a new table each time the array length changes. In SDFITS, we now start a new table each time the array length changes rather than using variable length arrays. At present we would like to have the data layout of both telescopes match what Arecibo is currently doing, as these files appear to be reasonable in size and the data is readily accessed through the heap. However, we invite arguments as to why the format/layout of the data should be changed.

Option 2: Row Contents. We can put each individual dump for each sampler and polarization into separate rows or put all data (regardless of sampler & polarization) for each dump/integration in one row. Right now, both SDFITS and bdfits put the dump information into separate rows.

Non-Spectral Line Data

We would also like feedback from the community as to how non-spectral line data (e.g. continuum data) should be dealt with.

Additional Comments

-- KarenONeil - 26 Mar 2004