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Old April 30th 07, 06:28 PM posted to sci.astro.fits
Steve Allen
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Default [fitsbits] Packed binary values

On Mon 2007-04-30T12:37:54 -0400, William Pence hath writ:
Mike Nolan a ecrit :
At moderate data rates, the header information changes slowly compared
to the spectral dump rate, and the time axis may become nondegenerate
within a record.


One could write the packed data to a bit column in the binary table
with TFORMn = 'rX'. The TDIMn keyword could be used to convey the number
of bits per sample. For example, a 1-dimensional 256-sample spectrum
with 2 bits per sample could be stored with

TFORMn = '512X'
TDIMn = '(2,256)'

This could be extended to higher dimensional data. If the record
contained the spectrum that was read out a 4 successive times, then it
could be stored with


I'm pretty sure that a binary table like this will also allow
the WCS conventions to describe a non-degenerate temporal axis.

With the usual caveats about the explicit ambiguity, it should be
straightforward to use the methods of WCS Papers II & III to describe
more coordinate axes than there are recorded in the table column.

--
Steve Allen WGS-84 (GPS)
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