[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)
UCO/Lick Observatory Natural Sciences II, Room 165 Lat +36.99855
University of California Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m