The Haleakala Stokes Polarimeter Data File Format

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In trying to read an HSP datafile with IDL, the following was learned.

1) There is a 512 byte header.  There appears to be a 1536 bytes
at the end of the file, or 3/4 of a datapoint.

2) The bytes must be swapped with SWAP_ENDIAN.

3) Every datapoint has 1024 integers.  The first 4 x 128 are
the I, Q, U, and V spectra.  The last 512 include X, other stuff, and
presumably a pointing header.

4) The scan is boustrophedonic.

5) Points off the limb are not recorded.  This causes some
mismatch in pointing.  Slop contributes about 2 pixels of odd-even
line shift.

Barry LaBonte
December 6, 2000

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     Last modified: Wed Oct 29 07:00:38 HST 2003