Subject: compressed fits format

From: Alain MAURY <maury at ocar01.obs-azur.fr>
Date: 22 Oct 1996 20:24:56 GMT

Dear all fitsers...
I am sorry to post this here since I guess it may be a question
which appear every 2 weeks ( ? ).
Is there any standard for compressed fits files ?.
I am about to include two modes of compression on our images, one
with a lossless algorithm ( storage of the difference between 2 16
bits pixels on a single byte, I presume this well known algorithm
has even a name... ), and a lossy one after the one used for
the digitised sky survey ( using H transform ). I assume I am not
the only one who has to take care of more than 1 gigabytes of images
per night, and would like to know is there are standard FITS keywords
describing these compression ( COMPRESS = T ? )
We decided it was much better to perform real time processing of the
data, then compress it by a factor of 10 and store it on CD ROMs ( which
would then hold about a week of observations ) rather than to store
everything on tape which cannot be read after 3 years... and would
prefer to conform to some kind of standard if there is such a thing.
Alain

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From: Arnold Rots <arots at xebec.gsfc.nasa.gov>
Date: Thu, 24 Oct 1996 12:30:32 -0400 (EDT)

We skirted the issue by gzipping all our FITS files ...

  - Arnold Rots
    RXTE-GOF, GSFC