Subject: AML, a new format for astronomy based on SGML

From: Damien <DG.Guillaume at ulst.ac.uk>
Date: Wed, 28 Jan 1998 22:45:42 +0000

The main goal of FITS was to provide a standard exchange format
for astronomy. With some advantages, especially its flexibility,
it really became used by everybody in astronomy.
However, it is still limited to some data, and is
completly ignoring (as far as I know) astronomical articles or
data on single astronomical objects (amongst many other).
Also, it has become a bit outdated as an exchange format (strange
80 characters lines in the header, no structure, ...)

This is why I started the creation of a new exchange format
for astronomy, within my thesis on information retrieval in
astronomy. It is based on SGML and as such is much more flexible,
readable by any SGML/XML browser/parser, and is appropriate
to the web.
AML is now supporting 4 astronomical data types, but is in
no way restrictive: astronomical objects, articles, tables
and images. Because only characters may be used in SGML,
and because it is easier to manage metadata this way, the big binary
files (such as tables or images) are external to the AML files,
and are referenced in AML as images are referenced in HTML.
I began the creation of an AML browser on the web (a Java applet),
so that anyone can easily read these files.

There are of course some interactions between FITS and AML,
especially for astronomical images: as everybody is now using
FITS, the translation in the two directions must be easy.
To enable an easy translation, I just copied the FITS keywords
and put them into AML in an SGML-way. However, some improvements
may be easy to do on that basis, such as classifying FITS
header information (on the image, on the observations, and so on).

As I hope AML could become a standard format, I cannot
define it alone, and I'm now looking for people interested in
its definition. Maybe it could be seen not as a rival, but as
a new version of FITS...

More information on AML is available at:
http://www.infm.ulst.ac.uk/~damien/these/

Damien Guillaume

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From: Peter Bunclark <psb at ast.cam.ac.uk>
Date: Thu, 29 Jan 1998 09:17:58 +0000

You can't replace FITS unless you do handle large binary images. 
Perhaps you could use FITS as your image format, which would be
referenced from AML.

Peter.

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From: Damien GUILLAUME <guillaum at newb6.u-strasbg.fr>
Date: Thu, 29 Jan 1998 22:20:10 +0100

> You can't replace FITS unless you do handle large binary images.

There's no reason why my system would not be able to handle large
binary images (which is the common case in astronomy).

> Perhaps you could use FITS as your image format, which would be

Yes, it's exactly what I'm doing now. But the meta-information
is duplicated: it is both in the AML file and in the FITS header.
I can also delete the header of the FITS file, but I prefer to
give the two possiblities: pointing from AML to a FITS file,
or pointing only to the raw data. The risk is that someone
may change the FITS file with a usual image processing program
without changing the AML file accordingly. So, my software will
have to check the FITS file each time it loads a corresponding
AML file. But it's not really a problem: the AML files will always
be used with a software, for transfert, translations or browsing.

Damien