Re: [ITP] astrometry.net-0.38-1

[Jussi Kantola <jussi.kantola@gmail.com>]

On Fri, Oct 7, 2011 at 5:20 PM, Marco Atzeri wrote:
> Hi Jussi,
> could you clarify the usage/scope of
> usr/lib/astrometry/libbackend.so ?

I'm not a programmer of astrometry.net, and don't know how it works
internally (except that it's looking for
"stars" in the image to be solved, then constructs quads from the
stars and matches the quads to an index).
However I had to modify backend-main.c so that the config file (which
defines the location of index files)
could be read from cygwin's preferred location,
/usr/share/astrometry/etc/backend.cfg.

From backend-main.c:

/**
 * Accepts an augmented xylist that describes a field or set of fields to solve.
 * Reads a config file to find local indices, and merges information about the
 * indices with the job description to create an input file for
'blind'.  Runs blind
 * and merges the results.
 */

Not supposing everyone's an amateur astronomer, please allow me to decipher:

field = field of view, starfield, the area of the sky that's contained
in the image that is to be solved;
solving = figuring out the sky coordinates of the field
indices = files containing the known coordinates of celestial objects
(esp. stars)
blind = blind solver/solving, ie. no other fore-knowledge of the
contained field is required

> for what I see, none of the 77 exe you have in
>   usr/bin
> is using it.

At least solve-field.exe (and/or the tools called by solve-field) uses
it, as it was complaining about
missing files before I did the modification.  I don't know enough
about the linking of cygwin software
to comment why it's not showing in f.e. "ldd /usr/bin/solve-field.exe".

-- 
jussi