[AstroPy] Cross matching two source lists

Eduardo Bañados Torres eebanado at uc.cl
Fri May 11 09:57:01 EDT 2012

Hi Thomas,

I'm not sure if this is what you want, but I'm using LSD to
cross-match huge catalogs (3pi of the sky), LSD is written in python
and is multi-thread! so is very fast (though the installation is not
that trivial).

The first line of the documentation is:

The Large Survey Database (LSD) is a framework for storing,
cross-matching, querying, and rapidly iterating through large survey
datasets (catalogs of >109 rows, >1 TB) on multi-core machines. It is
implemented in Python, written and maintained by Mario Juric

all the information is here:

Well if you need more help or examples you can contact me

and yes.. I also think it would be nice to have a cross-matching
algorithm in astropy


On Fri, May 11, 2012 at 3:08 PM, Erin Sheldon <erin.sheldon at gmail.com> wrote:
> Excerpts from Thomas Robitaille's message of Fri May 11 04:03:18 -0400 2012:
>> Hi everyone,
>> I am looking for a Python package that can do arbitrary and efficient
>> cross-matching of source lists, i.e. some kind of kd-tree that uses
>> spherical rather than euclidean distances. Is anyone aware of such a
>> package?
> Hi Thomas-
> The HTM module in esutil does this.
>    http://code.google.com/p/esutil/
>    http://code.google.com/p/esutil/source/browse/trunk/esutil/htm/__init__.py
> It indexes the sky using a Hierarchical Triangular Mesh, which is a
> quaternary tree.
> Example to find the closest match between two lists within an arcsecond:
>    from esutil import htm
>    h = htm.HTM()
>    maxrad=1.0/3600.0
>    m1,m2,radius = h.match(ra1,dec1,ra2,dec2,maxrad)
> m1 and m2 are index arrays for the matched pairs and radius is the
> match distance.  You can also allow more than one match.
> I hope this helps,
> -e
> --
> Erin Scott Sheldon
> Brookhaven National Laboratory
> _______________________________________________
> AstroPy mailing list
> AstroPy at scipy.org
> http://mail.scipy.org/mailman/listinfo/astropy

Eduardo Bañados Torres

More information about the AstroPy mailing list