Ability to step through DVO database in subsections that cover entire catalog

[Michael Wood-Vasey]

Dave Monet and I would be interested in being able to grab subsections of a DVO database in a systematic and comprehensive way. For example, we would like to grab 20 square degree sections at a time in such a way that we are guaranteed to eventually cover the entire sky. Being able to choose to either have or not have duplications would be a useful option, but having no duplicates would probably be the preferred default.

As discussed in Tuesday's IPP workshop, one way Gene suggested to do this was to use 'gcat' to get a list of all catalog files and then be able to pass a catalog file to mextract (and potentially related utilities such as imextract). E.g.

gcat 0 0 180

to get a list of all catalog files in 'catlist' (how do you store the results of this command to arrays?). And then

for cat in catlist:

mextract -catfile cat ra, dec, [etc.]
write output.txt ra, dec, [etc.]

endfor

I suppose one could manually do this from the outside by manually extract the files and creating a DVO database for each, but that seems a bit ugly and not really a useful thing to include into scripts.

[eugene]

there is an existing utility in dvo to define the region of interest based on catalog file names:

mextract ra dec -cpt n0730/0748
avextract ra dec -cpt n0730/0748

or by list of catalog files:

mextract ra dec -cptlist (filename)

where filename contains names like n0730/0748 separated by whitespace.

Unfortunately, these features both seem to trigger segfaults at the moment.