I'd like to download catalog data for WISE objects that lie anywhere on the sky, and satisfy a few constraints. What is the best way to do this?
Posted by Vandana Desai on 14 June 2013 01:34 PM

Depending on the nature of the constraints, you could be looking at downloading a very large number of objects. To prevent a single user's very large query from impacting our performance for other users, IRSA's catalog search tool will fail for queries that result in tables larger than about 2 Gb. Here is a simple strategy to follow if you suspect that your results table will be very large.

For efficiency, use the polygon search (rather than ra/dec constraints) to perform your query on a region that is a square degree in area. Check the size in Gb (S) of your output file. The area in square degrees that you can use for future searches with the same constraints will be roughly A = 2 / S. Smaller areas are less likely to fail.

You will have to divide the sky up into chucks of area A, and perform your query separately on each chunk. Wait for a single query to complete before launching another one. Do not run multiple large queries simultaneously.

(1 vote(s))
This article was helpful
This article was not helpful

Comments (0)