Some loose, fairly obvious, ideas I had were something spider's web based (catching bugs) - or catching a cricket (or baseball) ball. Don't be limited to that. In fact forget I said anything ;-)
But it seems to me that the idea of "catching" should feature in the design - I'm open to alternatives.
I'd ideally like the typography to be distinctive too.
Because the word "CATCH" is an acronym it should be capitalised.
The (current) home of CATCH is this GitHub repository:
At some point I'll create a dedicated landing page, away from GitHub, where the logo would be featured more prominently.
I also tend to do presentations on the subject. Something that presents well - perhaps with decomposable components (e.g. text and artwork that can be used separately) would be welcome - but it's not a showstopper.
One of the themes of CATCH is that it simplifies things - so I'd like to emphasize simplicity, too,
I have two (quite old now) blog posts on CATCH. Could be worth a look for inspiration, although it's quite technical material: