{"action":"created","issue":{"url":"https://api.github.com/repos/astropy/astropy/issues/3594","labels_url":"https://api.github.com/repos/astropy/astropy/issues/3594/labels{/name}","comments_url":"https://api.github.com/repos/astropy/astropy/issues/3594/comments","events_url":"https://api.github.com/repos/astropy/astropy/issues/3594/events","html_url":"https://github.com/astropy/astropy/issues/3594","id":61210549,"number":3594,"title":"Postage stamps from WCS","user":{"login":"gully","id":860227,"avatar_url":"https://avatars.githubusercontent.com/u/860227?v=3","gravatar_id":"","url":"https://api.github.com/users/gully","html_url":"https://github.com/gully","followers_url":"https://api.github.com/users/gully/followers","following_url":"https://api.github.com/users/gully/following{/other_user}","gists_url":"https://api.github.com/users/gully/gists{/gist_id}","starred_url":"https://api.github.com/users/gully/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/gully/subscriptions","organizations_url":"https://api.github.com/users/gully/orgs","repos_url":"https://api.github.com/users/gully/repos","events_url":"https://api.github.com/users/gully/events{/privacy}","received_events_url":"https://api.github.com/users/gully/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/astropy/astropy/labels/coordinates","name":"coordinates","color":"c7def8"},{"url":"https://api.github.com/repos/astropy/astropy/labels/Feature%20Request","name":"Feature Request","color":"bfdadc"},{"url":"https://api.github.com/repos/astropy/astropy/labels/wcs","name":"wcs","color":"c7def8"}],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":20,"created_at":"2015-03-13T19:59:29Z","updated_at":"2015-06-11T18:38:08Z","closed_at":null,"body":"I see a good amount of duplicate code on GitHub for making \"Postage Stamps\" from a larger file.  A GitHub search for \"astropy postage stamp WCS\" provides 15 hits.  A search for \"postage stamp\" within the astropy repository yielded nothing, so I think it's safe to say that this functionality does not exist specifically in astropy.  Am I wrong?  Making \"postage stamps\" is a common use case in astronomy.\r\n\r\nI think it would make sense to add this functionality directly into astropy, probably in the wcs module.  I know it's lame to make a feature request rather than a pull request, but when it comes to wcs there is a lot of nuance that is probably over my head.  Like I said, there are many existing examples of this functionality, so those would be a great starting point.  I would be happy to collaborate with someone on this feature, if it is deemed worthy of integration into astropy."},"comment":{"url":"https://api.github.com/repos/astropy/astropy/issues/comments/111235029","html_url":"https://github.com/astropy/astropy/issues/3594#issuecomment-111235029","issue_url":"https://api.github.com/repos/astropy/astropy/issues/3594","id":111235029,"user":{"login":"larrybradley","id":4992897,"avatar_url":"https://avatars.githubusercontent.com/u/4992897?v=3","gravatar_id":"","url":"https://api.github.com/users/larrybradley","html_url":"https://github.com/larrybradley","followers_url":"https://api.github.com/users/larrybradley/followers","following_url":"https://api.github.com/users/larrybradley/following{/other_user}","gists_url":"https://api.github.com/users/larrybradley/gists{/gist_id}","starred_url":"https://api.github.com/users/larrybradley/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/larrybradley/subscriptions","organizations_url":"https://api.github.com/users/larrybradley/orgs","repos_url":"https://api.github.com/users/larrybradley/repos","events_url":"https://api.github.com/users/larrybradley/events{/privacy}","received_events_url":"https://api.github.com/users/larrybradley/received_events","type":"User","site_admin":false},"created_at":"2015-06-11T18:38:08Z","updated_at":"2015-06-11T18:38:08Z","body":"@mcara  I don't think it's a problem to have CRPIX outside of the cutout image.  The advantage of shifting CRPIX (and not CRVAL) is that the existing SIP coefficients will work fine and the spherical projection remains the same (as @astrofrog mentioned).\r\n\r\nGood point on the tabular distortions.  Unfortunately, I don't think there's any good way to propagate them and apply them to the cutout image (thankfully these distortions are usually small).  If they are present, then I'll issue a warning and remove them from the cutout wcs object.  Otherwise, the tabular distortions would be applied incorrectly (wrong pixels) to the cutout image.  Thanks."}}