{"action":"created","issue":{"url":"https://api.github.com/repos/kbarbary/sep/issues/37","repository_url":"https://api.github.com/repos/kbarbary/sep","labels_url":"https://api.github.com/repos/kbarbary/sep/issues/37/labels{/name}","comments_url":"https://api.github.com/repos/kbarbary/sep/issues/37/comments","events_url":"https://api.github.com/repos/kbarbary/sep/issues/37/events","html_url":"https://github.com/kbarbary/sep/pull/37","id":150149837,"number":37,"title":"Adding the errors on the variances ERRX2, ERRY2, and ERRXY","user":{"login":"cmccully","id":5331996,"avatar_url":"https://avatars.githubusercontent.com/u/5331996?v=3","gravatar_id":"","url":"https://api.github.com/users/cmccully","html_url":"https://github.com/cmccully","followers_url":"https://api.github.com/users/cmccully/followers","following_url":"https://api.github.com/users/cmccully/following{/other_user}","gists_url":"https://api.github.com/users/cmccully/gists{/gist_id}","starred_url":"https://api.github.com/users/cmccully/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/cmccully/subscriptions","organizations_url":"https://api.github.com/users/cmccully/orgs","repos_url":"https://api.github.com/users/cmccully/repos","events_url":"https://api.github.com/users/cmccully/events{/privacy}","received_events_url":"https://api.github.com/users/cmccully/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":18,"created_at":"2016-04-21T18:14:56Z","updated_at":"2016-04-29T23:08:45Z","closed_at":null,"pull_request":{"url":"https://api.github.com/repos/kbarbary/sep/pulls/37","html_url":"https://github.com/kbarbary/sep/pull/37","diff_url":"https://github.com/kbarbary/sep/pull/37.diff","patch_url":"https://github.com/kbarbary/sep/pull/37.patch"},"body":"This pull request should add the errors on the variances (which measure the shapes of the psfs). \r\n\r\nI think most of the code is pretty simple. There are two main gotchas that I discovered. The first is that if the object is blended, both the centroid and the variance (and therefore the error on the variance as well) are calculated with respect to the previous centroid. This was a little odd to me, but as long as that is the expected behavior then its fine. \r\n\r\nThe second gotcha is that currently if no \"error\" is given,  the error on the variances return all NaNs. I think that is alright, but might be worth adding documentation somewhere. \r\n\r\nThoughts?"},"comment":{"url":"https://api.github.com/repos/kbarbary/sep/issues/comments/215904253","html_url":"https://github.com/kbarbary/sep/pull/37#issuecomment-215904253","issue_url":"https://api.github.com/repos/kbarbary/sep/issues/37","id":215904253,"user":{"login":"cmccully","id":5331996,"avatar_url":"https://avatars.githubusercontent.com/u/5331996?v=3","gravatar_id":"","url":"https://api.github.com/users/cmccully","html_url":"https://github.com/cmccully","followers_url":"https://api.github.com/users/cmccully/followers","following_url":"https://api.github.com/users/cmccully/following{/other_user}","gists_url":"https://api.github.com/users/cmccully/gists{/gist_id}","starred_url":"https://api.github.com/users/cmccully/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/cmccully/subscriptions","organizations_url":"https://api.github.com/users/cmccully/orgs","repos_url":"https://api.github.com/users/cmccully/repos","events_url":"https://api.github.com/users/cmccully/events{/privacy}","received_events_url":"https://api.github.com/users/cmccully/received_events","type":"User","site_admin":false},"created_at":"2016-04-29T23:08:45Z","updated_at":"2016-04-29T23:08:45Z","body":"I believe so. Isn't that required in extract if no error matrix is passed? In that case how is the threshold calculated? Is it considered an absolute number? Can you point me to that line of code. \r\n\r\nTo follow the manual from sextractor, I would think that we would need access to the sky rms and the gain and the image values in analyse.c. The original code base has this \"field\" type that has some of this info.  The alternative is to do things after the fact in cython, but move away from the original code base (which would be easier). What are your thoughts?\r\n\r\nAlso what is the difference between value and cvalue? I couldn't figure it out."}}