{"action":"created","issue":{"url":"https://api.github.com/repos/lofar-astron/factor/issues/126","repository_url":"https://api.github.com/repos/lofar-astron/factor","labels_url":"https://api.github.com/repos/lofar-astron/factor/issues/126/labels{/name}","comments_url":"https://api.github.com/repos/lofar-astron/factor/issues/126/comments","events_url":"https://api.github.com/repos/lofar-astron/factor/issues/126/events","html_url":"https://github.com/lofar-astron/factor/issues/126","id":170588534,"number":126,"title":"Negative source holes in facetimage","user":{"login":"adrabent","id":19146990,"avatar_url":"https://avatars.githubusercontent.com/u/19146990?v=3","gravatar_id":"","url":"https://api.github.com/users/adrabent","html_url":"https://github.com/adrabent","followers_url":"https://api.github.com/users/adrabent/followers","following_url":"https://api.github.com/users/adrabent/following{/other_user}","gists_url":"https://api.github.com/users/adrabent/gists{/gist_id}","starred_url":"https://api.github.com/users/adrabent/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/adrabent/subscriptions","organizations_url":"https://api.github.com/users/adrabent/orgs","repos_url":"https://api.github.com/users/adrabent/repos","events_url":"https://api.github.com/users/adrabent/events{/privacy}","received_events_url":"https://api.github.com/users/adrabent/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":10,"created_at":"2016-08-11T07:50:51Z","updated_at":"2016-08-25T13:57:55Z","closed_at":null,"body":"Hi,\r\n\r\nwhen I use CASA as facet imager, now strange negative sources appear in the facetimage step.\r\nI marked them with red circles.\r\n![negative_sources](https://cloud.githubusercontent.com/assets/19146990/17581833/5c7e562a-5fa8-11e6-829e-8f53460222f2.png)\r\n\r\nThose negative sources appear in all (!) facet images. In some of them it seems to be kind of symmetric:\r\n\r\n![negative_sources2](https://cloud.githubusercontent.com/assets/19146990/17581898/e3382c0e-5fa8-11e6-9ead-5c47aec2eb81.png)\r\n\r\nI'm not really sure if anybody else is using CASA as facet imager, but couldn't this be something like aliasing?"},"comment":{"url":"https://api.github.com/repos/lofar-astron/factor/issues/comments/242396029","html_url":"https://github.com/lofar-astron/factor/issues/126#issuecomment-242396029","issue_url":"https://api.github.com/repos/lofar-astron/factor/issues/126","id":242396029,"user":{"login":"darafferty","id":5547918,"avatar_url":"https://avatars.githubusercontent.com/u/5547918?v=3","gravatar_id":"","url":"https://api.github.com/users/darafferty","html_url":"https://github.com/darafferty","followers_url":"https://api.github.com/users/darafferty/followers","following_url":"https://api.github.com/users/darafferty/following{/other_user}","gists_url":"https://api.github.com/users/darafferty/gists{/gist_id}","starred_url":"https://api.github.com/users/darafferty/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/darafferty/subscriptions","organizations_url":"https://api.github.com/users/darafferty/orgs","repos_url":"https://api.github.com/users/darafferty/repos","events_url":"https://api.github.com/users/darafferty/events{/privacy}","received_events_url":"https://api.github.com/users/darafferty/received_events","type":"User","site_admin":false},"created_at":"2016-08-25T13:57:55Z","updated_at":"2016-08-25T13:57:55Z","body":"Actually, thinking about it some more, I guess using a padding factor should be fine after all, as it is the region near the model image edges that's most severely affected by aliasing, the size of which of course scales with the model size. "}}
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