# New use of \`isPrimary\` that began in \`w\_2021\_12\` **URL:** \ **Category:** DM Notifications\ **Tags:** source, catalogs, pipe\_tasks\ **Created:** [May 13, 2021, 8:17pm UTC](https://www.rubin.community/t/new-use-of-isprimary-that-began-in-w-2021-12/4957 "2021-05-13T20:17:46Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![jeffcarlin](https://sea2.discourse-cdn.com/flex002/user_avatar/www.rubin.community/jeffcarlin/32/491_2.png) [@jeffcarlin](https://www.rubin.community/u/jeffcarlin)\ **Post date:** [May 13, 2021, 8:44pm UTC](https://www.rubin.community/t/new-use-of-isprimary-that-began-in-w-2021-12/4957/2 "2021-05-13T20:44:00Z")
Thanks, Fred - this is really helpful! I have a couple of initial questions (and need some more time to digest the details): > [@fred3m](#): > > An easy way to get unique sources is to remove all of the sources with `detect_isPatchInner==True & detect_isTractInner==True` Does this mean to say to _select_ sources with these flags set to True, or am I misunderstanding? > [@fred3m](#): > > The `detect_isPrimary` flag can be thought of as a flag to include the most common catalog of unique sources that users will want to make measurements on. Note that this completely excludes sources in overlap regions, whereas any analysis will likely also want to include some selection criteria to choose which version of sources from the overlap region to use. Is this a change from previous behavior for `detect_isPrimary`? I think that in the past this flag did not completely ignore the overlap regions. If it really does leave out overlap regions, then could you clarify which flag(s) one would use to select “the best measurement of all well-measured sources?” I recognize that this is vague/ambiguous, but am just thinking about what a typical user might select as a “clean” catalog for their science. --- _[View the full topic](https://www.rubin.community/t/new-use-of-isprimary-that-began-in-w-2021-12/4957)._