Is there a way to obtain errors for the barycenter coordinates and the brightness values?

[mapfiable]

The method sep.extract returns no error for the barycenter coordinates x and y or the brightness values like flux for example. Is there a way to obtain those? Also, since flux is the sum of the member pixels (in unconvolved data), does that mean only pixels that are completely within the aperture are counted? Or does it also in part count pixels that are clipped by it? Is sep.sum_ellipse the method that is invoked for this calculation, or would it return different results if applied to the sep.extract data?

[kbarbary]

The method sep.extract returns no error for the barycenter coordinates x and y or the brightness values like flux for example. Is there a way to obtain those?

The sep.extract documentation is misleading here: The parameters errx2 and erry2 are actually the variance in the barycenter coordinates x and y (the "error" squared). See the relevant Source Extractor manual section for details.

since flux is the sum of the member pixels (in unconvolved data), does that mean only pixels that are completely within the aperture are counted?

In the results of sep.extract, there are no apertures. A given pixel is either fully a member of an object or it is not. An object's member pixels can have any shape (often with jagged edges). For aperture photometry, you must use the sep.sum_... functions.

Is sep.sum_ellipse the method that is invoked for this calculation, or would it return different results if applied to the sep.extract data?

sep.extract does not call any of the sep.sum_... functions itself.

[mapfiable]

I see, thanks a lot!