Lens light model modeling background instead

[PrayaagKatta]

Hey again,
I wanted to ask about why this happens - When I have one sersic ellipse for modeling the lens light, it tends to model the background instead. I am giving the 'background_rms' kwargs value by calculating the rms from a small region from the data, is there anything I am missing?

[sibirrer]

@PrayaagKatta you calculated the background rms, which is the scatter in background pixels. Did you subtract the MEAN background counts from the data?
If not, the Sersic might try to mimic this constant offset as good as it can (but will fail). Try to subtract the background as good as possible. You can also add a 'UNIFORM' light model to the lens_light_model_list that can on the fly introduce a constant surface brightness model (positive and negative) to adjust the background level

[PrayaagKatta]

Ah I see, thank you for the answer and the tip about the uniform light model. (For some other lenses, I hadn't explicitly subtracted the mean background value from the data so I was surprised to see this happening for this lens.)