Extended Data Fig. 2: Comparison of averaged background frames computed for each reduction pipeline.

a, A median out-of-transit integration from the stage 2 output files of the jwst pipeline in data numbers per second (DN s⁻¹). b1,c1,d1,e1, Estimated median background frames for four example pipelines: nirHiss (b), supreme-SPOON (c), transitspectroscopy (d) and iraclis (e). All reduction pipelines use the predefined zodiacal background model provided on the STScI JDox User Documentation website. nirHiss estimates the zeroth-order contaminants by taking a smoothed median from the F277W filter integrations. We note that the background frame from supreme-SPOON (c1) for group eight is shown here and was scaled by a factor of about 0.02 to lie on the same scale as the background from the other three pipelines. iraclis subtracts a median per column to remove further 1/f noise. b2,c2,d2,e2, Background-subtracted median integrations for each pipeline, plotted in DN s⁻¹ but scaled from −5 to 5 to highlight subtle changes in the background. For these integrations, we define out of transit as integrations 1–200 and 400–518. (https://github.com/afeinstein20/wasp39b_niriss_paper/blob/main/scripts/edfigure2.py).