I was having a look at JWST's NIRISS data of WASP96 (specifically at the x1dints fits file which should be already calibrated). From this, I would like to obtain a result in a fashion similar to the transmission spectrum showcased by the JWST collaboration during the first images reveal.
Now, I'm new to exoplanets and their spectra, and so I ask to the specialists out here: what is the standard technique to retrieve the transmission spectrum for such objects? Moreover, are there specific python implementations/packages that are best to perform it?
My guess is the following (please correct me if I'm wrong!): the fits file I've downloaded from the archive contains several spectra of WASP96 taken over the exposure time. I should maybe implement a (or utilize a pre-existing) method to pinpoint the instant at which we have the biggest flux decrease in all wavelengths due to the planet's passage in front of the star, and then pinpoint the instant at which the transit is complete. Then, I could retrieve the median stacked spectra of the star alone and the median stacked spectra of the star during the transit and perform a subtraction. Is this (broadly speaking) a correct procedure?