After running Astrodrizzle to combine several FLT files into one image, a '_drz_sci.fits' and '_drz_wht.fits' file are produced. Using the 'IVM' and 'ERR' weighting schemes gives hugely (1x10^11) different values in the 'wht' map, and I am confused about what this actually is. The '_drz_wht.fits' file produced when setting final_wht_type = 'IVM' has values close to what I'm expecting for the rms, but then why is it called a 'wht' map?
In the end, I am looking for an RMS map for use with Source Extractor and GALFIT, which does not include the contribution from the objects themselves. Can you advise on how to produce what I need? I am aware from a previous discussion that the handbook Section 4.2.12A is incorrect on this matter.