SIMBAD references

The goal of this exercise is to determine, for JWST NIRSpec IFU observations, whether dedicated background observations and leakcal exposures are worth the extra observing time. Do you need dedicated backgrounds? They're important if you want to measure the shape of the continuum; for continuum-subtracted line fluxes it will not make so much of a difference. Do you need leakcals? Leakcals slightly reduced the noise, at a 1% level. If you are tight on time and have decent signal-to-noise ratio for your emission lines, you can probably skip them.