@JohnDallman Yep. I think a good parallel -- though in reverse order -- might be the advent of stellar spectroscopy; Fraunhofer found spectral lines in both solar spectra and the spectra of other stars.

@controlgroup Yeah, that's basically the idea.

@causative In the context in which the instrument is used, I think there's not a clear line between what constitutes a detection or not -- just varying degrees of confidence. If you can determine the statistics of the background, you can use Monte Carlo simulations to calculate the false alarm probability; the question is then what's an acceptable false alarm probability. For what it's worth, in my work, $5\sigma$ typically constitutes a possible detection, but I don't do imaging, and certainly not real-time computations.

@Idon'tknow I think your only options would be a) make the star a bit brighter or b) add some greenhouse gases to the atmosphere.

@Idon'tknow Is there a particular reason you can't move the planet any closer to the star?

@MrUnavailable I don't know -- hopefully someone else can provide an estimate.