A crucial test for astronomical spectrograph calibration with frequency combs

Understand

Laser frequency combs (LFCs) are well on their way to becoming the next-generation calibration sources for precision astronomical spectroscopy.

• This development is considered key in the hunt for low-mass rocky exoplanets around solar-type stars whose discovery with the radial-velocity method requires cm/s Doppler precision.
• In order to prove such precise calibration with an LFC, it must be compared to another calibrator of at least the same precision.
• Being the best available spectrograph calibrator, this means comparing it to a second - fully independent - LFC.