The Keck Planet Finder Exposure Time and RV Precision Calculator simulates photon-limited uncertainties across a range of expected stellar and observational parameters. Synthetic stellar spectra (Allard et al., 2012) are scaled using modeled atmospheric and instrumental efficiency curves, remapped onto the KPF spectral format (including instrument resolution, sampling, blaze functions, echelle order distribution). Velocity uncertainties are then calculated on a per-pixel basis using the RV information content formalism of Bouchy et al. (2001) and Murphy et al. (2007). Read noise (assumed 3 electrons per pixel) from the CCD is included in the flux uncertainty. Final performance estimates are presented as a function of stellar spectral type, target brightness, and exposure time. Examples of plots and explorations possible with the calculator are shown below.


Download the KPF Exposure Time (and RV Precision) Calculator to further explore the capabilities of this upcoming next-generation instrument.


Relative information content comparison between spectral types as a function of wavelength. Over-plotted are the wavelengths of relevant stellar activity indicators that lie within the KPF bandpass. Each grid point represents a separate echelle order. Also shown is a telluric model for Maunakea at z = 30 degrees.


Limiting magnitudes to reach a velocity uncertainty limit, as a function of stellar temperature and brightness. This is composed of photon noise and a projected instrumental error of 35cm/s — stellar jitter is excluded.


The KPF ETC is developed by Sam Halverson.