What priors to use?

[gully]

Here are my thoughts on priors:

uniform in logg, uniform in T_eff

These are the parameters of interest.

Fraction of a pixel for v_z.

This is effectively a wavelength calibration consideration, since the spectra are insufficiently low-spectral resolution to assess v_z for any plausible range.

vsini rebranded to sigma_R

The uncertainty in the spectral resolution is much larger than the vsini. They have slightly different kernels, so this requires a tweak to the update_theta function.

flat in logOmega (for now)

We have distances estimates and decent priors for radii for these objects, so we could assign an informative prior on Omega. For now, let's just allow the values to float and see what we get. We could repeat the experiment later and see if we get a consistent estimate for effective temperature.

maximum deviation for Cheb calibration polynomials

Already in place, this seems to make the most sense. I lowered the peak-to-valley to 2%, which is about equal to the maximum S/N per pixel.

+/-5% in sigmaAmp

We assume we have estimated the mean sigma correctly to within 5%, which is probably accurate. I did impute some sigma values (they had zero values before), but this level of uncertainty seems to be fine.

logAmp?

getting this wrong caused major errors before. We have put a cap of logAmp < -17 from trial and error, and by-eye checking.

GP length scale?

Ideally this should be comparable to the slit function. In practice the length scale likes to smooth out correlated residuals from errors in the broad band brown dwarf spectral shape. I assigned 5000 - 25000.

[gully]

We mostly did this for the SpeX PRZ data, so we should be all set.