comment on goodness of Temperature controls:

Since the frequency is wandering by ~3 kHz at the hours time scales, we can estimate the differential cavity temperature to be:

delta T = (1/CTE) * df / (c / lambda) = (1 / 5e-7) * (3 kHz / 300 THz) = 20 micro-K

If someone can plot the NPRO SLOW signals at the similar time scales, we would know what the CMRR is. But I think 20 uK is probably just fine.