Comparison With Other Observatory Sites

ESO / Chile: A DIMM survey of the seeing conditions at the ESO observatory sites at La Silla and Paranal in Chile has been underway for several years. The resulting  distribution for Paranal is  similar to that for La Palma, with a slightly better median of 0.66 arcsec. The median seeing at La Silla is 0.87 arcsec.
Comparison of DIMM seeing survey results for the WHT (Solid line) and Paranal (broken line) sites.
Mauna Kea: No DIMM survey has been carried out at the Mauna Kea, so that there is very little unbiased  seeing data (i.e. independent of telescope-based effects) for the site.  However, data from the wavefront sensor of the PUEO adaptive optics system on the 3.6m CFHT has been studied using a method similar to that for the JOSE r0 measurements, and so is unaffected by telescope defocus, optical aberrations or guiding errors (Rigaut, F., 1998, PASP, 110, 152) . The measured Zernike variances show a Noll distribution in most cases, so that dome seeing is probably not significant. A distribution of r0 values measured on 16 nights at the CFHT has a median value of 15.8cm, when corrected for zenith distance according to  sec(z)3/5 . This corresponds to a median image FWHM of 0.65 arcsec at 500nm.
IAC: The IAC has conducted extensive DIMM surveys at both the La Palma and Tenerife sites.

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