The above Seeing graph show the seeing as measured with the CCD guide cameras of the Magellan Telescopes. Since June 25, 2003 (JD 2452816), the guide cameras have been operated using an RG610 filter. The raw FWHM values are corrected for airmass assuming:

FWHM_corr = FWHM_obs / airmass^0.6

Warning: These measurements do not necessarily reflect the actual seeing at the telescopes since 1) the guider optics are not capable of producing images better than 0.4 arcsec (FWHM), and 2) the guide stars are several arc minutes off-axis and are uncorrected for aberrations in the telescope optics.