Cerro Tololo Site Seeing Results


The CTIO site seeing monitor is a Differential Image Motion Monitor (DIMM) which is in operation since August 2000 (replacing the old Carnegie seeing monitor). See more detail here. Every minute, it updates the site seeing value, which is corrected to the zenith and for a wavelength of 500nm.

The listing gives the UT time and date, the name of the star being observed, the and the secant of the zenith distance. It then lists the number of measurements ('n') done in a one minute interval, the FWHM seeing measured longitudinally in the subapertures (l), the average of long. and trans. measurements in arcsec ('Seeing': this is the one you care about), the FWHM seeing measured transversally in the subapertures ('t'), the flux, the equivalent r0 (in cm), and the differences in columns ('dX':should be near 85) and lines ('dY': should be near 0) between the 2 images.



jhughes@noao.edu