Just in case folks get the wrong impression, Steve "almost" perpetuates two myths about seeing (i.e. atmospheric turbulence): >> Even though the breeze did make the seeing mediocre... and >> All the brightest stars, regardless of their altitude, >> were blinking on and off....not just twinkling. First, the wind, per se, does _not_ make the seeing bad. The reason the seeing was relatively poor (it wasn't in fact that bad), was because we're at the bottom of a fairly sharp trough. Secondly, naked-eye scintillation is not directly correlated with seeing in the telescope (say, as measured by the image-blur size and its motion in small apertures). The seeing is actually pretty predictable, and is shown in simple graphic form extending 36 hours downstream by the well-known 'Clear Sky Clock' pages. You can also see more geographic details (though the models have rotten spatial resolution) at: http://www-frd.fsl.noaa.gov/mab/tke/tke_new.cgi or... http://www.rap.ucar.edu/projects/itfa/turbfc1.html ...which are different flavors of the same turbulence model. These are intended for aviation use, so have short look-ahead times, but the 'Clear Sky Clock' set-up extends them out farther. When taken together with considerations of local effects (in Arizona, cool air drainage especially), it makes fairly accurate predictions of seeing. \Brian -- See message header for info on list archives or unsubscribing, and please send personal replies to the author, not the list.