Old Image Quality
Starting in the first period of 2001 we began collecting HET fhwm,
ee50 and ee80 image quality data with the LRS "pre" images as reported in the
night reports. Beginning in 2002 we started also measuring the FWHM in the
LRS "pre" images. Site seeing data are gathered using the Differential Image
Motion Monitor (DIMM). DIMM data are reported in the night report for every
science object when the DIMM is operational since the first period of 2002.
The entire DIMM data set is archived and will be made accessible on the web.
In the third period of 2003 we began measuring the FWHM for HRS observations
from the FIF bent prime guider. Thus as of the first period of 2004
FWHM data now comes from two source LRS "pre" images and the FIF guider while
ee50 data comes exclusively from LRS "pre" images.
The link below will give you the most up-to-date statistics.
Old Sky Brightness
HET sky brightness data are derived from g1 and g2 spectra and
entered in the night reports.
During dark time an observer can expect the sky brightness
per square arcsecond to be between 21.1 and 21.4 mag.
Last updated: Thu, 23 Nov 2017 16:42:16 -0600 shetrone