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Earthshine blog

"Earthshine blog"

A blog about a telescopic system at the Mauna Loa Observatory on Hawaii to determine terrestrial albedo by earthshine observations. Feasible thanks to sheer determination.

ND0.9 filters do nothing

Optical design Posted on Dec 21, 2011 20:43

On the lamp in the dome we can test the densities of the various ND filters by calculating and comparing the observed fluxes with and without the filters. So far I have tested most of the ND0.9 filters. They appear to be blanks – or have not rotated into position.

Filter Without ND With ND0.9
B 3511 3512
V 26500 26500
VE1 210700 209700
VE2 268200 273000
IRCUT 196050 no data

The numbers are in counts/second and are based on the measured mean counts in the various frames and the exposure time MEASURED and reported in the FITS header.

When fog falls yea verily upon the mountain

Observing log Posted on Dec 21, 2011 15:26

A skycam image showing where there is fog on the mountain. The navigation beacons are hazed out (in the NNW) so there’s fog at ground level. Close up please!