Earthshine blog

Earthshine blog

"Earthshine blog"

A blog about a system to determine terrestrial albedo by earthshine observations. Feasible thanks to sheer determination.

JD2456046 - weather log

Observing logPosted by Peter Thejll Apr 29, 2012 08:04AM
12.8 degrees C in dome at start - 45 F outside on MLO mast
9 m/s increasing at start. At xxx.86 the wind is 16 ms or 20 mph. Steady from South.
RH 15%

Exposure factors for the filters are very good this night:

B 34.0
V 11.8
VE1 2.6
VE2 10.0
iIRCUT 2.6

These are factors, note xposure times. The exposure time is some number times the above. A typical IRCUT exposure time may be 0.008 s. The code we have - - scales a table like the above one appropriately for the lunar phase.

Later: The above factors seem inadequate on another night with the Moon rising - B is overexposed while VE1, VE2 and IRCUT are at 12000. Hmmm.

A bit later still: Hmmm - the above problem was due to hanging shutter - but a very consistently hanging shutter! So the table is OK. B is perhaps a bit high but now V and VE2 are just right.

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