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In a skydip, the atmospheric emission, as seen by the receiver (
), is
measured at equally spaced airmass (
).
is a combination of
the atmospheric emission
and of losses
|
(7) |
And the atmospheric emission is the sum of the atmospheric emission in both
receiver bands
|
(8) |
each contribution computed from an equivalent atmospheric temperature
and opacity
|
(9) |
The zenith opacity can be written as a combination of a dry and wet components
|
(10) |
where
is the opacity due to the permanent components of the
atmosphere (mainly oxygen) and
is proportional to the varying
amount of water vapor amount (
) in the atmosphere:
Assuming that
and
are independent of the elevation and
that
and
are correctly modeled by an atmospheric model,
we obtain that
is a function of
,
,
,
and the airmass (
). If
and
are assumed to be
measured by other means, then
and
can be fitted through
the measured couples (
,
).
Next: Load calibration and determination
Up: Description of the calibration
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Gildas manager
2014-07-01