Keywords: atm-comparison

Next: Load calibration and determination Up: Description of the calibration Previous: Description of the calibration Contents

### Skydips and determination of the forward efficiency

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 Previous: Description of the calibration Contents