# Inclinometers

All antennas are equipped with one inclinometer, that should allow determination of the inclinations without astronomical pointing. Regular monitoring of the inclinometer outputs must be made. It is especially important to get the inclinometer results before and after each pointing session. To use the inclinometers:

- Send an antenna North at some elevation, chosen to avoid the sun at any azimuth, for example using antenna Iant
  $ COO ANTE Iant HO 180D 85D NULL, under DCL, or
  OBSSOURCE INCLINO, OBSLOAD, within OBS
- Once the antenna stops, run the inclinometer program
  $ INC Iant /PLOT

The antenna will do a full turn at the current elevation, and a sine curve will be fit to the inclinations measured every 5 degrees. From this fit, the parameters MVE and MVN are derived from the azimuth axis tilt measured by the inclinometers using three additional corrections:

- a change of sign due to conventions on the orientation of the vertical.
- a local vertical correction to refer the inclinations to the vertical of the array center
- a global gravity corrections of MVE = +10", MVN = +7", to correct for large scale deviations of the gravity field due to the Alps.

The resulting MVE and MVN are displayed and written in the file INTER_BASE:INCLINO.ANi, where i = Iant. The fit is displayed by GreG if you specified the /PLOT option for the INC command. A hardcopy possibility is offered.