Interferometer_sensitivity_studies (General)swinkels, vajente - 11:03 Monday 10 August 2009 (24156)
Print this reportDaily modulation of horizonSince a few days, there is a daily drop in the horizon of about half a megaparsec. This drop starts usually in the late morning, peaks around the late afternoon and disappears around midnight, see fig 1. Looking at the spectogram in fig 2, it seems that this is mainly caused by some noise appearing around 120 Hz. Some shift reports indicate wind activity and indeed there is a clear daily pattern in the wind-speed (probably the daily sea-breeze which is typical for this kind of hot weather). It is however not easy to discriminate between several things happening with daily periodicity. One easy suspect would be some air-conditioning machine, which has to work harder during the late afternoon.
