Change of Splittings in the Pulsating Subdwarf Balloon 090100001

We present the first results obtained during the multi-site campaign on the brightest pulsating sdB star Balloon 090100001. Our campaign was carried out in August and September 2005 spanning over seven weeks. In order to decrease aliases and noise level as much as possible, we used eight telescopes situated around the world. From the frequency analysis of the 2005 data, we confirm most of frequencies discovered during the 2004 campaign, including frequencies found in the vicinity of the principal mode. It turns out that this region contains a single dominating mode, an equidistant triplet and a quintuplet. The triplet and quintuplet have nearly the same separations, clearly indicating that rotational splitting might be involved. However, the splitting of multiplets increased by about 15% between 2004 and 2005. As far as we are aware, this is the first example of such a large change of frequency splitting in a pulsating star.