2006BAVSR..55....4H

We discuss new results of an observation campain on the RRab star SW Bootis in 2004 and 2005 by members of the BAV. The star is already known as showing quite a large secular period change [1]. We could show that the all available data (see GEOS RR Lyrae database [2]) together with the new results can be well explained by a constant increase of the period of 1.8055 x 10-9 per day. This is less than derived by Bonov [1] but in good agreement with [6]. The revised elements of SW Bootis are: E0=2453540.49221 and P=0.513548d. In obvious contrast to the older literature we did not find an in- dication for a Blazhko effect within the limits of our observational precision. The observed fluctuations in brightness in maximum and minimum light are below 0.02 mag. Also no statistically significant (O-C)-scatter has been identified from the newer CCD measurements within the observational uncertainties. This is in contrast to older literature [3] but agrees very well with recently published remarks originating from an analysis of ROTSE data [4].