Data Reduction pipeline for MOST Guide Stars and Application to two Observing Runs

A Data Reduction pipeline for MOST Guide Star data is presented together with the results obtained for two observing runs in 2004 (i.e. κ Ceti 2004 and HR 1217 2004 runs) containing four and seven Guide Stars respectively. Among these Guide Stars, four are clearly variable with only one known before the MOST observations: the long period variable HD24338 (M2III). The data reduction relies on the decorrelation technique employed by Reegen et al. (2006) for their data reduction pipeline of MOST Fabry targets. The main difference is that the MOST Guide Star data include no background information. A coarse on-board background subtraction is performed, but leaves considerable residual stray light in the data, which is subject to a more sophisticated reduction 1Based on data from the MOST (Microvariability & Oscillation of STars) satellite, a Canadian Space Agency mission jointly operated by Dynacon, Inc., the University of Toronto Institute of Aerospace Studies, and the University of British Columbia, with assistance from the University of Vienna, Austria. M.Hareter, P. Reegen, R.Kuschnig, et al. 49 technique. Since at least four stars are observed simultaneously, common features of the light curves can be recognized and removed. Among different data reduction methods, the decorrelation technique is more versatile and often has better results than differential photometry or data smoothing. Individual Objects: HD 20884, HD20790, HD 24338, HD24217