Looking for suitable equipment and programs to reduce my first PHEMU91 recordings, I finally ended up at Bureau des longitudes in Paris, where the equipment setup of the AVIA system was used (figure 1, [Arl89] ).
Figure 1: Equipment setup of the AVIA system
The basic idea of the programs is to define two sets of embracing windows around both the object of interest and the reference object (figure 2). The purpose of the largest of the two windows is to be able to substract background, like you would do for photoelectric recordings. The reference object gives you the possibility to correct for any tranparency fluctuations and will serve as a fixed magnitude level. Figure 3 shows what resulting lightcurves look like. Quite a heap of noise but a well defined dip for the mutual event.
Figure 3: Resulting lightcurve
Small movements introduced by bad tracking do not pose a real problem. Just define larger windows that will include the movement of the objects of interest. In case there are no other objects in the vicinity of the objects of interest, this procedure will only introduce some extra noise. In cases of very severe movements you simply reject the recording or you could try a different approach.
