The numerical kernel approach to difference imaging has been implemented andapplied to gravitational microlensing events observed by the PLANETcollaboration. The effect of an error in the source-star coordinates isexplored and a new algorithm is presented for determining the precisecoordinates of the microlens in blended events, essential for accuratephotometry of difference images.
[26 authors including Y. Tsapras] Accepted by MNRAS, 8 pages, 4 figures.
