Microlensing results from APO monitoring of the double quasar Q0957+561A,Bbetween 1995 and 1998

If the halo of the lensing galaxy 0957+561 is made of massive compact objec ts (MACHOs), they must affect the lightcurves of the quasar images Q0957+56 1 A and B differently. We search for this microlensing effect in the double quasar by comparing monitoring data for the two images A and B obtained wi th the 3.5m Apache Point Observatory from 1995 to 1998 - with intensive num erical simulations. This way we test whether the halo of the lensing galaxy can be made of MACHOs of various masses. We can exclude a halo entirely ma de out of MACHOs with masses between 10(-6) M. and 10(-2) M. for quasar siz es of less than 3 x 10(14) h(60)(-1/2) 60 cm, hereby extending previous lim its upwards by one order of magnitude.