DETECTION AND CORRECTION OF SCATTERED-LIGHT IN THE 2.1-M SAN-PEDRO MARTIR TELESCOPE

We have used the pinhole camera method (Grundhal & Sorensen 1966) to e valuate the amount of scattered light present at the exit pupil of the f/7.5, 2.1-m San Pedro Martir telescope. A substantial amount of scat tered light, originating from multiple reflections off the inner walls of the sky baffles was found to be present; this scattered component directly affects the quality of the flat-field calibration frames, whi ch is in turn reflected on the accuracy of CCD bidimensional photometr y. Corrective action has been performed on the primary's sky baffle, s uccessfully eliminating most of the spurious scatterea component.