The following calibration format can be used directly in IRAF.digiphot.photcal.invertfit. The instrumental magnitudes mU, mB, and mV are -2.5*log(counts/s)+25. For the these images, the average parameters for UBV are the following: Airmass---1.17, 1.15, 1.18 Integration time (s)---1800, 2400, 1200 Pixel scale (arcsec)---1.134, 1.134, 1.134 # Wed 14:13:01 29-May-2002 begin BFIT status 0 (Solution converged) variance 1.494586E-4 stdeviation 0.01222533 avsqerror 1.560404E-4 averror 0.01249161 avsqscatter 6.004668E-5 avscatter 0.007748979 chisqr 0.9578196 msq 1.429604E-4 rms 0.0119566 reference mB fitting (BV+V)+b1+b2*XB+b3*BV+b4*BV*XB weights photometric parameters 4 b1 (constant) b2 (fit) b3 (constant) b4 (constant) derivatives 4 0.1 0.1 0.1 0.1 values 4 3.443 0.2235634 -0.0187 0. errors 4 0. 0.001561286 0. 0. # Wed 14:13:31 29-May-2002 begin VFIT status 0 (Solution converged) variance 2.718539E-4 stdeviation 0.01648799 avsqerror 3.494839E-4 averror 0.01869449 avsqscatter 1.184234E-4 avscatter 0.01088225 chisqr 0.7778723 msq 2.582612E-4 rms 0.01607051 reference mV fitting V+v1+v2*XV+v3*BV+v4*BV*XV weights photometric parameters 4 v1 (constant) v2 (fit) v3 (constant) v4 (constant) derivatives 4 0.1 0.1 0.1 0.1 values 4 3.122 0.1285986 -0.0159 0. errors 4 0. 0.002098214 0. 0. # Thu 11:03:34 06-Jun-2002 begin UFIT status 0 (Solution converged) variance 0.002012777 stdeviation 0.04486399 avsqerror 0.002012014 averror 0.04485548 avsqscatter 0.001132588 avscatter 0.03365395 chisqr 1.000379 msq 0.001925265 rms 0.04387784 reference m1 fitting (UB+BV+V)+u1+u2*X1+u3*BV+u4*BV*X1 weights photometric parameters 4 u1 (fit) u2 (constant) u3 (constant) u4 (constant) derivatives 4 0.1 0.1 0.1 0.1 values 4 5.285 0.598 -0.177 0. errors 4 0.003 0. 0. 0.