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 DDO 43 images, the average parameters for UBV are the following: Airmass---1.33, 1.04 1.16 Integration time (s)---1800, 1800, 900 Pixel scale (arcsec)---1.134, 1.134, 1.134 # Thu 15:09:26 30-May-2002 begin BFIT status 0 (Solution converged) variance 4.731225E-4 stdeviation 0.02175138 avsqerror 4.716113E-4 averror 0.02171661 avsqscatter 2.930113E-4 avscatter 0.01711757 chisqr 1.003204 msq 4.336956E-4 rms 0.02082536 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 3.445 0.2522084 -0.022 0. errors 4 0. 0.003991939 0. 0. # Thu 15:09:48 30-May-2002 begin VFIT status 0 (Solution converged) variance 3.186176E-4 stdeviation 0.01784986 avsqerror 3.344381E-4 averror 0.01828765 avsqscatter 1.270007E-4 avscatter 0.01126946 chisqr 0.9526951 msq 2.958592E-4 rms 0.01720056 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 3.017 0.137418 0.045 0. errors 4 0. 0.002664746 0. 0. # Thu 11:50:02 11-Jul-2002 begin UFIT status 0 (Solution converged) variance 0.004286912 stdeviation 0.06547451 avsqerror 0.004285706 averror 0.06546531 avsqscatter 0.003317559 avscatter 0.05759826 chisqr 1.000281 msq 0.004224783 rms 0.06499833 reference mU fitting (UB+BV+V)+u1+u2*XU+u3*BV+u4*UB*XU weights photometric parameters 4 u1 (fit) u2 (constant) u3 (constant) u4 (constant) derivatives 4 0.1 0.1 0.1 0.1 values 4 5.251 0.459 -0.121 0. errors 4 0.003 0. 0. 0.