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---1.22, 1.04, 1.1 Integration time (s)---1800, 2400, 1200 Pixel scale (arcsec)---1.134, 1.134, 1.134 # Thu 17:22:21 30-May-2002 begin BFIT status 0 (Solution converged) variance 2.919443E-4 stdeviation 0.01708638 avsqerror 2.934487E-4 averror 0.01713034 avsqscatter 9.893559E-5 avscatter 0.009946637 chisqr 0.9948735 msq 2.822128E-4 rms 0.01679919 reference m1 fitting (BV+V)+b1+b2*X1+b3*BV+b4*BV*X1 weights photometric parameters 4 b1 (constant) b2 (fit) b3 (constant) b4 (constant) derivatives 4 0.1 0.1 0.1 0.1 values 4 3.434 0.3398903 -0.0157 0. errors 4 0. 0.002096669 0. 0. # Thu 17:23:06 30-May-2002 begin VFIT status 0 (Solution converged) variance 3.533681E-4 stdeviation 0.01879809 avsqerror 3.510584E-4 averror 0.01873655 avsqscatter 1.724228E-4 avscatter 0.01313099 chisqr 1.006579 msq 3.402804E-4 rms 0.01844669 reference m2 fitting V+v1+v2*X2+v3*BV+v4*BV*X2 weights photometric parameters 4 v1 (constant) v2 (fit) v3 (constant) v4 (constant) derivatives 4 0.1 0.1 0.1 0.1 values 4 3.009 0.2183592 0.0415 0. errors 4 0. 0.002304921 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.