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---1.60, 1.66, 1.57
Integration time (s)---2400, 2400, 1200
Pixel scale (arcsec)---1.134, 1.134, 1.134

# Wed 09:51:06 29-May-2002
begin	UFIT
	status	0	(Solution converged)
	variance	0.002807827
	stdeviation	0.05298893
	avsqerror	0.004408114
	averror		0.06639363
	avsqscatter	0.001309995
	avscatter	0.03619386
	chisqr		0.6369677
	msq		0.002711005
	rms		0.05206731
	reference	mU
	fitting		(UB+BV+V)+u1+u2*XU+u3*UB+u4*UB*XU
	weights		photometric
	parameters	4
		u1	(constant)
		u2	(fit)
		u3	(constant)
		u4	(constant)
	derivatives	4
		0.1
		0.1
		0.1
		0.1
	values	4
		5.04
		0.463949
		-0.112
		0.
	errors	4
		0.
		0.005936652
		0.
		0.

# Wed 09:51:38 29-May-2002
begin	BFIT
	status	0	(Solution converged)
	variance	7.376013E-4
	stdeviation	0.02715882
	avsqerror	9.027324E-4
	averror		0.03004551
	avsqscatter	2.369830E-4
	avscatter	0.01539425
	chisqr		0.8170763
	msq		7.121667E-4
	rms		0.02668645
	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
		3.388
		0.2456194
		-0.0237
		0.
	errors	4
		0.
		0.002651105
		0.
		0.

# Wed 09:52:10 29-May-2002
begin	VFIT
	status	0	(Solution converged)
	variance	4.553543E-4
	stdeviation	0.02133903
	avsqerror	6.226407E-4
	averror		0.02495277
	avsqscatter	1.746930E-4
	avscatter	0.01321715
	chisqr		0.7313276
	msq		4.406655E-4
	rms		0.02099203
	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
		3.082
		0.1349849
		-0.0157
		0.
	errors	4
		0.
		0.002211011
		0.
		0.

# Fri 12:04:18 08-Nov-2002
begin	UFIT
	status	0	(Solution converged)
	variance	0.003893676
	stdeviation	0.06239933
	avsqerror	0.003891669
	averror		0.06238325
	avsqscatter	0.003243723
	avscatter	0.05695369
	chisqr		1.000516
	msq		0.00385269
	rms		0.06207004
	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
		5.3269
		0.423
		-0.0687
		0.
	errors	4
		0.002
		0.
		0.
		0.