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---1.08, 1.00, 1.04
Integration time (s)---1800, 1800, 1200
Pixel scale (arcsec)---1.134, 1.134, 1.134

# Wed 09:38:20 05-Jun-2002
begin	UFIT
	status	0	(Solution converged)
	variance	0.01122167
	stdeviation	0.1059324
	avsqerror	0.01231251
	averror		0.1109617
	avsqscatter	0.01099251
	avscatter	0.1048452
	chisqr		0.911404
	msq		0.01085968
	rms		0.1042098
	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
		5.203
		0.5026113
		-0.0911
		0.
	errors	4
		0.
		0.01420032
		0.
		0.

# Wed 09:41:23 05-Jun-2002
begin	BFIT
	status	0	(Solution converged)
	variance	0.001075729
	stdeviation	0.03279831
	avsqerror	0.001074409
	averror		0.03277817
	avsqscatter	9.276905E-4
	avscatter	0.03045801
	chisqr		1.001229
	msq		0.001015966
	rms		0.03187422
	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
		3.668
		0.2268837
		-0.0274
		0.
	errors	4
		0.
		0.005712632
		0.
		0.

# Wed 09:42:06 05-Jun-2002
begin	VFIT
	status	0	(Solution converged)
	variance	0.001750071
	stdeviation	0.04183385
	avsqerror	0.002313507
	averror		0.04809893
	avsqscatter	0.001546741
	avscatter	0.03932863
	chisqr		0.756458
	msq		0.001680068
	rms		0.04098863
	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
		3.246
		0.1149137
		-0.0167
		0.
	errors	4
		0.
		0.006344703
		0.
		0.