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---1.16, 1.49, 1.11
Integration time (s)---1800, 1200, 600
Pixel scale (arcsec)---1.134, 1.134, 1.134

# Tue 08:16:17 18-Jun-2002
begin	UFIT
	status	0	(Solution converged)
	variance	0.003666018
	stdeviation	0.06054765
	avsqerror	0.0036644
	averror		0.06053429
	avsqscatter	0.002292743
	avscatter	0.04788259
	chisqr		1.000442
	msq		0.003580763
	rms		0.05983947
	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
		5.196
		0.4683865
		-0.093
		0.
	errors	4
		0.
		0.005730249
		0.
		0.

# Tue 08:16:55 18-Jun-2002
begin	BFIT
	status	0	(Solution converged)
	variance	6.539484E-4
	stdeviation	0.02557242
	avsqerror	6.517855E-4
	averror		0.02553009
	avsqscatter	2.973674E-4
	avscatter	0.01724434
	chisqr		1.003318
	msq		6.390859E-4
	rms		0.02528015
	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
		3.562
		0.2586217
		-0.0166
		0.
	errors	4
		0.
		0.002193695
		0.
		0.

# Thu 15:06:44 30-May-2002
begin	VFIT
	status	0	(Solution converged)
	variance	3.555940E-4
	stdeviation	0.0188572
	avsqerror	3.599697E-4
	averror		0.01897287
	avsqscatter	1.463815E-4
	avscatter	0.01209882
	chisqr		0.9878443
	msq		3.469210E-4
	rms		0.01862581
	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
		0.128904
		0.045
		0.
	errors	4
		0.
		0.001483865
		0.
		0.