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---1.04, 1.11, 1.46
Integration time (s)---2400, 2400, 1200
Pixel scale (arcsec)---1.134, 1.134, 1.134

# Wed 14:13:31 29-May-2002
begin	VFIT
	status	0	(Solution converged)
	variance	2.718539E-4
	stdeviation	0.01648799
	avsqerror	3.494839E-4
	averror		0.01869449
	avsqscatter	1.184234E-4
	avscatter	0.01088225
	chisqr		0.7778723
	msq		2.582612E-4
	rms		0.01607051
	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
		3.122
		0.1285986
		-0.0159
		0.
	errors	4
		0.
		0.002098214
		0.
		0.

# Fri 16:32:08 31-May-2002
begin	BFIT
	status	0	(Solution converged)
	variance	3.962124E-4
	stdeviation	0.01990508
	avsqerror	3.988900E-4
	averror		0.01997223
	avsqscatter	1.932560E-4
	avscatter	0.01390165
	chisqr		0.9932874
	msq		3.860531E-4
	rms		0.01964824
	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
		3.652
		0.284154
		-0.0153
		0.
	errors	4
		0.
		0.002054963
		0.
		0.

# Thu 10:51:37 11-Jul-2002
begin	UFIT
	status	0	(Solution converged)
	variance	0.002457423
	stdeviation	0.0495724
	avsqerror	0.00245627
	averror		0.04956077
	avsqscatter	0.001893266
	avscatter	0.04351167
	chisqr		1.000469
	msq		0.002308488
	rms		0.04804673
	reference	mU
	fitting		(UB+BV+V)+u1+u2*XU+u3*BV+u4*UB*XU
	weights		photometric
	parameters	4
		u1	(fit)
		u2	(constant)
		u3	(fit)
		u4	(constant)
	derivatives	4
		0.1
		0.1
		0.1
		0.1
	values	4
		5.075891
		0.686
		-0.1758558
		0.
	errors	4
		0.01318199
		0.
		0.01666166
		0.