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---1.3, 1.0, 1.02
Integration time (s)---1800, 1800, 1200
Pixel scale (arcsec)---1.134, 1.134, 1.134

# Thu 15:11:57 30-May-2002
begin	BFIT
	status	0	(Solution converged)
	variance	8.922030E-4
	stdeviation	0.02986977
	avsqerror	8.909081E-4
	averror		0.02984808
	avsqscatter	6.125225E-4
	avscatter	0.02474919
	chisqr		1.001453
	msq		8.497171E-4
	rms		0.02914991
	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
		3.445
		0.2701167
		-0.022
		0.
	errors	4
		0.
		0.00365938
		0.
		0.

# Thu 15:12:28 30-May-2002
begin	VFIT
	status	0	(Solution converged)
	variance	3.749936E-4
	stdeviation	0.01936475
	avsqerror	3.736763E-4
	averror		0.01933071
	avsqscatter	1.557280E-4
	avscatter	0.0124791
	chisqr		1.003525
	msq		3.620628E-4
	rms		0.01902795
	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
		0.1593955
		0.045
		0.
	errors	4
		0.
		0.001785195
		0.
		0.

# Thu 11:48:45 11-Jul-2002
begin	UFIT
	status	0	(Solution converged)
	variance	0.005657332
	stdeviation	0.07521524
	avsqerror	0.005655774
	averror		0.07520488
	avsqscatter	0.005097186
	avscatter	0.07139458
	chisqr		1.000275
	msq		0.005468755
	rms		0.07395103
	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
		0.444
		-0.121
		0.
	errors	4
		0.003
		0.
		0.
		0.