**Table 1:** Program Stars - observations are from either the 1m JKT (Lennon et al. 1992), 2.5 m INT or 4.2 m WHT (northern) or 1.5 m CTIO (southern). Two estimates of interstellar reddenings are given, based on intrinsic colours adopted from Schmidt-Kaler (1982) and from theoretical continuum fits to UV spectrophotometry and optical photometry (no spectrophotometry was available for HD 194279 or HD 148688). The majority of our targets are probable cluster/association members, whilst absolute magnitudes are adopted for the remainder, based on average values of Magellanic Cloud members from Fitzpatrick (1991), Parker (1993) and Massey et al. (1995), except that HD 190603 is set at M_V=-7.5 mag. References to cluster/association distances are: (a) Brown et al. (1994); (b) Blaha & Humphreys (1989); (c) Baume et al. 1999; (d) Baume et al (2003); (e) Garmany & Stencel (1992); (f) Humphreys (1978).
HD	Name	Sp type	V	B-V	E(B-V)		Assoc.	DM	Ref	M_V	$\Delta M_{V}$	Obs
			mag	mag	(B-V)₀	UV	mag		mag	mag
30614	$\alpha$ Cam	O9.5 Ia	4.29	+0.02	0.29	0.32		10.0		-6.6	$\pm$ 0.5	WHT
37128	$\epsilon$ Ori	B0 Ia	1.70	-0.19	0.05	0.06	Ori OB1b	7.8	a	-6.3	$\pm$ 0.5	WHT/INT
91969		B0 Ia	6.52	+0.00	0.24	0.26	NGC3293	12.2	d	-6.4	$\pm$ 0.3	CTIO
94909		B0 Ia	7.34	+0.48	0.72	0.75 $\ddag$		11.5		-6.4	$\pm$ 0.5	CTIO
122879		B0 Ia	6.42	+0.12	0.36	0.37		11.7		-6.4	$\pm$ 0.5	CTIO
38771	$\kappa$ Ori	B0.5 Ia	2.05	-0.18	0.04	0.07	Ori OB1c	8.0	a	-6.1	$\pm$ 0.5	WHT/INT
115842		B0.5 Ia	6.02	+0.29	0.51	0.57 $\ddag$		11.3		-6.9	$\pm$ 0.5	CTIO
152234		B0.5 Ia (N wk)	5.44	+0.20	0.42	0.45	Sco OB1	11.5	c	-7.4	$\pm$ 0.5	CTIO
2905	$\kappa$ Cas	BC0.7 Ia	4.16	+0.14	0.35	0.39	Cas OB14	10.2	b	-7.1	$\pm$ 0.3	WHT/INT
91943		B0.7 Ia	6.73	+0.07	0.28	0.22 $\ddag$	NGC 3293	12.2	d	-6.3	$\pm$ 0.3	CTIO
152235		B0.7 Ia (N wk)	6.34	+0.51	0.72	0.75 $\ddag$	Sco OB1	11.5	c	-7.4	$\pm$ 0.5	CTIO
154090		B0.7 Ia	4.87	+0.26	0.47	0.49 $\ddag$		10.2		-6.8	$\pm$ 0.5	CTIO
13854		B1 Iab	6.48	+0.28	0.47	0.55	Per OB1	11.8	e	-6.8	$\pm$ 0.5	WHT/INT
91316	$\rho$ Leo	B1 Iab (N str)	3.85	-0.14	0.05	0.06		10.5		-6.8	$\pm$ 0.5	CTIO
148688		B1 Ia	5.33	+0.33	0.52	0.52 $\ddag$		10.5		-6.8	$\pm$ 0.5	CTIO
14956		B1.5 Ia	7.19	+0.72	0.90	0.95 $\ddag$	Per OB1	11.8	e	-7.4	$\pm$ 0.5	WHT/INT
152236	$\zeta^{1}$ Sco	B1.5 Ia⁺	4.73	+0.48	0.66	0.69	Sco OB1	11.5	c	-8.8	$\pm$ 0.5	CTIO
190603		B1.5 Ia⁺	5.65	+0.54	0.72	0.80 $\ddag$		10.9		-7.5	$\pm$ 1.0	WHT/INT
14143		B2 Ia	6.66	+0.50	0.67	0.70	h Per	11.8	e	-7.2	$\pm$ 0.3	WHT/INT
14818	10 Per	B2 Ia	6.25	+0.30	0.47	0.52	Per OB1	11.8	e	-7.0	$\pm$ 0.5	WHT/INT
41117	$\chi^2$ Ori	B2 Ia	4.63	+0.28	0.45	0.48	Gem OB1	10.9	b	-7.6	$\pm$ 0.3	WHT
194279		B2 Ia	7.05	+1.02	1.19	1.26 $\ddag$	Cyg OB9	10.4	f	-7.0	$\pm$ 0.3	WHT/INT
198478	55 Cyg	B2.5 Ia	4.86	+0.42	0.57	0.59	Cyg OB7	9.5	f	-6.4	$\pm$ 0.3	WHT
14134		B3 Ia	6.55	+0.45	0.58	0.65 $\ddag$	h Per	11.8	e	-7.1	$\pm$ 0.3	JKT/INT
53138	o² CMa	B3 Ia	3.01	-0.08	0.05	0.07		10.2		-7.3	$\pm$ 0.5	JKT/INT

$\textstyle \parbox{16cm}{ $\ddag$ : UV spectrophotometry absent or poor quality, leading to uncertain reddening from this technique.}$

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