5 Results

The results of the present observations are listed in Table 5, arranged as follow:

• Column 1: galaxy name;
• Column 2 and 3: ON and OFF band filters;
• Column 4: telescope used;
• Column 5: year of the observation;
• Column 6: integration time per filter;
• Column 7: transmissivity of the filter at the redshifted H$\alpha$ line;
• Column 8: Normalization factor obtained by dividing the flux of several field stars in the ON band frame to the OFF band frame, $n_{\rm\frac{ON}{OFF}}$. In photometric conditions this quantity gives the transmission difference between the ON and the OFF band filters. Under non photometric conditions $n_{\rm\frac{ON}{OFF}}$ includes variations in the sky transparency. The average values $n_{\rm\frac{ON}{OFF}}$ obtained in photometric conditions are $n_{\frac{6561}{6450}}$ = 1.00 $\pm$ 0.03, $n_{\frac{6612}{6561}}$= 1.15 $\pm$ 0.03, $n_{\frac{6612}{6450}}$ = 1.10 $\pm$ 0.02 and $n_{\frac{6569}{6744}}$=1.18 $\pm$ 0.03;
• Column 9: the correction factor for [SII] contamination K (Calar Alto observations of Virgo galaxies) defined in Eq. (3) of Paper I (K=1.00 for no correction);
• Column 10: H$\alpha$+[NII] equivalent width (H $\alpha+[{\rm NII}] EW$), and error, in Å;
• Column 11: log of the H$\alpha$+[NII] flux and error, in  $\rm erg~ cm^{-2} ~s^{-1}$, uncorrected for underlying Balmer absorption and galactic extinction;
• Column 12: a flag indicates whether the frame was taken under photometric (P) or cirrus (C) conditions;
• Column 13: H$\alpha$+[NII] morphology of the galaxy: N: nucleated, S: spiral shape, D: diffuse, H: dominated by asymmetric, giant HII regions;
• Column 14: notes to the present observations;
• Column 15 and 16: H $\alpha+{\rm [NII]} EW$ and $F(\rm H\alpha+[NII])$ flux from the literature;
• Column 17: references to the H$\alpha$ data available in the literature;
• Column 18: an asterisk indicates a note at the end of the table.

The red continuum images of the detected galaxies with structure in their H$\alpha$emission are shown as contours plots superposed to the H$\alpha$+[NII] net image (grey levels) in Fig. 1.

The H$\alpha$+[NII] morphology is generally very different from the red continuum one. In only a few objects the spiral morphology can be seen in the H$\alpha$+[NII] image (see Col. 13 of Table 5), as in VCC 307, while in other galaxies the dominant star forming regions are located in the nucleus (see for example VCC 801) or in giant HII regions distributed non-uniformly throughout the disc of the galaxy, as in VCC 664. In some other objects the emission is diffuse (VCC 497).

   

Table 5: The results of the observations.

Virgo
									This work					Literature
VCC	ON	OFF	Tel	Year	T	R(Ha)	$n_{\rm\frac{ON}{OFF}}$	K	H $\alpha+[{\rm NII}] EW$	$F({\rm H}\alpha+[{\rm NII}])$	Phot	Morph	Notes	H $\alpha+[{\rm NII}] EW$	$F({\rm H}\alpha+[{\rm NII}])$	Ref.	Notes
(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)	(11)	(12)	(13)	(14)	(15)	(16)	(17)	(18)
67	6561	6450	OHP	2000	60	0.78	0.98	1.00	27 $\pm$ 3	-12.69 $\pm$ 0.05	P	H		-	-	-
92	6561	6450	OHP	1998	30	0.79	1.00	1.00	9 $\pm$ 1	-11.53 $\pm$ 0.06	P	DS		-	-11.50	Ko	*
145	6561	6450	OHP	2000	45	0.68	1.02	1.00	7 $\pm$ 1	-	C	DS		-	-12.04	Y
165	6561	6450	OHP	2000	30	0.77	1.02	1.00	0 $\pm$ 2	-	C			-	-	-
167	6561	6450	OHP	2000	30	0.78	1.02	1.00	3 $\pm$ 1	-	C	DS		-	-11.52	Y
222	6612	6561	OHP	2000	45	0.67	1.11	1.00	2 $\pm$ 1	-12.75 $\pm$ 0.07	P	N		-	-	-
234	6569	6744	CA	1999	30	0.80	1.10	0.64	13 $\pm$ 12	-12.31 $\pm$ 0.23	P	ND		-	-	-
267	6569	6744	CA	1999	30	0.85	1.11	0.66	11 $\pm$ 18	-12.83 $\pm$ 0.45	P	S		16 $\pm$ 3		Hi
307	6612	6561	OHP	1998	30	0.68	1.16	1.00	29 $\pm$ 1	-10.96 $\pm$ 0.05	P	S		32 $\pm$ 1	-10.91	KK	*
315	6612	6450	OHP	2000	45	0.65	1.08	1.00	0 $\pm$ 1	-	P			-	-	-
341	6612	6450	OHP	2000	45	0.68	1.08	1.00	2 $\pm$ 1	-12.86 $\pm$ 0.16	P	ND		-	-	-
371	6569	6744	CA	1999	30	0.75	1.16	0.63	2 $\pm$ 2	-	P			-	-	-
375	6569	6744	CA	1999	30	0.70	1.18	0.61	-1 $\pm$ 4	-	P			-	-	-
382	6569	6744	CA	1999	30	0.75	1.21	0.63	30 $\pm$ 4	-11.78 $\pm$ 0.05	P	HN		-	-	-
386	6569	6744	CA	1999	30	0.70	1.19	0.61	-1 $\pm$ 11	-	P			-	-	-
408	6569	6744	CA	1999	30	0.67	1.15	0.67	4 $\pm$ 3	-12.41 $\pm$ 0.20	P	D		-	-	-
483	6569	6744	CA	1999	30	0.82	1.16	0.64	31 $\pm$ 7	-11.61 $\pm$ 0.07	P	S		17 $\pm$ 2	-11.81	R	*
497	6569	6744	CA	1999	30	0.82	1.16	0.64	15 $\pm$ 8	-11.86 $\pm$ 0.14	P	D		-	-	-
524	6612	6450	OHP	2000	30	0.42	1.14	1.00	5 $\pm$ 1	-12.52 $\pm$ 0.09	P	D		-	-	-
559	6561	6450	OHP	2000	45	0.78	1.03	1.00	2 $\pm$ 1	-12.86 $\pm$ 0.15	P	N		-	-	-
570	6569	6744	CA	1999	30	0.82	1.43	0.64	-1 $\pm$ 11	-	C			-	-	-
596	6612	6561	OHP	1998	30	0.64	1.18	1.00	18 $\pm$ 1	-11.01 $\pm$ 0.05	P	S		18 $\pm$ 1	-11.05	KK	*
608	6612	6561	OHP	1998	30	0.66	1.18	1.00	-1 $\pm$ 1	-	P			-	-	-
630	6612	6561	OHP	2000	45	0.64	1.10	1.00	7 $\pm$ 2	-12.62 $\pm$ 0.12	P	SD		-	-	-
634	6561	6612	OHP	1998	30	0.76	0.85	1.00	2 $\pm$ 2	-	P			-	-	-
656	6612	6450	OHP	2000	45	0.43	1.13	1.00	9 $\pm$ 1	-	P	NDS		6	-	GS
657	6612	6450	OHP	2000	45	0.27	1.13	1.00	-1 $\pm$ 1	-	P			-	-	-
664	6569	6744	CA	1999	30	0.82	1.17	0.64	101 $\pm$ 52	-12.12 $\pm$ 0.11	P	H		164	-	GS
672	6612	6450	OHP	2000	45	0.41	1.10	1.00	-1 $\pm$ 1	-	P			-	-	-
697	6612	6450	OHP	2000	45	0.50	1.10	1.00	15 $\pm$ 8	-12.81 $\pm$ 0.21	P	S		-	-	-
792	6612	6450	OHP	2000	30	0.43	1.11	1.00	10 $\pm$ 2	-12.02 $\pm$ 0.13	P	DS		-	-12.64	Ko	*
794	6612	6450	OHP	2000	45	0.40	1.11	1.00	-1 $\pm$ 2	-	P			-	-	-
797	6612	6450	OHP	2000	30	0.28	1.06	1.00	-1 $\pm$ 13:	-	C		*	-	-	-
798	6612	6450	OHP	2000	30	0.28	1.06	1.00	7 $\pm$ 1:	-11.87 $\pm$ 0.12:	N	ND	*	-	-	-
801	6612	6450	OHP	2000	45	0.66	1.11	1.00	69 $\pm$ 2	-11.57 $\pm$ 0.12	P	N		-	-11.56	Ko	*
836	6612	6561	OHP	2000	60	0.67	1.17	1.00	15 $\pm$ 1	-11.67 $\pm$ 0.13	P	NS		64	-	GS
857	6612	6450	OHP	2000	30	0.40	1.06	1.00	12 $\pm$ 4	-	C	S		-	-12.25	Ko	*
865	6561	6450	OHP	2000	40	0.78	1.04	1.00	34 $\pm$ 2	-12.12 $\pm$ 0.05	P	SH	*	-	-	-
873	6569	6744	CA	1999	20	0.85	1.19	0.65	10 $\pm$ 2	-12.18 $\pm$ 0.07	P	S		16 $\pm$ 1	-11.97	B	*
874	6569	6744	CA	1999	30	0.82	1.18	0.65	3 $\pm$ 3	-12.93 $\pm$ 0.26	P	S		-	-12.47	Ko	*
905	6612	6450	OHP	2000	45	0.52	1.29	1.00	39 $\pm$ 16:	-12.64 $\pm$ 0.14:	N	S	*	-	-	-
912	6569	6744	CA	1999	30	0.84	1.21	0.65	8 $\pm$ 10:	-12.56 $\pm$ 0.31:	Y	NS	*	-	-12.31	Ko	*
916	6569	6744	CA	1999	30	0.82	1.20	0.64	-1 $\pm$ 7	-	P			-	-	-
939	6612	6450	OHP	2000	45	0.51	1.29	1.00	40 $\pm$ 13:	-	C	S		24 $\pm$ 5	-12.37	R	*
958	6561	6450	OHP	2000	45	0.78	0.94	1.00	7 $\pm$ 1	-	C	NS		-	-12.70	Ko	*
979	6561	6450	OHP	2000	45	0.76	1.00	1.00	9 $\pm$ 1	-	C	N		-	-12.22	Ko	*
984	6569	6744	CA	1999	30	0.82	1.17	0.65	1 $\pm$ 4	-	P		*	-	-	-
1003	6612	6450	OHP	2000	45	0.48	1.06	1.00	5 $\pm$ 3	-11.72 $\pm$ 0.13	P	ND	*	-	-13.15	Ko
1145	6569	6744	CA	1999	20	0.82	1.16	0.64	11 $\pm$ 3	-11.73 $\pm$ 0.09	P	H		-	-11.91	Ko	*
1182	6744	6569	CA	1999	30	0.82	0.86	1.00	42 $\pm$ 3	-13.08 $\pm$ 0.05	P	HS		-	-	-
1190	6561	6450	OHP	2000	45	0.76	0.96	1.00	3 $\pm$ 1	-12.49 $\pm$ 0.08	P	ND		-	-	-
1192	6569	6744	CA	1999	30	0.82	1.17	0.64	-1 $\pm$ 3	-	P			-	-	-
1203	6569	6744	CA	1999	30	0.82	1.17	0.64	3 $\pm$ 8	-	P			-	-	-
1205	6569	6744	CA	1999	30	0.75	1.17	0.63	11 $\pm$ 4	-12.50 $\pm$ 0.11	P	S		38	-	GS
1375	6612	6561	OHP	2000	45	0.65	1.17	1.00	28 $\pm$ 3	-	C	S		33 $\pm$ 5	-11.69	KK

 

Table 5: continued.

									This work					Literature
VCC	ON	OFF	Tel	Year	T	R(Ha)	$n_{\rm\frac{ON}{OFF}}$	K	H $\alpha+[{\rm NII}] EW$	$F({\rm H}\alpha+[{\rm NII}])$	Phot	Morph	Notes	H $\alpha+[{\rm NII}] EW$	$F({\rm H}\alpha+[{\rm NII}])$	Ref.	Notes
(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)	(11)	(12)	(13)	(14)	(15)	(16)	(17)	(18)
1401	6612	6561	OHP	1998	20	0.68	1.17	1.00	6 $\pm$ 1	-11.48 $\pm$ 0.07	P	S		6 $\pm$ 2	-11.50	KK	*
1412	6569	6744	CA	1999	30	0.82	1.21	0.64	-1 $\pm$ 2	-	P			-	-	-
1450	6569	6744	CA	1999	30	0.84	1.13	0.65	69 $\pm$ 22	-11.89 $\pm$ 0.08	P	H		72	-	GS
1453	6569	6744	CA	1999	30	0.82	1.13	0.65	1 $\pm$ 15	-	P			-	-	-
1540	6612	6561	OHP	2000	30	0.65	1.10	1.00	20 $\pm$ 1	-	C	S		-	-11.35	Ko	*
1552	6569	6744	CA	1999	30	0.85	1.20	0.65	2 $\pm$ 10	-	P			3	-	GS
1555	6612	6561	OHP	1998	30	0.68	1.14	1.00	17 $\pm$ 4	-11.26 $\pm$ 0.11	P	S		14 $\pm$ 3	-11.43	KK	*
1562	6612	6561	OHP	1998	20	0.66	1.19	1.00	20 $\pm$ 2	-11.37 $\pm$ 0.06	P	SN		18 $\pm$ 4	-11.48	KK	*
1572	6612	6561	OHP	2000	30	0.66	1.10	1.00	-1 $\pm$ 2	-	C			-	-	-
1575	6561	6450	OHP	1998	30	0.73	1.02	1.00	13 $\pm$ 1	-12.73 $\pm$ 0.06	P	H		54	-	GS
1588	6569	6744	CA	1999	30	0.82	1.16	0.64	3 $\pm$ 3	-12.56 $\pm$ 0.32	P	S		-	-	-
1673	6612	6561	OHP	1998	30	0.68	1.13	1.00	15 $\pm$ 1	-12.00 $\pm$ 0.05	P	S		11 $\pm$ 3	-12.10	K	*
1676	6612	6561	OHP	1998	30	0.68	1.13	1.00	19 $\pm$ 1	-11.74 $\pm$ 0.05	P	S		20 $\pm$ 5	-11.70	K	*
1690	6561	6612	OHP	1998	30	0.78	0.87	1.00	2 $\pm$ 1	-12.02 $\pm$ 0.25	P	S		6 $\pm$ 2	-11.62	KK	*
1730	6569	6744	CA	1999	30	0.82	1.20	0.64	4 $\pm$ 4	-12.62 $\pm$ 0.25	P	SD		-	-12.57	Ko	*
1760	6612	6450	OHP	2000	40	0.38	1.11	1.00	5 $\pm$ 2	-12.46 $\pm$ 0.16	P	NDS		-	-	-
1859	6569	6744	CA	1999	30	0.82	1.24	0.64	-1 $\pm$ 12	-	P			-	-12.67	Ko
1868	6569	6744	CA	1999	30	0.80	1.24	0.65	3 $\pm$ 9	-	P			-	-	-
1931	6612	6450	OHP	2000	30	0.47	1.10	1.00	36 $\pm$ 20	-13.33 $\pm$ 0.32	P	N		-	-	-
1941	6612	6450	OHP	2000	30	0.50	1.10	1.00	-1 $\pm$ 4	-	P			-	-	-
1943	6612	6450	OHP	2000	30	0.44	1.10	1.00	24 $\pm$ 2	-11.67 $\pm$ 0.07	P	S		19	-11.82	Kpc	*
14063	6612	6450	OHP	2000	30	0.48	1.07	1.00	32 $\pm$ 2	-11.24 $\pm$ 0.10	P	S		-	-	-
71060	6612	6561	OHP	2000	30	0.66	1.12	1.00	44 $\pm$ 1	-11.97 $\pm$ 0.04	P	NHS		55	-	GS
Coma/A1367 supercluster
									This work					Literature
CGCG	ON	OFF	Tel	Year	T	R(Ha)	$n_{\rm\frac{ON}{OFF}}$	K	H $\alpha+[{\rm NII}] EW$	$F({\rm H}\alpha+[{\rm NII}])$	Phot	Morph	Notes	H $\alpha+[{\rm NII}] EW$	$F({\rm H}\alpha+[{\rm NII}])$	Ref.	Notes
160065	6744	6569	CA	1999	10	0.83	0.87	1.00	-1 $\pm$ 2	-	P		*	-	-	-
160069	6744	6569	CA	1999	20	0.82	0.87	1.00	-1 $\pm$ 2	-	P		*	-	-	-
160213	6744	6569	CA	1999	20	0.68	0.87	1.00	57 $\pm$ 3	-12.92 $\pm$ 0.05	P	H	*	-	-	-
160214	6744	6569	CA	1999	20	0.84	0.87	1.00	-1 $\pm$ 1	-	P		*	-	-	-
160215	6744	6569	CA	1999	20	0.84	0.87	1.00	-1 $\pm$ 2	-	P		*	-	-	-
160216	6744	6569	CA	1999	10	0.84	0.87	1.00	-1 $\pm$ 2	-	P		*	-	-	-
160221	6744	6569	CA	1999	10	0.82	0.87	1.00	-1 $\pm$ 3	-	P		*	-	-	-
160222	6744	6569	CA	1999	10	0.05	0.87	1.00	-1 $\pm$ 22	-	P		*	-	-	-
161043	6744	6569	CA	1999	30	0.77	0.84	1.00	-1 $\pm$ 1	-	P			-	-	-
161069	6744	6569	CA	1999	30	0.82	0.84	1.00	24 $\pm$ 1	-12.66 $\pm$ 0.05	P	H		-	-	-
A2197/A2199
									This work					Literature
CGCG	ON	OFF	Tel	Year	T	R(Ha)	$n_{\rm\frac{ON}{OFF}}$	K	H $\alpha+[{\rm NII}] EW$	$F({\rm H}\alpha+[{\rm NII}])$	Phot	Morph	Notes	H $\alpha+[{\rm NII}] EW$	$F({\rm H}\alpha+[{\rm NII}])$	Ref.	Notes
224008	6744	6569	CA	1999	30	0.75	0.81	1.00	14 $\pm$ 2	-12.95 $\pm$ 0.07	P	D		-	-	-
224009	6744	6569	CA	1999	30	0.70	0.81	1.00	14 $\pm$ 2	-12.69 $\pm$ 0.07	P	S		-	-	-
224037N	6744	6569	CA	1999	30	0.70	0.84	1.00	6 $\pm$ 2	-13.40 $\pm$ 0.12	P	N		-	-	-
224037S	6744	6569	CA	1999	30	0.77	0.84	1.00	5 $\pm$ 1	-13.54 $\pm$ 0.08	P	N		-	-	-
224038	6744	6569	CA	1999	30	0.82	0.84	1.00	115 $\pm$ 2	-12.14 $\pm$ 0.04	P	H		123 $\pm$ 3	-12.24	G
224046	6744	6569	CA	1999	30	0.77	0.84	1.00	17 $\pm$ 2	-12.88 $\pm$ 0.07	P	NDS		-	-	-

 

Table 5: continued.

Nearby galaxies
									This work					Literature
Name	ON	OFF	Tel	Year	T	R(Ha)	$n_{\rm\frac{ON}{OFF}}$	K	H $\alpha+[{\rm NII}] EW$	$F({\rm H}\alpha+[{\rm NII}])$	Phot	Morph	Notes	H $\alpha+[{\rm NII}] EW$	$F({\rm H}\alpha+[{\rm NII}])$	Ref.	Notes
M51	6561	6450	OHP	2000	15	0.77	1.02	1.00	18.6 $\pm$ 1.6	-10.55 $\pm$ 0.05	P	S	*	24 $\pm$ 2	-10.52:	KK	*
M81	6561	6450	OHP	2000	10	0.78	0.96	1.00	9.7 $\pm$ 2.9	-10.30 $\pm$ 0.13	P	SN	M	-	-10.34	D	*
M82	6561	6450	OHP	1998	15	0.77	0.93	1.00	42.3 $\pm$ 0.5	-10.22 $\pm$ 0.04	P	N		-	-10.04	Y	*
M106	6561	6450	OHP	2000	15	0.76	0.95	1.00	12.3 $\pm$ 2.0	-	C	S	M	11	-10.66	Kpc	*
N925	6561	6450	OHP	2000	30	0.74	0.98	1.00	23.3 $\pm$ 4.1	-	C	S		-	-11.10	Y
N1637	6561	6450	OHP	2000	60	0.68	1.09	1.00	9.9 $\pm$ 1.7	-	C	S		16 $\pm$ 2	-11.68	KK
N2403	6561	6450	OHP	2000	10	0.77	0.92	1.00	64.4 $\pm$ 11.8	-	C	S	M	26	-10.34	Kpc
N2541	6561	6450	OHP	2000	40	0.75	0.92	1.00	39.6 $\pm$ 8.0	-	C	S		46 $\pm$ 7	-11.64	R
N2805	6612	6561	OHP	2000	60	0.65	1.07	1.00	52.3 $\pm$ 11.2	-	C	S		-	-	-
N2903	6561	6450	OHP	2000	30	0.76	1.00	1.00	15.0 $\pm$ 1.3	-11.07 $\pm$ 0.08	P	S	*	-	-10.67	Y	*
N5195	6561	6450	OHP	2000	15	0.77	1.10	1.00	3.5 $\pm$ 2.3	-12.18 $\pm$ 0.99	C	N	*	20:	-	K	*

Notes:

M in notes indicates a mosaic of several frames; if not specified, the given data are alternative values in the literature with reference.

VCC 92: $F({\rm H}\alpha+[{\rm NII}])=-11.43$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y); H $\alpha+[{\rm NII}] EW=12$ Å  (GS). VCC 307: H $\alpha+[{\rm NII}] EW=31\pm1$ Å  (H), H $\alpha+[{\rm NII}] EW=42\pm1$ Å  (GS), $F({\rm H}\alpha+[{\rm NII}])=-10.89$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y), $F({\rm H}\alpha+[{\rm NII}])=-10.95$ $\rm erg~ cm^{-2} ~s^{-1}$ (Ko).

VCC 483: H $\alpha+[{\rm NII}] EW=11\pm2$ Å, H $\alpha+[{\rm NII}] EW=18\pm1$ Å  (GS), $F({\rm H}\alpha+[{\rm NII}])=-12.02$ $\rm erg~ cm^{-2} ~s^{-1}$ (KK), $F({\rm H}\alpha+[{\rm NII}])=-11.95$ $\rm erg~ cm^{-2} ~s^{-1}$ (Ko), $F({\rm H}\alpha+[{\rm NII}])=-11.74$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y).

VCC 596: H $\alpha+[{\rm NII}] EW=21\pm1$ Å  (GS), $F({\rm H}\alpha+[{\rm NII}])=-11.13$ $\rm erg~ cm^{-2} ~s^{-1}$ (Ko), $F({\rm H}\alpha+[{\rm NII}])=-11.09$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y).

VCC 792: $F({\rm H}\alpha+[{\rm NII}])=-12.28$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y).

VCC 797: at the border of the filter.

VCC 798: at the border of the filter; observed in non photometric conditions; flux calibrated on VCC 857 from Y.

VCC 801: H $\alpha+[{\rm NII}] EW=52\pm3$ Å (GS).

VCC 857: H $\alpha+[{\rm NII}] EW=-1\pm3$ Å (KK), H $\alpha+[{\rm NII}] EW=1\pm3$ Å (H), $F({\rm H}\alpha+[{\rm NII}])=-11.97$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y).

VCC 865: 2 coherent measurements.

VCC 873: H $\alpha+[{\rm NII}] EW=11$ Å(Kpc), H $\alpha+[{\rm NII}] EW=14$ Å(GS), $F({\rm H}\alpha+[{\rm NII}])=-12.38$ $\rm erg~ cm^{-2} ~s^{-1}$ (Kpc).

VCC 874: H $\alpha+[{\rm NII}] EW=10\pm3$ Å (GS).

VCC 905: observed in non photometric conditions; flux calibrated on VCC 939 from R.

VCC 912: vignetted; poor quality; H $\alpha+[{\rm NII}] EW=12\pm7$ Å (H), H $\alpha+[{\rm NII}] EW=24\pm7$ Å (GS), and $F({\rm H}\alpha+[{\rm NII}])=-12.16$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y).

VCC 939: $F({\rm H}\alpha+[{\rm NII}])=-12.28$ $\rm erg~ cm^{-2} ~s^{-1}$ (Ko)

VCC 958: $F({\rm H}\alpha+[{\rm NII}])=-11.81$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y)

VCC 979: $F({\rm H}\alpha+[{\rm NII}])=-12.10$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y)

VCC 984: vignetted.

VCC 1003: H $\alpha+[{\rm NII}] EW=1\pm3$ Å (GS).

VCC 1145: H $\alpha+[{\rm NII}] EW=8\pm3$ Å (GS).

VCC 1401: $F({\rm H}\alpha+[{\rm NII}])=-11.21$ $\rm erg~ cm^{-2} ~s^{-1}$ (Ko), $F({\rm H}\alpha+[{\rm NII}])=-11.14$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y).

VCC 1540: $F({\rm H}\alpha+[{\rm NII}])=-11.28$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y).

VCC 1555: H $\alpha+[{\rm NII}] EW=3\pm3$ Å (GS), $F({\rm H}\alpha+[{\rm NII}])=-11.21$ $\rm erg~ cm^{-2} ~s^{-1}$ (Ko), $F({\rm H}\alpha+[{\rm NII}])=-11.26$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y).

VCC 1562: $F({\rm H}\alpha+[{\rm NII}])=-11.42$ $\rm erg~ cm^{-2} ~s^{-1}$ (Ko), $F({\rm H}\alpha+[{\rm NII}])=-11.34$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y).

VCC 1673: $F({\rm H}\alpha+[{\rm NII}])$ in reference does not include the whole galaxy. Other references give: H $\alpha+[{\rm NII}] EW=20\pm3$ Å (GS), $F({\rm H}\alpha+[{\rm NII}])=-11.91$ $\rm erg~ cm^{-2} ~s^{-1}$ (Ko).

VCC 1676: $F({\rm H}\alpha+[{\rm NII}])$ in reference does not include the whole galaxy. Other references give: H $\alpha+[{\rm NII}] EW=27\pm3$ Å (GS), $F({\rm H}\alpha+[{\rm NII}])=-11.59$ $\rm erg~ cm^{-2} ~s^{-1}$ (Ko).

VCC 1690: H $\alpha+[{\rm NII}] EW=5\pm3$ Å (GS), $F({\rm H}\alpha+[{\rm NII}])=-11.83$ $\rm erg~ cm^{-2} ~s^{-1}$ (Ko), $F({\rm H}\alpha+[{\rm NII}])=-11.24$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y).

VCC 1730: H $\alpha+[{\rm NII}] EW=9\pm3$ Å (GS).

VCC 1943: $F({\rm H}\alpha+[{\rm NII}])=-11.94$ $\rm erg~ cm^{-2} ~s^{-1}$ (Ko), $F({\rm H}\alpha+[{\rm NII}])=-11.79$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y).

160065, 160069, 160213, 160214, 160215, 160216, 160221, 160222: affected by stray light from bright star.

M51: another image taken in non photometric conditions gives H $\alpha+[{\rm NII}] EW=18\pm5.4$ Å; other references give: H $\alpha+[{\rm NII}] EW=28\pm4$ Å, $F({\rm H}\alpha+[{\rm NII}])=-10.5$ $\rm erg~ cm^{-2} ~s^{-1}$ (not including the entire galaxy) (K); $F({\rm H}\alpha+[{\rm NII}])=-10.33$ $\rm erg~ cm^{-2} ~s^{-1}$ (Y).

M81: $F({\rm H}\alpha+[{\rm NII}])=-10.32$ $\rm erg~ cm^{-2} ~s^{-1}$ (Gr); H $\alpha EW=6$ Å, $F(H\alpha)=-10.49$ $\rm erg~ cm^{-2} ~s^{-1}$ (Kpc; no [NII] included).

M82: H $\alpha+[{\rm NII}] EW=45$ Å (K92), H $\alpha+[{\rm NII}] EW=110$ Å (GS).

M106: [NII] not included in the reference values.

N2903: another image taken in non photometric conditions gives H $\alpha+[{\rm NII}] EW=12\pm3$ Å; alternative value in the literature: H $\alpha+[{\rm NII}] EW=28$ Å  in K92.

N5195: another image taken in non photometric conditions gives H $\alpha+[{\rm NII}] EW=2\pm1$ Å; alternative value in the literature: H $\alpha+[{\rm NII}] EW=3.5$ Å  in K92.

References: KK: Kennicutt & Kent (1983); K: Kennicutt et al. (1987); Y: Young et al. (1996); Hi: Hippelein et al., in preparation; R: Romanishin (1987); B: Boselli et al. (2002), Paper III; G: Gavazzi et al. (1998); D: Devereux et al. (1995); Gr: Greenawalt et al. (1998); K92: Kennicutt (1992) (spectroscopic survey drifting the telescope over the entire disc of the galaxy); Kpc: Kennicutt, private communication; Ko: Koopmann et al. (2001); GS: Gavazzi et al., in preparation (spectroscopic survey drifting the telescope over the entire disc of the galaxy).

5.1 Recalibrations

16 galaxies previously observed with the Calar Alto 3.5 m telescope (Hippelein et al., in preparation) in non photometric conditions were reobserved at the OHP with 5 min exposures in the ON band filter in order to achieve a flux calibration. If $n_{\rm\frac{ON_{CA}}{ON_{OHP}}}$ is the normalization constant between the ON band Calar Alto and OHP images (normalized to the same integration time), the ON band zero point for Calar Alto observations $Zp_{\rm ON_{CA}}$ is given by the relation:

$${Zp_{\rm ON_{CA}} = \frac {Zp_{\rm ON_{OHP}}}{n_{\frac{\rm ON_{CA}}{\rm ON_{OHP}}}}}$$ (1)

where $Zp_{\rm ON_{OHP}}$ is the OHP zero point determined for the galaxy at a given airmass. $Zp_{\rm ON_{CA}}$ does not need to be corrected for airmass.

The resulting fluxes are given in Table 6.

 

 

Table 6: Calibration of the Calar Alto 1993 observations.

VCC	Tel	H$\alpha$+[NII]EW	F(H$\alpha$+[NII])	F(H$\alpha$+[NII])$_{\rm L}$	Ref.
87	OHP	$20 \pm 1$	$-12.83 \pm 0.25$:	-12.94	GH
152	OHP	$9 \pm 1$	$-12.63 \pm 0.26$	-
159	OHP	$19 \pm 1$	$-13.21 \pm 0.32$	-
446	OHP	$18 \pm 1$	$-13.47 \pm 0.15$	-
641	OHP	$20 \pm 1$	$-13.55 \pm 0.08$:	-
995	OHP	$32 \pm 1$	$-12.98 \pm 0.13$	-
1002	OHP	$9 \pm 1$	$-12.10 \pm 1.00$:	-
1189	OHP	$21 \pm 1$	$-12.66 \pm 0.19$	-
1419	OHP	$5 \pm 2$	$-13.06 \pm 0.79$	-
1486	OHP	$12 \pm 1$	$-13.17 \pm 1.00$:	-
1507	OHP	$11 \pm 1$	$-13.51 \pm 0.24$	-
1569	OHP	$14 \pm 2$	$-13.45 \pm 0.31$	-
1678	OHP	$55 \pm 8$	$-12.56 \pm 1.00$:	-
1929	OHP	$13 \pm 2$	$-12.75 \pm 0.45$	-
1932	OHP	$16 \pm 1$	$-12.32 \pm 0.49$	-
2037	OHP	$16 \pm 1$	$-13.82 \pm 0.62$	-13.53	B
2066	OHP	$6 \pm 1$	$-12.47 \pm 1.00$:	-

Notes: 2037: also observed by GH ( $F(\rm H\alpha+[NII])=-13.47$ $\rm erg~ cm^{-2} ~s^{-1}$).
References: B: Boselli et al. (2002), Paper III; GH: Gallagher & Hunter (1989).

Figure 2: Comparison with data in the literature: open dots are for KK, filled dots for Y, filled squares for H, x for R, + for Ko, $\curlywedge$ for K, open triangles for B, open squares for D, stars for Gr, filled triangles for G, filled pentagons for Kpc, open pentagons for GH, open exagons for K92 and filled exagons for GS.

5.2 Comparison with the literature

Fluxes and equivalent widths given in this paper are in general consistent with available measurements, as shown in Fig. 2. The average value of the difference between our measurements and those available in the literature is: ${\rm H}\alpha+[{\rm NII}] EW_{\rm TW}-{\rm H}\alpha+[{\rm NII}] EW_{\rm L}= 0 \pm 10$ Å and $-\log F({\rm H}\alpha+[{\rm NII}])_{\rm TW}$ + $\log F({\rm H}\alpha+[{\rm NII}])_{\rm L} = -0.04 \pm 0.32$  $\rm erg~ cm^{-2} ~s^{-1}$ (in the comparison of the H $\alpha+[{\rm NII}] EW$ we excluded those long slit spectra of Gavazzi et al. not including the entire galaxy). The outlying galaxy in the flux-flux relation is VCC 1003. Spectroscopic observations (GS) give an H $\alpha+[{\rm NII}] EW$ smaller than that obtained in this work; the flux given in Table 5 could thus be overestimated. The outlying galaxies in the equivalent width relation, whose $\alpha+[{\rm NII}] EW$ are significantly higher in this work with respect to the literature, are VCC 798 (open dot), VCC 857 (filled square) and VCC 1003 (filled exagon). As explained in the notes of Table 5, the value given for VCC 798 is highly uncertain. The H$\alpha$ image of VCC 857 shows emission in small, low surface brightness HII regions. We thus trust our value.