2 Observations and data reduction

Galaxies in the present study were primarily selected among the objects brighter than $B_{\rm T}\leq17.0$ in the VCC Catalogue of Virgo Cluster galaxies by Binggeli et al. (1985). CGCG (Zwicky et al. 1961-68) galaxies in the region $11^{\rm h}30^{\rm m}<\alpha<13^{\rm h}30^{\rm m}; 18^{\circ}<\delta<32^{\circ}$, containing the Coma-A1367 supercluster, were also selected as filler objects. Long-slit, low dispersion spectra of 76 galaxies were obtained in several observing runs since 1999 using the imaging spectrographs BFOSC and LFOSC attached to the Cassini 1.5 m telescope at Loiano (Italy), to the 2.1 m telescope of the Guillermo Haro Observatory at Cananea (Mexico), respectively, and with the CARELEC spectrograph (Lemaitre et al. 1990) attached to the 1.92 m telescope of the Observatoire de Haute Provence (OHP) (France).

Table 1 lists the characteristics of the instrumentation in the adopted set-up.

Figure 2: The distribution in celestial coordinates of 913 Virgo galaxies with $V\leq 24\, 000$  $\rm km~ s^{-1}$(right) and a wedge diagram (left) (same symbols as in Fig. 1)

Figure 3: The distribution in celestial coordinates of 1109 galaxies in the direction of the Coma supercluster with measured redshift (top) and a wedge diagram (bottom) (same symbols as in Fig. 1)

 

 

Table 2: Parameters of the observed Virgo galaxies

Gal.	RA(1950)	Dec. (1950)	Type	$B_{\rm T}$	V	$\pm$	Lines	Run	Memb	new Memb	$v_{\rm alt}$	ref
	h m s	$^{\rm o}~'~''$		mag	km s-1
(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)	(10a)	(11)	(12)
VCC 0007	120645.60	114230.0	Sc	15.04	18675	425	A	Can	bk	bk
VCC 0014	120717.80	113205.0	BCD?	16.50	17891	35	E	L00	-	bk
VCC 0019	120740.80	132800.0	BCD?	16.50	6803	99	E	L00	-	bk
VCC 0045	120934.70	152315.0	BCD?	16.00	15236	36	E	L00	-	bk
VCC 0064	121008.50	114955.0	Sab	15.04	18142	336	A	Can	bk	bk
VCC 0074	121031.80	161024.0	BCD?	16.30	861	78	E	Can	-	m
VCC 0099	121128.90	70004.0	Sa?	14.81	2476	214	E	L99	-	m	2444	GGH98
VCC 0196	121400.00	94624.0	BCD?	16.50	13024	57	E	L00	-	bk
VCC 0225	121439.00	83612.0	BCD?	17.00	21345	126	E	L00	-	bk
VCC 0249	121509.00	133930.0	Sa	14.61	7491	61	E	Can	bk	bk
VCC 0323	121633.20	60012.0	Sa	14.91	2402	358	A	L99	-	m	2756	GGH98
VCC 0362	121709.00	54856.0	Sa	14.51	1300	304	A	L99	-	m	1536	GGH98
VCC 0397	121739.00	65402.0	dE?	15.00	2411	809	A	L99	-	m	2495	GGH98
VCC 0482	121900.80	50324.0	S0a	14.77	1802	709	A	L99	-	m	2170	GGH98
VCC 0486	121903.80	60235.0	S0a	14.50	2386	252	A	L99	-	m	2498	GGH98
VCC 0510	121922.80	155518.0	dE	15.13	804	151	A	Can	m	m
VCC 0541	121945.00	43348.0	BCD	16.00	23511	50	E	L00	-	bk
VCC 0573	122009.60	55454.0	Sc	15.20	23083	189	E	Can	bk	bk	23083	NED
VCC 0583	122014.40	154636.0	Im	15.76	-72	475	A	L99	m	m
VCC 0723	122149.80	131824.0	dS0?	15.04	125	50	A	L00	-	m
VCC 0762	122230.00	74660.0	dE	15.30	1341	211	A	Ohp	m	m
VCC 0794	122250.40	164224.0	dS0	15.50	918	817	A	Ohp	m	m
VCC 0817	122306.00	160642.0	dE	15.00	1168	153	A	Can	m	m
VCC 0991	122445.90	142525.0	dE	14.70	-406	239	A	L99	m	m
VCC 1028	122506.60	144360.0	dS0?	15.70	21	158	A	Ohp	-	m
VCC 1174	122645.80	101246.0	BCD?	15.50	11840	52	E	L99	-	bk
VCC 1270	122743.80	84800.0	Sa	15.00	11687	440	A	Can	bk	bk
VCC 1304	122809.00	152412.0	dS0	15.50	-108	294	A	L99	m	m
VCC 1389	122919.80	124530.0	dE	15.91	936	193	A	Can	m	m
VCC 1395	122923.40	85248.0	dE?	16.20	22900	100	E	L00	-	bk
VCC 1423	122942.60	31630.0	BCD?	16.00	13079	98	A	Can	-	bk
VCC 1608	123247.60	62325.0	E	14.20	2285	193	A	L99	-	m	2464	GGH98
VCC 1643	123321.00	60212.0	S0	15.20	12509	258	A	Ohp	-	bk	12563	GGH98
VCC 1671	123359.60	62641.0	dS0	14.80	11608	809	A	L99	-	bk	11846	GGH98
VCC 1687	123416.20	42242.0	dE	15.10	616	122	A	Can	-	m
VCC 1836	123749.80	145930.0	dS0	14.54	1927	148	A	Can	m	m
VCC 1849	123803.60	94942.0	BCD?	16.20	15905	50	E	L00	-	bk
VCC 1906	123932.20	155438.0	S0	15.70	314	138	A	Can	-	m
VCC 1927	124005.40	105024.0	Sc	14.91	20085	180	A	Can	bk	bk
VCC 1936	124014.40	94654.0	dS0	15.68	985	276	A	Ohp	m	m
VCC 1947	124023.30	35701.0	dE	14.56	1083	405	A	L99	-	m	944	GGH98
VCC 1956	124036.00	35118.0	S..	15.10	14691	51	E	L99	-	bk	14659	GGH98
VCC 1982	124119.20	114412.0	dE	15.30	938	464	A	Ohp	m	m
VCC 1997	124151.60	102742.0	Sb	15.10	9210	46	E	Can	bk	bk
VCC 2015	124240.20	103554.0	BCD?	16.20	2545	115	E	L00	-	m
VCC 2042	124407.20	93448.0	dE	14.84	1765	154	A	Can	m	m
VCC 2077	124604.50	110851.0	Sab	15.20	11860	225	A	Can	bk	bk
VCC 2082	124727.60	113206.0	S..	15.30	7421	26	E	Can	bk	bk

 

 

Table 3: Parameters of the observed Coma galaxies

Gal.	RA(1950)	Dec. (1950)	Type	$B_{\rm T}$	V	$\pm$	Lines	Run	Memb	$v_{\rm alt}$	ref
	h m s	$^{\rm o}~'~''$		mag	km s-1
(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10a)	(11)	(12)
127-028	113851.25	250457.3	S0	15.60	3518	330	A	L99	fg
127-029N	113859.62	260956.6	E	16.30	7407	14	E	Can	m
127-029S	113900.06	260926.5	E	16.30	6927	113	A	Can	m
97-153W	114513.24	184955.0	S..	16.30	11156	20	E	Can	bk
97-153E	114515.08	184936.7	S..	16.30	20261	112	E	Can	bk
127-057S	114550.62	260223.9	S..	16.50	13666	75	E	Can	bk
127-057N	114551.69	260251.3	S..	16.50	13718	15	E	Can	bk
127-102	115130.07	232813.1	E	15.70	7799	139	A	Ohp	m
128-028W	120405.12	260142.4	E	16.40	7353	198	A	Can	m
128-028E	120406.94	260150.2	E	16.40	13788	143	A	Can	bk
98-088	120903.25	201024.8	S0	15.70	6564	215	A	Ohp	m
128-055	121122.87	220200.8	S0	15.70	7227	330	A	L99	m
98-120	121341.37	194405.9	E	15.70	13208	202	A	Ohp	bk
98-127	121409.85	183918.2	E	15.70	8954	203	A	Ohp	bk
99-013	121638.07	193306.1	Sc	15.70	7297	16	E	Ohp	m
128-083	121936.55	240846.0	E	15.70	10182	129	E	Ohp	bk
128-083E	121939.64	240847.5	E	17.00	10292	164	A	Ohp	bk
128-085	122150.98	212612.2	Sc	15.60	914	21	E	Ohp	fg
99-066	122620.69	194525.9	Sb	15.70	13582	86	E	Ohp	bk
129-003	122631.44	245429.9	Sc	15.70	14572	9	E	Ohp	bk
99-067	122635.25	191652.4	E	15.70	14393	250	A	Ohp	bk
159-087E	124810.87	274149.8	Sbc	15.70	12286	16	E	Ohp	bk
160-036S	125435.00	305820.9	S0	16.00	15302	177	A	Can	bk
160-036E	125438.62	305831.5	E	16.50	14880	185	A	Can	bk
160-163S	131035.69	272401.1	E	16.50	17929	178	A	Can	bk
160-163	131036.56	272421.7	S0a	15.70	18015	72	E	Can	bk
161-029	131912.70	263359.0	Sb	15.70	4930	11	E	Ohp	m
161-061S	132554.00	285542.1	S..	15.60	11281	32	E	Can	bk	11247	G99
161-061N	132554.69	285657.4	E	16.50	10564	165	A	Can	bk

The observations at Loiano were performed using a 2.0 or 2.5 arcsec slit, depending on the seeing conditions, generally oriented E-W. Every galaxy spectrum was preceded and followed by an exposure of a HeAr lamp to secure the wavelength calibration. The exposure time ranged between 20 and 90 min (1999 run) according to the brightness of the target objects, or 15 min (2000 run) owed to the much higher quantum efficiency of the new EEV detector.

The observations at Cananea were carried out with a 1.9 arcsec slit, generally oriented N-S. Every galaxy spectrum was preceded and followed by an exposure of a XeNe lamp to secure the wavelength calibration. The exposure time ranged between 20 and 40 min according to the brightness of the target objects.

The observations at OHP were carried out with a 2.5 arcsec fixed slit, generally oriented E-W. Every galaxy spectrum was preceded and followed by an exposure of a HeAr lamp to secure the wavelength calibration. The exposure time ranged between 20 and 30 min according to the brightness of the target objects. In all runs the observations were obtained in nearly photometric conditions, with thin cirrus. The orientation of the slit was modified from the set-up given above when two adiacent objects were observable in the same exposure.

The data reduction was performed in the IRAF-PROS environment. After bias subtraction, when 3 or more frames of the same target were obtained, these were combined (after spatial alignment) using a median filter to help cosmic rays removal. Otherwise the cosmic rays were removed under visual inspection. The wavelength calibration was checked on known sky lines. These were found within $\sim$ 1 $\rm\AA$ from their nominal value, providing an estimate of the systematic uncertainty on the derived velocities of $\sim$ 50 $\rm km~ s^{-1}$. After subtraction of the sky background, one-dimensional spectra were extracted from the frames. These spectra were analyzed with either of two methods:
1) individual line measurement: all spectra taken at Loiano 2000 were inspected and emission/absorption lines were identified. Emission lines include H$\alpha$, [NII] and [SII]. Absorption lines include the MgI, Ca-Fe and Na. The galaxy redshift was obtained from these individual measurements. If more than one line was identified, the galaxy redshift was derived as the weighted mean of the individual measurements, with weights proportional to the line intensities;
2) cross correlation technique: spectra obtained in all the remaining runs were analyzed using the cross-correlation technique of Tonry & Davis (1979). This method is based on a "comparison" between the spectrum of a galaxy whose redshift is to be determined, and a fiducial spectral template of a galaxy (or star) of appropriate spectral type to contain the wanted absorption/emission lines. The basic assumption behind this method is that the spectrum of a galaxy is well approximated by the spectrum of its stars, modified by the effects of the stellar motions inside the galaxy and by the systemic redshift. For this purpose high signal-to-noise spectra were taken of four template galaxies: M 105 and M 32 (absorption lines) and VCC 1554 and IC 342 (emission lines), which were converted to the restframe $\lambda$. The observed redshifts ( $V_{\rm obs}$) were not transformed to Heliocentric.