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Galaxy coordinates. II. Accurate equatorial coordinates for 17298 galaxies
Using images of the Digitized Sky Survey we measured coodinates for17298 galaxies having poorly defined coordinates. As a control, wemeasured with the same method 1522 galaxies having accurate coordinates.The comparison with our own measurements shows that the accuracy of themethod is about 6 arcsec on each axis (RA and DEC).
| The large-scale distribution of late-type galaxies between Virgo and the Great Wall
Neutral hydrogen data are presented for 88 of the Virgo Cluster Cataloggalaxies thought on morphological grounds to lie in the background ofthe cluster. We confirm that the morphological assignment of clustermembership works quite well; very few of the 'background' galaxies arein fact at cluster redshifts. The resulting sample of redshifts, alongwith optical redshifts from the literature, allow us to explore thelarge-scale distribution of galaxies in the space between the LocalSupercluster and the Great Wall. Galaxies in a larger window around theVirgo Cluster, but at redshifts between Virgo and the Great Wall, have afairly low average number density, but the distribution is far fromuniform: Some portions resemble voids, but in other portions galaxiescan be assigned to clouds or filaments of appreciable size (sometimescontaining bound groups). We investigate the luminosity function inhigh- and low-density regions of our galaxy sample, which excludes theVirgo Cluster proper. We find no significant difference. However, ourselection procedures are insensitive to galaxies of very low surfacebrightness, which have been reported to be more abundant in low-densityregions. The average probability of a line of sight intersecting theoptical disk of our sample galaxies is derived separately for the VirgoSupercluster region (redshifts below 3500 km/s) and for the regionbehind (out to 10,000 km/s). The number density ratio of Ly-alpha forestlines to galaxies is larger by a factor of order 10 in the far(low-density) region than in the near. A survey of recent literature ongalaxy redshifts uncovers a new candidate, MCG 0-32-16, for the lowestredshift absorption line.
| The distribution of the spiral galaxies in the direction of the Coma/A 1367 supercluster
The three-dimensional distribution of spiral galaxies is analyzed for a1080 sq deg region surrounding the Coma cluster, A 1367 and Zw 74-23(NGC 5416 cluster). H I observations of spiral galaxies having angulardiameters less than 2 arcmin, with the exception of six NGC objects andone IC object, are used, detecting 87 galaxies with 67 redshiftsreported for the first time. A population of faint isolated galaxies asmuch as 30 deg from Coma or A 1367 is found having radial velocitiesnear 7000 km/s, and a group between Coma and A 1367 is found containingno galaxies with m(p) less than 15.0. South of A 1367 three groups arefound located 12 deg from the core with radial velocities near 7000 km/sand a projected diameter less than 2 Mpc. South of 20 deg declination atleast four clusters and isolated galaxies are found which could be partof the southern extension of the Coma-A 1367 supercluster. Assuming allthe detected isolated spirals belong to the Coma-A 1367 supercluster,the angular extent of the supercluster is almost a radian in the planeof the sky.
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