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Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
| An image database. II. Catalogue between δ=-30deg and δ=70deg.
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
| H I observations of galaxies in the Hercules supercluster
An H-I survey of the Hercules supercluster region was conducted using21-cm line observations of galaxies listed in the Uppsala GeneralCatalog of Galaxies (Nilson, 1973). It is found that thethree-dimensional distribution of the sample deviates markedly from thatexpected for a randomly distributed sample, and that the sample volumecontains an underdense region in front of the supercluster. An upperlimit to the expansion velocity of this underdense region of 400 km/s isobtained.
| A redshift survey of low-surface-brightness galaxies. I - The basic data
Initial results from a 21 cm redshift survey of 375 very low surfacebrightness galaxies contained in the Uppsala General Catalog of Galaxiesare presented. The selection criteria and detection statistics as afunction of the sample optical properties are fully discussed. Theredshift distribution for the sample exhibits a pronounced peak at 5000km/s, corresponding to the well-studied Perseus-Pisces supercluster. Theoverall detection rate was 65 percent, and the bulk of the detectionsare genuine low surface brightness spiral galaxies, may with linewidthsin excess of 300 km/s, as opposed to true dwarf galaxies. It is arguedthat most of the nondetections are unlikely to be gas-poor dwarfs, butinstead are galaxies with velocities beyond 10,000 km/s. Taken as awhole, the sample demonstrates that optical surface brightness is notnecessarily a reliable indicator of intrinsic luminosity or mass.
| 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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