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Faint Features of Interacting Galaxies Revealed by the Digital Coaddition of 13 Tech-Pan Films of the Virgo Cluster
We have digitally coadded APM scans of 13 Kodak TechPan films of the SEregion of the Virgo Cluster of galaxies. The ~6.2°×6.2°field of the R-band films combined with the resolution of ~2 arcsecpixel^- results in data-file sizes of about 222 MBytes. The 13 scannedfilms have been aligned, coadded, corrected for vignetting effects andcleaned of stellar features. To illustrate the astrophysical uses ofthis technique, we present high-contrast images of a sample ofinteracting galaxies in the field. Several very faint features (but veryclearly seen in the coadded array) - such as the interaction between IC3481, IC 3481A and IC 3483, and NGC 4410A and B and IC 790 - have beenpresented with clarity for the first time.
| Results of the digital co-addition of thirteen Schmidt films of the Virgo cluster of galaxies
We have digitally co-added APM scans of 13 Kodak TechPan films of the SEregion of the Virgo cluster of galaxies. The ~ 6.2degr x 6.2degr fieldof the R-band films combined with the resolution of ~ 2 arcsec pixel(-1)results in data file sizes of about 222 MBytes. The 13 scanned filmshave been aligned, co-added, corrected for vignetting effects andcleaned of stellar features. To illustrate the astrophysical uses ofthis technique, we present high contrast images of a sample of Virgocluster and background galaxies. Several very faint, but very clearlyseen features, such as the interaction between IC 3481, IC 3481A and IC3483 and filaments outside of the common envelope of NGC 4438 & NGC4435, can be seen for the first time. We present an image of the halo ofM 87 showing its great extent, and an image of the central regions ofthe cluster which shows no real evidence for interactions between thegalaxies in this region. We also present high-quality images of thepreviously-identified ``jet" and shell features around M 89. We alsopresent an image of the whole field which appears to show largevariations in brightness of the intra-cluster medium across the region,with the brightest regions in the northern part in the central regionsof the cluster, though we caution against this interpretation until wehave investigated the large variation in emulsion sensitivity acrossindividual films more thoroughly.
| Total magnitude, radius, colour indices, colour gradients and photometric type of galaxies
We present a catalogue of aperture photometry of galaxies, in UBVRI,assembled from three different origins: (i) an update of the catalogueof Buta et al. (1995) (ii) published photometric profiles and (iii)aperture photometry performed on CCD images. We explored different setsof growth curves to fit these data: (i) The Sersic law, (ii) The net ofgrowth curves used for the preparation of the RC3 and (iii) A linearinterpolation between the de Vaucouleurs (r(1/4) ) and exponential laws.Finally we adopted the latter solution. Fitting these growth curves, wederive (1) the total magnitude, (2) the effective radius, (3) the colourindices and (4) gradients and (5) the photometric type of 5169 galaxies.The photometric type is defined to statistically match the revisedmorphologic type and parametrizes the shape of the growth curve. It iscoded from -9, for very concentrated galaxies, to +10, for diffusegalaxies. Based in part on observations collected at the Haute-ProvenceObservatory.
| The ``Virgo photometry catalogue''; a catalogue of 1180 galaxies in the direction of the Virgo Cluster's core
We present a new catalogue of galaxies in the direction of the VirgoCluster's core: the Virgo Photometry Catalogue (VPC)*. This cataloguecontains 1180 galaxies (including background objects) within a 23square-degree area of the sky centred on R.A._{1950.0} = 12h 26m anddec._{1950.0} = 13(deg) 08'. The VPC galaxy sample comprises ofnon-stellar objects brighter than B_J25 = 19.0; thecompleteness limits being B_J25 ~18.5 for the northern halfof the survey area and B_J25 ~18.0 for the southern half.Independently-calibrated photographic surface photometry is presentedfor over 1000 galaxies in the U, B_J and R_C bands. Parameters listedfor catalogued galaxies include: equatorial coordinates, morphologicaltypes, surface-brightness profile parameters (which preserve themajority of the original surface photometry information), U, B_J &R_C isophotal magnitudes, B_J and [transformed] B total magnitudes,(U-B_J) and (B_J-R_C) equal-area and total colours, apparent angularradii, ellipticities, position angles, heliocentric radial velocitiesand alternative designations. All total magnitudes and total colours areextrapolated according to a new system denoted t in order to distinguishit from the T system already in use. The VPC is based primarily on four(one U, two B_J and one R_C) UK-Schmidt plates, all of which weredigitised using the Royal Observatory Edinburgh's (ROE) COSMOS measuringmachine. All magnitudes, colours and surface-brightness parameters arederived from numerical integrations of segmented plate-scan data, exceptfor (in 109 cases) saturated or (in 51 cases) inextricably-mergedimages; our segmentation software being able to cope with the vastmajority of image mergers. * Appendices B, C and E, which contain thesurface photometry, the main catalogue and the summary cataloguerespectively, are only available in electronic form. They can beobtained from La Centre des Donees astronomiques de Strasbourg (CDS) viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html.
| The UV properties of normal galaxies. III. Standard luminosity profiles and total magnitudes.
In the previous papers of this series we collected and reduced to thesame system all the available photometric data obtained in theultraviolet (UV) range for normal (i.e. non active) galaxies. Here weuse these data to derive standard UV luminosity profiles for threemorphological bins (E/S0; Sa/Sb; Sc/Sd) and extrapolated totalmagnitudes for almost 400 galaxies. We find that: 1) the UV growthcurves are well matched by the B-band revised standard luminosityprofiles, once a proper shift in the effective radius is applied, and 2)the UV light in early-type galaxies is more centrally concentrated thanthe visible light.
| The UV properties of normal galaxies. II. The ``non-IUE'' data.
In the last decade several satellite and balloon borne experiments havecollected a large number of ultraviolet fluxes of normal galaxiesmeasured through apertures of various sizes and shapes. We havehomogenized this data set by deriving scale corrections with respect toIUE. In a forthcoming paper these data will be used to derive standardluminosity profiles and total magnitudes.
| A catalogue of early-type galaxies with emission lines
Spectroscopic and photometric data on 289 early-type galaxies (E and S0)with optical emission lines are presented and possible correlationsamong properties of the galaxies in the sample are investigated. Theoccurrence of phenomena as radio emission, presence of neutral hydrogenand dust shows an increase in comparison with the occurrence of the samephenomena in these morphological classes as a whole. There is noevidence of a relationship between apparent shape and presence ofionized gas in the central regions.
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