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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.
| Low-frequency radio continuum evidence for cool ionized gas in normal spiral galaxies
A 57.5-MHz survey of a total of 133 (mostly late-type spiral) galaxieshas resulted in the detection of 68. The ratio of observed intensitiesto intensities extrapolated from higher-frequency measurements is wellcorrelated with the axial ratio of the observed galaxies, and isinterpretable due to increasing free-free absorption of nonthermalemission in galaxy disks with increasing tilt. The implied free-freeabsorption is interpreted as due to the pervasive presence of a clumpymedium of well-mixed, nonthermally emitting, thermally absorbing gaswith small filling factor.
| The Asiago Supernova Catalogue
A Catalogue of Supernovae (SNe) is presented which tabulates the maindata relative to all extragalactic SNe discovered up to 1988 December31, and to their parent galaxies. In total 661 SNe are listed of which267 are classified. For an easier consultation, two lists are givenwhere the SNe are ordered chronologically and by Right Ascension,respectively. The overall distribution of classified supernovae over themorphological types of their parent galaxies is also presented in asummary table.
| On the local environment of extragalactic supernovae
Since Type II supernovae (SNs II) have never been observed in ellipticalgalaxies and tend to occur in the arms of spirals, it is generallybelieved that they are associated with the classic Population I tracersof the arms: giant H II regions and OB associations. However, thisassociation has never been directly demonstrated with an adequate numberof supernovae. An attempt was made to search for evidence of massivestar formation in the immediate vicinity of 56 SNs II. High-qualityoptical galaxy photos have been located for 29 out of the 56 SNs II. Ofthese 29 supernovae, 25 lie toward or very near nebulous knots, theplausible signature of star-forming complexes. It is argued that such alarge number of apparent coincidences cannot result from chancesuperposition. These coincidences provide the most direct evidence todate to support the hypothesis that most, if not all, SNs II arise frommassive progenitors. The local environment of Type I supernovae inspiral and irregular galaxies is also discussed.
| A Checklist of Supernovae in the NGC and IC Galaxies Through 1985
This Checklist of Supernovae in the NGC and IC Galaxies Through 1985 ispresented to assist those interested in undertaking a visual orphotographic search for extragalactic supernovae. Some galaxies appearto have had more than one or two supernovae, and these should bemonitored closely for any new outbursts.
| A revised supernova catalogue
Essential data for 568 supernovae, discovered since 1885 up to 1983, andtheir parent galaxies are presented. This catalogue updates and revisesprevious listings, and some of its information is summarized in tabularand graphical form and briefly discussed. An appendix listing the mainreferences to observations of supernovae outside the optical range isprovided.
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