Galaxies at low-redshift typically possess negative gas-phase metallicity gradients (centres more metal-rich than their outskirts). Whereas, it is not uncommon to observe positive metallicity gradients in higher-redshift galaxies (z<0.6). Bridging these epochs, we present gas-phase metallicity gradients of 84 star-forming galaxies between 0.08<z<0.84. Using the galaxies with reliably determined metallicity gradients, we measure the median metallicity gradient to be negative (-0.039^+0.007^_-0.009_dex/kpc). Underlying this, however, is significant scatter: (8+/-3)% [7] of galaxies have significantly positive metallicity gradients, (38+/-5)% [32] have significantly negative gradients, (31+/-5)% [26] have gradients consistent with being flat. (The remaining (23+/-5)% [19] have unreliable gradient estimates.) We notice a slight trend for a more negative metallicity gradient with both increasing stellar mass and increasing star formation rate (SFR). However, given the potential redshift and size selection effects, we do not consider these trends to be significant. Indeed, once we normalize the SFR relative to that of the main sequence, we do not observe any trend between the metallicity gradient and the normalized SFR. This is contrary to recent studies of galaxies at similar and higher redshifts. We do, however, identify a novel trend between the metallicity gradient of a galaxy and its size. Small galaxies (rd<3kpc) present a large spread in observed metallicity gradients (both negative and positive gradients). In contrast, we find no large galaxies (rd > 3 kpc) with positive metallicity gradients, and overall there is less scatter in the metallicity gradient amongst the large galaxies. These large (well-evolved) galaxies may be analogues of present-day galaxies, which also show a common negative metallicity gradient.
A systematic search by microscope for non-stellar objects on 19 POSS II R film copies has led to the detection of 3455 objects. The vast majority are obscured galaxies, most of which are new. We present coordinates and optical diameters of these galaxy candidates, list coincidences with objects in optical and infrared catalogues.
This document describes a computer version of that part of the CGCG (Zwicky et al. 1961-68) containing all the alphanumeric information for galaxies. All known errors found by Zwicky and many others are corrected as well as erroneous quotations from other catalogs (Shapley & Ames 1932, Bigay 1951, Pettit 1954, Humason et al. 1956, Holmberg 1958). It is an illusion to consider all the errors are found. There are some misprints even in the most extended list of misprints (Paturel et al. 1991). We have compiled two files: zwi_gal.ori and zwi_gal.add. The first one contains the original information from CGCG for galaxies. The second one contains the data from above mentioned other catalogs given in CGCG. We have made no attempts to supply the catalog with any new information. A detailed comparison with the machine-readable version of Zwicky galaxies prepared by R.S. Hill (NSSDC ADC #7049 or CDS VII/49) was performed. Our version contains more data on individual galaxies - designation, description, magnitudes, velocity. All galaxies in the Coma center are included. However Hill's version contains data for Zwicky fields, Palomar Sky Survey plate number as well as Mead-Luyten-Palomar number. There are 27837 different galaxies and 29418 entries in CGCG.