Observing the Shakhbazian Compact Groups of Galaxies
As their name suggests, compact groups are small systems of several galaxies in a compact configuration on the sky. The first example was found over one hundred years ago by Stephan (1877) who observed it visually using the 80-cm Foucault telescope of the Observatoire de Marseille. Stephan's Quintet is a small group of five galaxies, three of which show strong tidal distortions due to gravitational interaction. A second example was found 71 years later by Seyfert (1948) from a study of Harvard Schmidt plates. Seyfert's Sextet is one of the densest groups known, having a median projected galaxy separation of only 6.8h-1 kpc (the Hubble Constant H0 = 100h km s-1 Mpc-1).
The Palomar Observatory Sky Survey (POSS) provided a new and extensive resource for the systematic investigation of small groups of galaxies. Two catalogs, the Atlas of Interacting Galaxies (Vorontsov-Velyaminov 1959, 1975) and the Atlas of Peculiar Galaxies (Arp 1966), contain galaxies or galaxy groups selected on the basis of visible signs of interaction or peculiar appearance. In addition to Stefan's Quintet and Seyfert's Sextet, these include many new compact groups, including a striking chain of five galaxies, VV 172.
Prior to these, Shakhbazian (1957) had discovered a small dense cluster of 12 faint red galaxies that appeared so compact that they were initially mistaken for stars. Over the next two decades, Shakhbazian and collaborators examined over 200 POSS prints covering 18% of the sky and cataloged 376 additional "compact groups of compact galaxies" (Shakhbazian 1973, Shakhbazian & Petrosian 1974, Baier et al. 1974, Petrosian 1974, 1978, Baier & Tiersch 1975, 1976, 1978, 79). Apart from occasional photographic or spectroscopic observations (eg. Mirzoian et al. 1975, Tiersch 1976, Massey 1977, Shakhbazian & Amirkhanian 1979, Vorontsov-Velyaminov et al. 1980, Vorontsov-Velyaminov & Metlov 1980) these systems initially received little attention. However, interest in them is growing. Although the majority seem to be small clusters, they share some of the properties, and pose some of the same questions, as do compact groups.
© NASA/IPAC Extragalactic Database
Since 1997 I observed with my 18-inch Dobsonian telescope the following Shakhbazian compact groups:
1, 3, 5, 14, 16, 19, 21, 26, 30, 38, 40, 44, 49, 60, 63, 90, 98, 154, 166, 202, 317 and 322
Click to proceed to observations.
|Digitized Sky Survey
The Digitized Sky Surveys were produced at the Space Telescope Science Institute under U.S Government grant NAG W-2166. The images of these surveys are based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope. The plates were processed into the present com pressed digital form with the permission of these institutions The National Geographic Society - Palomar Observatory Sky Atlas (POSS-I) was made by the California Institute of Technology with grants from the National Geographic Society The Second Palomar Observatory Sky Survey (POSS-II) was made by the California Institute of Tech nology with funds from the National Science Foundation, the National Geographic Society, the Sloan Foundation, the Samuel Oschin Foundation, and the Eastman Kodak Corporation The Oschin Schmidt Telescope is operated by the California Institute of Technology and Palomar Observatory The UK Schmidt Telescope was operated by the Royal Observatory Edinburgh, with funding from the UK Science and Engineering Research Council (later the UK Particle Physics and Astronomy Research Council), until 1988 June, and thereafter by the Anglo-Australian Observatory The blue plates of the southern Sky Atlas and its Equatorial Extension (together known as the SERC-J), as weil as the Equatorial Red (ER), and the Second Epoch [red] Survey (SES) were all taken with the UK Schmidt.