madbadgalaxyman
22-08-2012, 11:15 AM
A lot of you will be aware of the fact that, when doing a search of the internet, high quality images of many bright southern galaxies are often much harder to find than high quality images of bright northern galaxies.
There has long been a need for a comprehensive collection of good quality images of the entire population of Bright Southern Galaxies.
We are fortunate that such a collection of galaxy images has recently been put online:
The Carnegie-Irvine Galaxy Survey (also known as the CGS)
http://cgs.obs.carnegiescience.edu/CGS
This is a remarkable and comprehensive online Atlas of southern galaxies, containing high quality images...…better still, viewing of the imaging data is free of charge for the general public.
The summary page on the Atlas website states that this Atlas includes images of the 600 brightest galaxies in the southern sky, all of them of Blue magnitude less than 13 .
Therefore, this Atlas of Galaxies includes Good Quality images of a large fraction of those galaxies which southern amateurs are able to image or visually observe in substantial detail!
As a person who is totally obsessed by southern galaxies, I must say that it is wonderful to finally have good images available for the majority of the least frequently imaged and least known bright galaxies in the southern sky; indeed, there are good numbers of southern non-NGC galaxies in this atlas where the primary galaxy identification is the ESO catalog or the IC catalog. These southern ESO and IC objects are often the least known and studied bright galaxies in the sky.....
((
Note 1 : I am not, as yet, familiar with the precise contents and border conditions of the sample of bright galaxies that has been included in this Atlas of Galaxies
Note 2 : This is a magnitude-limited sample of galaxies, so Dwarf and Low Surface Brightness galaxies often do not make it into this Atlas; most of the atlas galaxies are either giant or sub-giant in luminosity.
Note 3 : This atlas includes only a modest number of type S0 and S0/a galaxies. To find more high-quality S0 galaxy images, see the website of the “NIRS0S” survey, which can be found using Google search. You can also use SDSS Skyserver to find good images of large numbers of S0 galaxies.
))
Another very important aspect of this galaxy atlas is that these images are fully calibrated, so that the user can look up observational parameters such as angular diameters & magnitudes & colors of the Atlas galaxies. The authors have derived a great deal of catalog-type numerical data from their images, for each and every galaxy they imaged, and this data can be looked up for each galaxy. This atlas of galaxies includes a lot of numerical data about each galaxy.
For the more scientifically oriented, here is a list of some of the available data that the authors have derived from the galaxy images:
- the radial Surface Brightness profiles of each galaxy as measured in the B & V & R & I filters
- other characteristics of the isophotes of each galaxy , e.g. how the ellipticity and position angle of the galaxy varies with radius
- derived image parameters for each galaxy: ellipticity, angular diameter, apparent magnitude of the galaxy in several bandpasses, galaxy inclination & position angle, surface brightness, etc., etc.
- maps of each galaxy’s colors, showing the variation over the face of the galaxy of color indices such as B-R and R-I
- information about the morphology of each galaxy.
The Carnegie-Irvine Galaxy Survey is indeed a treasure trove for amateur Imagers and Deep Sky Observers. It is also a rich resource for people who want to study a large & calibrated sample of galaxy images in a scientific manner.
There has long been a need for a comprehensive collection of good quality images of the entire population of Bright Southern Galaxies.
We are fortunate that such a collection of galaxy images has recently been put online:
The Carnegie-Irvine Galaxy Survey (also known as the CGS)
http://cgs.obs.carnegiescience.edu/CGS
This is a remarkable and comprehensive online Atlas of southern galaxies, containing high quality images...…better still, viewing of the imaging data is free of charge for the general public.
The summary page on the Atlas website states that this Atlas includes images of the 600 brightest galaxies in the southern sky, all of them of Blue magnitude less than 13 .
Therefore, this Atlas of Galaxies includes Good Quality images of a large fraction of those galaxies which southern amateurs are able to image or visually observe in substantial detail!
As a person who is totally obsessed by southern galaxies, I must say that it is wonderful to finally have good images available for the majority of the least frequently imaged and least known bright galaxies in the southern sky; indeed, there are good numbers of southern non-NGC galaxies in this atlas where the primary galaxy identification is the ESO catalog or the IC catalog. These southern ESO and IC objects are often the least known and studied bright galaxies in the sky.....
((
Note 1 : I am not, as yet, familiar with the precise contents and border conditions of the sample of bright galaxies that has been included in this Atlas of Galaxies
Note 2 : This is a magnitude-limited sample of galaxies, so Dwarf and Low Surface Brightness galaxies often do not make it into this Atlas; most of the atlas galaxies are either giant or sub-giant in luminosity.
Note 3 : This atlas includes only a modest number of type S0 and S0/a galaxies. To find more high-quality S0 galaxy images, see the website of the “NIRS0S” survey, which can be found using Google search. You can also use SDSS Skyserver to find good images of large numbers of S0 galaxies.
))
Another very important aspect of this galaxy atlas is that these images are fully calibrated, so that the user can look up observational parameters such as angular diameters & magnitudes & colors of the Atlas galaxies. The authors have derived a great deal of catalog-type numerical data from their images, for each and every galaxy they imaged, and this data can be looked up for each galaxy. This atlas of galaxies includes a lot of numerical data about each galaxy.
For the more scientifically oriented, here is a list of some of the available data that the authors have derived from the galaxy images:
- the radial Surface Brightness profiles of each galaxy as measured in the B & V & R & I filters
- other characteristics of the isophotes of each galaxy , e.g. how the ellipticity and position angle of the galaxy varies with radius
- derived image parameters for each galaxy: ellipticity, angular diameter, apparent magnitude of the galaxy in several bandpasses, galaxy inclination & position angle, surface brightness, etc., etc.
- maps of each galaxy’s colors, showing the variation over the face of the galaxy of color indices such as B-R and R-I
- information about the morphology of each galaxy.
The Carnegie-Irvine Galaxy Survey is indeed a treasure trove for amateur Imagers and Deep Sky Observers. It is also a rich resource for people who want to study a large & calibrated sample of galaxy images in a scientific manner.