Sloan DSS Galaxies
Overview
The multifaceted Sloan Digital Sky Survey (SDSS) is an ambitious project to image and get spectra for about 35% of the sky. These spectra allow astronomers to probe deeply into the universe. The survey measured the position and brightness of almost 1 billion objects, and obtained spectra to more than 4 million objects.
Sloan DSS operates many investigations on all manner of objects. Here, we focus on the redshift survey which yields galaxies and quasars (discussed in Quasars).
A face-on view of the Sloan DSS Galaxies. Similar to the 2dF Galaxies, Sloan observed in two general directions in the sky, and we see the resulting slices here. Sloan’s slices are wider, covering more of the sky, but they are also thicker, particularly the one on the right side in this image.
An edge-on view of the Sloan DSS Galaxies, revealing the wide swaths of data and the more concentrated trio of slices on the left.
The Project
The SDSS telescope is located at Apache Point Observatory in south-central New Mexico (US) and began operating in June 1998. It is 2.5 meters (8.2 feet) in diameter and was designed specifically for this mapping project. The telescope takes images of the sky as well as spectra for individual objects.
The spectral range for the SDSS is 380 to 920 nanometers, stretching from the blue end of the visible spectrum to the red end and barely into the infrared.
The Distribution
The SDSS galaxies are similar to the 2dF data in that they form triangular wedges, revealing those parts of the sky observed by the telescope. If the entire sky were covered, you would see a spherical distribution of galaxies surrounding the Milky Way. With only 35% of the entire sky observed, we see plenty of empty space—areas that have not been observed by SDSS.
These galaxies extend beyond the 2dF survey to distances that exceed 5 billion light years. However, the weblike structure of clusters, filaments, and voids seems to fade by about 2 billion light years. Beyond this distance, the completeness of the survey drops so that only the intrinsically bright galaxies are visible.
The weblike cosmic large-scale structure is echoed in these data, with orange clusters standing out among the less dense areas filled with green and aqua galaxies.
The Sloan DSS Galaxies from the outside. The large-scale structure we are used to seeing is more local to the Milky Way, while the data are more homogenous toward the outskirts.
Profiles
Dossier
Census: |
2,862,767 galaxies |
|---|---|
Asset File: |
|
OpenSpace Version: |
4 |
Reference: |
|
Prepared by: |
Brian Abbott, Zack Reeves (AMNH), Eric Gawiser (Rutgers) |
Source Version: |
12.08 |
License: |