Nebulae
Bigger, Better Catalog Unveils Half a Billion Celestial Objects
June 4, 2001 · NASA · Rosette Nebula; NGC 2237 · Monoceros
Zoom to full resolution See where it is in the 3D sky Original on NASA ↗
These frames are samples from the photographic sky surveys, which have been digitized by a technical team at the Space Telescope Science Institute to support the Hubble Space Telescope operations. The team processed these images to create a new astronomical catalog, called the Guide Star Catalog II. This project was undertaken by the Space Telescope Science Institute as an upgrade to an earlier sky survey and catalog (DSS-I and GSC-I), initially done to provide guide stars for pointing the Hubble Space Telescope. By virtue of its sheer size, the DSS-II and GSC-II have many research applications for both professional and amateur astronomers.
[Top] An example from the DSS-II shows the Rosette Nebula, (originally photographed by the Palomar Observatory) as digitized in the DSS-I (left) and DSS-II (right). The DSS-II includes views of the sky at both red and blue wavelengths, providing invaluable color information on about one billion deep-sky objects.
[Bottom] This blow-up of the inset box in the raw DSS-I scan shows examples of the GSC-I and the improved GSC-II catalogs. Astronomers extracted the stars from the scanned plate of the Rosette and listed them in the catalogs. The new GSC-II catalog provides the colors, positions, and luminosities of nearly half a billion stars - over 20 times as many as the original GSC-I. The GSC-II contains information on stars as dim as the 19th magnitude.
About the colours
DSS-II image (top right) Blue (DSS-II): IIaJ emulsion plus GG395 filter Red (DSS-II): 103aE emulsion
About the data
Guide Star Catalog II (GSC-II) — replacing DSS-I and GSC-I — is a census of every star with luminosities down to the 19th magnitude. It is assembled from exposures of the sky taken at Blue (IIaJ emulsion + GG395 filter) and Red (IIIaF emulsion + RG610 filter) wavelengths.
Digitized Sky Survey (DSS) is the collection of raw sky survey scans.
The GSC-II catalog and DSS are available at http://archive.stsci.edu/mast.html .
DSS-I (top left), DSS-II (top right), GSC-I(bottom left), and GSC-II (bottom right)
