Bigger, Better Catalog Unveils Half a Billion Celestial Objects
About This Image
Caption
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.
Credits
NASA, the DSS-II and GSC-II Consortia (with images from the 'Palomar Observatory-STScI Digital Sky Survey of the northern sky, based on scans of the Second Palomar Sky Survey are copyright © 1993-1999 by the California Institute of Technology)Keywords
| About The Object | |
|---|---|
| Object Name | Rosette Nebula; NGC 2237 |
| Object Description | Emission nebula |
| R.A. Position | 06h 31m 40.0s |
| Dec. Position | 04° 57' 47.99" |
| Constellation | Monoceros |
| Distance | 920 pc (5500 light-years) |
| Dimensions | This image is 30 arcminutes square. The entire nebula is roughly 130 light-years across. |
| About The Data | |
| Data Description | 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) |
| Instrument | Glass photographic plates taken at the Schmidt telescope at the California Institute of Technology's Palomar Observatory; scanned for the Digitized Sky Survey Projects. |
| Exposure Dates | April 4, 1953, Exposure Time: 45 minutes (DSS-I), March 29, 1998, Exposure Time: 50 minutes (DSS-II red), January 18, 1997, Exposure Time: 30 minutes (DSS-II blue) |
| Filters | DSS-I (top left): 103aE emulsion DSS-II (top right): IIIaF emulsion + RG610 filter (red), and IIaJ emulsion + GG395 filter (blue) |
| About The Image | |
| Color Info | DSS-II image (top right) Blue (DSS-II): IIaJ emulsion plus GG395 filter Red (DSS-II): 103aE emulsion |
| About The Object | |
|---|---|
| Object Name | A name or catalog number that astronomers use to identify an astronomical object. |
| Object Description | The type of astronomical object. |
| R.A. Position | Right ascension – analogous to longitude – is one component of an object's position. |
| Dec. Position | Declination – analogous to latitude – is one component of an object's position. |
| Constellation | One of 88 recognized regions of the celestial sphere in which the object appears. |
| Distance | The physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs. |
| Dimensions | The physical size of the object or the apparent angle it subtends on the sky. |
| About The Data | |
| Data Description |
|
| Instrument | The science instrument used to produce the data. |
| Exposure Dates | The date(s) that the telescope made its observations and the total exposure time. |
| Filters | The camera filters that were used in the science observations. |
| About The Image | |
| Image Credit | The primary individuals and institutions responsible for the content. |
| Publication Date | The date and time the release content became public. |
| Color Info | A brief description of the methods used to convert telescope data into the color image being presented. |
| Orientation | The rotation of the image on the sky with respect to the north pole of the celestial sphere. |