On the right is part of the first image taken with NASA's Hubble Space Telescope's (HST) Wide Field/Planetary Camera. It is shown with a ground-based picture from Las Campanas, Chile, Observatory of the same region of the sky. The Las Campanas picture was taken with a 100-inch telescope and its typical of high quality pictures obtained from the ground. All objects seen are stars within the Milky Way galaxy.
The images of the stars in the ground-based picture are fuzzy and in some cases are overlapping, because of smearing by the Earth's atmosphere. The same stars in the HST frame are sharper and well resolved, as shown by the double star at the top of the image. By avoiding the Earth's atmosphere, the HST gives sharper images and better resolution. In this early engineering picture, the HST images are roughly 50 percent sharper than the ground-based images.
Technical Details: The first image taken with the HST is intended to assist in focusing the telescope. The region observed is centered on the 8.2 magnitude star HD96755 in the open cluster NGC 3532, in the southern constellation Carina. Identical small subsections of the HST and ground-based image pictures were chosen to highlight the difference in resolution. The field shown is approximately 11 x 14 arcseconds in size and does not contain HD96755.
The ground-based image was taken by Dr. Eric Persson at the Las Campanas Observatory in Chile, using the 100-inch DuPont reflector. We thank the Observatories of the Carnegie Institution of Washington for permission to use this picture. The three-second integration was made with a single Texas Instruments charge-coupled device (CCD) of the type used on HST. A broadband visual filter equivalent to the HST filter was used. The small field shown was extracted from an observed area covering 130 arcseconds on a side.
The HST image is a thirty-second exposure taken by the Wide Field/Planetary Camera. The picture shown was extracted from the area observed by the WF-3 OCD using the F555W broadband filter. The measured width of star profiles (FWFM) gives a good indication of the angular resolution. For the Las Campanas picture, the FWFM is 1.1 arcseconds, typical of exposures from the best ground observations. The FWFM of the stars in the HST picture is about 0.8 arcseconds, which points out the remarkable increase in resolution of the HST even at this early stage of the focusing task.
Credits
NASA, ESA, and STScI;Ground Image: E. Persson (Las Campanas Observatory, Chile)/Observatories of the Carnegie Institution of Washington
| About The Object | |
|---|---|
| Object Name | NGC 3532, HD96755 |
| R.A. Position | 11h 5m 33.0s |
| Dec. Position | -58° 43' 48.0" |
| 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. |
