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How to Retrieve Compressed FITS Images Images in NEDNED includes images from across the electromagnetic spectrum of extragalactic objects of all types. Many of the images are for extended sources from the final release of the The Two Micron All-Sky Survey. Digitized Sky Survey images exist for all objects in NED and are centered on the NED positions. If errors exist in the positions, the objects may not be centered in the image, or may even be outside the boundaries of the image. Should you find such an error, please send us a message. NED provides images "on-the-fly" from the DSS. After your image search has been completed, you may resize DSS images if they are too small or too large. Please note that the Aladin service does not work for some browsers. See this FAQ regarding interoperability with the Chrome browser.
Images Searches by NameNED's name interpreter recognizes most of the well-known prefixed names used in the literature (e.g. NGC 224, IRAS F00400+4059, 1ES 0039+409). NED Standard Names has more information on NED's naming conventions. Data EntryType the name of the object you wish to search for in the "Object name:" box. The NED interface allows substantial freedom in formats and conventions for names, so type the name in any format you wish. When you submit your search, NED's name interpreter will attempt to translate your input into a name that NED recognizes. If it cannot interpret the name you typed, a page will appear with a message explaining the most likely problem with your input. These usually fall into three categories, all explained in the message. In all three cases, click your browser's "Back" button to go back to the search page, and enter another object name. (1) If the name you entered has an acceptable catalog name, but the object number within the catalog is not within the range of numbers for that catalog, the page will tell you this. An example is "M111"; there are only 110 entries in the Messier catalog. (2) If the catalog name itself is ambiguous, the page will list the acceptable possibilities. An example is "A123"; this could be "Abell 123", "Arakelian 123", "Arp 123", "Asiago1 023", or "[RC1] A1203". (3) If the name interpreter does not recognize the catalog, the page will sometimes suggest alternative catalogs, sometimes not. In either case, click the "Back" button and try another name. After you have typed in the name of your object, click the "Submit Query" button to initiate the image search. ResultsWhen a search has completed successfully, the interface opens a new page with a summary listing of the available images for the object. Each listing is accompanied by a small "postage stamp" representation. Click on that to have your browser open a new window showing the image at full resolution (this assumes that your browser supports viewing of GIF files, either internally, or via a helper application). FITS formatted versions of the images may be downloaded by clicking on "Retrieve" in the "FITS File" column of the table. You may also view the "FITS Header", and use Aladin to manipulate the image and overlay catalogs on it. Other information given includes the waveband (in astronomical jargon) used for the image, the image dimensions in arcminutes, the image resolution in arcseconds, the telescope used to obtain the image, and the reference to a published description of the image. You may also change the image size for DSS images. Digitized Sky Survey images in NED appear courtesy of AURA/STScI. Images Searches by CoordinatesThrough a collaboration with IRSA and the VAO, FITS images archived in NED can now be queried by celestial coordinates and areal coverage. Clicking on the link will take you to a documented page where you may search for images by coordinate or by areal coverage on the sky via a map. Retrieving Compressed FITS ImagesTo save disk space and transmission time, the FITS (Flexible Image Transport System) images in NED are compressed using "gzip", a standard UNIX compression utility. We have found that some older versions of Netscape Navigator on UNIX systems remove the ".gz" suffix from these compressed image files during downloading. This will leave a compressed FITS file with a truncated name like "[filename].FITS" instead of the proper "[filename].FITS.gz". If you encounter this problem, there are several ways to restore the missing suffix: (A) Exit Navigator, go to the directory where the image was saved, and add the ".gz" suffix to the filename. The file can then be uncompressed using "gunzip" as usual.
(B) Change your Version 3 and earlier Navigator setup as follows:
1) Click: "Options"
"General Preferences"
"Helpers"
2) If there is not an entry in the table headed "MIME
Configuration Files" reading something like "image/x-fits",
create one:
a) click "New",
b) type in the "Description" box: FITS Images
in the "Type" box: image/x-fits
in the "Suffix" box: fits fit fts FITS FIT
c) in the large "Handle By" box, choose the
"Unknown: PromptUser" radio button
d) click "OK".
3) If there is an entry in the table reading something like
"image/x-fits", make sure it matches the set up outlined
in Step 2 above by clicking on the entry to highlight it,
then click "Edit", and check the table entries. Click
"OK" or "Cancel" to close the Edit window.
4) Click "OK" to close the "Options" window.
5) Click "Options" again, and finally
6) If your browser has a "Save Options" menu entry, click it,
then click "OK" when Navigator says "Options have been saved."
(C) Exit Navigator, go to the directory where your Navigator setup
files are stored (usually your home directory) and add the following
line to the ".mime.types" file: image/x-fits fit fits fts FIT FITS While any of these options should correct the problem, the second and third are "permanent" fixes.
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NED Standard NamesObject names are separated into catalog identifier and member identifier. The name interpreter checks the catalog identifier to certify that it points uniquely to a catalog recognized by the database. The name interpreter then checks the member identifier to certify that it corresponds to the conventions of the catalog identified (e.g. is it a sequential number, or a combination of numbers and letters, etc?), and that it does not exceed certain limits (e.g. the number of objects in catalog). The left hand column of the following table contains examples of input names recognized by the interpreter. The right hand column shows the NED standard formats.
Names with square bracket prefixes (e.g. "[HB89]" and "[WB92]") usually come from papers published in journals, while those names with unbracketed prefixes (e.g. "NGC" and "IRAS") usually come from separately published catalogs. There are exceptions, however; examples include "[RC2]" and "87GB". Some names have combination prefixes (e.g. "87GB[BWE91]" and "ABELL 400:[D80]"). Objects in multiple systems without existing unique names are formed by the name of the system itself followed by "NEDnn", where "nn" is a decimal number starting with "01" (example: "ARP 294 NED01" and "ARP 294 NED02"). Similarly, objects found only in catalog notes are given names beginning with the name of the cataloged object followed by "NOTESnn" (example: "UGC 01562 NOTES01" and "UGC 01562 NOTES02"). Sources named in non-optical catalogs or lists, which are later found to be coincident with galaxies but which are not renamed, have "ID" appended to their original names (example: "IRAS 04356+3412 ID"). In this case, the Preferred Object Type is also changed to "Galaxy".
2MASS ImagesHere is a brief description of 2MASS, the extended source database, and the extended source images, courtesy of Tom Jarrett and the 2MASS Team.
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