NED Frequently Asked Questions -- Specific NED search and retrieval

Search and Retrieval

  • Q.: Is there any way to retrieve all of the objects mentioned in a given paper?

    A.: Any of the search options in the "Literature" menu will return a list of papers. Click on the reference code for the paper in question. This will open a new screen with the title and abstract text (if available), and a link to Retrieve NNN NED Objects ("NNN" is the number of NED objects included in the reference). This will give you a list of all NED objects mentioned in the selected paper.

  • Q.: How can I find all of the papers written by a given author?

    A.: If the author is among the first 20 or so listed for an extragalactic paper, select the Author Name option in the "Literature" menu. This option will open the Search for Abstracts by Author Name screen. Submit the query using the author's last name as input parameter.

    Only the first 160 ASCII characters of the author list and article title can be searched or displayed on the results page. Long author lists and long titles are not completely displayed, and author searches will not return papers when the name is not included in the first 160 characters of the author list. Note, however, that NED's abstracts include the full title and author list, so you may use a Text Search to find authors in long author lists.

  • Q.: How can I find the QSO 2251+113 without doing a position search?

    A.: You may use the IAU Format option from the "Objects" menu. This option will open the Search for Object for Given IAU Name screen. You may then submit the query using an IAU-style name as the input parameter.

  • Q.: In the Advanced All-Sky Search page, is it possible to add a filter for the V magnitude of the target?

    A.: Yes. In the "Photometric Constraints" section of the page, you may choose many different passbands, including Johnson V. These constraints use NED's "Photometry Data Frames". If an object does not yet have photometry available through the Photometry option in the "Data" menu on the home page, it will not be included in a search depending on photometric constraints.

  • Q.: Is there any way to retrieve data concerning velocity dispersions within galaxies, so I can get, for example, the velocity distributions of stars as a function of galaxy morphology?

    A.: NED does not yet list velocity dispersions for its galaxies. However, you may use the Text Search option to scan NED's titles and abstracts, and LEVEL 5, for papers that contain velocity dispersions.

  • Q.: Is there a way that I can get measured fluxes for my objects using NED?

    A.: For single objects, you may search NED's photometric database using the Photometry option in the "Data" menu on the home page.

  • Q.: Is there a way to perform a NED search for objects based only on spectroscopic redshifts, and not on redshifts from colors or magnitudes?

    A.: We adopt spectroscopic redshifts whenever they are available. Sometimes, however, only a photometric redshift is available for an object, or the source of a redshift is not clearly stated in the published paper. In those cases, we flag the redshifts if we know that they are not from spectroscopy. It is still possible, however, for photometric redshifts to slip in unflagged. In cases of doubt, we urge you to go back to the published paper to check the source of the redshifts.

  • Q.: When I use the search for References from the "Literature" menu on NED's home page, why do I sometimes get results referring to papers that are not related to my intended object?

    A.: The default for this type of search is to return all "related" objects, that is, all objects with the same root name. For example, if you search for NGC 1614, you will also get references for NGC 1614A, NGC 1614:SN 1996D, etc.

    If you want just the references for a specific object, set the Related object name search? option to No.

  • Q.: Why does a search for M51 return the wrong position?

    A.: "M51" refers to the pair of galaxies, NGC 5194 and NGC 5195, not just to the larger spiral NGC 5194. The position that NED adopts for M51 is therefore the mean position of the two galaxies.

    We treat other pairs, triplets, groups, and clusters listed in NED the same way: we adopt mean positions for all the galaxies rather than for just the brightest or for the most centrally-located.

    Many pairs and triplets in NED have position errors that -- rather than representing the 95% confidence ellipse -- represent half the separation of the objects. The "error ellipse" therefore encloses both/all positions for the member galaxies.