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Image and Catalog Archive Introduction

Catalogue and Image Database Introduction

(Introduction | Guide | Service Notes | Interactive Search | VO Cone Search)

This facility allows you to extract catalogue data and plot up finder charts. In addition, we have available the raw images from scanning the major photographic surveys. You can overplot the catalogue data onto the images, as well as overplot your own additional markers.

In normal operation, users input their query through a web interface, and all returned information shows up in a new web page.

If you find this useful, please let us know, and if you have problems, please let us know.

Acknowledgment: If you have found the USNO Archive helpful in your work, the following acknowledgment would be appreciated:

   This research has made use of the USNO Image and Catalogue Archive
   operated by the United States Naval Observatory, Flagstaff Station

Server Status (as of 17 Dec 2008 4pm MST):

  • Catalogue Extraction: Functional
  • Finding Charts: Functional
  • Image Server: Functional

Service Notes: Recent changes or items related to this service.

Server Overview

This Image and Catalog archive service provides tabular data and image data about objects and regions of the sky.  The service began in the late 1990s as a simple finder chart generating program, and evolved to include USNO star catalogs and the digitized images of the sky that they were derived from.  

The first catalog used was the USNO-A2.0 catalog.  This was constructed from objects detected in the scans of photographic Schmidt plates taken at several observatories around the globe.  These photographs were digitized using the special purpose Precision Measuring Machine (PMM) at USNO Flagstaff, and then object catalogs were derived from the objects detected in the images.  The original plan was to distribute object catalogs only.  However, computer hardware evolved fast enough to make it practical to provide direct access to the original images as well.  In January 2000, we began serving out the image data in the PMM archive.

When you request data, you have the option of getting catalogue data and/or retrieving the pixel or image data for the PMM images that cover the field of your request. All of the surveys listed in the table below have been scanned, and the pixels are being loaded onto RAID disk arrays. Image retrieval will NOT be instantaneous, but you should receive your data within 30 seconds to a minute (it will depend upon the load on the system).  You have the option of being notified by e-mail when your request is finished. To understand this service little better, please see the discussion of the PMM.


  • Whole sky coverage.
  • The Schmidt plates have been scanned at a resolution of 0.9 arcsec/pixel.
  • The data are digitized at 8 bits in transmission by the Precision Measuring Machine.
  • Data from multiple epochs, and in multiple colors are available. For example, for a field that was covered by both the POSS-I and POSS-II surveys, we make available both sets of scans, including the O and E plates from POSS-I and the J, F and N plates from POSS-II. Additionally, if the particular field is in an overlap region between two plates, you will get separate images from each plate.
  • The Plate Logs for the surveys are now on-line through the main server help file.

Particular Limitations:

  • Any requests for pixel images larger than 40 arcmin square will silently be reduced to 40 arcmin square, though the finder chart will be as requested (up to 2 degrees square).
  • Images near the poles are not yet handled properly. You have been warned.
  • I am still in the process of validating the pixel data. In essence this means that I have not yet checked that all the plates are what we claim. There are over 12,000, so this will take a while. If you notice something that seems strange, please let me know.

Additional caveats regarding the pixel service: this is still somewhat beta test software right now, and I am only one person with other responsibilities. I am working on this as fast as I can. I am happy to hear your suggestions for ways to improve this service, and will do what I can to incorporate them. If you find a bug, or something that seems wrong, PLEASE PLEASE let me know.

As of 04 January 2001, we have available on-line images of the following surveys (and more will be available shortly):

            Survey                               Photographic
  Name      Description                          Colors        Fields
  ----      -----------                          ------        ------
  POSS-I  - 1st epoch Palomar Obs. Sky Survey    103aO         All (1-937)
            including the WhiteOak Extension     103aE         All (1-1037)

  POSS-II - 2nd epoch Palomar Obs. Sky Survey    IIIaJ         All (2 - 898)
                                                 IIIaF         All (2 - 898)
                                                 IV-N          All that were taken (2 - 898, less 24 fields)

  SRC-J   - SRC  Southern J Survey               IIIaJ         All (1-606)

  SERC-EJ - SERC Southern Equatorial J Survey    IIIaJ         All (607-894)

  ESO-R   - ESO  Southern R Survey               IIIaF         All (1-606)

  SERC-ER - SERC Southern Equatorial R Survey    IIIaF         All (607-894)

  AAO-R   - Anglo-Australian Obs. Southern R     IIIaF         All (1-606)

        COMING SOON:
  LUYTEN  - Luyten's 2nd Epoch Northern Plates                 All scanned

  PIMWA   - Palomar Infra-Red Milky Way Atlas    IV-N          All scanned (1-80)
                                                 098-0         All scanned (1-80)

  AAO-N   - Anglo-Australian Obs. Southern N     IV-N          Scanned 816 of 894

  AAO-sR  - Southern Milky Way Atlas             IIIaF         All scanned (1-163)
  SPM     - The Yale Southern Proper Motion Survey             All scanned

Last updated: 2008Dec13 by sel