The Astrogeo VLBI FITS image database

 

The Astrogeo VLBI FITS image database contains 122,741 brightness distributions of 20262 compact radio sources, mainly active galaxy nuclea (AGN), generated by analyzing very long baseline interferometry (VLBI ) surveys — dedicated radioastronomy observations of large lists of radio sources on networks of radio telescopes spread at distances of thousand kilometers. The primary database contents is not pictures, but brightness distribution in a digital form, specifically in FITS format, and calibrated visibility data, which makes it possible to use this database for scientific work. Derived quantities, such as visualization of images and estimates of the correlated flux density are also available.
The images were contributed by courtesy of many authors.

The database can be searched using one of these methods:

In addition to brightness distribution, estimates of the correlated flux density from VLBI experiments for a number of sources are available. Currently, they are not included in the database and are not searched.

The contents of the database can also accessible as

Each image is represented with six files:

  1. the calibrated and edited set of visibility (i.e. cross-correlation function) points in FITS format;

  2. the set of clean components that models the source brightness distribution in FITS format;

  3. the picture of the source image in Postscript format;

  4. the plot of dependence of the correlated flux density on the baseline length in Postscript format;

  5. the plot of the uv-coverage;

  6. the table with the total correlated flux density; the median correlated flux density at baseline lengths less than 900 km, the median correlated density at baseline lengths greater than 5000 km. For many sources images at more than one epoch, at more than one frequency bands are available.

The images in FITS format submitted by authors were pre-processed to a standardized form. The process of standardization involved: a) assignment of new names to each file; b) adding 14 new keywords in the FITS headers; c) removal of lengthy history records; d) generating the pictures and plots in Postscript format; e) generating the table with estimates of the correlated flux density.

Authors who contributed images (in alphabetic order)

The authors provided written consent to display their results at this web resource.

How to submit images

If you have images that you would like to be incorporated in the database, you are welcome to submit them. At minimum, two files per source should be available for submission: 1) a map in FITS format; 2) calibrated visibilities in FITS format. Images are grouped in campaigns that usually correspond to individual observing projects. Each submission for a given campaign should be accompanied with an ascii file with meta-data and an cross-reference table between sources names embedded in the FITS-file header and 10-character long IAU J2000 source names. Just send the link to the tar-files with data and the metadata to the database maintainer, Leonid Petrov.

Usage policy

The contents of this database is protected by the copyright law. All rights to images belong to image authors. You can download and use the contents of this database for your personal work. If you would like to reproduce images from this database in any sort of publications, please ask permission of the image author. You can find image author name in the FITS header. If you use images in your publication, you are encouraged to acknowledge The Astrogeo VLBI FITS image database in your publication but this acknowledgment is not sufficient: you are required to cite original publications. You are encouraged to contact with the authors of images who will instruct you how to cite properly his or her contribution. You can put a reference to this database or any file from this database in any electronic or printed document. You are not allowed to make available at your web or ftp site or to distribute by other means original and derived products, including but not limited postscript or gif pictures of any source found on this web resource, without written permission from the image authors.

Acknowledgments

The use of Very Long Baseline Array (VLBA) data is acknowledged. VLBA is operated by the National Radio Astronomy Observatory, which is a facility of the National Science Foundation, and operated under cooperative agreement by Associated Universities, Inc. The use of the VLBA under the US Naval Observatory's time allocation is acknowledged. This work supports USNO's ongoing research into the celestial reference frame and geodesy. These data were retrieved from the VLBA public archive.

The use of Long Baseline Array (LBA) data is acknowledged. The LBA is a part of the Australia Telescope National Facility which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.

The use of European VLBI Network (EVN) data is acknowledged. The European VLBI Network is a joint facility of independent European, African, Asian, and North American radio astronomy institutes.

The use of Korean and VLBI Exploration for Astrometry VLBI Networks (KVN and KaVa) data The KVN and VERA are operated by the the Korea Astronomy and Space Science Institute and the National Astronomical Observatory of Japan.

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