11 inches), and add a copyright notice at the
bottom of each page.
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PS reprint
A. Accomazzi, C. S. Grant, G. Eichhorn, M. J. Kurtz, S. S. Murray
Smithsonian Astrophysical Observatory, 60 Garden Street,
Cambridge, MA 02138
The documents may be accessed by either requesting an article by specifying the journal name, volume and page, by requesting a table of contents of a particular journal, or directly from the list of references generated by a query to the ADS abstract service.
For each available article we provide the options of browsing the pages on-line, retrieving either a PostScript or a PCL document suitable for printing, requesting the document to be faxed anywhere in the US, or downloading the scanned images to a local computer.
The NASA Astrophysics Data System (ADS) created the Article Service as an enhancement to its on-line bibliographic resources---namely the Abstract Service---in order to provide astronomers and librarians with unrestricted access to full-text articles of the major astronomical journals.
Thanks to a fruitful collaboration with the American Astronomical Society (AAS), in 1994 we received permission to scan and place on-line the articles published in the Astrophysical Journal Letters from 1975 up to date. The positive feedback from our users has prompted us to increase the scope and coverage of the project, and we are now scanning and making available on-line the Astrophysical Journal itself. At the date of this writing, there are five years of the Astrophysical Journal available on-line, from January 1990 to December 1994.
The ADS project has also obtained permission to scan the following journals from their respective publishers:
We are currently negotiating with the major European and Japanese Journals to obtain permission to carry their articles.
In the rest of this paper we will describe the process used to generate the on-line articles, the interfaces allowing users to search and browse the full-text articles, and the different options available for creating hardcopies of the papers on-line.
The documents provided on-line by the ADS Article Service are generated by scanning the journals at high resolution (all the journals except for the ApJ Letters are being scanned at 600dpi) using a high speed scanner and generating a 1 bit/pixel monochrome image for each page.
The files created are then automatically processed in order to
de-skew and center the text in each page, resize images to a standard US
Letter size (8.5 11 inches), and add a copyright notice at the
bottom of each page.
For each original scanned page, three separate image files of different resolutions are generated and stored on disk. The image formats and compression used were chosen based on the available compression algorithms and browser capabilities. The availability of different resolutions allows users the flexibility of downloading either high or medium quality documents.
The available file formats are:
All the documents available through the World Wide Web interface to the Article Service are generated from this set of input files. The file formats and encoding schemes adopted provide the best compression for the data at hand, minimizing data storage needs.
On-line access to the full-text articles is provided by the ADS World Wide Web (WWW) services, allowing unrestricted access to our system from any Internet site. For each journal article available on-line we provide a bibliographic entry in text form, an inlined GIF image to allow on-line browsing of the full text document, and several retrieval options to allow hardcopying of the document.
To facilitate searching and browsing through our article database, a number of different HTML user-interfaces have been designed:
Institutions and individuals that require customized access to articles or bibliographies in our on-line services can do so by simply creating forms that access the ADS article service interface programs with the proper input parameters. A discussion of how this can be accomplished is given in Eichhorn et al. (1996).
During the past several months we have expanded the data retrieval options for the benefit of our users, adding more file formats to the menu of available data types for each article page. For each of the available formats, data are compressed using the most efficient and compact encoding supported by the file format at hand, in order to minimize document transfer time over the network.
Currently users may select among the following formats when requesting a document for hardcopy:
Simple local customization of the browser's configuration files allows users to either display the retrieved articles, save them to a file, or print them as they are downloaded from the ADS article server. We plan to include more asynchronous retrieval options in the near future in order to provide a better service to users with low-bandwidth access to our system, including e-mail delivery of articles.
The success of the ADS abstract and article services indicates that astronomers and librarians at scientific institutions are eager to take advantage of the latest technology in order to increase their productivity and improve the quality of their work.
The evolution of the Internet and the World Wide Web and the explosion of astronomical services on the WWW has enabled the ADS project to provide access to its data holdings in an open and uniform environment, allowing hyperlinking of its resources with other on-line resources. An example of such interaction is the cross-referencing of the AAS bibliographical resources (Boyce, Dalterio & Biemesderfer 1996) and the ADS services.
The ADS project intends to increase its role in the astronomical and scientific community by expanding the article service to become a digital library for astronomy. To this end, we would like to include all the major astronomical journals while continuing to provide a sophisticated environment for searching the astronomical literature.
We are grateful to the American Astronomical Society for allowing the creation of the article service. This work is funded by the NASA Astrophysics Program under grant NCCW-0024.
Eichhorn, G., Accomazzi, A., Grant, C. S., Kurtz, M. J., & Murray, S. S. 1996, this volume
1PostScript is a trademark of Adobe Systems Incorporated