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The International Variable Star Index (VSX)
A New Central Storehouse for Variable Star Data Now available at the AAVSO web site is a new utility: The International Variable Star Index (VSX). This program serves two distinct functions: an easy portal to access information about variable stars that is far more extensive than the GCVS; and a method of uploading variable star information. The information access includes all known cross references, basic parameters such as period and variability type, and finding charts. The upload feature permits information update on known variables (such as a new period) as well as entering new variable stars into the system. Introduction The International Variable Star Index (VSX) is a comprehensive relational database of known and suspected variable stars gathered from a variety of respected published sources and made available through a powerful Web interface which provides the tools for visitors to search and view the data, registered users to revise and add to the data, and authorized moderators to vet the data, creating a consistently reliable "living" catalog of the most accurate and up-to-date information available on these objects. Data on variable stars are constantly changing. New and ongoing surveys are locating new variable stars every day. Corrections to errors in the data are always coming in. But all of this work to refine what we know about these stars is happening at different times and in different places. The mission of VSX is to bring all of that new information together in a single data repository, make it accessible to the public via a simple web interface, and provide the tools necessary for the controlled and secure revising of the data. VSX was conceived and created by amateur astronomer Christopher Watson in response to the specific desires of the members of the Chart Team and the Comparison Star Database Working Group of the American Association of Variable Star Observers (AAVSO), as well as the broader perceived need for a globally-accessible central "clearing-house" for all up-to-the-minute information on variable stars, both established and suspected. The VSX web site was designed to be the on-line medium by which variable star data are made available to the public, and through which the data are maintained, revised, and commented upon. This database literally comes alive with input from the world of registered contributors.
In order to keep VSX up to date and populated with the latest corrected findings, authorized moderators constantly review and revise the metadata, always citing sources for any new details, and fully documenting the rationales behind any additions or changes. By maintaining a strict version control on all records, the history of the gathered knowledge on each variable star can be traced, validated, and followed up on by those who rely on this information to be accurate and true. Moderators use a secure login to access on-line tools for working with the database. All modifications or additions submitted are queued in a staging table, and peer reviewed. When the submission is cleared, it is promoted to the live database, and all particulars about the change/addition are logged with the revision. The modification is assigned a revision number, which can be referenced at any time to retrieve any version of the data for any particular star. Promoted revisions later determined to be erroneous for any reason, can be rolled back. The data moderators reserve the right at all times to reject a submission for modification or new variable star. Web-based tools for querying VSX in various ways are available to the public. The public data returned in a query transaction contains all the accumulated data for the most recent revision level for each star in the recordset, including details of all modifications made to the data, and references to support those changes. Previous revisions may also be viewed. The public interface does not include the means for modifying the data in any way, but a form for sending suggestions for modification to the Project Administrator is made available. The Database The VSX database was initially populated with the entire Combined General Catalog of Variable Stars (GCVS 4.2, 2004 Ed.). This included the main lists from Vol. I-III, the NSV catalog of suspected variable stars and its supplements, all cross-identifications from Vol. IV, and all references and remarks from all volumes. Differences between the published 2004 Edition of the GCVS and the "living" version available from the Sternberg file servers were then culled and integrated. On top of this base data set were added the published catalogs of red variables from the Northern Sky Variability Survey (NSVS), the detected variables from the 3rd All Sky Automated Survey (ASAS-3), all new variables reported in the various volumes of the Information Bulletin on Variable Stars (IBVS), the Miras and eclipsing binaries found and published from Phase 2 data of the Optical Gravitational Lensing Experiment (OGLE-II), the bright contact and near-contact binaries extracted from data of the Robotic Optical Transient Search Experiment (ROTSE-I), and the new variable stars discovered from offered images to the MISAO Project. All together, this became the Base 1.0 Version of the VSX object table. Internal relations between the object, reference, remark, and cross-identification tables were established programmatically using the various source data. New, unpublished cross-identifications between the various catalogs were generated through custom cone search algorithms, and then verified. The Web Site The International Variable Star Index web site may be accessed at: The VSX Web site and database is maintained by volunteers and hosted on systems maintained by AAVSO staff at its headquarters in Cambridge, Massachusetts, USA. Paper on VSX A paper on The International Variable Star Index (VSX) was submitted and accepted for presentation at The 25th annual Symposium on Telescope Science (SAS). Principal Architect Christopher Watson will speak at SAS on VSX. Click the link below to view the paper. AAVSO 95th Spring Meeting Presentation A PowerPoint presentation on VSX was given by Principal Architect Christopher Watson at the 95th Spring Meeting of the AAVSO in Rockford, Illinois on Saturday, May 6, 2006. Click the link below to view that presentation. Acknowledgments The developer would like to thank the American Association of Variable Star Observers, and in particular, Arne Henden, Aaron Price and Kate Davis, for their unwavering support and assistance in bringing VSX to life. The following individuals volunteered many hours of their time helping to make VSX as complete, accurate, and easy to use as possible, and we thank them for their expertise and their generosity: James Bedient |
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