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),
and 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
general public, and through which the data are maintained, revised, and commented upon. This database
literally comes alive with the input from the world of registered contributors.
In order to keep VSX up to date and populated with the latest corrected findings, registered
and approved individuals 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.
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), and the bright contact binaries
extracted from data of the Robotic Optical Transient Search Experiment (ROTSE-I). 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.
Modifying the Database
Moderators use a secure log-in to access on-line tools for working with the database. All modifications
or additions submitted are queued in a staging bin, 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 and/or Project Administrator at all
times reserve the right to reject a submission for modification or new variable star, and may, at their
discretion, revise any submission made to VSX for clarity, consistency, or convention.
Querying the Database
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.