VizieR Catalog Cross-correlation and VOPlot
The new VizieR Catalog Search and Cross-correlation tool allows MAST
users to search the entire set of 4,000 VizieR catalogs and cross
correlate the results with any MAST mission. This web-based search
tool accesses one of the several VizieR catalog servers (e.g. at CfA)
as a web service and retrieves the search results in a
machine-readable VOTable XML format.
Users can use the VizieR search form
(http://archive.stsci.edu/vizier.php)
to search for a particular
catalog using catalog name, mission name, target name, wavelength
range, author name or keywords (as in the VizieR search based at the
Centre de Donnees astronomiques de Strasbourg (CDS)). A catalog of
interest can be selected from the returned list. Users can then search
within the catalog based on internal object parameters, and may
cross-correlate the full catalog or the refined list of objects with
any selected MAST mission. This provides a way for users to
effectively search MAST by object class, where the object class is
specified as a parameter in an object catalog (e.g., spectral type in
the Hipparcos catalog). In the cross correlation mode, the search tool
retrieves ra and dec values for each found VizieR catalog entry and
performs a cone search using a specified search radius. Because this
process is repeated for each VizieR catalog entry and each selected
MAST mission, execution times can become rather long for large
requests.
Users may also upload their own object catalog and cross-correlate it
with MAST holdings (http://archive.stsci.edu/xcorr.php?form=fuf).
Another recent improvement is that the WFPC2 Associations (see
http://archive.stsci.edu/hst/wfpc2/)
can now be accessed by the cross
correlation search. Output from the cross-correlation search may now
be requested in several different formats (including VOTable).
Another new feature is the ability to plot search results from any
MAST mission or the VizieR catalog search with a new JAVA-based
graphical display tool called VOPLot
(http://vo.iucaa.ernet.in/~voi/voplot.htm).
This new tool allows users to plot the search results from any numerical field returned in
a search as a histogram, or as a scatter plot against any other field,
as well as to display statistics on the results. VOPlot was developed
as a part of the Virtual Observatory - India initiative by Persistent
Systems (PSPL) and the Inter-University Centre for Astronomy and
Astrophysics (IUCAA), in collaboration with CDS, and the European AVO
project.
As a simple example, after using the VizieR search and selecting the Abell Catalog
of Rich Clusters of Galaxies, voplot was used to plot magnitude vs redshift.
New additions to the Pointings Search Tool
The MAST `pointings' search (http://archive.stsci.edu/cgi-bin/point)
allows users to determine which regions of the sky HST has observed,
and to do sophisticated searches based on the number of observations,
number of filters, time between observations, etc., for a given
region. In addition to WFPC2, STIS (images), FOC, and NICMOS, the
Advanced Camera for Surveys (ACS) and WFPC2 associations have now been
added to the pointings database. Please see the webpage
(http://archive.stsci.edu/cgi-bin/point) for details on how the
pointings are defined for each different instrument.
GALEX Early Release Observations now available at MAST
By Myron Smith