The HST Cache ­ Metadata and Services
Felix Stoehr (fstoehr@eso.org), Jonas Haase , Daniel Durand , Alberto Micol & Marco Lombardi
11211( ST­ECF/ESO, NRC/HIA/CADC)
1n2Abstract

Web Interface

We present new developments of the HST Cache that are related to the greatly improved
metadata now available within the system. This work includes the interface to CAOM,
new SSAP and SIAP VO services, the integration of HLA images produced at CADC andSTScI into the HST Cache metadata tables as well as work on improved user interfaces.

Significant effort has been devoted to improving the main archive search interface. A
more concise user interface was achieved by using theme­grouped keywords, tooltip
help panels, and tooltip previews. The goal was to provide information to the user only
where needed and to reduce the need for scrolling the pages. Programmatic access tothe VOTables for the full archive is available[5]. The results of the queries are presented
using code from STScI (Rick White) repackaged by Tom McGlynn[6] and features
sortable and drag­droppable columns. Two choices for download are available: eitheranonymous direct download of the products over the web or the submission of a request
for data delivery on DVD, Blu­Ray or hard­disk.

New Metadata
The HST Cache is an automatic system to reprocess and recalibrate all HST datasets on
a 24/7 basis using the latest software and reference files. The products are then stored
on spinning disks for immediate download or delivery through VO protocols.
One of the goals of the HST Cache project was to improve both the quantity and qualityof metadata available for each dataset. This covers the physical description of the dataon the spatial, spectral and temporal axes but also includes derived metadata such as
the instrument footprint[1] or the data type (imaging, 1D spectroscopy, ...). The new
metadata are conceived for maximum scientific exploitation of the archive. Users willneed less knowledge of the HST internals.

We also developed a one­line command interface that can understand simple queries
such as "ACS F775W within 20 arcmin from NGC 220" or complex ones involving
keywords, operators, and parentheses. The interface, that also offers auto­completion,
will be integrated into theweb search page soon.

The system was also upgraded to be able to cope with non­refreshed data products. Asof now we have ingested the HLA WFPC2 images produced at CADC and STScI.

CAOMThe Common Archive Observation Model[2] is a generic data model developed at CADC
that captures quantities and relations of astrophysical observations. The metadata
collected in the HST Cache is fully CAOM compliant and software has been developed tofill the CAOM as just one more step of the HST Cache pipeline. The Virtual Observatory
is constructing an Observation Data Model that will be used for the Table AccessProtocol (ObsTAP). Early discussions on this model show that the the metadata in theHST Cache is a superset of the data required.

Previews
We compute previews for (nearly) all of the datasets in the HST Cache. After our own
custom normalisation is applied, we use Aladin[3] to create JPG image files. These files
are equipped with AVM/XMP[4] tags.

archive.eso.org/hst/science

VO Services
The HST Cache is now fully equipped with VO services (SSAP and SIAP) both for theclassical HST collection aswell as the imaging HLAproducts (WFPC2) and thespectral HLA products,
produced at ST­ECF. These
services return VOTables
with footprints whereavailable.

stecf.org/hst­vo/hst_sia
stecf.org/hst­vo/hst_ssa
stecf.org/hst­vo/hla_sia
stecf.org/hst­vo/hla_ssa

M101 in VirGO[7] using the HST/HLA SIAP services

Outlook
WFC3 preview of NGC 6302

STIS preview of Markarian 1383

Several improvements are foreseen in the near future: adding a file­upload query
capability, improving metadata quality and integrating the one­line command interface.

References[1] www.spacetelescope.org/about/further_information/newsletters/html/newsletter_45.html[2] P. Dowler, S. Gaudet, D. Durand, R. Redman, N. Hill, S. Goliath, ASP, ADASS XVI, 2007
[3] aladin.u­strasbg.fr[4] virtualastronomy.org/avm_metadata.php[5] archive.eso.org/wdb/html/wdb.html[6] ivoa.net/internal/IVOA/InterOpOct2008Applications/XSLT­JavaScript.pdf[7] archive.eso.org/cms/virgo
ADASS 2009, Sapporo