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ROSAT Archives
The ROSAT X-ray satellite has produced various archives containing raw data, fields and various source catalogues. GAVO provides access to the ROSAT All-Sky Survey (RASS) fields and a number of the catalogues. Ths fields are currently only available as links from a static download page. It is planned that in the near future the IVOA standard Simple Image Access Protocol (SIAP) will be supported. The source catalogues are made available through the IVOA standard Simple Cone Search (SCS) query. Apart from implementing this protocol as the prescribed HTTP GET request, we have also wrapped it with various standard Web interfaces and made it available as Web services.ROSAT All-Sky Survey Source Catalogues
The ROSAT All-Sky Survey (RASS) has produced a number of catalogues that GAVO publishes in a new manner. We provide services for querying the existing source catalogues as well as the new catalogue containing all the photons that were detected during this surevy mode.The ROSAT Bright and Faint Source Catalogues (BSC, FSC) can be obtained in file format from the ROSAT datacenter through anonymous FTP. GAVO provides access to these catalogue through standard services such as the SCS. For optimal flexible access GAVO has created a mirror of the catalogue, hosted on the GAVO machines in a PostgreSQL 7.3 database. We have enriched the orignal datasets with a HEALPix (http://www.eso.org/science/healpix/) index and unit-sphere Cartesian coodinates for optimal query performance. For a description of how this indexing is implemented in our system see elsewhere on this site.
ROSAT All-Sky Survey Photon Catalogue
We have created a new data product by publishing the RASS photon catalogue. So far the photons were available through the ROSAT Web site, but in a form that was not user friendly and did not allow simple queries like an SCS to be implemented. To provide access to this fundamental observable of the ROSAT mission, we have stored every photon observed in ROSAT's all-sky survey mode in a PostgreSQL relational database.For each single photon this new catalogue contains the arrival time, the sky position in equatorial and galactic coordinates, the isotropic positional error, the detector pulse-height channel, the corrected photon energy in keV, the detector X and Y pixel coordinates, and the total exposure time at the position of the photon.
This catalogue is published using the same SCS services as the other ROSAT source catalogues. The implementation of these services uses SQL queries. To tune these queries we have added to the original observables extra columns containing positional information in a form that allow faster execution of positional queries. The details of this procedure are explained elsewhere on this site.
The results of such a cone search can be obtained in any of the standard formats also supported for the source catalogues.
ROSAT All-Sky Survey Fields
The raw data obtained during the all-sky survey phase of the ROSAT mission have been used to create a set of pseudo images sampling the whole sky (see plot for a PDF diagram of the field distribution on the sky). For a complete description of the sampling strategy and for FTP access to the individual fields see the RASS page at MPE.GAVO has made a subset of the field products available for direct HTTP-based download from the following link. This subset consists of the images and backgrounds in the three different bands (broad (im1/bk1), hard(im2/bk2) and soft(im3/bk2)) and the exposure maps(mex). In the near future this archive will be expanded with more advanced discovery and retrieval functions after which we will also add the ROSAT pointed observations.
