Peculiarities and shortcomings

You may notice the following peculiarities and shortcomings with selections extracted from remote catalogues.

1. The selection does not contain all the columns which you expected to be present in the catalogue. Sometimes the remote versions of catalogues contain only some of the columns present in the full catalogue (as published, or as available from the CDS). Obviously, the decision about which columns to include in the on-line catalogue rests entirely with the institution which is providing it and is entirely outwith the control of Starlink. The catalogues available from Leicester usually seem to contain most of the columns available in the corresponding originals.

2. If the remote catalogue is a `data archive' then usually the returned selection will contain at least one `odd' column comprising a list of URLs (see Section , above). This column is intended to to give access to an image or other `bulk' data for each object. CURSA contains no facilities to process these columns and access the bulk data.

3. The protocol used to return the catalogue of selected objects is rather deficient in metadata (see Section ). In particular, the only information returned for each column is its name; the units, data type and external format are not specified. The Right Ascension and Declination are exceptions in that they are returned with known units.