Normal use of votcopy is pretty straightforward.
We give here a couple of examples of its input and output.
Here is an example VOTable document, cat.vot:
<VOTABLE> <RESOURCE> <TABLE name="Authors"> <FIELD name="AuthorName" datatype="char" arraysize="*"/> <DATA> <TABLEDATA> <TR><TD>Charles Messier</TD></TR> <TR><TD>Mark Taylor</TD></TR> </TABLEDATA> </DATA> </TABLE> <RESOURCE> <COOSYS equinox="J2000.0" epoch="J2000.0" system="eq_FK4"/> <TABLE name="Messier Objects"> <FIELD name="Identifier" datatype="char" arraysize="10"/> <FIELD name="RA" datatype="double" units="degrees"/> <FIELD name="Dec" datatype="double" units="degrees"/> <DATA> <TABLEDATA> <TR> <TD>M51</TD> <TD>202.43</TD> <TD>47.22</TD> </TR> <TR> <TD>M97</TD> <TD>168.63</TD> <TD>55.03</TD> </TR> </TABLEDATA> </DATA> </TABLE> </RESOURCE> </RESOURCE> </VOTABLE>Note that it contains more structure than just a flat table: there are two
TABLE elements,
the RESOURCE element of the second one being nested
in the RESOURCE of the first.
Processing this document using a generic table tool such as
tpipe or tcopy would lose this structure.
To convert the data encoding to BINARY format, we simply execute
stilts votcopy format=binary cat.votand the output is
<?xml version="1.0"?> <VOTABLE> <RESOURCE> <TABLE name="Authors"> <FIELD name="AuthorName" datatype="char" arraysize="*"/> <DATA> <BINARY> <STREAM encoding='base64'> AAAAD0NoYXJsZXMgTWVzc2llcgAAAAtNYXJrIFRheWxvcg== </STREAM> </BINARY> </DATA> </TABLE> <RESOURCE> <COOSYS equinox="J2000.0" epoch="J2000.0" system="eq_FK4"/> <TABLE name="Messier Objects"> <FIELD name="Identifier" datatype="char" arraysize="10"/> <FIELD name="RA" datatype="double" units="degrees"/> <FIELD name="Dec" datatype="double" units="degrees"/> <DATA> <BINARY> <STREAM encoding='base64'> TTUxAAAAAAAAAEBpTcKPXCj2QEecKPXCj1xNOTcAAAAAAAAAQGUUKPXCj1xAS4PX Cj1wpA== </STREAM> </BINARY> </DATA> </TABLE> </RESOURCE> </RESOURCE> </VOTABLE>Note that both tables in the document have been translated to BINARY format. The basic structure of the document is unchanged: the only differences are within the
DATA elements. If we ran
stilts votcopy format=tabledataon either this output or the original input then the output would be identical (apart perhaps from whitespace) to the input table, since the data are originally in TABLEDATA format.
To generate a VOTable document with the data in external files,
the href parameter is used. We will output in FITS format
this time. Executing:
stilts votcopy format=fits href=true cat.vot fcat.votwrites the following to the file
fcat.vot:
... <DATA> <FITS> <STREAM href="fcat-1.fits"/> </FITS> </DATA> ... <DATA> <FITS> <STREAM href="fcat-2.fits"/> </FITS> </DATA> ...(the unchanged parts of the document have been skipped here for brevity). The actual data are written in two additional files in the same directory as the output file,
fcat-1.fits and
fcat-2.fits. These filenames are based on the
main output filename, but can be altered using the base
flag if required. Note this has also given you FITS binary table
versions of all the tables in the input VOTable document, which can be
operated on by normal FITS-aware software quite separately from the VOTable
if required.