http://gsss.stsci.edu/webservices/vo/ConeSearch.aspx?CAT=GSC23&RA=21.0&DEC=42.0&SR=0.01&VERB=3

Line 154: W50: Invalid unit string 'pixel'
  <FIELD name="semiMajorAxis" ID="semiMajorAxis" datatype="float" ucd="phys.angSize.smajAxis" unit="pixel" >

Line 154: W50: Invalid unit string 'pixel'
  <FIELD name="semiMajorAxis" ID="semiMajorAxis" datatype="float" ucd="phys.angSize.smajAxis" unit="pixel" >