Getting SDSS r' and g' catalogues from topcat

• Open topcat
• click on VO menu at the top
• Select 'cone search'
• In the keywords box put 'SDSS' which stands for Sloane Digital Sky Survey
• Press 'Find Services' button and wait a bit
• Pick SDSS DR9 Sloan Digital Sky Survey Data Realease 9
• In the table below pick PhotoObjAll table (not the spectra)
• In Object name, put 'M35' (without quotes)
• press resolve button to get M35 coordinates
• put 0.5 in the radius box and keep the units as degrees (M35 is ~28arcmin across)
• Press OK and wait for table to download
• Check that the data looks ok by clicking on 'Sky Plotting Window' in teh main topcat window.
• Save the table in vot format for future use