Characterizing bar structures: application to NGC 1300, NGC 7479 and NGC 7723

Detailed surface photometry has been carried out for three barred galaxies with use of high resolution CCD broad-band images in the B, V and I bands. Using azimuthal luminosity profiles and their decomposition into Fourier Se ries, the structural parameters (length and strength) of the bars in the th ree galaxies have been obtained. We have also inferred the corotation radii (CR) using information available in the B - I and B - V colour index profi les. The regions selected for the CR were the ends of the bars, or a little further out and with an older stellar population than the surrounding regi ons. The resulting values, R-CR similar to 100 "+/-10 " for NGC 1300, R-CR similar to 63 " for NGC 7479 and R-CR similar to 23 " for NGC 7723, are in agreement with those previously reported in the literature. This demonstrat es the utility of accurate photometry for this type of observation.