First three plots are magnitude difference (in the sense UKIDSS - 2MASS) for JHK for IC 4665. There are a total of 52854 matches with 2MASS over the whole area covered for IC 4665. This excludes 14964 points with any 2MASS magnitude as only an upper limit. In each plot, the subset conforms to the 2MASS error (m_cmsig) <= 0.1 && mergedClass = 0 (excludes likely noise points).

Second three plots are the UKIDSS JHK magnitudes vs. the magnitude difference (in the same sense as before) for UKIDSS JHK in the range 14 to 16 AND with 2MASS error on the magnitude <= 0.2 only. This should help limit the effect of large errors in 2MASS for these relatively faint magnitudes.

I have also subdivided UKIDSS JHK into one magnitude bins, over the range 10th-17th mag. No other constraints are applied. These .gif plots (UKIDSS mag. vs. difference) are all bundled into a tarfile.

Finally, statistics for each magnitude bin for JHK are shown in tabular form. The 2nd column is the number of points; the 3rd is the mean offset from zero of the magnitude difference, and the 4th column the standard deviation of the magnitude difference.

The final plots deltam.gif are the results of internal cross-correlation within the entire GCS. The SQL used to do this is also given. Mag. differences are in magnitudes, positional differences in arcsec. There are 22903 points in the cross-correlation.

-- TrKendall - 29 Jul 2005