The following plots compare the 2MASS photometry for tiles that were observed
by both the northern and southern telescopes. I selected tiles that had
a quality score of >= 8. Within these tiles, I further selected sources
that had
a) a blend flag of "111",
b) a confusion flag of "000",
c) a photometric uncertainty of <= 0.05 in the appropriate band, and
d) >= 5 detections on individual frames.
The photometric comparisons done for each combination
of Read 1/2 photometry (4 possible combinations total). The following plots
shows the results, where I plot histograms of the photometric differences
for each band, and a hess diagram that plots the photometric differences as a
function of magnitude (contours are drawn at 0.1, 0.2, 0.3, ..., 0.9 of the
peak density).