for MS $0451.6-0305$, and 21.7 for MS $0440.5+0204$, respectively, using point sources, and they decreased to about 65% for objects with exponential profiles at these magnitudes. The completenesses at $K'=22.0$ of point-source detection were $\sim$ 50% and $\sim$ 60%, respectively for MS $0451.6-0305$ and MS $0440.5+0204$.

We adopted the photometric system from Holtzman et al. (1995) for deriving the $R_{\rm{c}}$-band magnitudes from the HST F702W-band data, which are suitable for comparing the previous ERO surveys. We assumed the color of Sbc galaxies at a redshift of $z = 1--2$ ($V-R \sim 1.1$), which is the same manner of transformation adopted by G.P. Smith et al.(2002). The systematic uncertainty of this conversion is $\leq$ 0.1, which arises from the likely presence of both more and less evolved galaxies than the adopted Sbc spectral type. We independently checked the observed FOCAS $R_{\rm{c}}$-band magnitudes with these transformed magnitudes for the same objects, and confirmed the consistency with each other. In the following discussions, we use the $R_{\rm{c}}$-band magnitudes which were transformed from the F702W magnitudes.

figure 1 shows a $K'$ vs $R_{c}-K'$ diagram for the 2 fields with lines of $R_{\rm{c}}-K' = 5.3$ and 6.0, which are our used ERO selection criteria. Most 