  We report on early results from deep and wide-field narrow-band imaging on a
543 arcmin^2 area of the Subaru Deep Field. We find 87 Lya emitters (LAEs) at
z=4.86(+/-0.03) which are photometrically selected by a combination of two
broad bands (R and i') and one narrow band (NB711; 7126A FWHM=73A). We derive
the luminosity functions (LFs) of the LAEs at Lya luminosity and at
UV-continuum (1700A) luminosity. The LFs show little evolution between z=3.4
and z=4.86 either in Lya or UV-continuum emission. The amplitude of the LAE LF
tends to decline at the bright magnitudes more rapidly than that of the LBG LF
at similar redshifts. We calculate the angular correlation function of our LAEs
up to ~15 arcmin separations. The angular correlation w(theta) is found to
increase with decreasing angular separations, showing a clear signal of
clustering. It is also found that the distribution of LAEs shows a large
density gradient with a scale of >~15 arcmin, which would indicate the
existence of a large-scale structure of LAEs on >~20h^(-1) Mpc scales.We fit
the observed correlation function by Aw theta^(-0.8) to find Aw=29arcsec^(0.8).
The estimated correlation length is r0=3.5(+/-0.3)h^(-1)Mpc in comoving units
(Omega_m=0.3 and Omega_Lambda=0.7), which is slightly larger than the value for
z~4 LBGs with i'<26. We calculate the angular correlation function for two
sub-samples of the 87 LAEs divided by Lya luminosity, UV-continuum luminosity,
and Lya equivalent width (EW). The Lya bright sub-sample shows a larger
correlation amplitude than the Lya faint sub-sample, while no significant
difference is found for the sub-samples divided by UV-continuum luminosity or
EW.
