We use the SCUBA-2 submillimeter camera mounted on the JCMT to obtain extremely deep number counts at 450 and 850 \mu m. We combine data on two cluster lensing fields , A1689 and A370 , and three blank fields , CDF-N , CDF-S , and COSMOS , to measure the counts over a wide flux range at each wavelength .
We use statistical fits to broken power law representations to determine the number counts .
This allows us to probe to the deepest possible level in the data .
At both wavelengths our results agree well with the literature in the flux range over which they have been measured , with the exception of the 850 \mu m counts in CDF-S , where we do not observe the counts deficit found by previous single-dish observations .
At 450 \mu m , we detect significant counts down to \sim 1 mJy , an unprecedented depth at this wavelength .
By integrating the number counts above this flux limit , we measure 113.9 ^ { +49.7 } _ { -28.4 } Jy deg ^ { -2 } of the 450 \mu m extragalactic background light ( EBL ) .
The majority of this contribution is from sources with S _ { 450 ~ { } \mu { m } } between 1–10 mJy , and these sources are likely to be the ones that are analogous to the local luminous infrared galaxies ( LIRGs ) .
At 850 \mu m , we measure 37.3 ^ { +21.1 } _ { -12.9 } Jy deg ^ { -2 } of the EBL .
Because of the large systematic uncertainties on the COBE measurements , the percentage of the EBL we resolve could range from 48–153 % ( 44–178 % ) at 450 ( 850 ) \mu m. Based on high-resolution SMA observations of around half of the 4 \sigma 850 \mu m sample in CDF-N , we find that 12.5 ^ { +12.1 } _ { -6.8 } % of the sources are blends of multiple fainter sources .
This is a low multiple fraction , and we find no significant difference between our original SCUBA-2 850 \mu m counts and the multiplicity corrected counts .