North Ecliptic Pole Wide Field Survey of AKARI: Survey Strategy and Data
  Characteristics
  We present the survey strategy and the data characteristics of the North
Ecliptic Pole (NEP) Wide Survey of AKARI. The survey was carried out for about
one year starting from May 2006 with 9 passbands from 2.5 to 24 micron and the
areal coverage of about 5.8 sq. degrees centered on NEP. The survey depth
reaches to 21.8 AB magnitude near infrared (NIR) bands, and ~ 18.6 AB
maggnitude at the mid infrared (MIR) bands such as 15 and 18 micron. The total
number of sources detected in this survey is about 104,000, with more sources
in NIR than in the MIR. We have cross matched infrared sources with optically
identified sources in CFHT imaging survey which covered about 2 sq. degrees
within NEP-Wide survey region in order to characterize the nature of infrared
sources. The majority of the mid infrared sources at 15 and 18 micron band are
found to be star forming disk galaxies, with smaller fraction of early type
galaxies and AGNs. We found that a large fraction (60~80 %) of bright sources
in 9 and 11 micron stars while stellar fraction decreases toward fainter
sources. We present the histograms of the sources at mid infrared bands at 9,
11, 15 and 18 micron. The number of sources per magnitude thus varies as m^0.6
for longer wavelength sources while shorter wavelength sources show steeper
variation with m, where m is the AB magnitude.
