  We present the design, construction, and commissioning results of ARCONS, the
Array Camera for Optical to Near-IR Spectrophotometry. ARCONS is the first
ground-based instrument in the optical through near-IR wavelength range based
on Microwave Kinetic Inductance Detectors (MKIDs). MKIDs are revolutionary
cryogenic detectors, capable of detecting single photons and measuring their
energy without filters or gratings, similar to an X-ray microcalorimeter. MKIDs
are nearly ideal, noiseless photon detectors, as they do not suffer from read
noise or dark current and have nearly perfect cosmic ray rejection. ARCONS is
an Integral Field Spectrograph (IFS) containing a lens-coupled 2024 pixel MKID
array yielding a 20"x20" field of view, and has been deployed on the Palomar
200" and Lick 120" telescopes for 24 nights of observing. We present initial
results showing that ARCONS and its MKID arrays are now a fully operational and
powerful tool for astronomical observations.
