THE INTERACTION BETWEEN SPIRAL GALAXIES IC-2163 AND NGC-2207 .1. OBSERVATIONS

High-resolution H I observations taken at the VLA of the interacting p air of galaxies NGC 2207 and IC 2163 are presented, compared with opti cal and radio continuum images, and analyzed with detailed computer si mulations (in Paper II) in order to determine the orbits and study the effects of in-plane and out-of-plane tidal forcing during a recent, c lose, nonmerging encounter between galaxies of comparable mass. IC 216 3 has an ocular shape (an eye-shaped central oval with a sharp apex at each end) and a double-parallel arm structure on the side opposite NG C 2207. Our observations of IC 2163 find (1) an intrinsically oval sha pe to the disk, (2) large streaming motions along the oval, (3) H I ti dal arms located symmetrically on opposite sides of the nucleus (even though one side is obscured by NGC 2207 at optical wavelengths), and ( 4) a line-of-sight velocity difference of 70-100 km s(-1) between the two components of the double-parallel arm. Optical surface photometry of IC 2163 indicates that most of the stars in the interarm region hav e been cleared away and put into the central oval and tidal arms. The kinematic and structural anomalies of IC 2163 are consistent with the predictions of N-body galaxy encounter simulations if NGC 2207 moved a pproximately in the plane of IC 2163 in a prograde sense. The companio n, NGC 2207, shows different types of disturbances. The main body of H I gas in NGC 2207 forms a broad, clumpy ring that contains relatively thin stellar arms and corresponds to a plateau in the radial distribu tion of optical light. The most massive H I clouds in the ring do not always coincide with the stellar arms. The ring is broken in the south , and a filamentary pool of H I extends 40 kpc farther south. The velo city field in the main disk of NGC 2207 is highly distorted with isove locity contours that are shaped like an open trailing spiral, and the H I line profiles in this region are very broad with Gaussian dispersi ons of 40-50 km s(-1). The kinematic disturbances in NGC 2207 suggest that the main tidal force on NGC 2207 was perpendicular to its disk. T he companion side of the H I ring is unusually bright in lambda 20 cm radio continuum emission, perhaps indicating a shock front. There is n o significant excess of star formation in these galaxies, but there ar e several 10(8) M. gas clouds in each disk, some of which may eventual ly become detached dwarf galaxies.