  $\theta$ Cygni is an F3 spectral-type main-sequence star with visual
magnitude V=4.48. This star was the brightest star observed by the original
Kepler spacecraft mission. Short-cadence (58.8 s) photometric data using a
custom aperture were obtained during Quarter 6 (June-September 2010) and
subsequently in Quarters 8 and 12-17. We present analyses of the solar-like
oscillations based on Q6 and Q8 data, identifying angular degree $l$ = 0, 1,
and 2 oscillations in the range 1000-2700 microHz, with a large frequency
separation of 83.9 plus/minus 0.4 microHz, and frequency with maximum amplitude
1829 plus/minus 54 microHz. We also present analyses of new ground-based
spectroscopic observations, which, when combined with angular diameter
measurements from interferometry and Hipparcos parallax, give T_eff = 6697
plus/minus 78 K, radius 1.49 plus/minus 0.03 solar radii, [Fe/H] = -0.02
plus/minus 0.06 dex, and log g = 4.23 plus/minus 0.03. We calculate stellar
models matching the constraints using several methods, including using the Yale
Rotating Evolution Code and the Asteroseismic Modeling Portal. The best-fit
models have masses 1.35-1.39 solar masses and ages 1.0-1.6 Gyr. theta Cyg's
T_eff and log g place it cooler than the red edge of the gamma Doradus
instability region established from pre-Kepler ground-based observations, but
just at the red edge derived from pulsation modeling. The pulsation models show
gamma Dor gravity-mode pulsations driven by the convective-blocking mechanism,
with frequencies of 1 to 3 cycles/day (11 to 33 microHz). However, gravity
modes were not detected in the Kepler data, one signal at 1.776 cycles/day
(20.56 microHz) may be attributable to a faint, possibly background, binary.
Asteroseismic studies of theta Cyg and other A-F stars observed by Kepler and
CoRoT, will help to improve stellar model physics and to test pulsation driving
mechanisms.
