  Using the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on
board the Hubble Space Telescope, we have obtained F110W (J-band) and F160W
(H-band) images of three fields in NGC3379, a nearby normal giant elliptical
galaxy. These images resolve individual red giant stars, yielding the first
accurate color-magnitude diagrams for a normal luminous elliptical. The
photometry reaches 1 magnitude below the red giant branch tip with errors of <
0.2 mags in F110W-F160W. A strong break in the luminosity function at F160W =
23.68 +/- 0.06 is identified as the tip of the red giant branch (RGB);
comparison with theoretical isochrones implies a distance of 10.8 +/- 0.6 Mpc,
in good agreement with a number of previous estimates using various techniques.
The mean metallicity is close to solar, but there is an appreciable spread in
abundance, from at least as metal poor as [Fe/H] = -1.5 to as high as +0.8.
There is a significant population of stars brighter than the RGB tip by up to
about 1 magnitude. The observations of each field were split over two epochs,
separated by 2-3 months, allowing the identification of candidate long period
variables; at least 40% of the stars brighter than the RGB tip are variable.
Lacking period determinations, the exact nature of these variables remains
uncertain, but the bright AGB stars and variables are similar to those found in
metal rich globular clusters and are not luminous enough to imply an
intermediate age population. All of the evidence points to a stellar population
in NGC3379 which is very similar to the bulge of the Milky Way, or an
assortment of Galactic globular clusters covering a large metallicity spread.
