AAS Meeting #193 - Austin, Texas, January 1999
Session 8. Galactic Morphology and Stellar Populations
Display, Wednesday, January 6, 1999, 9:20am-6:30pm, Exhibit Hall 1

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[8.11] Studying Faint Field Galaxies Using NICMOS/HST Parallel Images

L. Yan, P.J. McCarthy, L.J. Storrie-Lombardi, R.J. Weymann (Carnegie Obs.)

The NICMOS parallel imaging program has provided a wealth of data at near-IR wavelengths with HST resolution. To date, this survey has covered a total area of ~200 sq. arcminutes. We present the preliminary results from our analysis of F160W NICMOS Parallel images. The F160W images reach 3\sigma depths of H= 24.3 - 25.5 in a 0.6'' diameter aperture for integration times of 2,000 to 13,000 seconds. From a set of data covering ~9~sq. arc-minutes, we derived the first deep H-band galaxy counts (Yan et al. 1998, ApJL, 503, 19). The slope of the counts for H< 20 is 0.31, consistent with various K-band measurements from the Keck telescopes. The measured number counts vs. magnitude relation is reasonably well fitted with no-evolution models with a low \Omega value to H = 23.5, beyond this our counts show an excess compared to the no evolution model. The half-light radii of galaxies decline steeply with apparent magnitude and reach the NIC3 the resolution limit at H = 23.5. The red envelope of the J-H vs. H color magnitude diagram follows the minimal evolution track down to H = 22. Ground-based BVRI imaging of these fields has revealed a number of extremely red galaxies with R - H > 6.


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