UV and Optical Surface Photometry of NGC~1068 from UIT and Ground-Based Observations

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Session 46 -- Seyfert Galaxies and LINERS
Display presentation, Thursday, January 13, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[46.08] UV and Optical Surface Photometry of NGC~1068 from UIT and Ground-Based Observations

L.J. Roberts (Hughes STX), M.N. Fanelli (NRC/LASP/GSFC), S.G. Neff, E.P. Smith (LASP/GSFC/NASA), K.P. Cheng (Hughes STX), P.M.N. Hintzen (CSULB/LASP/GSFC), R.W. O'Connell (UVa), R.C. Bohlin (STScI), M.S. Roberts (NRAO), A.M. Smith, T.P. Stecher (LASP/GSFC/NASA)

We present a photometric analysis of ultraviolet (UV) and optical image data for NGC~1068. The UV data were obtained by the Ultraviolet Imaging Telescope (UIT) in two bands: far-UV (FUV), $\lambda_{eff} \sim 1520 $\ \AA, and near-UV (NUV), $\lambda_{eff} \sim 2490 $\ \AA. Associated optical CCD images in the B and R bandpasses were obtained at KPNO and at Mt. Laguna Observatory of San Diego State University.

Using annular aperture photometry and isophotal fitting techniques, we derive structural parameters such as disk scale lengths, central surface brightness, luminosity, and isophotal diameters. The radial brightness profile is best described by two components with a distinct break at $r \sim 90^{\prime\prime}$ (6.5 kpc). This break is present in the NUV, B, and R bands, with the NUV bandpass being the most pronounced. Both components are consistent with an exponentially declining light profile, with the outer component ($90^{\prime\prime} < r < \ \sim 200^{\prime\prime}$) showing a more shallow gradient.

Maps of the UV-optical color distribution ($m_{\mathrm{uv}}$ -- $m_{\mathrm{optical}}$) reveal the dust distribution, the underlying old stellar population and areas of recent massive star formation. The broken circumnuclear ring of luminous knots appears blue in UV-optical colors. However, their FUV -- NUV colors are more complex; exhibiting a range of colors, $- 0.5 < $ FUV -- NUV $ < +0.5$, most likely produced by patchy extinction. These maps also show a uniform red disk at $r > 50^{\prime\prime}$ (3.5 kpc) with a NUV -- B color $\sim 1.4$ mags and a NUV -- R color $\sim$ 2.9 mags.

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