2 Observations and Data Analysis

The Hubble Space Telescope (HST) observations of NGC5189 were obtained on 2012 July 6 (Program 12812, PI: Z. Levay) using the Wide Field Camera 3 (WFC3) instrument through the Ultraviolet-Visible (UVIS) channel configuration with the F673N, F657N, F502N, F814W, and F606W filters. These observations listed in Table 1 were taken with exposures of 4200, 3900, 8400, 360, and 300 sec, respectively. The WFC3 images were downloaded from the archive, and reprocessed using the AstroDrizzle task of the HST DrizzlePac v2.0 software package1 (Gonzaga et al., 2012) in PyRAF v2.1.14, a Python-based command language for IRAF tasks. The sky background is automatically calculated for each image and subtracted using the function AstroDrizzle at a sampling sky width of $ 0.1 \sigma$ and clipping limit of $ 1\sigma $. While the sky subtraction is performed, pixels within $ 1\sigma $ of the sky median value are excluded from the drizzled images. The WFC3 images were then aligned with the drizzled F814W image as a reference frame using the DrizzlePac functions TweakReg and TweakBack, and cosmic rays were removed from the images using the AstroDrizzle task from the DrizzlePac tools.

The systemic radial velocity of NGC 5189 is $ -8\pm4$ kms$ ^{-1}$ (Manick et al., 2015), so the velocity shift is negligible, and the F657N, F502N, and F673N filters do cover the H$ \alpha $$ \lambda $6563, [OIII]$ \lambda $5007, and [SII] $ \lambda \lambda $6716,6731 emission lines, respectively.

Figure: From left to right, and top to bottom, dereddened, continuum-subtracted flux maps on logarithmic scales (unit in $ 10^{-15}$ ergcm$ {}^{-2}$s$ {}^{-1}$arcsec$ {}^{-2}$) of H$ \alpha $$ \lambda $6563, [OIII]$ \lambda $5007, [SII] $ \lambda \lambda $6716,6731 emission lines, and continuum flux-density on a logarithmic scale (unit in $ 10^{-15}$ ergcm$ {}^{-2}$s$ {}^{-1}$arcsec$ {}^{-2}$Å$ {}^{-1}$) estimated at $ \lambda $6563. Images include only pixels with at least statistically significant 1$ \sigma $ sky. The green rectangle indicates the $ 120\hbox {$^{\prime \prime }$}\times 90\hbox {$^{\prime \prime }$}$ region of NGC 5189 used for detailed diagnostic mappings. Note that the upper value of the colorbar for the continuum map has been scaled down to show the faint nebular continuum.

Ashkbiz Danehkar