All Figures

Figure 1: Top panels: vs. color-magnitude diagrams for all the stars in Field 1 (left) and Field 2 (right) is shown with black dots. Bottom panels: vs. color-magnitude diagrams for Field 1 (left) and Field 2 (right) stars. Variable stars with reliably determined periods (significance parameter from Fourier analysis <0.7) are indicated with red circles and green boxes indicate those with less reliable periods (significance 0.7). Dotted line at shows RGB tip magnitude.

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In the text

	Figure 2: Histogram showing the amplitude distribution of LPVs in Field 1 (solid line) and 2 (dotted line).
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In the text

	Figure 3: Amplitudes as a function of periods (top) and mean magnitudes (bottom) for Field 1 (left) and 2 (right).
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In the text

	Figure 4: K-band luminosity function for all variables with well established periods (Fourier analysis significance <0.7) in Field 1 (solid line) and Field 2 (dotted line).
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In the text

Figure 5: Comparison of the K-band luminosity functions of Field 1 in NGC 5128 halo (beaded blue histogram) with those of the Galactic bulge (solid black histogram) and of two fields in the bulge of M 31 (dotted magenta histograms). All luminosity functions have been normalized in the range -6.5<MK<-5.5. The Galactic bulge data are from Zoccali et al. (2003) and the two M 31 bulge luminosity functions are from Stephens et al. (2003; fields F3 and F4).

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In the text

	Figure 6: Histogram showing the period distribution of LPVs in Field 1 (solid line) and 2 (dotted line).
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In the text

Figure 7: Comparison of period distributions for Miras in globular clusters (Feast et al. 2002), in the Galactic bulge Sgr I field (Glass et al. 1995) and in the LMC (Cioni et al. 2001) with NGC 5128 Miras in both fields studied in this work. Optically discovered Miras in the Sgr I field in the Galactic bulge are shown as open histogram, while the 10 IRAS sources identified in the same field are plotted with shaded histogram. Miras ( ) in NGC 5128 with colors redder than are shown with shaded histogram.

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In the text

	Figure 8: Color-color diagrams for all the stars with ALLFRAME photometry errors smaller than 0.25. LPVs are indicated with red circles (secure periods) and green squares (less certain periods). Reddening vector for E(B-V)=0.5 is shown. Lines indicate intrinsic colors of Galactic giants (solid red line) and dwarfs (dashed blue line) from Bessell & Brett (1988).
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In the text

	Figure 9: Bona fide C-star candidates in NGC 5128: LPVs with and in NGC 5128 are plotted as filled blue circles (Field 1) and filled red squares (Field 2). Obscured O-rich (open circles) and C-rich (crosses) LPVs in the LMC (Whitelock et al. 2003) are plotted for comparison. See text for the explanation of the model colors.
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In the text

	Figure 10: Period-color relations. For comparison a linear fit to the LMC period-color relations (Feast et al. 1989) is shown (solid line in all three panels). In period-(J-K) diagram a linear fit to Sgr I Miras (Glass et al. 1995) is shown with dashed line.
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In the text