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Thank you all. Mike: the luminance data is based upon 49 exposures of 600 seconds each, all at 1x1 binning with a QSI 683wsg. As you know, the signal is buried on top of and within the sky glow. In principle, one just has to integrate for long enough to average away the noise in the sky glow. However, as the sky glow increases, the integration time required to recover a smooth signal becomes impractically large. I am located in the southern suburbs beside Royal National Park and NGC 5128 passes through the “sweet spot” in my sky, south of zenith, but still high up in the sky where I can make out 5th magnitude stars with the naked eye. I leave the scope running all night and try to record the luminance data when the object passes through the celestial meridian between midnight and 4 am when the sky is darkest. This is a lot of hard work which is something I think you know all about.
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