Venus Image 2024/11/21(UT)
Niall MacNeill
N.MacNeill
| Niall MacNeill |
Well if Jupiter is no good here, we can still image Venus which is well placed for us now. The first image is a colour one (RGB). Despite Venus being reported as featureless in visible light, I have rarely found that to be so. When we see it through the eyepiece it is so bright, that any colour is washed out, but the camera and filters do a good job of showing the subtle hues across the planet's cloud tops and there is to my eye a correlation with the UV and IR images. I used my QHY5III200, which has excellent sensitivity in IR to image at both IR 850nm BP and also using my Methane Band filter, 889nm with a Bandwidth (BW) of 18nm. Some subtle features were visible with both these filters and what's nice is that I could see that they corresponded pretty well. I slightly prefer the Methane band image and the reason that I use it is because all wide band filters suffer from an amount of atmospheric dispersion at low altitudes. The narrowband of the Methane Band filter avoids that and there is plenty of light to get an image. The second image is the straight UV, which as usual shows the most detail and structure. I colourised it violet/ purple for aesthetic reasons. The third image is an IR(G)UV image where the IR(CH4) is set to Red, a 50:50 IR:UV blend is set to Green and the UV is set to Blue. Finally my Wratten#47 Violet filter shows some nice structure like the UV, so I used it to produce a B(V)UV false colour image where the Blue is set to Red, the Violet to Green and again the UV to Blue. This is what I call a false colour, spectrum shifted image, where instead of RGB, as our eyes can see, we have BVUV. A bit of a contrivance I know, but it does bring together an RGB equivalent but at the blue-violet end of the spectrum. Some use the Wratten #47 filter as an alternative to UV as it is much less expensive.
[Niall MacNeill : Wattle Flat,NSW,Australia]
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Venus Section
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