Here is my yesterday's attempt for Venus image with Baader CaK filter. I captured also through 760nm and 950nm IR filter, but without any visible details. Anyway, I made false RGB composite. Today morning I also try to capture my first Jupiter of season. It is still low here in Europe, but seeing wasn't bad, so I took some pict also . And here you can see ther result with 8" Newton, QHY5 mono and visual R,G,B filters.
Venus came up quite well and Jupiter looks good. No doubt as Jup rises higher for your location you will get better resolution, however this is a good job for so early in your season.
Your Venus image is impressive, particularly the cloud detail in the blue spectral region. Did you have any trouble getting enough signal while using the CaK filter?
Ray:I also had Baader UVenus filter, but image was only a little bit lighter (I guess about 10% over CaK). On the other hand, CaK gives more contrast and sharp image, cause of 8nm bandwidth. So I stick with this filter. And it still can be used also for CaK imaging of the Sun, where makes a good job too. In this session I used 66ms exposure @ 92% gain. But exposure may vary, cause it's very sensitive to sky transparency. In bad condition I easily reach 200-300ms exposures!
Hi Roman
Re your Io question, I could not find a lot of info on the spectral reflectance of Jupiter and Io, but what I did find suggests that Io looks brighter than Jupiter in the IR because it has significantly higher reflectivity than the planet in that region. It seems that the surface of Io is largely covered by a bright SO2 frost, which remains highly reflective in the near IR, but the top layers of the planet have spectra with significant absorption bands and therefore lower reflectivity. Would not claim that this is a definitive answer, but it could explain the observations.
Regards Ray
Thanks for answer. It makes sense. I though that it's cause the IR trasnmit also 889nm - methane line, where moons are very bright. But your explanation sounds more realistic .
. And here you can see ther result with 8" Newton, QHY5 mono and visual R,G,B filters.
