Venus from 29-March-23; UV and IR

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KMH
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Venus from 29-March-23; UV and IR

Post by KMH »

I managed to capture some UV and IR Venusian cloud features on 3/29/23. The seeing was quite poor, but I was keen to try out a new UV filter - a 400/40 nm filter from Thor Labs. I also have a Baader U Venus filter, but have not had very good success with it - light transmission in that wavelength band is quite low through my Celestron 11 and 2x Powermate (though I note that Alexandros posted terrific UV images through his C14 a few weeks ago). It was hypothesized by a planetary imager on a different forum that the 400/40 nm filter would be much better for use with SCTs/barlows, showing similar details (maybe slightly less contrast) but with much better light transmission. I found that to be true - I could reduce exposure by a factor of 15x relative to the Baader UV filter. I hope to be able to try it out with better seeing this week.

Capture information for UV is:
Celestron Edge11
2x PowerMate
ASI462MM with 4.0 ms exposures and gain 202 (33%)
8000/74000 frames stacked
Thor Labs 400/40 nm filter

For IR I used a Baader 685nm long-pass filter.

Firecapture/Autostakkert/AstraImage/Photoshop - with a sharpening assist from a cyber-friend (Photoshop high-pass filter, which I have not used before but worked really well)

BTW, the Thor filter is only 1" diameter, so will not fit in most conventional astronomical filter cells. But, Thor also sells "lens tubes" for mounting 1" optics and filters. There is a 0.3" long version that does well as a filter cell for 1" filters.
https://www.thorlabs...ctgroup_id=3307
The catch is that the threads are SM1, which is 1.035"x40 (1.25" eyepiece threads are M28.5x0.6). There are two solutions:

Thor also sells C-mount to SM1 adapters.
https://www.thorlabs...tgroup_id=12627
Here the cell+adapter can be threaded into a video camera. Some shimming (like metallic tape) is necessary when mounting to the scope, because the SM1 diameter is 1.20".

Alternatively, an SM1 to M28.5x0.6 adapter can be used. I found one on ebay (from RafCamera - they are now out of stock), or someplace like Precise Parts can make one.

Anyway, here are the pix.....

Kevin

venus 032923 UV vs IR small.jpg
venus 032923 UV vs IR small.jpg (42.94 KiB) Viewed 971 times
Last edited by KMH on Sun Apr 09, 2023 9:27 pm, edited 1 time in total.


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Re: Venus from 29-March-23; UV and IR

Post by KMH »

Alexandra - I can't get the picture to show up. Is SolarChat having a problem? I don't see any issue on my computer.

Thanks!
Kevin


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Re: Venus from 29-March-23; UV and IR

Post by rsfoto »

KMH wrote: Sun Apr 09, 2023 8:14 pm Alexandra - I can't get the picture to show up. Is SolarChat having a problem? I don't see any issue on my computer.

Thanks!
Kevin
Hi Kevin,

You need to convert your images to JPG format.

Not a single internet browser is capable of opening TIF files.

When you save them then the colour profile format should be sRGB in order to have the best viewing experience.

regards Rainer


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Re: Venus from 29-March-23; UV and IR

Post by KMH »

rsfoto wrote: Sun Apr 09, 2023 9:19 pm
KMH wrote: Sun Apr 09, 2023 8:14 pm Alexandra - I can't get the picture to show up. Is SolarChat having a problem? I don't see any issue on my computer.

Thanks!
Kevin
Hi Kevin,

You need to convert your images to JPG format.

Not a single internet browser is capable of opening TIF files.

When you save them then the colour profile format should be sRGB in order to have the best viewing experience.

regards Rainer



Rainer - Thanks! That worked. Kevin


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Re: Venus from 29-March-23; UV and IR

Post by Montana »

Wow!! these are a fabulous pair :bow :bow :bow

I need to sell my Baader U as it is useless to me, it doesn't let enough light through for my camera. So well done, this other filter looks good!

Alexandra


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