After reading Venus Cloud Discontinuity, an article at and reading the science paper that it cited I looked into the feasibility of capturing the cloud discontinuity phenomenon. The article said that an Italian had imaged a CD on June 4. The 2020 paper mentioned that Venus’ clouds rotate once every five days. I believe the CD to be short lived, so I asses my chances of having captured it today as small. I had imaged Venus during the winter and wanted to return to that target when it was positioned at a higher elevation above the horizon this spring. Stellarium showed Venus at 50 degrees elevation at when I looked at 0930, and that it would culminate on the meridian at 64 degrees elevation at about 1030.

A couple more tidbits out of the paper. It said that a telescope aperture of .2 meters or larger was required. The Meade is .3 meters and is already positioned on the mount. The paper relied on amateurs’ images, many of which were captured with the ASI290mm – another match! And finally, nearIR and UV filters are required. It specified a nearIR band range. I think that my nearIR filter is in the range (have to check), and I have the UVenus filter. Putting all of that together, I was ready to image Venus.

Set up, power up and target acquisition (at least the first attempt) all went very smoothly.

But not so fast! With the exception of a clear patch to the north, the sky was cloudy. Astrospheric forecasted average transparency from 1000 through 1200, and at 1000 the cloud cover changed to a few passing clouds. The temperature was 76 degrees at the beginning of the session at 1000 and had elevated to 82 degrees by the end of the session at 1145. I got a good deal warmer than I would have liked.

Equipment was G11, Meade LX850, 31mm x 7 EFW, TV 2.5x PM, and ZWO ASI290mm.

The Good: I slewed to Venus, used the flip mirror and eyepiece to nudge the scope to where it needed to be, and I found Venus in the Firecapture display immediately upon flipping up the mirror. I did a quick capture in L so that I would at least have something if the session went bad.

The Bad: I had to reacquire the target a couple of times but didn’t get as lucky as I did on the first attempt.

The Ugly: The session went bad. I was not able to change filters via Firecapture. Firecapture would show me the correct icon for whatever filter that I asked for, but the filter wheel was connected but would not rotate. I worked around this using Sharpcap for the first time. With my eyes on the filters, I could see the filter wheel operating correctly. It’s the same thing only different, so I had to learn my way around. I could not get ROI imaging to work the way it does in Firecapture, so I captured two minutes of the full sensor frame in IR and UV.

Post session to-do list:

Figure how to regain control of the filter wheel via Firecapture, which I like much better than Sharpcap.

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