Venus is the closest, most easily identified, planet by eye. However, good close images of Jupiter, Mars, and Saturn are much easier to find. Part of the reason is the uniformity of its cloud cover which hides all surface features on Venus. Sometimes it is possible to capture a few features in the clouds. After capturing the crescent shape of Venus for comparison with the Moon, I wanted to try a more detailed infrared image with a different camera.
When Venus makes it's closest approach to the Earth, it is very near a direct line between the Earth and Sun and not visible in most telescopes. Its crescent shape becomes thin as it appears larger. Now is a good time to try to catch some of the elusive cloud detail.
Venus is always near the horizon when the sky is dark because it is near the Sun. At a low angle, light from Venus makes a longer pass through the Earth's atmosphere. An approaching cold front than a couple of days ago made turbulence worse. I abandoned my plans for an infrared image and captured full color data. Thanks to lucky image stacking, I was able to capture another nice image of the crescent.
The animated GIF video sample below shows the first few seconds of my data slowed down by 10X. It's easy to see how badly atmospheric turbulence distorts the image:
Usinging lucky image stacking techniques here is my final image:
Venus magnitude -4.5 and 38.3 arc sec in diameter, taken 2020-04-30 02:12 UT from my driveway in Austin, Texas: Questar 1300/89 mm telescope, with a Dakin 2x Barlow lens for an effective focal length of about 2600mm at f/30, with a ZWO ASI224MC planetary color video camera and Firecapture. Exposure 1 msec and gain 209 at 100 fps with 12,201 frames captured. Best 10% of frames captured with a 1.5x drizzle stack in Autostakkert 3. LR deconvolution and wavelet processing in Lynkeos with final crop and exposure adjustments in Photoshop.
Content created: 2020-04-30
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