Friday, 6 December 2019, was mostly cloudy. Saturday, 7 December, I was walking around our land and I saw this.

It is probably a cow pelvis but I have no idea how it got here. I have been in that area before, just not recently.

Sunday morning, 8 December, there were some fascinating clouds over Mt Lemmon south of Oracle. The Tucson office of the National Weather Service tweeted this to me: "These clouds are showing evidence of Kelvin–Helmholtz instability."

Late Sunday night and into Monday morning, 9 December, we had a thunderstorm come through (0.39" rain). Monday afternoon another storm came through (0.15"). Tuesday, 10 December, was clear. At least it was clear until sunset approached when clouds began arriving from the northwest.

Open: Tuesday, 10 December 2019, 1751 MST Temperature: 53°F

Session: 1411 Conditions: Partly cloudy

Equipment:
Camera:
D850 DSLR

As the observatory still has no power I did not open the dome this night. I did set up my D850 DSLR on a tripod on the observatory patio. Besides the Venus-Saturn conjunction (1°50') there would also be a pass of the International Space Station (ISS).

I took the following photos of the Venus-Saturn conjunction with a 600mm lens (f/8, 1/160sec, ISO 400) and a 50mm lens (f/2.8, 1/20sec, ISO 3200). The inset shows Saturn full scale with the 600mm lens.

During the ISS pass I took many photos at various exposures from f/6.3, 1/640sec to 1/3200sec, ISO 1600, using the 600mm lens. The dot at the center of the photo shows how the ISS appeared in the full frame image. The inset at the top shows the full scale images of the ISS as its apparent size and perspective changed during the near horizon-to-horizon pass.

I then took some photos of the nearly Full Moon using the 600mm (f/11, 1/400sec, ISO 100; cropped) and 50mm lens to show the clouds, the Moon above the Hyades in the constellation of Taurus, and the observatory dome (f/2.8, 1/20sec, ISO 4000).

The sky was now mostly cloudy so I ended this session.

Close: Tuesday, 10 December 2019, 1835 MST Temperature: 50°F

Session Length: 0h 44m Conditions: Mostly cloudy

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