A Foggy Night on Mauna Loa

Posted by Josh Walawender on Sun 14 June 2020

June 13

I went up on Saturday night for my second observing night of the weekend. The inversion layer clouds could not have been more different. The clouds last night at Kaohe were almost non-existant and Kaohe got noticeably less humid around 9pm when the down slope catabatic wind started up.

Tonight, the inversion was well defined, thick with clouds, and high. From the site I chose (the "wind sock" along the Mauna Loa access road), the clouds were just below me at sunset and I could see that Kaohe was covered with a thick layer.

Worse than that, as the sun set, the clouds crept higher and higher until we could feel droplets of water hitting us. Though we could still see stars, the blowing mist kept the covers on the telescopes until about 9:15 PM which is when we finally emerged from the clouds. It wasn't a big shift, the clouds were still thick just below us on the slopes of the mountain, but it was enough to observe.

The four of us that were there observed for a few hours. I packed up first at about 11:15 PM. The seeing was variable, with some good moments and then deteriorating. The wind was a constant 10 mph which limited high power viewing.

I watched Io emerge from in front of Jupiter with the planet very low on the horizon during that period of good seeing.

During the period of fog, my iPad which I'd set out in preparation for observing got soaked and the cold and wind drained the battery, so I did not have a chance to take my usual observing notes for this session. It recovered once it dried off and was plugged in.

I did manage to see comet C/2019 T2 PanSTARRS in the SVX152. It was easily bright enough to see, but the nucleus was indistinct and elongated with no sharp core to it.

I spent most of the rest of the night hitting some nice bright targets similar to last night and with the observing going a bit later, I got to spend some time in the Summer Milky Way which was rising.