Comet C/2020 F3 (NEOWISE)—IV

The comet continues to rise higher in the northwestern sky after sunset. It is now in a position so that I can get reflections of the comet in water at the same time that the comet is above the San Francisco Peaks. So I worked out the geometry and set up on Ashurst Lake, southeast of Flagstaff.

Comet C/2020 F3 (NEOWISE) over Ashurst Lake.
Comet C/2020 F3 (NEOWISE) over Ashurst Lake.

It didn’t work out for a couple of reasons. There was too much wind and the surface of the water remained ruffled rather than smooth. And then, as the comet was sinking lower in the sky and the winds began to diminsh clouds developed.

So, I’ll have to try this one again when I get better conditions.

Comet C/2020 F3 (NEOWISE)—II

The comet is now visible in the evening sky but also remains visible in the morning sky. Evening twilight is bright enough to make it difficult to see the comet without binoculars or long exposures on a camera. That will change quickly as the comet moves higher in the northwestern sky in the coming days and weeks.

Comet C/2020 F3 (NEOWISE) is visible in the evening twilight over Flagstaff, Arizona.
Comet C/2020 F3 (NEOWISE) is visible in the evening twilight over Flagstaff, Arizona.

Above is an image of the comet in the evening sky. Layers of clouds and moisture threatened to interfere but actually made the photograph more interesting with saturated twilight colors.

This image is a stack of ten images each 4 secs exposure at ISO 1600, ƒ/1.8, and 85mm focal length. The individual images were stacked using Starry Landscape Stacker. 

 

A New Comet in the Sky

A recently discovered comet is now shining brightly in the morning sky. Comet C/2020 F3 (NEOWISE) was first spotted March 27, 2020, by NASA’s NEOWISE space-borne telescope. The comet passed inside Mercury’s orbit on 03 July 2020 and quickly brightened as it as heated by the intensity of the Sun.

Comet NEOWISE rises above Grand Canyon. Also visible are Venus, Hyades, and Pleiades.
Comet NEOWISE rises above Grand Canyon. Also visible are Venus, Hyades, and Pleiades.

The comet has been rising around the start of Astronomical Twilight when the eastern horizon is just beginning to brighten. Within about 45 minutes to an hour—or shortly after the start of Nautical Twilight—the morning sky has become bright enough to make observation difficult.

The image above was taken as the comet rose above Grand Canyon. Also visible in the image are the planet Venus, the bright star Aldebaran, and the Hyades and Pleiades star clusters.

Comet NEOWISE rises above the eastern horizon on 06 July 2020.
Comet NEOWISE rises above the eastern horizon on 06 July 2020.
Comet NEOWISE on 06 July 2020.
Comet NEOWISE on 06 July 2020.
Comet NEOWISE on 07 July 2020.
Comet NEOWISE on 07 July 2020.

By the third week middle of July the comet will shift from the morning sky into the evening twilight sky. Again, there will be a short window of time in which it is easily observed but viewing the evening is far easier than the morning.

 

Some Interesting Wave Clouds

For a few hours this morning (02 July 2020) the clouds were amazing. Laminar, wave-like clouds were visible across a portion of the sky and moving quickly to the north. Farther south, the sky remained clear. These clouds were apparently forming in a region of orographic uplift generated by the Mogollon Rim.

Wave clouds over Flagstaff.
Wave clouds over Flagstaff.
Wave clouds over Flagstaff.
Wave clouds over Flagstaff.
Wave clouds over Flagstaff.
Wave clouds over Flagstaff.

But these clouds weren’t actually a surprise. Yesterdays models were forecasting a thin layer of moisture around 700 mb with much drier conditions both above and below that level.

Observed sounding from KFGZ at 1200 UTC 02 July 2020
Observed sounding from KFGZ at 1200 UTC 02 July 2020
24-hour forecast sounding for KFLG for 1200 UTC 02 July 2020
24-hour forecast sounding for KFLG for 1200 UTC 02 July 2020

The GFS did a good job of forecasting both the thin layer of moisture and the stronger winds embedded in that layer. But where did those stronger winds and moisture originate?

HYSPLIT backward trajectories.
HYSPLIT backward trajectories.

A look back using backward trajectories from the HYSPLIT model reveals some interesting origins. Higher-level air parcels originated over the northeast Pacific while low-level parcels originated over the eastern Pacific. The water vapor satellite images shows both of these source regions to be very dry.

Water vapor satellite image from 1200 UTC 29 June 2020.
Water vapor satellite image from 1200 UTC 29 June 2020.

The moist layer had its origins along the Mexico coast. The water vapor image shows substantial moisture associated with Tropical Depression FOUR-E.

Tropical depression FOUR-E.
Tropical depression FOUR-E.

So the shallow mid-level moist layer had its origins in the remnants of a tropical disturbance. Very interesting!