Bidding farewell to a fine comet

Fiber-optic star trails, fireflies, the ISS & NEOWISE. July 17, 2020. This photo is a 52-minute star trail made from 526 consecutive shots, each six seconds long, ISO 800, 15mm at f/2.8, Nikon D810. Photo by Alan Studt.

Comet C/2020 F3 (NEOWISE) was the finest comet to grace the skies of the Northern Hemisphere in quite some years. Amateur astronomers and photographers the world over made fascinating observations and beautiful images of the comet and its surprisingly long tail. By July 5, NASA’s Parker Solar Probe had captured an image of the comet, from which astronomers also estimated the diameter of the comet nucleus at approximately 5 km. or about three miles; that’s a reasonably large size but around average for a comet. The large nucleus offered plenty of volatile materials for the Sun to stir into tail formation.

On July 23 the comet reached perigee with Earth and is now speeding toward the outer Solar System, not to revisit the inner planetary neighborhood for several thousands of years. So, though relatively near Earth the object is fading fast. Lately astronomers and astrophotographers have been grabbing the last views they will have of C/2020 F3 before it fades to obscurity.

Here are some photos made by members of the Cuyahoga Astronomical Association (CAA) as a cometary farewell of sorts:

C/2020 F3 NEOWISE as viewed from Veteran’s Memorial Park in Avon Lake just before 11 p.m., July 24, 2020. Photo by Alan Studt.

Alan Studt’s lovely portrait of the comet shows its tails remain, if faded, long and expansive. He wrote, “Beautiful night by the lake last night. Took these at Veteran’s Memorial Park in Avon Lake just before 11 p.m. Pretty large group of people hanging out. The comet was definitely much dimmer than the previous Friday.”

Technical Information: Tamron 70-200mm f/2.8 lens, on a Nikon D850.
The comet image is made from 14 shots (2.5 seconds, ISO 10,000, at 200mm, f/2.8). Stacked in Deep Sky Stacker & post processed in Lightroom and Photoshop. Seventy-five shots but got the best star field alignment using only 14 shots. Also used dark & flat frames.
C/2020 F3 NEOWISE as viewed from Letha House Park in Medina County, Ohio, at 10:36 p.m. July 24, 2020. Photo by James Guilford.

James Guilford was at Letha House Park, July 24, attempting to record detailed images of the comet nucleus and close tail. The green coloration of the comet was a surprise to him, even after reading the observations of others. “All of my comet shots Friday night show a green nucleus,” Guilford said, “and it grew brighter as I processed the images later. I’d have liked to have picked up more of the tail but, given the circumstances, I’m pretty happy with what I got.” Both he and other Letha House Park observers could see a green tint by eye through telescopes. He and others also report the comet was barely within the range of eyesight but only at its highest above the horizon and only via averted vision.

Technical Information: Canon EOS 6D Mk. 2, at prime focus of 1800mm FL Cassegrain telescope, eight light exposures plus darks, ISO 1250, 15 seconds per exposure, stacked in Starry Sky Stacker, processed in Photoshop.

C/2020 F3 NEOWISE nearly lost amongst the stars. Photo by Jon Salontay.

Jon Salontay also photographed the comet that Friday. Above we see how it is nearly lost, even to the camera, amongst the stars. Technical Info.: Time – 11:32 p.m., Canon T5i with 18-75mm zoom lens at 18 mm, exposure 30 seconds at F/5.6, ISO 800. Brightness & Contrast adjusted.

C/2020 F3 NEOWISE via telescope. Photo by Jon Salontay.

Salontay then turned his telescope on the “dirty snowball.” Technical Info.: Time – 12:13 a.m., July 25. Celestron 8-inch SCT on Advanced VX Mount, Canon T5i, 15 seconds, ISO 1600. No out-of-camera adjustment.

He wrote, “Although I’ll try to follow it telescopically over the next month, how about another comet before the year is out? It’s a lot of fun.”