C/2022 E3 (ZTF)

Last March the folks at the Zwicky Transient Facility picked up an object using their wide field survey. It was soon determined that this was a comet heading inbound for a rendezvous with the Sun after a 50,000 year absence. The orbital calculations along with the comet's brightness led astronomers to predict that C/2022 E3 (ZTF) might become a naked-eye object soon after its perihelion on January 12th, peaking as it makes its closest approach to Earth on February 1st. Given it's the brightest comet to grace our skies since Neowise in the summer of 2020 I thought it was worth trying to observe it and possibly get an image or two last Friday.

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Jan 27, 2023 21:45 ET from Towson, MD
Clear skies, 35°F with light wind
Seeing 3/10 Transparency 9/10

First up is a quick scan of the area just a little NW of β Ursae Minoris (Kochab) using the 15x70 Oberwerk binoculars. At 2nd magnitude and a deep orange color it is easy to pick out Kochab from even my Bortle 8 skies to start the brief star hop. A little pan to the right and up and I can quickly see what appears to be a tiny, weak nebulosity. Working to hold the binoculars steady enough to get a good look I confirm that we have a comet that should be an easy target.

Rolling the 10" Cyrus Newtonian out I ditch getting 2-star alignment in favor of just using the finder scope to target the fuzzy visitor. It's readily visible in the spotting scope so it doesn't take long to sweep it up in the 40mm eyepiece. It's set in a nice star field and there is a star-like nucleus along with a diffuse, weak haze representing its coma. No real color can be discerned. Bumping up to the 25mm Plossl to darken the background a bit the coma is a little easier to see but in all honesty I cannot make out any shape to it that would let me guess as to the presence of a tail and its direction. It certainly seems to be at about 5th magnitude as predicted.

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To round out my ZTF session I grab my Canon camera and put the kit 70-300mm lens on. This time I try to avoid focus issues by targeting the almost 1st quarter moon and dialing it in to be as sharp as possible. At 200mm focal length I should get a reasonable size for the comet, and the rule of 500 suggests an exposure of 2½ seconds. But a quick test exposure shows unacceptable trailing at 2 seconds, so I drop it back to 1 second and begin firing off pictures, accumulating about 100 of them. From there I drop the focal length down to 70mm and run a series of 6 second exposures before calling it a night.

A few months ago Sky & Telescope ran a nice spread on nightscape photography. Among the tools that they mentioned was Sequator, a free program that I had not heard of before that stacks your images and can "freeze" the foreground. Sounded like a perfect tool to use for my ZTF images, so I downloaded and did a quick YouTube video to get me oriented to its use. I have to say it was much easier and faster than my standard go-to in this scenario (Deep Sky Stacker), although it could not keep my foreground tree from blurring, likely because of the breeze shifting its branches. But the resulting TIF yielded a very nice result after having some tweaking in Photoshop, especially given the minimal effort I put into the capture.

While the comet is outbound to the Kuiper belt deep freeze, we do have a couple of opportunities to get some interesting shots of it as it photo-bombs a few celestial luminaries as it leaves the stage:

Feb 6: The comet swings close by Capella

Feb 11: ZTF buzzes Mars

Feb 15: The green ghost will contrast nicely with nearby Aldebaran

While comet C/2022 E3 ZTF is likely to fall short of the media hype, it still is an interesting and readily accessible example of what most comets look like - star-like nucleus encased by a puffy, tenuous cloud.